Navitron Renewable Energy and Sustainability Forum

HEAT PUMPS & Geothermal Energy => Heat Pumps => Topic started by: rogermunns on December 29, 2010, 04:00:14 PM



Title: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 29, 2010, 04:00:14 PM
Me again.

The situation is now that I can get things going but after about 10 minutes the compressor turns off on Eo04.

I cannot understand what I need to do - I can see from the pdf that its related to          'how long in seconds the HP switch of the compressor stays open (Ec06)'

Can I change this setting and, if so, how, and is that wise?

Just to refresh, I have shorted wires 31 and 32 to wire 30, but in addition I have a flow valve in the well line which cuts all power if well pump fails.

I don't know what the water flowrate is from the well pump. But in steady running (during the 10 minutes or so that the compressor is on) the water inlettemp from well is 12.2deg.C and the return is 6.9deg. C.

I have serious concerns about flow from the circulating pump to the UFH loops. I have 7 loops, each about 110metres long, 'standard' dia 16mm. I have a flowmeter on each loop and only loop 2 shows any flow  (about 4litres/minute). I realise I need all loops flowing, I'm sure the Grundfos would like to flow 40litres/minute or so. I have had endless trouble with, presumably, air.  I have tried closing loop 2 to try to get any other loop purged, but failed. Naturally I was reluctant to dead-head the Grundfos, but it was only for a few seconds.

Could anyone please help with advice? I will look for another forum that might concentrate on UFH technicals........................


Title: Re: Seem to be over the main problems, but still not right..........
Post by: dhaslam on December 29, 2010, 04:18:54 PM
What valves do you have on the  separate UFH circuits, are you sure they are opening properly?   The wax type  valves can be checked by running your finger  over the valve top  and you can tell  if it is open slightly.     Is it normal to run a heat pump without any kind of buffer tank?   Surely there will always be a problem  if circulation is just cut off rather than controlling  the heat pump by water temperature.     


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Countrypaul on December 29, 2010, 04:30:15 PM
Just an observation since I do not yet have a heat pump. But you indicate that the source water temperature is dropping by oslightly more than 5 degrees and I would assume that you well pump will deliver roughly the same as the UFH pump so about 40l/min (this may be entirely wrong though). If your UFH pump is only managing 10% of what you hope then that may be 10 time hotter than expected. So if you expected it to rise by 5 degrees it may be rising by 50 and as such causing an over temeperature problem.  Could you use a large bucket/barrel  of water for the output and see if circulating the water freely solves the problem of the HP stopping?

You may have solved the original problem completely, but the UFH blockages may be causing a second issue that appears to be the HP.

I have no experience on these things, this is just an suggestion from someone who maybe in a similar position in teh future.

Paul


Title: Re: Seem to be over the main problems, but still not right..........
Post by: ecogeorge on December 29, 2010, 05:33:34 PM
Compressor overload is usually because it can't disapate the heat (poor flow into house) or can't disapate the cold (poor flow into well in your case).
Can you confirm 110% your flows??

Check the well is easy, - see the speed at which it returns to the well.Your return dropping by 5 degrees suggests that this flow is good.-- but still check it!
The house circuit is a bit harder, as if the flow rate is poor the return temp will not display a high figure and therefore not turn off the compressor.
It sounds as if the heat cannot be removed quickly enough from the heat exchanger. I echo countrypaul and suggest temporary inlet and outlet into a 40 gal drum to check correct operation. Use 32mm mdpe pipe from heat pump.
What size are the pipes to & from the heatpump on the house side ?  should be 28mm cooper or 32mm mdpe IMHO.
As various zones get to temp will the flow slow?
Have you got a buffer tank? if not why not? 
I would use a buffer tank to reduce compressor cycling (when you finally get it running continuously)  and use a "normal" central heating pump to circulate in the house. The WR09 pump is a bit overkill (energy sapping) for domestic heating circulation- use it only for the buffer tank supply.
I expect Welshboy or Alan will be along soon with more learned suggestions.
rgds George.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on December 29, 2010, 07:07:04 PM
As Ecogeorge says it is likely that the heat is not leaving the heat pump heatx fast enough.
Firstly I would check the pump speed - set it to max
If that fails purge each loop with a hosepipe to ensure you have flow through the ufh pipes and this would then confirm they did not kink when they were laid.
You are then left with the valves to check and bleeding.

7 loops @110m each should keep it running for quite a while - Ours will run ok with 5 loops @100m each even if I turn off the upstairs rads.

Good luck


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 29, 2010, 07:48:07 PM
Thanks, all, for (again) valuable help.

I do not really understand the role of a buffer tank but I'll google it and learn up.

I will try the excellent idea of mocking the UFH up with a large tank of water.

I think this is the right answer - the UFH is not efficient enough to get rid of the heat.

Over the next few days I hope that I will be able to report success, I sense the finish post is near.

You all have been really kind and generous in giving your help.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on December 29, 2010, 11:24:58 PM
if your 16mm pipe is 12mm internal (at a guess) and you have 700m or pipe total.... that will only hold about 80litres of water

and your heat pump can heat up that 80litres of water quicker than the heat can be transferred out of the pipe and into your floor/house - especially when some rooms are turned off, or are up to temperature so shut off / reduce flow automatically

if only 2 rooms are being heated then there is only 24(ish) litres of water to heat, 2 would be 36(ish) etc. etc....


once you're heating less water/rooms, the heat pump will have to turn on and off a lot to maintain the temperature of the water, as the temperature falls slightly the heat pump will come on, run for a shot time then shuts off, a short time later the water temperature has fallen again so it comes on again etc. etc.

all the on/off/on/off running doesn't do your heat pump any good and is the most inefficient way to run it
(start up can use up to ten times run current, and is also when most component failures happen)


so... it's best to add a buffer tank....  hot you connect it up depends on your system.... but it does what it says on the tin, it's a buffer tank on the output of the heat pump, the idea being that if you heat up more water it will stay hotter for longer.... so the heat pump doesn't need to turn on and off so much :-)

heat pump heats the tank of water which is circulated around your house... if the tank temperature falls the heat pump comes on and heats it all up again... then shuts off.... the tank water keeps heating your house without the heat pump running.

do you have E7 power ? (cheap rate at night)


what size tank you go for depends on a couple of factors but mostly... how much space do you have for a tank ?

do you have E7 power (cheap night time rate) ?

if so, because you're heat is coming from the well water, which should be the same temperature day or night, you could save yourself a lot of money by fitting a bigger buffer tank / thermal store (same thing really) and running the heat pump overnight on cheap power... once your big tank is hot/warm it should be able to heat your house all day (or most of the day)


iirc that is how StBarnabas runs his system ?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on December 30, 2010, 12:31:09 AM
Roger, Please dont try to tamper with the high pressure cut out, its telling you as the others have said that your not getting a good flow through the heat exchanger. Perhaps as a tester, you can get a hold of a direct DHW cylinder and pipe it into that, take the UFH right off the top. You will need another pump though.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 30, 2010, 06:01:09 PM
I've had a lot more luck today with bleeding.

Our incoming mains water pressure is quite high (7+bar) so a couple of years ago, when we started to install washing machine  / dishwasher I put in a pressure reducer and lowered incoming to 3,5bar.

I have had to temporarily increase this reducer to 5 bar and have now manage to get 4 loops flowing properly. But not all seven, I'll have to continue tomorrow.

I can see the wisdom of a buffer volume. I have ample room to do this - I'll have a look around at how best to proceed.

Thanks again for the practical advice. 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 30, 2010, 07:50:14 PM
Thought I would try again, now that I had much more underfloor flow potential, after bleeding.

But no.

The UFH pump in the WRB09 doesn't seem to be man enough -if all loops are open then there is not enough umph to flow up any of them.

I tried twice this evening. No go - compressor cuts after 2 mins. with console display showing 43 deg. C. and rising fast.

More bleeding.....................

Any idea how much pressure is generated by the Grundfos?  I really can see that I need at least 5 bar.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogeriko on December 30, 2010, 08:36:18 PM
When the grundfoss hits an air bubble it stops pumping regardless of pressure.  I would disconect the return from the ufh and let the water flow, using the pressure from the mains, from the 7 pipes until all the air is gone and then reconnect it while the water is still flowing out that way no air can get in.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on December 30, 2010, 08:52:57 PM
The pump in ours has plenty of punch.
For the benefit of everyone trying to help can you tell us something about your system.
Wrb09 in basement- how much head are you trying to lift the heat ?
Any chance of a pic/sketch of the manifold pipework - Is there a lazy way for it to pump ?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Iain on December 30, 2010, 08:56:50 PM
Hi
Would an automatic air vent on the discharge of the pump help?
Iain


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on December 30, 2010, 09:17:39 PM
-if all loops are open then there is not enough umph to flow up any of them.

that bit doesn't make seance to me (even if that is what is happening)

have you tried running with 1 loop then turning the extras on one at a time ?

at a guess... I'd say that with them all open the flow must drop too low for your flow meter to pick up ?

if it's not that.... then that points to the possibility of there being another problem :o


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Countrypaul on December 30, 2010, 11:14:25 PM
I hope this is so obvious that you've already checked it but - Have you checked the pump and made sure it does work properly, or tried substituting another pump in to test things?

Paul


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 31, 2010, 09:31:38 AM
I've tried bleeding at the pump using the large screw that you undo if you want to turn the shaft. Am I letting air in?

UFH pump in HeatPump assembly is 2,0metres below bottom (feed in) manifold.

First photo shows the 8-way manifold in kitchen corner cupboard. There are 7 loops and one spare. I have coupled inlet and outlet of the spare, but kept those valves closed. Inlet is bottom, you can see the adjustable flowmeter displays. They're cr*p. Also you will note that the pipes going into the floor have coloured sleeves round them. Red and blue. You will see that the colours do not correspond to the main valve colours on the right. That's because, when I bought the manifold, the valve heads were on the wrong way round. A call to the supplier eco-hometec revealed that the flowmeters are on the inlet. So I swapped over the blue and red valve heads.

I'm only making a point of this because it's typical of the hassle and duff info that I've had concerning the manifolds and everything else to do with the installation of the UFH pipework.

Second photo is of a spare manifold, identical to the installed one except 6-way instead of 8-way. I got two manifolds because I needed about 800metres of pipework and that meant buying two complete kits. Two loops; 500m with 8-way manifold and 300m with 6-way manifold, two pumps.

On this second photo you can see inlet at bottom right (still with blue valve handle!) and each leg with a valve / flowmeter. Top leg has electro-actuated valves (some are fitted). In my installation I have no electro-actuators installed, I don't believe in room thermostats when the response time is hours. The intention was just to adjust the flow valve thingys as I need to.

The valve / flowmeters are really awkward to operate, especially being inside a cupboard. And I've only ever seen one of them indicating flow. They are poor IMHO. 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: titan on December 31, 2010, 09:59:03 AM


Top leg has electro-actuated valves (some are fitted). In my installation I have no electro-actuators installed,

Just a comment, in my system  the  the actuators open the valve so with no actuator heads fitted there would be no flow unless the screw caps are fitted.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Alan on December 31, 2010, 10:28:49 AM
On mine if the plastic cap is not fitted the valve is open.

If the actuator is fitted and not powered the valve is shut.

Regards

Alan


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 31, 2010, 10:30:51 AM
Same with mine Alan. Right stupid arrangement.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on December 31, 2010, 11:43:31 AM
you need to check the pump is full of water.... it won't do anything at all if it's full or air (or half full)

if it is full or water, you could try turning it around, so see if the water would flow in the opposite direction ? (worth a shot)


other than that, you'll either have to keep pushing it through with your hose pipe, or fit a bigger pump to try and force it through...... bigger pump idea might be best..... then you could just leave it turned off once everything is running and the water should circulate through it ok ?

something like this (http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9956450&fh_view_size=10&fh_location=%2f%2fcatalog01%2fen_GB&fh_search=pump&fh_eds=%C3%9F&fh_refview=search&ts=1293795245597&isSearch=true) should hit 80psi and 40l/min (a lot of people use these for bio diesel, and that's what they get).... as long as that's not going to knock any of your fittings off ?

do you have any kind of header tank in the system ? (I''m assuming not) - so you will need to sort out somewhere for the air to go while you push it through.... even if you just split your return pipe and put it in a bucket of water temporarily..... you need somewhere for the air to escape of you'll never be free of it


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Iain on December 31, 2010, 11:47:29 AM
Hi
Could a auto air vent on the output of the pump sort out the air problem? At least ensuring the pump is kept free of air to allow it to pump.
Iain


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on December 31, 2010, 12:19:59 PM
The pump on mine is a Grundfos 25-120-  this is a bit about them.

UPS 25-120 circulators are designed to cater for the majority of domestic wet central heating systems up to 35kW. UPS 25-120 has an energy saving 3 speed motor and can accommodate larger domestic systems and higher resistance microbore pipework.

The UPS 25-120 is a high head domestic circulator and normally requires a 1" BSP Union Set.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on December 31, 2010, 12:29:24 PM
This is a very old post link but maybe worth checking out as yours is an old machine

http://www.navitron.org.uk/forum/index.php/topic,572.msg3566.html#msg3566


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on December 31, 2010, 01:53:10 PM
Hmm.... is that auto air bleeders I see on the manifolds? Could the return one be pulling air in? Is the manifold the highest point of the system?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogeriko on December 31, 2010, 02:08:52 PM
getting air out of any system is difficult at best, opening the screw on the pump is not enough because you need a strong FULL PIPE flow to clear the air especially down hill. You have to close the taps one by one and undo each pipe from the return manifold and drain it into a bucket 20 to 30 litres each pipe. It has to drain fast with pressure to remove the air bubbles. Close the air release valve on the return manifold because the pump can suck air in there.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 31, 2010, 02:56:35 PM
You won't believe it, but at last it's right!

Bleeding bleeding! Main problem turned out to be those stupid flow valves which have a twin thread - I was only opening one).

Now, after 30 minutes or so running the system I have UFH water out of pump at 23deg. C (when I had flow probs this reached 48deg. C in 3 minutes or so before compressor tripped). UFH water return is at 16deg. C.

One thing, though  --  after switching on to go on to green light, UFH pump starts at once, another relayclicks in at about 40 seconds, but then it is several (7 or 8) minutes before compressor comes on.  Is this normal?

I still think I am down on flow, I'll crawl into the cupboard again and see whether I can twist any of the flow valves some more.   

One last thing a question about pressure rise of UFH water as the temperature goes up. Will the big red pancake expension thingy take it up? Remember, it is 6 years old. Should I charge it? How? Bike pump with pressure gauge?

Just  made it before the new decade begins!! Thanks again to all who have helped.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 31, 2010, 03:28:18 PM
Thanks to those who spoke of air and bleeding etc. I will look into more auto bleeders.

The manifold is not at the highest point. The system is pretty normal - 7 loops in ground floor, screeded over 7cm. But because we have concrete stairs (between 3 and 4 tonnes) I took one of the loops up to first floor attached onto the underside of the concrete stairs then back down again. At the top of the stairs I have access to this pipe - and I deliberately cut and fitted a tee at the top, valved so I could bleed any air that collected there. That complete loop is the least important of the house and could be locked out if necessary. That loop has been reassuring, 'cos I can directly feel the temperature rather than having to wait until the concrete floor warms up.

I am monitoring floor temperature above one of the loops (thermocouple taped to floor and covered with insulation). T = 15,8 deg. C. at the moment.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: titan on December 31, 2010, 04:09:08 PM
I sounds like you only have a vent on one loop (from 7) not having the manifold ( with flow and return autovents)  at the highest point  means air  may continue to cause  a problem. I have a similar set up to you with the  utilities in a basement, I would have liked the manifold down there also but  in the end decided it was too much of a risk of continual air entrapment problems. It is not a problem in a conventional radiator set up but UFH loops are prone to air problems if they are not purged with decent flow rates during commissioning and have permanent  effective autoventing in use. 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on December 31, 2010, 05:21:08 PM
Thank you Titan.  I will carefully watch what is happening  and, more probably-than-not, fit more autovents. I may also try to re-route the main pipes coming up from below, although that will be very difficult.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 01, 2011, 10:43:59 AM
Happy New Year to all members!

It's now run for 2 hours today, 4,5 hours yesterday with nothing to note except some icing up on pipes from the HP side.

Is this dangerous to the compressor / exchanger? How much icing up before switching off? Is there an autoshut-off for this situation?

Floor temperature has increased from 13,0 to 19,7 deg. C.

Well water temperature coming in has fallen from 12,5 to 10,7 deg. C.   Water returning to well temperature fallen from 7,4 to 4,5 deg. C.

I estimate amount of water in well is 6 cubic metres. Overnight temperature recovery of well water was from 10,9 to 11,4 deg. C. Given time, this would presumably recover back to 12+ deg. C.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 01, 2011, 11:57:04 AM
don't worry about the pipes icing up - just check the ice isn't going to drip and cause problems when it defrosts....

you can insulate the pipes, but if you do you'll have to wrap the insulation up tight (gaffa tape?) to stop the moisture getting in :-)


glad to hear it's all up and running :-)


EDIT/p.s. do you have any photos of the icing up ?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 01, 2011, 03:21:24 PM
Here is a pic of the icing up at it's worst.

When I went down into the basement I was surprised to see that although the compressor was running the UFH side had lost some temperature. I didn't check for flow in the flow valves (I would have had to go back upstairs); instead I  turned everytning off 'cos I was concerned.

Then I took this photo.

I'm a bit thwarted now 'cos the well water temp. is now 'only' 10,5deg. where I am pulling the water out (and at the bottom of the well the water is arriving back at 4,5deg.). Luckily the weather is not cold and we can wait for the well temperature to recover.

I think the fall away in UFH temperature might again be due to air troubles.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: titan on January 01, 2011, 05:50:59 PM
Roger,  Kensa mention about flat battery  starting a system for the first time, www.kensaengineering.com/downloads.asp    9th down the list on the left may be worth a read


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 01, 2011, 06:42:27 PM
Thanks Titan, that is very interesting and perfectly correct for our house - although we didn't start from as low as 5deg. C.

 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on January 01, 2011, 06:48:30 PM
The frost on the suction accumulator (middle) may not be cause for concern, its job is to stop liquid refrigerant from entering the compressor (which would be nasty for the valves) however, this frosting will affect the discharge (outlet) temps from the compressor as the two are related, you may want to check with other owners about the difference in the flow and return temps from the ground side, is the required flow rate being met?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 02, 2011, 07:16:17 AM
as above, it's probably normal... but you might want to have it checked out anyway....

if it's going to drip and leave a puddle then it's probably not supposed to be like that...

it could be caused by a hundred different things.... refrigeration systems need to be in exact balance to work properly... it might just need gassing up a bit ?

I'd call out a refrigeration engineer to check it if I were you.... try to get an old guy to come do it - a lot of the young ones don't know what they're doing in my experience...


if the accumulator is icing up, then there must be some liquid refrigerant making it's way back into it and evaporating there... I'm not sure if this is normal - or if it should only happen as a "fail safe" when something isn't right.... all my accumulators run on the high pressure side not the low pressure side, so I'm not familiar with that kind of system

is the thinner pipe coming out of the compressor (the high pressure / liquid pipe) hot ? it should almost be too hot to touch :o


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 07:52:58 AM
Knighty.  Thanks. But I live in rural France and (a) can't afford the 'artisan's charges) and (b) would not know who to ask. Or how to find out. Indeed, any thoughts of doing any modifications to my system are difficult - only when you've lived here can you really appreciate how different commercial life is is France compared to UK.

Best way for UK-ers to understand the difference is to imagine what UK was like 40 years ago. That's France today in many respects.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 08:07:42 AM
This morning on switch-on I've got error Po07. It says in the pdf manual that this is related to (in my case) well water temperature.

The file shows the message means that temperature is below [EP07] + 3deg. C. But then another table shows values for EP01  ...  EP06 but not EP07.

My incoming temperature is showing 9,5deg. C.

So I'm not sure what to do. And everything was going so well ...........

Any help, please? 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 08:26:16 AM
I again tried to turn on and this time, no error message, fired up OK.

So at the moment, I'm happy.

One thing that's happened that I do not understand is;

on Saturday I ran for 4hours 35mins with all seven UFH loops open. At 4 hours I turned off because of icing up of pipes (I now realise this is normal) but also of the two black canisters. See photo a few posts ago.

on Sunday I ran for 3hours 15mins with just three UFH loops open. I turned off because I was going to bed. There was no sign of icing of the canisters.

And, as I said in an earlier post, when I had canister freeze the outlet temperature on the UFH side had fallen. 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 02, 2011, 08:55:07 AM
chances are it will stop running the compressor every few hours or so to defrost the well water heat exchanger - or at least to make sure it doesn't ice inside...  which will give the ice/frost on the compressor etc.. a chance to defrost too :-)


I think you'll just have to run it for longer and see how it goes,,, refrigeration is a big of a mine field... a slight imbalance in the system can cause all kinds of weird and wonderful problems... which seam totally unrelated to the actual cause of the problems!


Title: Re: Seem to be over the main problems, but still not right..........
Post by: longstroke on January 02, 2011, 09:23:44 AM
Too slow typing this! Knighty has allready replied, but I hope this is of some use.

The lack of icing up on the sunday is due to the compressor not working so hard as you only had three loops open so you will probably find that the compressor was cutting in and out and the ambient temperature was enough to prevent external icing.

I've no idea what refrigerant gas you have in the heat pump but different gases have different properties and the data tables for the gas would be able to tell you what temperatures/pressures to expect on the suction (LP) side, this info may be in the user handbook and hopefully a knowledgeable heat pump owner/operator/installer/engineer will be able to give more specific advice.

It relates to the LP suction pressure, which would be affected by not having enough gas in the system as mentioned earlier by Knighty, but could also be caused by a duff expansion valve, inadequate evaporation due to too lower well water temps which in itself could be due to well capacity not being enough to keep up with the heat demand of the heat pump when running 7 loops, or possibly incorrect setpoints allowing the compressor to drag the LP pressure down too low.

However, the icing up is not necessarily incorrect - there are plenty of correctly gassed up fridge systems which operate with iced up LP sides due to the gas the're running and the operating temp required.

It is (or at least I find it can be) very difficult to judge how much gas a system needs due to the large number of variables involved. Trial and error tends to be the only option with systems that its not possible to pump out and refill with the correct weight of refrigerant gas which hopefully the manufacturer has been nice enough to specify.



Title: Re: Seem to be over the main problems, but still not right..........
Post by: wyleu on January 02, 2011, 11:41:16 AM
Best way for UK-ers to understand the difference is to imagine what UK was like 40 years ago. That's France today in many respects.

Isn't that the utopia the Daily Mail is constantly harking back to?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 02, 2011, 12:04:14 PM
rogermunns, if you buy yourself a set of refrigeration gauges (40, ebay) and an infra-red thermometer thingie.... you could post all the pressures/temperatures up on the refrigeration engineer forum and they'll probably be able to help....  there's a lot of very smart and well trained people on there.... and if you do need something doing, they might even be someone local to you on there who could help :-)

http://www.refrigeration-engineer.com/forums/


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 12:12:45 PM
Thanks Knighty, I'll look into that.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 12:14:00 PM
wyleu:

Yeah, but don't believe it!

For example, here in France copper plumbing comes in 10mm and 12 and 14 and 16 and 20 and bigger.

Waste plastic pipe in 32mm, 40, 50, 60, 80, 100, 150 and bigger.

But, round here, shops and even supershops carry little stock and very poor stock control. So all the popular sizes go. Especially in the Summer  - practically all the French get into their Renaults / Citroens / Peugeots and head for their French holidays in the same three weeks - so factories close and shelves empty. Very few places open on Saturday afternoons, Sunday, a lot have Monday off too.

But we love it. Mild, short winters and under 5 hours door-to-door, flying to Brum. to see family. Unless they are over here taking the rays.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 03:17:57 PM
Just had a thought.

Turned off today after 3 hours, problem being ice on both canisters and temp dropping on UFH circuit.

The thought is that maybe the machine had gone into 'cooling mode' which I guess would be it's way of not getting too cold. In the panic to turn off I didn't look to see if the display had gone to 'cooling'.

Could anyone confirm whether that's how it operates, please?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on January 02, 2011, 04:28:11 PM
Just had a thought.

Turned off today after 3 hours, problem being ice on both canisters and temp dropping on UFH circuit.

The thought is that maybe the machine had gone into 'cooling mode' which I guess would be it's way of not getting too cold. In the panic to turn off I didn't look to see if the display had gone to 'cooling'.

Could anyone confirm whether that's how it operates, please?
I don't think so.
As the temperature of your well is falling the HP is working harder to lift the temperature of your UFH.
You may find the well does not have enough capacity to run the HP for long periods.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 04:56:43 PM
Welshboy, HNY and thanks again. You've been a real brick.

After a couple of hours I ran again, but closed after an hour for the same reason.

But I looked at the display first - it hadn't changed.

What I did notice, however, was that well return temperature was now up to water temperature from the well.  i.e. the HP was no longer taking heat out of the well water.

Now the well will contain 'cold' water underneath 'warm' water. I have the pump near the surface, with the return pipe delivering lower down. I believe there are 4m of water height at about  1.2m diameter. Water surface is 4m below ground level so, the bottom of the well is about 8m down.

The well is hewn out of limestone which, however, is fissured and ground water level is up to the well water surface. So I suppose the water will gain heat again in time. 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: ecogeorge on January 02, 2011, 06:08:52 PM
How about fitting a tee in the well return and ocasionally dumping some return water down the drain ?

This would alow the well to refill - with warmer water ???  wouldn't it ?

rgds George.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 07:04:02 PM
George

I'll try that, got everything I need. Also, it will allow me to measure flowrate.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on January 02, 2011, 08:03:11 PM
Good Idea George.
Roger
The heat pump needs a flow rate of 1800 litres an hour. If you measure the drop in the well ( and its corresponding Volume) compared with your discharge to a soakaway you have an idea of the speed of the well  being refilled by groundwater and yo could adjust your spillage accordingly.

Just a thought


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 08:16:32 PM
I thought you might like to see the replies I have had from the American A/C forum when I posted my system information and my concerns about the ice on the compressor canister.

1.     I don't like the look of the frost on the compressor (bigger black pot) but would need to know evaporating pressure/temperature and compressor inlet temp to be sure.
If you run the system with a frozen evaporator you risk splitting it, this will likely write off the system.
I wouldn't expect to see frost anywhere on a chiller system, i wonder if your well water flow rates are correct?
The temperature drop in the supply water after only 9 hours is cause for concern too.....

2.    The water return temp to the well should really only be about 3C below the supply temp. So either your water supply is too slow (pump or piping too small) or you have a blockage, either at a filter or from debris from the bore getting to and clogging up the heat exchanger.
You also need to check the gas charge in the unit. An overcharged unit can frost up at the compressor similar to what you have there due to liquid feedback. However this may be contributed to by the poor water flow through the evaporator so fix that first.
Once the water drops to 4C you're in icing territory and run the risk of bursting the HX.

3.    Note that water to water systems don't defrost, they have no need to

4.    I agree. There is insufficient water flow... but no reason to believe the system is overcharged. We really can't tell if there are other problems until the water flow is right.

5.    Actually, reading your post again, you have 2 problems.
The flow is too slow,
Secondly your dump well is either dumping too close to the supply well or is upstream from the supply well and the water is short cycling i.e the same water you just extracted energy from is cooling the water that is being extracted from the supply well and dragging down your supply temp and efficiency of the unit.
The first is an easy fix, the second may require you to drill a new dump well or switch the pump from bore 1 to bore 2

And my reply to those comments;

Thank you all for speedy and informative replies.
I have to work within serious constraints. One is that, for this winter, the single well is my only possible source. By next winter I will have got my ground loop installed as well. There is no way that I can afford to have another well dug - space and expense and difficulty (rock from 1 foot down).
(For the ground loop I am going to lay the pipe on the rock and then build a raised bed 1.5 metres deep on top).
I don't really have enough ground available to supply all the heat I need.
Also, if the two methods of collection (well and ground) are not enough I intend to use swimming pool heat (through a heat exchanger) as well. My pool will have solar assistance, so hopefully the 55 cubic metres volume will help the complete overall requirement.
Hope that makes sense. The well supply was the easiest to get ready and the hope was that the groundwater surrounding the well would top up the water temperature within a few hours. I do have a second pump which I could use in addition
and also I could dump some return water to waste, thus encouraging the groundwater supply to replenish the well with warmer water.

So I am shutting down for a few days to see how the well water temperature recovers. I have a second pump I could easily drop into the well and run in tandem with the current one. Sadly the well level takes hours to replenish if I dump the  return, but just maybe I could return some of the water and dump the rest and find a balance.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: welshboy on January 02, 2011, 09:20:28 PM
Try Googling Rock saw trenching- there is some amazing kit to be had


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on January 02, 2011, 10:19:04 PM
Right, here goes, the replies you got were about as I expected,
1. he's right it could damage it but it should have an anti ice thermostat or temperature probe on the ground side heat exchanger, if its a stat its probably a manual reset if it trips.
2. roughly 3deg difference, if your well water is 9deg then the return from the ground side heat exchanger should be 5 or 6deg not 3deg as I think you posted a couple of days ago, have you got a filter on the water inlet to the ground side heat exchanger? I still think the flow through it is too low as well as the guy suggests. Overcharging can cause other problems not necessary icing of the evaporator side.
reply 3,4 and 5 pointing to lack of flow again.

I'm pretty sure your heat pump is using R407c refrigerant.

So basically, lack of flow through the ground side heat exchanger, would cause a low suction pressure at the compressor, the resulting evaporating temperature of the refrigerant is below 0deg causing icing on the suction accumulator and the compressor, a low suction temp will give you a lower discharge pressure and temperature at the compressor outlet, therefor a lower undefloor temp flow.

Another question, does it have a refrigerant sight glass? Although its probably charged correctly anyway.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 02, 2011, 10:23:28 PM
what kind of pump do you have in the well ?

what size of hose ?

and does the hose for the return water go right down into the well, or is it just sticking in the top of the well hole ?
(it should go down at least as far as the pump)


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 02, 2011, 11:28:04 PM
Yes it is 407c.
No sight glass.
It is a cheap submersible with 8,5m head capability. I have 4,5m head to get out of well, then down about 1,5m to the heatpump. I have pump about half-a-metre below water surface.
I am using 25mm MDPE pipe (used normally as underground water supply pipe) and the overall length from well pump to Heatpump about 28metres. And 30metres back, 'cos return pipe does go tobottom of well.

I will measure flowrate over the nextday or so. I should have done it before. But I can't believe it's anything like 1,8cubic m. / hour. And I will monitor if / how the temperature of the well water is recovering.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: ecogeorge on January 02, 2011, 11:30:51 PM
My moneys on 25mm pipe being too small !!!!!  go for 32mm it's not much more expensive.
rgds George.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 03, 2011, 04:49:36 PM
George, thanks. But impractical 'cos I have placed the 25mm pipes inside a 'gaine' (an 80mm dia. flexible plastic pipe) and buried the lot.  And I haven't the energy to dig up and replace.  Maybe in the Spring, when I will have a digger on site.

I do have a second identical pump and I could use this, again running 25mm pipe to / from HP, joining the other just as it reaches the HP. i.e. two identical runs in parallel. But this second set of pipes would be laying over the garden, maybe risky if we get big frost (which can happen here).

The well water temperature is slowly recovering but it will take 3 or 4 days before I can have the system running again.

I haven't been able to measure flowrate of the well pump yet. Maybe tomorrow.

Could someone please  answer a couple of Q's for me?

1.   what is the ideal inlet temperature into the WRB09 for the (in my case) well water? Or  inlet temperature from a Ground Loop?
2.   what would be the ideal length of underground pipe (25mm MDPE) and in what area of ground? My house has a heated floor area 170 sq. m.

Later this year I will be installing a ground loop as the main supply to the HP.

The well experiment was worthwhile to prove the HP after it had laid in the garage, sitting in ambient temperatures between -15 and +45 deg. C over a period of 5 years since it was purchased.




Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogeriko on January 03, 2011, 05:37:50 PM
Just pull the return pipe out of the well while its running to see the flow rate if not enough replace the pump with a stronger model that will pump 2 tons of water an hour through the existing pipe. Pipe size dosn't matter if you have a stronger pump. 8.5 meter head means the pump is not even capable of pumping 1 bar thats really weak. A good pump goes at least 40 meters of head (about 4 bar) that can push the water fast through all sorts of pipes and heat exchangers etc. could well be the problem, no pun intended.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: knighty on January 03, 2011, 05:54:05 PM
you could always just add an extra pump in-line higher up the system where it's easier to get to ?

with well water / ground source heat pump you really want as much flow as possible, the only thing holding you back is how much power the pump uses vs how much benefit the extra flow is


unless the pump is easy enough to get at.... in which case a proper well pump might be the best option - they're very expensive but you might get lucky on ebay ?


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on January 03, 2011, 08:19:52 PM
Before I reply to anything..... George  ??? No need to throw the towel in.

Roger, the ideal inlet temp would 'higher the better' higher = > COP
Another thing that just occurred to me is that your using fresh water, you might actually have ice accumulating inside the ground heat exchanger, possibly from about 8deg inlet and below, reducing the flow rate.
If you have a ground loop with antifreeze then it really doesn't matter, the lower it gets, the less heat output, so long as your mixture prevents freezing down to a certain level.

Maybe time to stick some Navi tubes outside and heat the well water  :)
 


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 04, 2011, 04:27:40 PM
Mostie; funny you should say that, it has gone through my head, we do have a good solar heater with a 200litre header tank. And we have had beautiful sunny days here since before Christmas. (Saw eclipse this morning.................).

Maybe a rig-up with the solar would be worthwhile, but maybe it will tempt fate regarding the weather!

I did also think of adding mains water to the well, but that's only at 8 deg. C.

As I hinted in earlier posts, this well thing was a bit of an experiment because I've not yet been able to dig out and install the pipes for 'proper' ground water collection. Maybe in the spring we'll be able to afford a digger for a couple of days and get this sorted.

There again if the climate has changed maybe we won't get any more winters here. I could only see two sunspots on the Sun today through my 'scope + solar filter while I observed the eclipse. And there should be more sunspots at this part of the 11-year Solar cycle.


Title: Re: Seem to be over the main problems, but still not right..........
Post by: Mostie on January 04, 2011, 10:23:46 PM
You might as well go the whole hog and fit the ground loop, an air to water heat exchanger with fans ( also called a dry cooler) and some solar tubes, pipe the lot back to a tank and then just select the source with the highest temperature.  :angel:

What got me thinking about that was the fact that other ground source owners claimed they ended up with a frozen back garden.  freeeze

That should give you something to think about  stir:


Title: Re: Seem to be over the main problems, but still not right..........
Post by: dhaslam on January 04, 2011, 10:52:51 PM
Four metres depth of water with 1.2 metres  diameter is only about 4500 litres of water  or about 5 kWh per degree of temperature drop if the well is static.  Also the water pump  that has a capacity of 8.5 metres head  will only produce a dribble at 8.5 metres.     It does seem like you need to get digging and make a decent ground loop,  you could still use the well as a small part of the  heat input.   The well will always have some  level of heat recovery, just not  enough it seems to keep the heat pump going.     


Title: Re: Seem to be over the main problems, but still not right..........
Post by: rogermunns on January 05, 2011, 02:53:03 PM
Thanks, all.

I think we are all agreed on what's wrong, although I am really pleased at how it's turned out, albeit a short series of running.

After having been stored for all that time and with no manual to help set the HP up I think we've all done well.

Virtually all of the glory goes to you people, thanks.

I will get down and dig out for the ground loop and will also shove some solar-heated water underground to help get the heat into the ground during the summer. Then in the autumn I'll switch the solar heat into the pool (well insulated on all faces including surface) so we get a little longer swimming season. Then in December / January I can start to take heat out of the pool and use it with the heatpump.