Air to water heat pump

about2build

Hi All,
Had my preliminary BER consultation and he is advising and air to water heat pump.....claiming a COP of 4. I have heard that this goes way down in cold weather- the time when it will be needed most? any thoughts on this. It works best with ufh but he has suggested rads for upstairs....will this not force the pump to hit overdrive??? It will be a well insulated house and is due to come in as a B1.

Condenser

about2build wrote: »

Hi All,
Had my preliminary BER consultation and he is advising and air to water heat pump.....claiming a COP of 4. I have heard that this goes way down in cold weather- the time when it will be needed most? any thoughts on this. It works best with ufh but he has suggested rads for upstairs....will this not force the pump to hit overdrive??? It will be a well insulated house and is due to come in as a B1.

You will get a COP of 4 at an air temp of 7C and a water outlet of 35C (A7/W35). For every degree the air temp drops away you will lose 2-3% efficiency.
If you use rads, you'll need a higher temp than 35C. In this case for every degree increase on the heating side you'll lose 2-3% efficiency. So in a scenario where its -2 outside and your producing 45C for your rads your COP will have dropped by at least 38%%. Giving you a whopping COP of 2.48. Do yourself a favour and avoid using rads with a heatpump and install a GSHP if going with a heatpump. Far higher and more stable COP.

Also find a person who knows about heatpumps, most BER assessors haven't a clue and yours certainly doesn't. He's chancing his arm

BryanF

about2build have you considered a phpp calculation to maximise building fabric etc before you work on your heating source and renewable requirements..

Do-more

+1 to what Condenser is saying, I'm in Sweden which is the biggest market for heat pumps in Europe and here the latest building regs now prohibit the use of air source heat pumps (both air to air and air to water) in new builds because they recognise the problems of poor COP at low temperatures. In particular the supply network has problems to meet the demand when everyone's HP is running at poor COP's in the coldest weather.

In Ireland the ambient relative humidity tends to be higher than here in Sweden so you have added inefficiencies as the HP will tend to ice up more often due to the moisture in the air and will run more frequent de-icing cycles.

I myself had intended to fit an air to air heat pump to satisfy my fairly small space heating demand due to the low capital cost and reasonable running cost even allowing for a relatively low COP in my calculations but because of the new regs have been forced into a re-think.

My site probably isn't suitable for geothermal as it is very sandy well drained soil and in any case the capital costs of installation are very high, about €15K here to install a 6kW HP.

What has been developed here to meet the new regulations is a new type of exhaust air heat pump which combines a balanced HRV with a 6kW exhaust air heat pump. It extracts the maximum amount of energy from the exhaust air by cooling it to -20degC before exhausting it outdoors. To use this unit here it must be in a house of up to 200m2 with an energy demand of less than 55kW/m2/a.

These have only been on the market for about 18 months so data on running costs is limited but it seems that in well insulated houses with low heating demands they work well provided you take the time to set them up correctly.

The control systems work on different "heating curves" depending on the local climate and it seems that owners who take the time to make adjustments over the entire range of ambient temperature conditions in order to achieve the best heating curve for them report the best results. This will take some months during the first year making small daily adjustments to optimise the system.

These units also have a immersion heater in them to help the HP at times when it is not able to heat sufficient hot water and the default settings for this also leads to problems. By default the immersion is available to come on at any time of the day, so if it is left like that what happens is that after hot water is drawn, say for a bath or shower the immersion will come on directly to get the hot water tank back up to temperature. But you can program the unit to block out the immersion for large parts of the day to prevent this from happening and ensure that it is the HP and not the immersion which is being used to heat the water.

One widely reported drawback of these units is that they are very noisy so special attention has to be made to soundproof the utility room where it is to be installed but once allowances are made for that when building, the extra cost shouldn't be too great.

Unfortunately all this info may well be academic as I don't think this HP is available on the Irish market yet, at least it isn't on the importers website in any case, but if you like to drop me a PM I will give you links to the unit and you can make enquiries if you are interested.

No matter what if you do go for any type of heat pump I would suggest that you use fan coils rather than radiators upstairs.

about2build

Thanks guys, unfortunately a lot of my fears have been confirmed here...Looks like back to the oil!! I'm meeting him next week and will put my reservations to him and see what he comes back with. Bryan-f I haven't gone for the phpp as I felt a prelim assessment would be sufficient. I amn't going passive but aiming for low energy.
I'm not prepared to go for the ground source pump...just dont think the initial outlay will ever be paid back.

Can any of ye suggest an alternative to ASHP or oil??

Assessor has calc heating load to be 75kW/m2/a

Condenser

Do-more wrote: »

+1 to what Condenser is saying, I'm in Sweden which is the biggest market for heat pumps in Europe and here the latest building regs now prohibit the use of air source heat pumps (both air to air and air to water) in new builds because they recognise the problems of poor COP at low temperatures. In particular the supply network has problems to meet the demand when everyone's HP is running at poor COP's in the coldest weather.

In Ireland the ambient relative humidity tends to be higher than here in Sweden so you have added inefficiencies as the HP will tend to ice up more often due to the moisture in the air and will run more frequent de-icing cycles.

I myself had intended to fit an air to air heat pump to satisfy my fairly small space heating demand due to the low capital cost and reasonable running cost even allowing for a relatively low COP in my calculations but because of the new regs have been forced into a re-think.

My site probably isn't suitable for geothermal as it is very sandy well drained soil and in any case the capital costs of installation are very high, about €15K here to install a 6kW HP.

What has been developed here to meet the new regulations is a new type of exhaust air heat pump which combines a balanced HRV with a 6kW exhaust air heat pump. It extracts the maximum amount of energy from the exhaust air by cooling it to -20degC before exhausting it outdoors. To use this unit here it must be in a house of up to 200m2 with an energy demand of less than 55kW/m2/a.

These have only been on the market for about 18 months so data on running costs is limited but it seems that in well insulated houses with low heating demands they work well provided you take the time to set them up correctly.

The control systems work on different "heating curves" depending on the local climate and it seems that owners who take the time to make adjustments over the entire range of ambient temperature conditions in order to achieve the best heating curve for them report the best results. This will take some months during the first year making small daily adjustments to optimise the system.

These units also have a immersion heater in them to help the HP at times when it is not able to heat sufficient hot water and the default settings for this also leads to problems. By default the immersion is available to come on at any time of the day, so if it is left like that what happens is that after hot water is drawn, say for a bath or shower the immersion will come on directly to get the hot water tank back up to temperature. But you can program the unit to block out the immersion for large parts of the day to prevent this from happening and ensure that it is the HP and not the immersion which is being used to heat the water.

One widely reported drawback of these units is that they are very noisy so special attention has to be made to soundproof the utility room where it is to be installed but once allowances are made for that when building, the extra cost shouldn't be too great.

Unfortunately all this info may well be academic as I don't think this HP is available on the Irish market yet, at least it isn't on the importers website in any case, but if you like to drop me a PM I will give you links to the unit and you can make enquiries if you are interested.

No matter what if you do go for any type of heat pump I would suggest that you use fan coils rather than radiators upstairs.

Those HRV heat pumps are on the market for years. They're no more than a glorified immersion. Avoid them like the plague.
They stopped using them 20yrs ago in Austria and Switzerland for that very reason.

Norwayviking

about2build wrote: »

Hi All,
Had my preliminary BER consultation and he is advising and air to water heat pump.....claiming a COP of 4. I have heard that this goes way down in cold weather- the time when it will be needed most? any thoughts on this. It works best with ufh but he has suggested rads for upstairs....will this not force the pump to hit overdrive??? It will be a well insulated house and is due to come in as a B1.

I think water to water heatpumps are more suited for the irish climate.
Allthough it cost more to have it installed,it would be a better option in the long run.;)

BryanF

about2build wrote: »

Thanks guys, unfortunately a lot of my fears have been confirmed here...Looks like back to the oil!! I'm meeting him next week and will put my reservations to him and see what he comes back with. Bryan-f I haven't gone for the phpp as I felt a prelim assessment would be sufficient. I amn't going passive but aiming for low energy.
I'm not prepared to go for the ground source pump...just dont think the initial outlay will ever be paid back.

Can any of ye suggest an alternative to ASHP or oil??

Assessor has calc heating load to be 75kW/m2/a

low energy? that only meeting the regs;)

a BER assessor is just complying with the limited nature of the DEAP software. where heat pumps are concerned you are right to be wary of there efficiency's.

do note that the BER is not known for its accuracy when it comes to predicting energy consumption or heat loss. also I think you've misunderstood the purposes of a phpp calculation, its to show you how you can get 15kwh/msq/y (or lower) and then you can compromise on the expense elements, but you'll still know what your heating system needs to do.. its not prefect but more accurate than DEAP thats for sure

Do-more

Condenser wrote: »

Those HRV heat pumps are on the market for years. They're no more than a glorified immersion. Avoid them like the plague.
They stopped using them 20yrs ago in Austria and Switzerland for that very reason.

My understanding is that the latest developments are not the same thing as the older ones Condenser. That I'm aware of the older units were only around 1.2kW HP capacity so naturally had to rely on the immersion to add a huge amount of heat. The new one incorporates a 6kW HP and as my heat demand is less than 3kW it should satisfy that without ever calling on the immersion.

Having said that I am wary of being an early adopter of new technology, especially when there is a significant cost involved.

It's fortunate that there is a large forum dedicated solely to heat pumps here and I have been following closely any threads relating to the unit I am interested in.

As I mentioned in my previous post there have been many instances of problems with people running on the factory settings but there is already a wealth of information out there on setting up the various parameters to get the best out of the unit.

I still have some reservations but with limited options open to me it looks like the best trade off at this stage.

L driver

ow energy? that only meeting the regs

a BER assessor is just complying with the limited nature of the DEAP software. where heat pumps are concerned you are right to be wary of there efficiency's.

do note that the BER is not known for its accuracy when it comes to predicting energy consumption or heat loss. also I think you've misunderstood the purposes of a phpp calculation, its to show you how you can get 15kwh/msq/y (or lower) and then you can compromise on the expense elements, but you'll still know what your heating system needs to do.. its not prefect but more accurate than DEAP thats for sure

+1. In a new build that is crazy energy. Take your time, research and employ the services of a professional. Take a holistic approach at the start and not add ons at different stages.

Condenser

Do-more wrote: »

My understanding is that the latest developments are not the same thing as the older ones Condenser. That I'm aware of the older units were only around 1.2kW HP capacity so naturally had to rely on the immersion to add a huge amount of heat. The new one incorporates a 6kW HP and as my heat demand is less than 3kW it should satisfy that without ever calling on the immersion.

Having said that I am wary of being an early adopter of new technology, especially when there is a significant cost involved.

It's fortunate that there is a large forum dedicated solely to heat pumps here and I have been following closely any threads relating to the unit I am interested in.

As I mentioned in my previous post there have been many instances of problems with people running on the factory settings but there is already a wealth of information out there on setting up the various parameters to get the best out of the unit.

I still have some reservations but with limited options open to me it looks like the best trade off at this stage.

You'd be right to sit back and wait in this case Do-more as regardless of power output, assuming the unit has a COP of 4, then it still must capture 75% of the energy from somewhere. Namely your house, so the net effect would be a delivery of 1.75kw of additional energy to the house per hour. In other words, a COP of 1.75. HRV heatpumps do not work well in any configuration, you can be assured of that.

Extract your energy from below ground and you'll be far better off.

refco

just as regards using a heatpump with rads i have seen it done in houses sucessfully also it should be noted that a lot of newer heatpumps are capable of 60 degree flow temps but in my experience even using rads a flow of 35 to 40 is sufficient to keep anyone comfortable it does mean leaving rads on longer compared to using oil and blasting them with 70 degree water for that warm feeling you get for an hour or two to get the effect but because the amount of water been used is far less then is used with ufh it is as efficient if not more so also if its a new build even though it would be more expensive you could go with low temp fan assisited rads instead of conventional ones and the beauty of this is turn heating on and house is warm no waiting 2 to 3 days for a massive slab of concrete to warm up before you feel benifits of making hundrends or thousands of litres of hot water

about2build

Thanks for all the good comments guys...and having read up it is a lot of energy to be expending...Any thoughts welcome on how I can reduce this consumption level...this i s the insulation I have at this stage
GROUND FLOOR 120mm kingspan tf70 under floor screed
perimeter insul of 25mm also required
FIRST FLOOR metal frame ceiling void be filled with rock wool
perimeter insul of 25mm also required here
WALLS bonded bead certainfil graphite .27 or similar in 150mm cavity
67.5 mm kingspan thermwall TW56 dry lining
WINDOW SILLS backed with 50mm KS TF70
ROOF 300MM of fibreglass quilt
triple glazed argon filled upvc windows throughout...u 0.8

thoughts?!

muffler

Please fix your post kboc by using the quote tags and standard black text. Thanks

Edit: Post by kboc now removed


.

about2build

thanks kboc and I am using mhrv and will be endeavouring to get house airtight as possible with possible assistance of an airtightness specialist..... Ya extra in the ceiling seems a good idea but if i lose the dry lining will it mot adversely affect my u value for walls currently 0.13?
thanks to all contributors again

Do-more

Condenser wrote: »

You'd be right to sit back and wait in this case Do-more as regardless of power output, assuming the unit has a COP of 4, then it still must capture 75% of the energy from somewhere. Namely your house, so the net effect would be a delivery of 1.75kw of additional energy to the house per hour. In other words, a COP of 1.75. HRV heatpumps do not work well in any configuration, you can be assured of that.

Extract your energy from below ground and you'll be far better off.

@Condenser I'm afraid I don't follow how you have arrived at a figure of 1.75, could you please expand on your calculation, if I have to dismiss this option I would like to do so based on solid figures.

Thanks.

Condenser

Do-more wrote: »

@Condenser I'm afraid I don't follow how you have arrived at a figure of 1.75, could you please expand on your calculation, if I have to dismiss this option I would like to do so based on solid figures.

Thanks.

Hi Do-more,

Responded by PM

about2build

Right guys, thanks again
After our second meeting and with some changes the heating load is down to 50 kwm2yr and I am now using under floor heating up and down stairs....separate zones for every room....
this should suit the air to water with an output of 35degrees??
With a high level of insulation and the mvhr unit also incorporated I think i have nailed down my primary energy source...thoughts??

My secondary source is a solid fuel stove with back boiler which will be linked to a loop of the underfloor as well as a couple of towel rails.....thoughts??

Thanks everyone again in advance

Condenser

about2build wrote: »

Right guys, thanks again
After our second meeting and with some changes the heating load is down to 50 kwm2yr and I am now using under floor heating up and down stairs....separate zones for every room....
this should suit the air to water with an output of 35degrees??
With a high level of insulation and the mvhr unit also incorporated I think i have nailed down my primary energy source...thoughts??

My secondary source is a solid fuel stove with back boiler which will be linked to a loop of the underfloor as well as a couple of towel rails.....thoughts??

Thanks everyone again in advance

Why are you using zoning? It won't save you any energy and the hrv will balance the heat spread throughout the house regardless. And zoning without a buffer tank will reduce the efficiency of your heat pump and will affect defrosting capacity.

Keep the stove off the ufh loop. You'll be running a high temp system along with a low temp system which is incompatible. Use the stove to heat your towel rails.

about2build

I'm using the zoning so that for example I can have only certain areas on at a given time eg living areas....or just downstairs etc

I agree with you that the boiler would be better with a couple of rails and rad or two as it will heat water to much higher temp but ber assessor recommended running a loop in the hallway underfloor so that it would radiate heat to the entire building when is for example there was a power cut or a prob with the pump....
what do you think condenser?? or any one else

Condenser

about2build wrote: »

I'm using the zoning so that for example I can have only certain areas on at a given time eg living areas....or just downstairs etc

I agree with you that the boiler would be better with a couple of rails and rad or two as it will heat water to much higher temp but ber assessor recommended running a loop in the hallway underfloor so that it would radiate heat to the entire building when is for example there was a power cut or a prob with the pump....
what do you think condenser?? or any one else

TBH your BER assessor sounds like he hasn't a clue and is only chancing his arm. It took advice from on here to get you down to a reasonable heatloss.

Shutting off zones will not save you any energy. Heat will flow from the warm rooms to the cool rooms so your HP will run just as much if not more and have many more start-ups and as I already mentioned the hrv will balance the heat across the house. You'll get no net advantage from zones and most likely make your system worse.

In a well insulated house you'll have adaequate heat from your ufh for 2 days in the event of a powercut. Make sure your screed is 70-80mm deep and you'll be fine.

about2build

Thanks condenser
I have opted for rads to be run off the stove and taken out the zoning...he is suggesting running the HP on a night saver but with temperature lower at night time does that make a lot of sense as efficiency will fall and thus negate any saving??
I think from what I have researched the installation and specification of the right pump is key so if you or any one else knows of good companies or installers in the Galway region please pm me

happylarry

Hey guys first off I'm no guru but I have an air to water heat pump installed 2 years ago,I have to say I'm very happy with it and it's costs ,I can't tell you cop and the likes but I can tell you the cost my house is 3000sqf all ground floor.we have no oil we moved in to the house in 2009 august to be exact .that was the year off the hard frost from aug to aug 2010 our total electricity bills for house was1300 euro that's with the pump running 24/7 and that's with hot water 24/7 aswell we have no other source off heating .now our house is well above and beyond what would be considered well insulated a3if not a2 standard .and this year I'm only putting the heating on between 11pm and 9am and the living area off the house only drops .5 off a degree all day .but I am considering putting a thermostat on the open side off the system because I think it's unnecessary to have the heat pump on all night,it's a 14kw daikan altherma mono bloc we have installed regards any feedback and questions are welcome

Hammy79

happylarry wrote: »

Hey guys first off I'm no guru but I have an air to water heat pump installed 2 years ago,I have to say I'm very happy with it and it's costs ,I can't tell you cop and the likes but I can tell you the cost my house is 3000sqf all ground floor.we have no oil we moved in to the house in 2009 august to be exact .that was the year off the hard frost from aug to aug 2010 our total electricity bills for house was1300 euro that's with the pump running 24/7 and that's with hot water 24/7 aswell we have no other source off heating .now our house is well above and beyond what would be considered well insulated a3if not a2 standard .and this year I'm only putting the heating on between 11pm and 9am and the living area off the house only drops .5 off a degree all day .but I am considering putting a thermostat on the open side off the system because I think it's unnecessary to have the heat pump on all night,it's a 14kw daikan altherma mono bloc we have installed regards any feedback and questions are welcome

HI,Could i ask you what the ball park price was for the heat pump and installation? I have a 3 year old house and would ideally like to get rid of oil boiler or even compine it with air to water. It is half rads half underfloor in 270m2 bunglow which is very well insuated.

Tommyboy08

Hammy79 wrote: »

HI,Could i ask you what the ball park price was for the heat pump and installation? I have a 3 year old house and would ideally like to get rid of oil boiler or even compine it with air to water. It is half rads half underfloor in 270m2 bunglow which is very well insuated.

You will have a problem with the rads and the heat pump, pm me the insulation info and area of house on underfloor and amount and type of rads and I can tell you what would suit you best and what it should cost you, then you can set about getting some prices

gerryh087

Tommyboy08 wrote: »

You will have a problem with the rads and the heat pump, pm me the insulation info and area of house on underfloor and amount and type of rads and I can tell you what would suit you best and what it should cost you, then you can set about getting some prices

Hi tommyboy Im starting new build of3500 sq ft and wondering about heating types and insul. also.At present I just have raft poured and was considering putting 100mm kspan in the floor.Is this enough ?Any comments would be great .Thanks

fclauson

about2build wrote: »

Thanks for all the good comments guys...and having read up it is a lot of energy to be expending...Any thoughts welcome on how I can reduce this consumption level...this i s the insulation I have at this stage
GROUND FLOOR 120mm kingspan tf70 under floor screed
perimeter insul of 25mm also required
FIRST FLOOR metal frame ceiling void be filled with rock wool
perimeter insul of 25mm also required here
WALLS bonded bead certainfil graphite .27 or similar in 150mm cavity
67.5 mm kingspan thermwall TW56 dry lining
WINDOW SILLS backed with 50mm KS TF70
ROOF 300MM of fibreglass quilt
triple glazed argon filled upvc windows throughout...u 0.8

thoughts?!

I would expand the cavity to 250 and do away with the 67.5 internal board
and I would up the floor from 120mm to 200
I would also put perimeter 25mm on all walls internal and external

and I would make sure I hace checked and calculated all of my thermal bridges

stonehinge

I'm not from media --just asking a simple question

Bee Man

gerryh087 wrote: »

Hi tommyboy Im starting new build of3500 sq ft and wondering about heating types and insul. also.At present I just have raft poured and was considering putting 100mm kspan in the floor.Is this enough ?Any comments would be great .Thanks

Expanded polyurethane (ie kingspan) is twice as good and twice as expensive as expanded polystyrene (ie aeroboard) until all the gas it is expanded with-argon- escapes in approx ten years. Then it is only as good as eps. Also eps is hydrophobic while epu is hydroscopic. When an insulation material becomes wet it becomes useless. Avoid any thin foil based insulation completely as only two percent of heat is lost through radiation thats all it can save you.

air

Bee Man wrote: »

Expanded polyurethane (ie kingspan) is twice as good and twice as expensive as expanded polystyrene (ie aeroboard) until all the gas it is expanded with-argon- escapes in approx ten years. Then it is only as good as eps.

This is untrue, while some gas is released, the U value of PUR is rated at the stable long term value of the insulation. Basically it over performs initially until performance drops to the quoted manufacturers figures.