Heat Pumps - post here.

Mazotasan

Some interesting experiences in here on heat pumps. I am currently looking at an air to water heat pump to fulfill the renewable requirement of part L...either that or solar. I found the payback on the solar to be quite long and havn't got the calcs on the air to water yet.

What I have found though is alot of poor experiences of heat pumps is either down to incorrectly spec'd equipment, poor installs/commissioning (installers not sticking with you until its performing correctly) and poor insulation in general. I met a guy (supplier/installer) on tuesday who has underfloor heating (think it was upstairs and downstairs) in a 355 square meter house with a water to water heat pump installed. Two years ago his electricity bill was €1500 for the year and last year was €1800 (think electricity went up). He does some welding and general workshop diy also...to me that was pretty impressive.

On his calculations over oil his real savings will be happening between years 5-10.

The air to water heat pump was giving a COP of 4 with an output temp of 35deg and outside temp 7degrees...if you had underfloor and ran this on the nitesaver you would have a nice set up. I am planning to use rads so need 55-60deg and the COP drops to just over 2 and would need to use day rate electricity so straight away performance drops and costs increase...so it looks like solar panels for me.

I think a lot of companies are quoting the highest COP figures achievable of their particular units under ideal conditions (for outside temp and delivered temp) which in reality only occur a small percentage of the time. The reality is also that there does appear to more failure stories out there than successful ones which is a pity because in essence I believe its good technology.

al2009

Mazotasan

A better sign of efficiency than COP is to ask for the SEER, this takes into account seasonal differences and can tell a very different story to the COP.

Also go for brands that you recognise, to me as a fridge engineer that would be Mitsubishi, Hitachi, Daikin etc, and yes we carry all these products but the difference is that any installers of the above have been vetted by the local representatives and trained, technical back up is guaranteed through the seller, i'm still amazed at the amount of people forking out 8 to 10k on brands that don't have a strong presence here, and as previous posters have said a proper site survey and load calculation goes a long way to a trouble free install.

IMO spend all you can on insulation first then worry about heating.........

al

kboc

Hi there,
I have been researching heat pumps now for 5 years and like many people thought i could make a decision for my new house but these sales reps/plumbers keep turning my head with their opinion.

One interesting point I have started to come across with some heat pump companies is whether to heat your DHW with the heat pump technology. Companies have started to suggest it is cheaper to buy the heat pump kit and more economical to run the heat pump which soley heats the concrete slab, the DHW is heated through a immersion heater. This is common practice in scandanavia.

Any suggestions, or experience?

Thanks

liamhana

Hi - Got a dunstar system in a few yrs ago, not an ounce of trouble but thinking of getting it serviced for the winter, as they seem to have gone bust, does anyone have a good service engineer in Galway region?

Poor Uncle Tom

PM's to liamhana only please.

holdfast

its cheaper for me to heat my DHW by immersion anyway. you can check it by:

17 kW X 0.08 euro x 0.75 hrs = 1.02
2.85 kW 0.08 euro x 1 hr = 0.23

and its gives me lots of hot water at min 60 deg c according to solar panel stat at btm of tank. people should check this and and rise temp of tank by immersion before heat pump kicks in. ( only if stat is installed on system to stop heat pump working if temp is too high in the tank is present)

KAGY

holdfast wrote: »

its cheaper for me to heat my DHW by immersion anyway. you can check it by:

17 kW X 0.08 euro x 0.75 hrs = 1.02
2.85 kW 0.08 euro x 1 hr = 0.23

and its gives me lots of hot water at min 60 deg c according to solar panel stat at btm of tank. people should check this and and rise temp of tank by immersion before heat pump kicks in. ( only if stat is installed on system to stop heat pump working if temp is too high in the tank is present)

I think that it would be common practice to use the heatpump to bring the water up to around 40deg and time the immersion to raise the temp further if needed.

In the calc above it's possible that you are mixing up the heat output of the pump with the electrical input. 17kW would mean that it was drawing 70Amps and assuming it was running for 1 hr a day would cost around 1 grand for the year (@18c/kwh) (just for hot water). Assuming for every 1kW of elec you are getting 4kw of heat out that 17kW heat output would need 2.25kW elec input.



If you want to calculate the cost of heating water:
Energy Required = (Litres of water) * (Temp difference) * 4.2 / 3600

Cost using immersion = Energy * cost per kWh
Cost using heatpump = Energy / COP * cost per kWh

the 4.2 is the heat capacity of 1 litre of water in kJ and the /3600 is the conversion factor to kWhr. COP is the coefficient of performance

holdfast

cheers kagy. is that 4.2 just divided by 3600 or all the formula

KAGY

holdfast wrote: »

cheers kagy. is that 4.2 just divided by 3600 or all the formula

It makes no difference, all the other operations are multiplication so it doesn't matter what order you do them in.

BTW I didn't explain why you'd only heat the water up to 35 or 40 deg using the heat pump. It's because the higher the temperature the more inefficient the heat pump becomes.

Lisa76

Does anyone have an air to water heat pump using a high velocity system? If so can you give us some advice is it any good efficient etc we really kow nothing about it and are very confused!!

Many thanks in advance

PJMCKE

Hi,
I am curious to posters here.

No one has mentioned the u values of their floors, or the thickness of their screeds or screed types. I am considering air to water heat pumps and with new regulations on u values of 0.15 this requires me putting in 120mm of kingspan K3. Experienced experts may comment on this 0.15 u value requirement.
I would love to hear from people who have poor geothermal performances on what their floor screeds and insulation is. It could be very possible that this is their reason for their high bills.

I have completed my pre BER and am assessing the options at present with respect to part L.
I am finding wood pellet options almost as expsensive if not more as geothermal. So why have the storage problems and pellet quality issues if I can get a system that is cheaper, complies with part L and is comparable in expense to heat the house.

Anyone.

cadrjr

soniag wrote: »

Hi there,

We have an Alpha Innotec heat pump installed for the last 3 years and every summer since it was installed it gives us trouble, but it has been out of service for almost a month now.
If we switch the heating part off and only use the hot water it works fine.
We are getting the same error code 716, a high pressure error every time.
The T*$$er that installed it came up to us once, had a quick look, said "he couldn't see anything wrong with it, (as I had rebooted the system)" and left again.
We spoke to another installer in the area but he doesn't deal with the Alpha Innotec model but is trying to help us.
We have adjusted the heating curve down to improve the Delta T but the system bombed again last night.
If anyone has any ideas I'd appreciate them. We have a 3500sq ft house with underfloor downstairs and rads upstairs. as i said, in the winter the system works great except for the high ESB bills, but we are planning on getting a heat loss survey done in the autumn.
Any help or suggestions gratefully accepted.

Sonia in Sligo:(

Hi Sonia,
did you ever get to the bottom of this fault ?
I've got an Ochsner HP with a high pressure error too.

Did you ever get the survey done? Did it help any ?
My HP costs me way to much also .....

CADRJR

0lddog

al2009 wrote: »

...........................Also go for brands that you recognise, to me as a fridge engineer that would be Mitsubishi, Hitachi, Daikin ................

al

Al,

Are you prepared to take on domestic work on these brands ?

If so, I would be grateful if you would PM me with your location & contact details

Thanks

0lddog

doncon

\Hi AL can you pm mre you contact details also

Paul Schweppe

I can quote performance figures for an 11 kW (Nominal) heat pump with which I am very familiar:
This specific unit has a heating capacity 10.05 kW when the leaving water is at 55 oC and outside air temperature is at +7oC. At these values the COP will be 2.36 i.e. 1 kW electricity in, 2.36 kW of Heat out.
On a similar unit (14 kW nominal) that has been designed for High Temperature applications the figures are as follows: The unit will deliver a heating capacity 11.6 kW when the leaving water is at 65 oC and outside air temperature is at -3oC with a COP of 2.03 i.e. 1 kW electricity in, 2.03 kW of Heat out.
An electrical element has a COP of 1 i.e. 1 kW electricity in, 1 kW of Heat out.
A Heat pump, by it’s nature, will always have a higher COP than an electrical element!!

Paul Schweppe

All the brands quoted above are leaders in the "split system" end of the Air Conditioning business. There are many other player in the refrigeration / heat pump market who offer high quality, well priced heat pumps with a full back up service provided by factory trained service engineers.

Paul Schweppe

Can’t help you with the insulation but I can tell you that we recommend that you apply 46mm to 56 mm of Concrete screed with a density of 350 kg/m3 over your UFH tubing. It is worth remembering that the controls you use on you UFH should take into account the thermal inertia of the concrete and the structure of your building; standard Weather Compensation controls / t’stats alone may not be sufficient to do this.
Re. The type refrigeration based heating systems (Geothermal and Air to Water) with the lowest capital or purchase cost are the DX Air to Water systems. With the DX units the heat is transferred from outside to inside via refrigerant gas and the water for the UFH / rads is heated inside the house, this contrasts with “Monobloc” type units where the water is heated outside in the unit and then pumped around the house. Both Geo and Air to Water heat pumps will easily provide the minimum of 10 kW hrs / m2 as per part L, furthermore the running costs of a well installed, efficiently controlled heat pump is very favourable when compared to that of a pellet boiler.

Oggie

Hi All,
Just moved into our newly built house approx 3 months ago. In the first month or so heating system seemed to be running very well. However it has been gradually getting worse. I have a horizontal loop propane filled geothermal pipes, with ufh connected to a pressurised cylinder. House is approx 2200 sq/ft with approx 800 sq/ft upstairs. Also have a 14Kw Stove hooked up to provide heat to the upstairs rads. Over the last 2-3 weeks our heat pump is running 24-7 but has failed to make it up to more than 18 deg and this is even with stove running. I am new to all this technology but I feel that something is seriously wrong. According to our engineer our soil is ideal for this system. Could it be an insulation problem? As far as I am aware insulation is installed correctly with pumped walls etc. At time of posting this the temp in house is 17.2 deg after running all night, however it is approx 1 - 2 deg outside. Flow temp is 32 deg return is 30 deg. compressor -.5 deg in approx 90 deg out. Can someone give me some advice please?

record

Oggie wrote: »

Hi All,
.....At time of posting this the temp in house is 17.2 deg after running all night, however it is approx 1 - 2 deg outside. Flow temp is 32 deg return is 30 deg. compressor -.5 deg in approx 90 deg out. Can someone give me some advice please?

Had similar problems myself (with an air-to-water heatpump in my case).

The problems could logically be caused by the following (not an exhaustive list):

- Heat pump not sized correctly - too small for your house.

- House not performing as expected in terms of heat retention.

- Problem with the heat pump.

- Combination of the above.

You could look at the following:

House not performing as expected in terms of heat retention:
Is the insulation is correctly installed - are there any draughts from poorly fitted windows, etc., hole-in-the-wall vents blowing a lot of cold air in, etc. Perhaps pay for a guy to come in with a thermal imaging camera to rule this out as an issue. This will detect any "cold bridging" (i.e. cold areas in the walls, roof, etc.). Remedial action can then be taken if needed.

Heat pump not sized correctly (too small for your house):
How was the size of the heatpump required for your house determined? Any of the companies that carry out BERs will be able to give you a reasonable indication of what your heat requirement should be (in KWs). It could be an issue that the heatpump is undersized. If this is the case, it could be set up to be backed up by a secondary heat source when it gets really cold outside (e.g. backed up by your stove or by an additional oil / gas boiler).

Problem with the heatpump:
Just to say at the outset that I am definitely not an expert on these things! Having said that, it does sound as if there is an issue there.

There could be a problem with the settings. For example, as a simple measure, you could try increasing the "heat curve" by a few degrees (say to +2 degrees). This makes a difference in my house, can't explain why, but it definitely helped. You should be able to do this simply enough through your heatpump controller.

Has the heatpump been installed correctly? I got a heating company to check mine as a second opinion, but had to just keep plugging away with the original suppliers to logically pinpoint where the problem was. In my case, it turned out that the underground pipe from the unit in the garden to the house (i.e. the one carrying the heated liquid) was not of the correct type. The correct, pre-insulated, pipe is very expensive and the fitter in my case took a short cut. As such, I was losing 7 degrees each way before my house gained any heat.

I'd be very interested to hear how you get on with your heatpump and hope you get it sorted.

al2009

Record

Is your heatpump a split type unit? ie water connections inside and not at the outdoor unit?

al

Oggie

Hi Record,
Thanks for advice. Had the heating guy at the house yesterday and he thinks that it is a problem with the compressor in the heat pump. Seems that there is a valve damaged or not working properly and this is causing the gas to leak from compressor?!. Hope to have the guys back in a few days to fix or change this valve! Soon know if its going right hopefully!! Are you happy with your heat pump overall? How long have you had it installed? Regarding the air to water, is it expensive to put in also?

bazual

Hi folks,
In a similar situation to Oggie.
We are in house since end of August.
House is 2400 sq feet 1 & 1/2 story. Cavity insulated with quinnterm insulation and all external walls are insulated with insulated plasterboard.
geothermal installed upstairs and downstairs, horizontal collectors to neura heat pump. Circulation pump and unit is located in the garage and pump is pumping whole house.
One temp sensor controller in hall downstairs controlling all. Manifold upstairs and downstairs with no temp guages. no temp guages in garage either so unable to determine flow and return.
Basically for example temp last night just before 11pm was 20degrees.
pump kicked in at 11pm for nightsaver to try reach 23 degs and supposed to run till 9am.
At 12:30am the temp in hall read 19.4 degs. Then in morning at approx 8:30am it read 18.9. So lost degress with 9 hours of running. Pump has been running pretty much all day now and temp is at 19.3
Last week it took 37 hours running straight to get from 18 to 21.5

Had rep out from installers yesterday and he used some thing to get the return and flow on pipes in garage. He said it was about 32 and 20. He thinks the circulation pump may be too small for the house and heat may be staying to long in pump or something like that.
So plumber now supposed to come out at weekend to check the problem.
Anyone any advice on what I should be asking or do you need any additional information.
Thanks for any help.
Bazual.

record

Oggie wrote: »

Hi Record,
Are you happy with your heat pump overall? How long have you had it installed? Regarding the air to water, is it expensive to put in also?

Very happy with the way it heats the house, gives a nice comfortable temperature throughout which I think I prefer when compared to radiators. Too early to say if I'm happy with it overall though as we have had problems, which are now almost fully resolved, which pushed up the operating costs.

Don't know how much it cost to put in the air-to-water system as it had already been installed when I purchased the house last year.

record

al2009 wrote: »

Record

Is your heatpump a split type unit? ie water connections inside and not at the outdoor unit?

al

I'm afraid I don't know what you mean by the above question?

record

bazual wrote: »

....Had rep out from installers yesterday and he used some thing to get the return and flow on pipes in garage. He said it was about 32 and 20. He thinks the circulation pump may be too small for the house and heat may be staying to long in pump or something like that.

With the system I have (air-to-water), the difference between the flow and return temperatures (i.e. the liquid leaving the unit after it is heated, and then returning to the unit after it offloads its heat into the house) is supposed to be no more than about 5 or 6 degrees. If it is greater than this, it indicates a problem. This could be, for example, poorly insulated pipes carrying the liquid to and from the house, or perhaps some grit blocking the pump. (I'm sure there are probably a load of other possible causes too - these are the only ones that I know about though!)

Oggie

bazual wrote: »

Circulation pump and unit is located in the garage and pump is pumping whole house.
One temp sensor controller in hall downstairs controlling all. Manifold upstairs and downstairs with no temp guages. no temp guages in garage either so unable to determine flow and return.

Bazual,

Just wondering should the hot water from the heat pump be going into a cylinder in the house and distributed from there to the manifold? I have a pump in the garage pumping to the house and one in the hot press taking it from the cylinder to the underfloor. You may have a different system though.

Is the heat pump providing you with hot water? Also as regards temp gauges, I presume that there should be two on each manifold, one for flow and one for return? And is there a central control unit with the system, which gives you temp of screed, hot water etc? Seem's a bit strange that you have no way of checking the system yourself apart from the stat in the hallway. I'm just comparing it with my system (which is not working!!)

bazual

Oggie wrote: »

Bazual,

Just wondering should the hot water from the heat pump be going into a cylinder in the house and distributed from there to the manifold? I have a pump in the garage pumping to the house and one in the hot press taking it from the cylinder to the underfloor. You may have a different system though.

Is the heat pump providing you with hot water? Also as regards temp gauges, I presume that there should be two on each manifold, one for flow and one for return? And is there a central control unit with the system, which gives you temp of screed, hot water etc? Seem's a bit strange that you have no way of checking the system yourself apart from the stat in the hallway. I'm just comparing it with my system (which is not working!!)

Hi Oggie, hot water from the heat pump goes straight to the house and straight to the manifold as far as i am aware. I have no hot press so to speak.
I would have thought I should have temp guages and will be asking for them when plumber comes this weekend, weather permitting.

Just as an update to everyone else, I have had the heating running constantly since my last post last night and however many hours there were leading up to that. The temp just hit 21 degrees there.
The temp does go up in the house but I need to run the heat pump for 30+ hours for it to start to rise.

Thanks
B~

bazual

record wrote: »

With the system I have (air-to-water), the difference between the flow and return temperatures (i.e. the liquid leaving the unit after it is heated, and then returning to the unit after it offloads its heat into the house) is supposed to be no more than about 5 or 6 degrees. If it is greater than this, it indicates a problem. This could be, for example, poorly insulated pipes carrying the liquid to and from the house, or perhaps some grit blocking the pump. (I'm sure there are probably a load of other possible causes too - these are the only ones that I know about though!)

Yup, I think this is what the rep said when he came out. It does sounds like it may be the pipes carrying from the garage to the house and once I get some temp guages on the manifold in the house that should give me a good idea of what the difference is.

Thanks for your help

B~

elainec

Hi

I hope someone can help. This is our second winter in our new house and our Air to Water Heat Pump is not working effectively in this cold weather. The average temperature in all the rooms is 14C with the Kitchen and Sitting Room at 10C. Our home is 2200 sq ft with vaulted ceilings in the kitchen and sitting room.
Our sole source of heat is the Heat Pump and we were told that its an economic form of heating. However last January and February our ESB costs were €800 per month!
I need to know if there are any experts in this type of heating who can advise us what we need to do to get it working efficiently. Unfortunately the Installer is no longer trading so I can't go back to him.

al2009

Elainec

Where are you based? What brand of heat pump is it?

al