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Author Topic: ASHP best setup for efficiency  (Read 1661 times)
brackwell
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« Reply #45 on: January 10, 2021, 04:34:26 PM »

Pleased to hear you are making progress perhaps one day you can do a summary of your achievements. Cheers for now.
Ken
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chris wills
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« Reply #46 on: January 10, 2021, 04:37:21 PM »

Pleased to hear you are making progress perhaps one day you can do a summary of your achievements. Cheers for now.
Ken

Thanks Ken, is it wise to say that dropping UFH stats and reducing ASHP will save money?
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chris wills
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« Reply #47 on: January 10, 2021, 08:15:14 PM »

Just one more thought. I have no mixer valve on my manifold so if I did add one and then turned the ashp up to 50, with the manifold set at 40 for example, then the rads could benefit from having much hotter water and the the ufh be good too?
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Countrypaul
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« Reply #48 on: January 10, 2021, 11:12:43 PM »

Just one more thought. I have no mixer valve on my manifold so if I did add one and then turned the ashp up to 50, with the manifold set at 40 for example, then the rads could benefit from having much hotter water and the the ufh be good too?

I would definitely think so - I have our thermal store set to 40C and the TMV on the UFH normally set to around 25C for the ground floor, but to 35C for the first floor bathrooms (fitting from below spreader plates to a 18 chipboard deck with tceramic tiles). The round floor has a 12 way manifold controllled by 6 thermostats via a wiring centre, the first floor is on a simple timer.

Depending on outside temperature etc. most of the ground floor loops will switch off around 08:00 and remain off during the day (except the kids playroom!). As soon as the last loop switches off so does the pump. The Thermal Store will normally request heat at 25C and cease at 40C. As mentioned earlier I set the thermstats up slightly overnight (E7 period) and back to normal when E7 finishes.

If you set the ASHP up to 50C and the manifold down to 40C that will be much less efficient than running both at 40C - assuming you are not on E7. You will have to balance that against the benefit you get from the rads beg at 50C rather than 40 for a longer period.
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ceisra
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« Reply #49 on: January 11, 2021, 09:50:05 AM »

Chris
Some of this may relate to your other post.

Apart from getting outside to clear 3inch of frozen snow away extrahappy

I have been reading as much info as I can find on your system.
Some of this is to confirm details
You say that there are 5 downstairs room thermostats. 1 for each under floor area
Are there room stats up stairs and if what regulates/controls the flow
The 5 solenoid valves on the manifold is it possible to check if they are 240volt or 24volt ( check for a label  )

Your flow meter glass tubes could etched ( like glasses go in a dish washer ) or just scale build up
You could try 2 things
put them over the upright pegs of the dishwasher if you have one ( with something over the top to stop them moving )

Or I am a big fan of https://www.dri-pak.co.uk/ and use soda crystals or citric acid to remove staining

Roger
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chris wills
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« Reply #50 on: January 11, 2021, 03:31:36 PM »

Chris
Some of this may relate to your other post.

Apart from getting outside to clear 3inch of frozen snow away extrahappy

I have been reading as much info as I can find on your system.
Some of this is to confirm details
You say that there are 5 downstairs room thermostats. 1 for each under floor area
Are there room stats up stairs and if what regulates/controls the flow
The 5 solenoid valves on the manifold is it possible to check if they are 240volt or 24volt ( check for a label  )


Your flow meter glass tubes could etched ( like glasses go in a dish washer ) or just scale build up
You could try 2 things
put them over the upright pegs of the dishwasher if you have one ( with something over the top to stop them moving )

Or I am a big fan of https://www.dri-pak.co.uk/ and use soda crystals or citric acid to remove staining

Roger


Hi Roger,

1. Yes 5 downstairs stats, 1 for each zone
2. A single room stat on first floor landing controls all the rads in 7 different rooms, although I only have rads running in 3 rooms and the others are off.
3. On the 3rd floor cinema room, all rads are off, only switch them on when planning to use the room.
4. With regards to flow control, the same pump that runs from the buffer tank works the UFH and the rads, it is controlled by an on/off timer as I posted previously
5. I can see on the actuators that they are 230v / 2w
6. I will try them in the dishwasher


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chris wills
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« Reply #51 on: January 11, 2021, 03:49:12 PM »

Just one more thought. I have no mixer valve on my manifold so if I did add one and then turned the ashp up to 50, with the manifold set at 40 for example, then the rads could benefit from having much hotter water and the the ufh be good too?

I would definitely think so - I have our thermal store set to 40C and the TMV on the UFH normally set to around 25C for the ground floor, but to 35C for the first floor bathrooms (fitting from below spreader plates to a 18 chipboard deck with tceramic tiles). The round floor has a 12 way manifold controllled by 6 thermostats via a wiring centre, the first floor is on a simple timer.

Depending on outside temperature etc. most of the ground floor loops will switch off around 08:00 and remain off during the day (except the kids playroom!). As soon as the last loop switches off so does the pump. The Thermal Store will normally request heat at 25C and cease at 40C. As mentioned earlier I set the thermstats up slightly overnight (E7 period) and back to normal when E7 finishes.

If you set the ASHP up to 50C and the manifold down to 40C that will be much less efficient than running both at 40C - assuming you are not on E7. You will have to balance that against the benefit you get from the rads beg at 50C rather than 40 for a longer period.

So how does it work on boilers which emmit temps of 80 deg C and are then mixed.
Surely there must be some benefit
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Countrypaul
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« Reply #52 on: January 11, 2021, 04:09:58 PM »

You have to remember on boilers that running at 80C rather than 70C it probably makes little overall difference to the boiler efficiency. If it is a condensing boiler there can be significant efficiency gains to be had by runing it in condensing mode (<55C I think - I dont have and haven't had a condensing boiler). I don't know if there is any ability for a condensing boiler to run at 30C and if so if there is any advantage compared to say 50C.

With a heat pump the higher the output temperature the lower the efficiency, so outputting 10KWh of heat at 25C will be more effficient (use significantly less electric) than outputting 10KWh at 50C. Have a look at COP vs output temperature at the various input temperatures for your heat pump.  Obvously there is no point in running the HP at a temperature that is too low to heat the property, so whilst 25C may do if it is 10C outside, you may find that you need 30C if it is 0C outside. Some heat pumps have compensation curves built in that you can adjust according to outside temperature to take care of this situation.

Where you have a mixed system such as radiators and UFH where the radiators want to run at a higher temperature and the UFH at a lower temperature the TMV will blend a little of the HW with the cooler water already circuating in the UFH loops to maintain that circuation water at 25C (of 30C etc). Idealy you want the UFH loops at fairly fixed temeperature to aviod too much expansion and contraction and if in a screed avoid cracking the screed with high temp sudden changes.

If circulating a large volume of low temperature water large pipes are also likely to be needed that compared to circulating a low volume of hot water. Some radiator systems are plumbed with 8mm or 10mm pipe and a boiler. Our UFH has 28mm pipes to the manifold from the thermal store, the TMV in our case is located close to the thermal store rather than on the manifold. The small 8mm or 10mm pipe is much easier to work with than rigid 15/22/28mm which will also have an impact on the installation cost.
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brackwell
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« Reply #53 on: January 12, 2021, 09:04:40 AM »

Chris,
When you refer to room stats i have been assuming you are referring to convential air temp measuring the room.?  This being the case the room stats are only dictating the heat loss of the house and therefore defining the demand on the HP,  they do not control the workings of the system. They are not controlling whether you run the HP for 24hr at low temp or for lesser hrs at a higher temp. You are controlling that by the choosing of the in/out temps of the HP and to a lesser extent by the flow rate of the water in the HP circuit, but this in turn is being dictated to you by how cool you can run the rads, the UFH being happy either way, and it is this which is dictating your efficiency and running costs. Sorry as i feel i have repeated previous but every time you mention that word boiler ...

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chris wills
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« Reply #54 on: January 12, 2021, 12:26:21 PM »

Chris,
When you refer to room stats i have been assuming you are referring to convential air temp measuring the room.?  This being the case the room stats are only dictating the heat loss of the house and therefore defining the demand on the HP,  they do not control the workings of the system. They are not controlling whether you run the HP for 24hr at low temp or for lesser hrs at a higher temp. You are controlling that by the choosing of the in/out temps of the HP and to a lesser extent by the flow rate of the water in the HP circuit, but this in turn is being dictated to you by how cool you can run the rads, the UFH being happy either way, and it is this which is dictating your efficiency and running costs. Sorry as i feel i have repeated previous but every time you mention that word boiler ...



Yes I agree with your comments mostly, however the stats (yes air temp units) dictate how hard the HP works as at the moment I have the flow set to 45deg, the stats are at 18 deg in each of the 5 zones and the pump rarely comes on. Rads upstairs are on in 3 rooms only and with the rad fans i fitted to the coldest room, they are great and temp is good too.
If I turn everything up (stats) then HP starts and stops very 15 mins or so.

I guess its trial and error to get it right. My next move it to drop the flow to 40 deg C and then see how it goes.

If this works OK then maybe drop a little more but think its knife edge stuff.

These settings now drop my 24 hour usage to 50 kWh instead of previous day at 70 kWh.
Going to try another few degrees on ashp
« Last Edit: January 12, 2021, 02:57:10 PM by chris wills » Logged
chris wills
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« Reply #55 on: January 13, 2021, 09:16:32 PM »

Just an update. Got the return flow on 37 and all ufh at 18. They all go to temp and switch off actuator on manifold.
Upstairs rads good too. Usage over 24 hours is 49kwh at 12p a kw.
Now dropped to 35 return flow to see what happens.
 
Letís see.

UPDATE now running at 40kwh per day with settings above.

Probably a bit better as the temp outside is not so cold atm


« Last Edit: January 14, 2021, 02:22:07 PM by chris wills » Logged
MyForest
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« Reply #56 on: January 18, 2021, 06:09:37 PM »

Hi folks,

I wanted to mention (yet again, sorry) that I built an open source app to help monitor your heatpump experiments:

https://github.com/MyForest/mmspheatpump

I hope you can see answers to a number of your questions in these threads, for example "is it a good idea to run continuously?" or "do programmable TRVs help?":

https://community.openenergymonitor.org/search?q=%40myforest%20%23hardware%3Aheatpump%20

CountryPaul: My system is much like yours so you might find the outcome more interesting than other people do Smiley

Anyway, I hope that helps, I'd love to have people's heatpumps run more efficiently so that the world is a better place.

Thanks
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benseb
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« Reply #57 on: January 19, 2021, 08:13:15 AM »

@MyForest

Your app/sw looks great.

What hardware did you need for the Enomcms? Iíve got an ecodan too

Aside from running a custom program, what general tips did you find work best for efficiency?

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