Navitron Renewable Energy and Sustainability Forum

HEAT PUMPS & Geothermal Energy => Heat Pumps => Topic started by: nowty on July 28, 2018, 12:16:01 PM



Title: Water Source Heat Pump Project
Post by: nowty on July 28, 2018, 12:16:01 PM
A few years ago I fixed a major problem under my house which involved building a reinforced concrete box culvert to slightly divert an underground river. sh*tfan:
When fixing the problem I purposely created a catchpit to provide a pool of subterranean water,

(a)   So I could easily pump out and harvest the water.
(b)   To incorporate a heat exchanger for a heatpump as water temp ranges from a high of 14 degrees in summer to a min of 7 degrees in winter.

(a) was done some years ago with over 190,000 litres extracted do far, (averaged 500 litres per day this month for the garden) exhappy:
 but for (b), I could not find much technical data for a water sourced heat pump so its been on the back burner. fpig:

Now I have found some good technical info on the Kensa heatpump website. It seems that for a water sourced heat pump in moving water, there is a 3 litres per minute per kW rule. Although it has not rained here for over two months I have measured a flow rate of around 15 litres per min which suggests I could theoretically extract 5 kW or so. Given that in winter the flow is generally better, maybe 7 or 8 kW is possible. The Kensa website also says one submersible mat with 250m of 32mm HDPE pipe can provide 6kW.

Hmmmmmm, I don’t have the space for 250m of 32mm HDPE and the manhole access is only 600mm wide but what if I used copper ? wacko
Its thermal conductivity is 800 times more than HPDE but then 250 / 800 = 0.3m of HPDE obviously would not work as its insanely short. Therefore I think the much lower thermal conductivity of water needs to be taken into account. Then I found on the EngineeringToolbox website that the overall heat transfer for copper as a heat exchanger in still water is circa 400w / k m2.

Therefore assume a 5 degree temp difference and an 8kW extraction I would need a copper surface area of 8000 / (400 x 5) = 4 m2.

I can buy coils of 25m of 10mm copper microbore pipe, each of which are easy to lower down the manhole. Each one has a surface area of 0.79 m2. So I bought one and I found it fitted easily with enough room for 4 or 5 of them. So that’s a total copper surface area of 3 or 4 m2. Mmmmmmm, its now getting interesting. :crossed

Ground source heatpumps seem to be pricey bits if kit, but I found an 8kW discontinued and ex display one currently in a showroom on fleebay being sold by a heatpump company for around £1k. So took a punt and it arrives next week. tumble:

Heatpump Spec
(https://s5.postimg.cc/e8h34ex6v/Heat_Pump_Spec.jpg) (https://postimages.org/)

Bought the rest of the copper and I have been prototyping the heat exchanger on my lounge floor, much to the dismay of SWMBO. :fight


(https://s5.postimg.cc/lzxt2z91z/Heat_Exchange_Design.jpg) (https://postimages.org/)


Obviously more to follow ..................................................... chocpot:


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on July 28, 2018, 02:51:29 PM
This looks really good Nowty.  I remember following your subterranean adventures.  The copper coils look good.  Is the water clean(ish) or is the copper likely to be attacked by the water?

Keep us informed as you progress looks like a really interesting project.

Andy


Title: Re: Water Source Heat Pump Project
Post by: nowty on July 28, 2018, 03:13:29 PM
The copper coils look good.  Is the water clean(ish) or is the copper likely to be attacked by the water?

The water is clean but it gets very cloudy when stirred up because of a layer of very fine silt. This silt builds slowly builds up in the catchpit, but gets cleared out when we have a heavy rain shower.

I have had a copper pipe connected to a small submersible pump down their for 5 years now for the water harvesting, and apart from a layer of crud on it, its fine.

I have two concerns,

1) The extra friction of the pipes causing more turbulence which may result in a slower max flow rate if we have a deluge.

2) I found a few stones in the catchpit the size of a fist so they must come through with some force, so there is potential for damage to the soft copper.


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on July 28, 2018, 03:36:21 PM
Can you get some mesh in front of the incoming flow to catch any large debris?


Title: Re: Water Source Heat Pump Project
Post by: nowty on July 28, 2018, 05:58:03 PM
Can you get some mesh in front of the incoming flow to catch any large debris?

Maybe, I will think about getting some stainless steel mesh if I can find some suitable for the job.


Title: Re: Water Source Heat Pump Project
Post by: donegal on July 28, 2018, 08:10:35 PM
Looking good, i cant wait to see how this turns out. You've a lot to live up to after the last project :genuflect.

Good luck


Title: Re: Water Source Heat Pump Project
Post by: titan on July 28, 2018, 08:19:30 PM
I would think with the copper coils that tight the total surface area would be reduced considerably. Had you considered pumping the water out and through an external heat exchanger, it would mean you would not be size constrained and could have optimum flow rates.


Title: Re: Water Source Heat Pump Project
Post by: ecogeorge on July 28, 2018, 09:44:14 PM
Excuse me if i am missing something here but why are you building a collector (be it mdpe pipe or copper) ? why not just pump the water through your heatpump and return to waste ??
George.


Title: Re: Water Source Heat Pump Project
Post by: nowty on July 29, 2018, 12:00:18 AM
Excuse me if i am missing something here but why are you building a collector (be it mdpe pipe or copper) ? why not just pump the water through your heatpump and return to waste ??
George.

I did consider this as this as an option. i.e. do an an open loop design instead of a traditional closed loop collector. But everything I have read recommends against it unless the water is very clean and deep, even then there are issues.
I would need a large settling tank and more pumps and filtration, even then you can feck your heat pump heat exchanger very quickly with corrosion or blockages. Lots of maintenance.
An open loop design requires considerably more energy to pump out the water.
The water could freeze in the heat exchanger as there is no antifreeze.
If I returned the waste water to the river then licencing with the Environment Agency may be required.

I currently pump small quantities out for harvesting purposes and its not without its problems so attempting to do it on a larger scale and filter it etc, I just don't want to go there.

It would be best to have a direct heat exchange design where the refrigerant gas is circulated in a small pipe in the the water but thats unlikely to be a DIY project.


Title: Re: Water Source Heat Pump Project
Post by: nowty on July 29, 2018, 12:21:59 AM
I would think with the copper coils that tight the total surface area would be reduced considerably. Had you considered pumping the water out and through an external heat exchanger, it would mean you would not be size constrained and could have optimum flow rates.

You could be right about the surface area being reduced, I did originally consider coiling it like a slinky and fixing it to a couple of strips of aluminium, but its just the practicality of doing it, and getting it all down there down a narrow manhole. I am hoping it won't make a huge difference as the thermal conductivity of copper is so huge compared with the water.

If you think about it, imagine it was a solid block of copper with hollow water channels within the block for the water to circulate. I think the most relevant factor would be the surface area of the water channels rather than just the surface area of the copper block exterior.

With regards to simply pumping the water out, I think I have answered it to my reply to ecogeorge.


Title: Re: Water Source Heat Pump Project
Post by: titan on July 30, 2018, 03:17:47 PM

With regards to simply pumping the water out, I think I have answered it to my reply to ecogeorge.

Not quite, I was suggesting through a heat exchanger, closed loop for your HP, with anti freeze, open with no contamination for the cooling water. Also the effective cooling area for the copper coils is that which is in contact with the coolant, the coils will be much less effective in tight coils.


Title: Re: Water Source Heat Pump Project
Post by: knighty on July 31, 2018, 02:47:58 PM
I think they're coiled a bit tight too... not enough room to let water flow between the coils?

could you coul the copper in slinky fashion - but keep the coils tight torture

run a few of lengths of copper/aluminium/stainless/whatever bar the full length and cable tie the coils to it

coils sized to fit down the length of the drain... then post them down? - guess you might have to cable tie the coils down in the hole to let you slide theme

you could rap all 4 coils at the same time, or have one after another... I guess if you're running them in parallel coil them all at the same time, if you're running them in series run them one after another?  (and flow water through them in opposite direction to the water flow through the drain)

put them in the drain pipe flowing away from your box area, then you can add some kind of rock catcher to the box area?



Title: Re: Water Source Heat Pump Project
Post by: nowty on July 31, 2018, 07:42:17 PM
I think they're coiled a bit tight too... not enough room to let water flow between the coils?

could you coul the copper in slinky fashion - but keep the coils tight torture

run a few of lengths of copper/aluminium/stainless/whatever bar the full length and cable tie the coils to it

Thats exactly what I had intended to do but when I went down the hole with a single 10m coil to see how it would fit as a slinky I realised its not really possible. Its difficult to explain, but the access, the shape, the depth, the claustrophobic space, working in cold water, all conspire against you.

The compromise was to use 25m coils all individually dropped in and tied together, at different depths and offset against each other so the water flow runs in and around each coil. After 4 of them, I found I had enough space for a 5th so I added another. The water is now packed with copper and I could not add any more. They are all paralleled up to give a similar cross sectional area to the main 22mm flow and return pipes.

If the ground loop temp keeps dropping and evidently its not working then I will have to re-visit the design and try to loosen out the coils, but I am hoping its just over engineered enough not to have to.

(https://s5.postimg.cc/tpnmyqguf/Manhole_pipes.jpg) (https://postimages.org/)

(https://s5.postimg.cc/f6ghxbfzr/Heat_Exchanger_in_place.jpg) (https://postimages.org/)


Title: Re: Water Source Heat Pump Project
Post by: Nickel2 on July 31, 2018, 09:32:31 PM
Gravy-mine springs to mind...  whistle


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on August 01, 2018, 09:45:33 AM
I've sussed it.
It's a ruddy great still he's making.

Send us a jar nowty!!


Title: Re: Water Source Heat Pump Project
Post by: Pile-o-stone on August 01, 2018, 10:18:31 AM
This is fantastic! I loved reading your original thread where you fixed your water erosion issue and then added the benefit of water recycling. It was an amazing example of life giving you lemons and you making lemonade. Even better, you're now looking at sticking electrodes into the lemon and extracting energy. This is superb, and I'm really looking forward to reading your new thread as this idea develops.

EDIT: I just re-read your old thread as I'm considering a rainwater harvesting project myself. It's still a great read but all of the photos have gone, which is a shame.


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 01, 2018, 09:59:38 PM
I just re-read your old thread as I'm considering a rainwater harvesting project myself. It's still a great read but all of the photos have gone, which is a shame.

Yes its the photo hosting site which changed its domain and all old photo links need to be edited for them to work. If I find some time I will re-edit them on that thread as some of the photos are classic. sh*tfan:

Todays job was finishing the plumbing of the ground loop at the heat pump end which included, full bore isolation valves, expansion vessel, air bleed valve and filling point with pressure gauge. I then air pressure tested the ground loop by using a pressure sprayer. :ballspin

Unfortunately it leaked badly. facepalm

Using leak detection spray (soapy liquid) I quickly found 4 compression joints which were pretty bad. Copious amounts of sealant compound and PTFE tape later and its sorted. :crossed

Pumped the air pressure up to 2 bar and its holding, I will check again in the morning. exhappy:

Also (very slowly) building a wall to hide it all.  :onpatrol

(https://s5.postimg.cc/d8so1wilz/Ground_Loop_End.jpg) (https://postimages.org/)


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 14, 2018, 10:40:58 PM
I now have the heatpump, there is not much to them, a compressor, a couple of heat exchanges, hhhmmmm no water pumps, I knew I should have asked. facepalm

(https://s5.postimg.cc/6sxj4rtc7/Heat_Pump.jpg) (https://postimages.org/)


So purchased two Lowara Ecocirc pumps for the ground and hot water loops. They are a new shaftless motor design and only use 40w for 6m of head and a max 3000 litres per hour, that should do it. :crossed

Then I did some calculations on the ground loop (wrong way round I know) and realised that I need around a 9m head pump to get the design flow of 1,500 litres per hour. Problem is that 6m pumps are cheap as chips but more powerful pumps are circa 4 or more times the price. wackoold

(https://s5.postimg.cc/py0sejfpz/Ground_Loop_Flow_Test.jpg) (https://postimages.org/)


Anyway I tested it with the Lowara pump and I measured a flow rate of 750 litres per hour. I was about to bite the bullet and purchase a more powerful pump but as I had two of the pumps I tried both in series and the flow rate improved to 1,100 litres per hour, we are getting there. Then I decided to add a 6th copper coil (which just about fitted) to the ground loop to reduce the pumping resistance. :ballspin

We then had a huge prolonged thunderstorm of biblical proportions and the river level rose half way up the manhole. I keep forgetting just how powerful flood water is and I started to wonder if all my tons of reinforced concrete and pre-stressed lintels would survive such punishment, let alone my copper heat exchanger. sh*tfan:

(https://s5.postimg.cc/uwoat243b/Storm_Flow.jpg) (https://postimages.org/)


Not only did it survive completely undamaged, the storm washed away all the silt and we are left with crystal clean water. exhappy:

(https://s5.postimg.cc/xqrg6hyjr/Manhole_Pipes_3.jpg) (https://postimages.org/)


Ordered another pump for the hot water loop but it arrived with a fault, so has had to go back. sh*tfan:

So I am now awaiting another before the big switch on test can commence. :crossed


Title: Re: Water Source Heat Pump Project
Post by: todthedog on August 15, 2018, 01:09:55 PM
Cracking Nowty enjoying this thread. :genuflect


Title: Re: Water Source Heat Pump Project
Post by: regen on August 18, 2018, 07:25:24 AM
super project-watching for the outcome.

Regen


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 18, 2018, 03:07:32 PM
Replacement pump arrived. help:

Will it work ? fpig:, will it even switch on ? banghead:, or go up in a puff of smoke ? sh*tfan:, what will SWMBO say if I have spent a grand on some scrap stainless steel ? :fight

Connected the final pump and for test purposes, the hot water loop is a builders bucket with 35 litres of water in it so it acts as a thermal store. Its raining so the river flow is more than average and the river temp is also higher than normal at 17 degrees. So conditions are about as favourable as they could be. :crossed


(https://s5.postimg.cc/5ot74c3zb/Heat_Pump_Test.jpg) (https://postimages.org/)


Switched on the unit, it makes a strange noise then falls silent. ???

Then the ground loop pump starts up, followed a minute later by the hot water loop pump. Soon after the compressor starts up and is reasonably quiet. I had screwed the unit down to a wooden plinth and added rubber feet just in case of excessive vibration, but I needn’t have bothered. Almost instantly the gauges on the exterior of the unit move in opposite directions and the hot water output feels slightly warm, with the ground loop getting colder with condensation forming on the ground loop pipes. :o


Wow, it actually works, and 17 mins later ……………………………………………..….. exhappy:


(https://s5.postimg.cc/nrm9vj4yv/Heat_Pump_Gauges.jpg) (https://postimages.org/)


(https://s5.postimg.cc/dhjuwamt3/Water_Temp.jpg) (https://postimages.org/)



A constant increase of 2 degrees per minute in the 35 litre builders bucket, from 18 degrees all the way up to 58 degrees in 17 mins when the high temperature tripped out the compressor. I have calculated that equates to a constant 5.7kW of heat output. The electricity consumption gradually increases in line with the compressor pressure, thus reducing the COP value. The ground loop rapidly drops in temperature for the first 5 minutes, then becomes constant. On the first run it stabilised at 10 degrees out and 14 degrees return.



(https://s5.postimg.cc/qn3yfsitj/Test_Run_1.jpg) (https://postimages.org/)



I have since re-ran the test each day, each time with differing pump flow rates and with different river conditions. From this I draw a number of conclusions.

1)   With a slower river flow the ground loop stabilises at a lower temp, first run was out 10 degrees and return 14 degrees (10 / 14). Subsequent runs with less river flow were 5 / 9 and 3 / 7. But the outcome was the same, no measurable difference in heat output or electricity consumption. I have read somewhere that the ground loop needs to go considerably below zero to make a difference.

2)   I slowed down the ground loop pumps and although the temperature difference between flow and return widened from 4 to 5 degrees, there was little measurable difference in heat output or electricity consumption.

3)   I slowed down the hot water loop pump and although the temperature difference between flow and return widened from 4 to 5 degrees, there was little measurable difference in heat output or electricity consumption. In fact the heat pump manual says for efficiency, the temp difference should be less that 6 degrees for optimum operation.

4)   The headline spec of 8kW seems to be a fair bit of an exaggeration. whistle

5)   The COP figures compare favourably with the findings of the Energy Savings Trust heat pump trials which published real life COP values.

6)   My crazy copper heat exchanger design seems to work as the ground loop temp is stabilising at above zero temperatures. :ballspin


Now I just have to work out what I am going to use it for. wackoold


Title: Re: Water Source Heat Pump Project
Post by: regen on August 18, 2018, 04:09:36 PM
Did not have to wait very long-what a great result.

A steady 5.7 kw of heat and a COP of 3.0 at 40 deg C- thats more than enough to heat my whole house even in a bad winter!

Wondering if you know the actual flow rates from the stream as i am more than a bit interested in this having failed with the hydro turbine route due to the complexity of the paper work/permissions. i have up to 100 lps available at the back door and a UFHS already installed which runs off a thermal store so this could be the way to go.

Regen


Title: Re: Water Source Heat Pump Project
Post by: djs63 on August 18, 2018, 05:38:21 PM
Nowty, I love it. Sadly I live on top of a gentle hill but my neighbour has a stream running past, it is about 4 metres wide with a good flow and the house used to be a Mill long ago, so they could copy your system.....


Title: Re: Water Source Heat Pump Project
Post by: Fintray on August 18, 2018, 07:14:01 PM
Brilliant and well done getting it all working.  :genuflect


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on August 18, 2018, 08:57:27 PM
Brilliant work Nowty, I wish I had a stream near by to tap in to.  Converting a potential problem inbto an ergy source is top dollar, hats off to you.

Andy


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 18, 2018, 10:21:05 PM
Wondering if you know the actual flow rates from the stream as i am more than a bit interested in this having failed with the hydro turbine route due to the complexity of the paper work/permissions. i have up to 100 lps available at the back door and a UFHS already installed which runs off a thermal store so this could be the way to go.

According to the Kensa Heap pump website, the rule of thumb with flowing water is 3 litres per minute for every 1kW of heat output. I originally measured the flow at around 30 litres per minute after it had not rained for over two months, therefore thought 5kW or so was possible. I measured it by jamming a two litre plastic measuring jug into the flow on the outlet pipe for 1 second and it filled it one quarter of the way, therefore half litre per second. wacko

100 lps is a potential 2 MW !, house is gonna be toasty. :hysteria


Title: Re: Water Source Heat Pump Project
Post by: todthedog on August 19, 2018, 06:08:12 AM
I wish that there was a hat doffing icon. :genuflect :genuflect

Brilliant work Nowty .

A genuine pleasure to read.


Title: Re: Water Source Heat Pump Project
Post by: regen on August 19, 2018, 08:02:31 AM
Wondering if you know the actual flow rates from the stream as i am more than a bit interested in this having failed with the hydro turbine route due to the complexity of the paper work/permissions. i have up to 100 lps available at the back door and a UFHS already installed which runs off a thermal store so this could be the way to go.

According to the Kensa Heap pump website, the rule of thumb with flowing water is 3 litres per minute for every 1kW of heat output. I originally measured the flow at around 30 litres per minute after it had not rained for over two months, therefore thought 5kW or so was possible. I measured it by jamming a two litre plastic measuring jug into the flow on the outlet pipe for 1 second and it filled it one quarter of the way, therefore half litre per second. wacko

100 lps is a potential 2 MW !, house is gonna be toasty. :hysteria

Thanks for the info Nowty. I only need 3kwh per hour as the house is very well insulated. The main point from your installation was your ability to use the copper pipe thus reducing the size of the collection area very significantly vs the poly pipe method. Being on a very sloping site flat ground adjacent to house is at a premium so being able to construct a small pit with an inflow and outflow is what will make this feasible for me.

Regen


Title: Re: Water Source Heat Pump Project
Post by: biff on August 19, 2018, 11:56:31 AM
Brilliant stuff Nowty,
                        I would love to do something similar,,just like Andy said,
                                              Biff


Title: Re: Water Source Heat Pump Project
Post by: Westie on August 19, 2018, 02:01:05 PM
Great work as usual Nowty, you never cease to amaze :)

 I just wondered, given the scale of the flow you seem to have available, whether you considered using a simple open loop ie. sucked in via a filter upstream and discharged downstream?





Title: Re: Water Source Heat Pump Project
Post by: Mostie on August 19, 2018, 03:17:17 PM
well done..... and dont forget the glycol Nowty


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 19, 2018, 09:49:32 PM
well done..... and dont forget the glycol Nowty

The ground loop has 20% of food grade glycol which is recommended for use in environmental sensitive places like rivers.


Title: Re: Water Source Heat Pump Project
Post by: nowty on August 19, 2018, 09:56:45 PM
Great work as usual Nowty, you never cease to amaze :)

I just wondered, given the scale of the flow you seem to have available, whether you considered using a simple open loop ie. sucked in via a filter upstream and discharged downstream?

Read back through page 1 of this thread, I answered a similar query.


Title: Re: Water Source Heat Pump Project
Post by: Westie on August 20, 2018, 08:05:57 AM
Great work as usual Nowty, you never cease to amaze :)

I just wondered, given the scale of the flow you seem to have available, whether you considered using a simple open loop ie. sucked in via a filter upstream and discharged downstream?

Read back through page 1 of this thread, I answered a similar query.

AH... sorry, I missed that.  I see your point, in fact the only example I've had  read of that had used open loop was drawn from ground water source which is probably a cleaner source than a river...


Title: Re: Water Source Heat Pump Project
Post by: nowty on September 12, 2018, 09:42:05 PM
Not much progress as I have been away for a couple of weeks, but decided as it seems to work ok, I would invest a little more money to heat my hot water with it. I already have free hot water in Summer with my Immersun diverters but don't get very much in Spring / Autumn. Also my current 200 litre tank is not large enough some days. A larger tank heated by heatpump running off PV + batteries, should be better for us, more hot water for less eleccy.

Picked up a surplus 300 litre indirect hot water cylinder with a very large internal coil specifically for heat pumps. 28m of 22mm corrugated stainless pipe rated at 57kW. Most standard cylinders of that size seem only to be rated at half that.

So hopefully I wont need to use a buffer tank to prevent excessive compressor cycling.

Also getting an Economy 7 meter fitted for use in winter.


(https://s5.postimg.cc/xstyu5fav/Heat_Pump_Cylinder.jpg) (https://postimages.org/)


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 03, 2018, 12:18:20 AM
Progress update, spent two weeks building a couple of walls, very tiresome work, sometimes I wish I never start these jobs. sh*tfan:

But now making good progress, tomorrow I decommission the old hot water cylinder and drain the heating system so I will have no hot water or heating till its done.  :winter

Also having a nightmare with elecy company trying to get an Economy 7 meter fitted. First it was no problem and the meter install appointment is booked. Then wait 3 weeks and they don't turn up or even say why. Then spend two days on the phone with various customer service bods telling me they had no resources, then I was on the wrong tariff, oh there is a technical problem, we will email you by the end of the day, etc, etc. Nothing happens. banghead:

Finally spoke to someone today who seemed to know what he was doing and spent quite some time getting the appointment re-booked. It kept failing on the system for different reasons but he persevered and kept me on the line until it was done. Promising but I'll believe it when I see it.


(https://i.postimg.cc/tgPt2Jh0/Installation_01.jpg) (https://postimages.org/)


Title: Re: Water Source Heat Pump Project
Post by: Fionn on October 03, 2018, 08:20:30 AM
Looks great nowty, are you using the same heat pump to drive the heating system and the new DHW tank?


Title: Re: Water Source Heat Pump Project
Post by: Pile-o-stone on October 03, 2018, 09:14:16 AM
This project is fantastic. I was just wondering though about the amount of heat loss due to the cylinder and heat pump being located outside? We have a 300l heatbank located in our utility room. The cylinder has 50mm of PUR type insulation built in and I built a similar frame around it as you're doing around yours, with 50mm celotex in the frame and 100mm celotex above. We still have heavy heat loss from the tank, and although the heat in within our home, I'd rather the heat be retained in the tank and used where I need it, rather than it heating a utility room that we don;t go into that often.

To try and remedy the heat loss, I'm looking at fitting another 50mm of celotex within the frame and wrapping the tank with a aerogel blanket (I'm sure I've seen a foil backed version that would look pretty good around the tank).

Do you have any plans to further insulate the tank and cupboard?


Title: Re: Water Source Heat Pump Project
Post by: biff on October 03, 2018, 09:45:51 AM
     Brilliant project Nowty, :genuflect
                            Biff
           
             


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 03, 2018, 09:55:27 AM
Looks great nowty, are you using the same heat pump to drive the heating system and the new DHW tank?


Yep, bottom left of the last pic you will see two zone valves. One for hot water and one for heating, each can be turned on with a wifi socket from my phone, can also be timed or have a countdown timer.


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 03, 2018, 10:08:02 AM
Do you have any plans to further insulate the tank and cupboard?

Yes I know I am taking a bit of a risk with heat loss having this outside, but I intend to insulate, insulate and insulate it all. Main reason was to get it as close to the heatpump as possible and it frees up space in my kitchen where the existing water tank is.

I am making some of this up as I go along, first was to build two brick walls front and back to hide it all, then decided to celotex the walls, then box the tank in, then lag the pipes, then ……………………………………….., depends on where all the pipes end up as the pipes can only go where they can.


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on October 03, 2018, 10:56:06 AM
Top job nowty.

I'd have thought, given that you would appear to have unlimited raw energy to tap into, that your heat losses are less of a concern. Once the system is hot and your house is warm your only going to be "topping up" the tank.

Keep up the good work.

Andy


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 10, 2018, 12:16:31 AM
More progress,

Temporarily removed my gas combi to get at the pipework to connect the heatpump to the heating system and to transfer the pre heated water from the old tank to the new one. bike:

I knew it was going to be difficult, and it was, the heating flow and return connections took me two days to connect due to some very difficult bends in awkward places under my floor. facepalm

(https://i.postimg.cc/SQZCJNs7/Pipework_Under_Gas_Boiler.jpg) (https://postimages.org/)


Combi gas boiler now back in and filled the new tank up with water, no leaks. Water is once again coming out of my taps. :ballspin

(https://i.postimg.cc/brFtMLMF/Water_Tank.jpg) (https://postimages.org/)

I still have a few modifications to do on the heating system so I cannot yet fill the heat pump heating circuit. But I connected my immersuns up to the tank immersions and as it was really sunny today dumped 10kWh into the tank so we had plenty of free running hot water.


Nearly there now. :crossed

Just noticed that my prospective Leccy supplier Utilita has increased their E7 night rate from 5.2p to 9.2p. sh*tfan:
Well that's busted my business plan. :'(

Now going to have to be Ebico at 7.7p with zero standing charge.


Title: Re: Water Source Heat Pump Project
Post by: linesrg on October 10, 2018, 07:37:59 AM
Mike,

I really do envy your situation and skills to be able to install this yourself. I could possibly manage but...............

My main point in posting relates to the inevitable narrowing of E7 prices as time goes on. It doesn't take a genius to work out that as more use is made of cheap E7 rate electricity the cost will go up thus reducing the level of savings we all carefully calculate in advance as part of the argument for making the changes we do.

Regards

Richard


Title: Re: Water Source Heat Pump Project
Post by: Nickel2 on October 10, 2018, 08:04:48 AM
Nice job!!   :genuflect
I like the use of coloured cable ties for identifying the flows, I'm going to replace all the bits of scribbled-on tape now. :)


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 10, 2018, 11:10:26 AM
Nice job!!   :genuflect
I like the use of coloured cable ties for identifying the flows, I'm going to replace all the bits of scribbled-on tape now. :)

Ah yes I should have provided a key, :hysteria

Red = Hot Water
Blue = Cold Water
Yellow = Heating Flow
Green = Heating Return
Red/Blue = Pre heated water from unvented tank as it could be hot or cold.


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 10, 2018, 11:18:02 AM
My main point in posting relates to the inevitable narrowing of E7 prices as time goes on. It doesn't take a genius to work out that as more use is made of cheap E7 rate electricity the cost will go up thus reducing the level of savings we all carefully calculate in advance as part of the argument for making the changes we do.

Yes, in the past E7 night rate used to be less than half price but now it is normally more than half price and usually with high standing charges.

I suspect that in future with more Solar in day, expensive Nuclear plants come on stream, more overnight use for domestic batteries and EVs it might narrow even more. But I think we will inevitably be in a situation where peak early evening costs will be prohibitably higher making domestic batteries possibly viable for the masses even if you don't have any PV.


Title: Re: Water Source Heat Pump Project
Post by: nowty on October 19, 2018, 06:13:01 PM
Project Update


I have yet to wire up the thermostats, etc, but I tested the heat pump today with all the plumbing complete and solely powered by PV with the autumn sunshine on both my new hot water tank and my central heating.

(https://i.postimg.cc/NMrR2PSm/Solar-heat-pump.jpg) (https://postimages.org/)


Works fine, ran it constantly for 3 hours, first heated 300 litre tank to about 50 degrees in around two hours and then I ran it on the heating circuit and house was very toasty. All radiators heated up to 35 degrees in little time.

(https://i.postimg.cc/4ykV6QRM/Radiator-temp.jpg) (https://postimages.org/)


Ground loop stayed several degrees above zero throughout and difference in flow and return temps for both ground and heating loops was 4 degrees.
So ground loop is big enough, water pump size is ok and I definitely do not need a buffer tank. Very happy. ralph:


Title: Re: Water Source Heat Pump Project
Post by: biff on October 19, 2018, 06:59:57 PM
Well done Nowty,
            This is a great help to the members like me who are considering like minded projects.
                                                Biff


Title: Re: Water Source Heat Pump Project
Post by: Nickel2 on October 19, 2018, 08:21:29 PM
Great Admiration! When life gives you lemons, forget lemonade, hold a cocktail party. I'd love to be in your position, but without the pre-courser stress of using your house foundations as a surfboard on the River Styx.
My your sun shine bright and your river flow clear for ever! :genuflect


Title: Re: Water Source Heat Pump Project
Post by: todthedog on October 20, 2018, 06:44:45 AM
A fantastically​ interesting thread.
An example on how to turn a potential disaster into a long term benefit.
As well as having us on the edge of our seats along the way. :genuflect :genuflect :genuflect


Title: Re: Water Source Heat Pump Project
Post by: offthegridandy on October 20, 2018, 06:41:40 PM
Thanks for sharing all  this and brilliant result.


Title: Re: Water Source Heat Pump Project
Post by: desperate on October 20, 2018, 07:11:45 PM
A fantastically​ interesting thread.
An example on how to turn a potential disaster into a long term benefit.
As well as having us on the edge of our seats along the way. :genuflect :genuflect :genuflect

Same as that, had me bricking it when you were underground, but  :genuflect  ....nuff said :)

Desp


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 12, 2018, 05:08:04 PM
Project Update

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree or so after 12 hours even if its cold outside. :winter

(https://i.postimg.cc/MHRXZ6MS/Insulation-Water-Tank.jpg) (https://postimages.org/)


Hot water and heating can now be operated with WiFi sockets via my smartphone. bike:
WiFi socket turns on a zone valve which turns on the heatpump if thermostats request demand for heat.
So can use timers and countdown timers with ease.

(https://i.postimg.cc/qB9CPYhr/Zone-valve-pumps.jpg) (https://postimages.org/)


As there is not enough PV leccy at this time of year I have been using it daily for 4 hours overnight on economy 7 for over a month now. It keeps house warm for the morning and we get a full tank of hot water. The gas boiler takes over the heating at 7:30am but because the house is already warm, it only comes on very low which seems to run more efficiently as gas consumption is significantly down, more so than I expected.

I will report back after I have a year of data to show how much total energy import has been saved.


Title: Re: Water Source Heat Pump Project
Post by: marshman on December 12, 2018, 08:03:40 PM

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree of so after 12 hours even if its cold outside. :winter



Interesting. My tank drops about 2-3 deg per 24 hours (and that is indoors!). It is a 300 ltr Joule. Don't think it is losing it through the pipes so I was considering adding more insulation around it. How much "extra" insulation have you put round yours?

Nice install by the way!

Roger


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 12, 2018, 10:10:26 PM

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree of so after 12 hours even if its cold outside. :winter



Interesting. My tank drops about 2-3 deg per 24 hours (and that is indoors!). It is a 300 ltr Joule. Don't think it is losing it through the pipes so I was considering adding more insulation around it.

How much "extra" insulation have you put round yours?

The tank is pre-insulated with 5cm of foam.

Then its boxed in on three sides and top by 5cm of celotex foam board. Corners of the box are filled with a hot water jacket panel. And several more jacket panels wrapped around the open side. With remaining gaps filled with some other bits of insulation.

If you place your hand between the jacket panels and the tank it feels warm as toast. Where as with only the tank insulation, the external parts of the tank would normally feel cold. So the extra insulation is certainly helping.


Title: Re: Water Source Heat Pump Project
Post by: marshman on December 13, 2018, 07:40:53 AM
Thanks for that info. I'm going to have a go at mine. Its a bit hard to get much down the back and on one side as it is close to the wall, but I'll pack in as much as I can and see what difference it makes. To be honest I am not overly impressed with the new tank in terms of heat loss. The old tank (copper with sprayed on foam - 30 years old) seemed to lose less heat - often stayed hot for 3 days, never seem to manage more than 2 with this tank. Pipe work is the same.

Roger


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 17, 2018, 05:29:59 PM
Quick update.

Everything has been working well but I have found one problem.

A few days ago I noticed that the ground loop was getting colder, a lot colder, dropping from above zero a couple of weeks ago, down to minus 8 or so but it was still working fine. :crossed

A day or so later the heatpump cut out a few times with low ground loop temp error and it was getting down to around minus 12 which is near the limit of my anti freeze solution. freeeze

I thought it might be game over until the river water temp rises again, its currently at about +8 degrees and wont rise again till around March. facepalm

I checked the river heat exchanger, expecting to see a block of ice but it was actually caked in silt so it was just insulating the copper from the water. :o

I knew the forecast for the following day was heavy rain so I just left it and it all cleared away by itself, all working again with return ground loop at +7 degrees. exhappy:

So should work all winter but I will need to occasionally pressure wash the silt off if it does not rain for a while. Its a bit of a pain as I hoped it would all be maintenance free but at least there is no fundamental problem with it.


Title: Re: Water Source Heat Pump Project
Post by: knighty on December 18, 2018, 05:45:55 PM
could you block/restrict the flow a little around the coils?

that way the water will flow into a smaller space and speed up... (same litres through smaller space) - the extra turbulence should.might/could clear the coils?


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 18, 2018, 06:52:00 PM
could you block/restrict the flow a little around the coils?

that way the water will flow into a smaller space and speed up... (same litres through smaller space) - the extra turbulence should.might/could clear the coils?


Not really.

I am going to install a remote temp sensor so I can keep an eye on the ground loop temp so I can easily see when its starting to drop too much. Its not something that happens quickly, only slowly over few weeks of little rain.


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 31, 2018, 02:49:39 PM
Another update.

The heatpump shut down again last night due to cold ground loop temp. sh*tfan:
Again the pipes were silted up and the flow temp was around minus 10 giving a layer of ice on the flow pipe. freeeze
First time I have seen that. :o

(https://i.postimg.cc/MTM8xx0j/Frozen-Pipe.jpg) (https://postimages.org/)

(https://i.postimg.cc/HLPCfjMg/Pressure-Washing-Before.jpg) (https://postimages.org/)

A quick pressure wash and now it runs above zero once again. :crossed
I also checked the river temp and its 11 degrees.

(https://i.postimg.cc/SKKhTcJd/Pressure-Washing-After.jpg) (https://postimages.org/)


Title: Re: Water Source Heat Pump Project
Post by: Countrypaul on December 31, 2018, 03:27:29 PM
Is it purely silt sticking to the pipes, or is there ice forming on them and holding onto the silt?  Either way you may want to consider putting some sort of alarm/warning somewhere obvious to you, which could be as simple as a a thermostatic switch illuminating a light when the pipe temperature gots close to zero giving you a little time to plan your clean up, rather than finding out after you've had 6 pints (not that you ever would of course  ;D ).


Title: Re: Water Source Heat Pump Project
Post by: nowty on December 31, 2018, 08:58:27 PM
Is it purely silt sticking to the pipes, or is there ice forming on them and holding onto the silt?  Either way you may want to consider putting some sort of alarm/warning somewhere obvious to you, which could be as simple as a a thermostatic switch illuminating a light when the pipe temperature gots close to zero giving you a little time to plan your clean up, rather than finding out after you've had 6 pints (not that you ever would of course  ;D ).

To be honest I don't know as it was 4:00am and I had just got up to relieve myself and I noticed I could not hear the flow pumps running. I did not look down the hole till the next day as I was half asleep and didn't want to fall down it in the middle of the night. It restarted and was ok for the rest of the night apart from the frosted flow pipe. freeeze

If it trips out its in the first few minutes of coming on when the COP level is at the highest and the temperature of the ground loop drops right off rapidly. Once the radiators are up to 30+ degrees the efficiency drops a bit and the ground loop temp always rises a bit so its then ok for the rest of the operating run.

Its only the second time its happened and its about two weeks since so a few seconds of pressure washing once a week should stop it happening in future. I have not got round to installing the remote temp sensor but the priority has obviosly increased so I will try and do it this week. There is an inbuilt temp sensor but its a pain to scroll through the remote control panel. facepalm


Title: Re: Water Source Heat Pump Project
Post by: knighty on December 31, 2018, 09:42:44 PM
do the pipes silt up and then clear themselves once there's a good bit of rain?

I think if you could put something big/heavy in the middle of the coil to make the water more turbulent around it, it might solve the problem for you.... the problem is getting something big/heavy down the hole and into the coil :-o


maybe stick a bit of plastic pipe in the hole and see if it silts up in the same way?

you'd need a much longer length but then you could use plastic... not having to de-silt the coils might be a big bonus once you get old?


Title: Re: Water Source Heat Pump Project
Post by: nowty on January 01, 2019, 12:46:57 AM
Yes all the silt clears out once we have a good rain shower.

There is nothing that can be done to increase the flow or turbulence, the flow is just so weak unless it rains.


Title: Re: Water Source Heat Pump Project
Post by: Nickel2 on January 01, 2019, 07:49:22 AM
Would it help to slip in lengths of plastic electrical conduit between the turns of the coils to help flow through them? As they are at the moment, tied in bundles, there will tend to be nulls/stagnant areas where water doesn't flow fast enough, so silt would be prone to collection.


Title: Re: Water Source Heat Pump Project
Post by: nowty on January 01, 2019, 04:37:29 PM
Maybe but its difficult to retrofit it now. I did think about doing this when I originally fitted it but, the coils are difficult to pull apart and I would have ended up with taller coils and less coils would have fitted under the water. I was also concerned that gravel might get trapped in the gaps and be difficult to shift. In hindsight I might have been better using 10m long coils instead of 25m long ones, then I could have fitted more of them which would have achieved a similar result.

Anyway it worked ok again last night with flow around zero degrees and return about +4 degrees so at least I know the pressure washing worked.

Its going to be vey sunny for the next couple of days so I might run it in the daytime and take some temperature measurements of the river water after its been ran for an hour. The river water was around 16 degrees back in Sept and now its 11 degrees but I have never measured it after the heatpump has been run for a while. I did some back of fag packet calculations a while ago and reckoned that the heatpump would drop the ambient river temp by about 5 degrees so it will be interesting to find out for real.




Title: Re: Water Source Heat Pump Project
Post by: Westie on January 01, 2019, 05:40:34 PM
Would it be possible to create a weir just upstream of the coils so the water would be turbulent?


Title: Re: Water Source Heat Pump Project
Post by: nowty on April 15, 2019, 01:11:05 PM
Project Update,

Over winter the GSHP has been running overnight on E7 but now we are running overnight on batteries (charged previously with solar) and during daytime on solar, backed up by batteries. I only expected that this would happen on the odd few really sunny days, but the high efficiency of the heat pump and my recent Sunny Island Upgrade and large battery integration has made this possible. So I reckon from April to Sept I will be importing hardly any gas. I have forecasted that this has dropped my annual gas import from 23,000kWh down to 13,000kWh, with an annual increase of imported elecy from 700kWh to 2,900kWh.

So overall, annual imported energy is down 7,800 kWh and the house is more comfortable as I am not letting the temp drop much overnight. I could decrease the gas even further with more imported elecy but that would be at an extra cost.

I have also found that if its not been raining for a week or so, all I need to do is simply spray the heat exchanger for a few seconds with a hose pipe from above every few days to keep the insulating silt level down. I dont need to go down the hole, only need to drag the man hole cover back a few inches and point the hosepipe down there.


Edit - Just to add that although imported energy is down 7,800kWh so big reduction in carbon footprint, the pounds cost is almost the same as even E7 rates are 3 times my gas rate so no cost savings at all. Maybe that means that gas is too cheap.


Title: Re: Water Source Heat Pump Project
Post by: Nickel2 on April 15, 2019, 02:23:36 PM
...Or maybe fit a spray-bar running from an electric pump, automated to operate every time the temperature differential gets out of range?


Title: Re: Water Source Heat Pump Project
Post by: nowty on June 13, 2019, 05:10:18 PM
Project Update,

The system has been running on solar PV and / or batteries for several months now, no imported elecy or gas required at nowty towers at all. exhappy:

But I ran into a problem a couple of weeks ago.

I noticed the ground loop was running very cold of late, like the middle of winter, below zero at times even though the river water temperature is now around 15 degrees.
Then the other day it kept shutting down due to cold ground loop, even after I had given the river heat exchanger a good rinse off. help:

Anyway, I soon found the fault, both my ground loop water pumps had failed. I guess one had failed some time ago and I had not noticed. sh*tfan:

Luckily I had bought a couple of spares so was back in operation in no time. My external fitting of the pumps meant a very easy swap over. :crossed

I think they have failed due to condensation. The pumps are installed upside down and lots of condensed water dripped down into the bit which houses the electrics. I then read the pump manual and it says you cannot pump fluids at a lower temp than ambient because of condensation issues. Hmmmmm, maybe I should read the instructions properly first. facepalm

I have now wrapped the pumps in insulation so they stay cold and this seems to have stopped the condensation so hopefully they will be ok. whistle
If not I will have to change them for another type.