Heat Pumps - post here.

samdeluxjones

Current status of heat pump.

Heating the underfloor has been off for about a month but circulation pump turns on every now and again.

The house is now heating the water in the system by 1 degree.

The house is concrete built and the little sun we are getting is heating it and keeping it at a steady 24-25 degrees.

Heat Pump.jpg

Latro

I don't quite get it why people claim here that in order to have heat pump to work properly you need to have passive spec house or near that.

It simply doesn't make sense to me.

So let me elaborate for a minute.
I need to invest large sum of money into insulation, hrv, air tightness etc get everything designed and commissioned by experienced and expensive specialist and then it will allow me to invest even larger sum of money into complicated, 20 grand worth of GSHP system that has to be replaced almost throughout after 15-20 or maybe even 10 years if you are unlucky?

If you have passive house wouldn't it make more sense to simply turn on lets say something like a 2000W kitchen oven with open door at 220C for 2-3 hours a day? 2000W run for 3 hours would cost you less than 1 euro per day.
Free heating system and the 20k euro kept in bank for 20 years will give you a nice return too

But on a more serious note. Why people think that there is some kind of secret magic behind running heat pumps. They are heating devices like oil, gas or anything else. Oh well the only "secret" is that you should not to try and produce too hot water with them if you want them run reasonably cheap. To compensate for low water temperature in the system you need large radiator and that's why underfloor is preferred for that because it is one big radiator.

There is a heat loss and heat gain. To keep the temperature constant at your desired level you need to compensate for the loss.
Switching from oil to HP or vice versa will not magically make your house warmer.
If you burn 2000L of oil per winter that means your heat loss was 20.000 kWh multiplied by your boiler efficiency(70-80%?) over that period.
With water to air heat pump you will probably get average efficiency of around 2.7, so to produce lets say 16.000kWh worth of heat that you need would cost you 16000/2.7 mutliplied by 0.15 euro (price of electricity per 1 kWh).

There you go. To produce 16k kWh worth of heat on oil will cost you around E1400. To produce 16k kWh on air to water heat pump will cost you E890. You save 510 a year at today's fuel prices. Life span of oil burner, life span of HP, service cost, comfort, future fuel prices? Answer for yourself.

If you go through 3000L of oil per winter the savings should be even bigger with the HP but if you only burn lets say 200L of oil during the winter with the passive house why would you invest into expensive HP at all?

mrawkward

Latro wrote: »

I don't quite get it why people claim here that in order to have heat pump to work properly you need to have passive spec house or near that.

It simply doesn't make sense to me.

So let me elaborate for a minute.
I need to invest large sum of money into insulation, hrv, air tightness etc get everything designed and commissioned by experienced and expensive specialist and then it will allow me to invest even larger sum of money into complicated, 20 grand worth of GSHP system that has to be replaced almost throughout after 15-20 or maybe even 10 years if you are unlucky?

If you have passive house wouldn't it make more sense to simply turn on lets say something like a 2000W kitchen oven with open door at 220C for 2-3 hours a day? 2000W run for 3 hours would cost you less than 1 euro per day.
Free heating system and the 20k euro kept in bank for 20 years will give you a nice return too

But on a more serious note. Why people think that there is some kind of secret magic behind running heat pumps. They are heating devices like oil, gas or anything else. Oh well the only "secret" is that you should not to try and produce too hot water with them if you want them run reasonably cheap. To compensate for low water temperature in the system you need large radiator and that's why underfloor is preferred for that because it is one big radiator.

There is a heat loss and heat gain. To keep the temperature constant at your desired level you need to compensate for the loss.
Switching from oil to HP or vice versa will not magically make your house warmer.
If you burn 2000L of oil per winter that means your heat loss was 20.000 kWh multiplied by your boiler efficiency(70-80%?) over that period.
With water to air heat pump you will probably get average efficiency of around 2.7, so to produce lets say 16.000kWh worth of heat that you need would cost you 16000/2.7 mutliplied by 0.15 euro (price of electricity per 1 kWh).

There you go. To produce 16k kWh worth of heat on oil will cost you around E1400. To produce 16k kWh on air to water heat pump will cost you E890. You save 590 a year at today's fuel prices. Life span of oil burner, life span of HP, service cost, comfort, future fuel prices? Answer for yourself.

I have a 1970's big windowed bungalow as was spending around €4K per annum on gas (modern condensing boiler with rads) electricity and some solid fuel. I added an extra layer of attic insulation, active air vents and an 8Kw AWS heatpump and ancillary DHW tank/controls. Mar 2017-Mar 2018, total energy spend €1429 with the comfort of 21C 24/7/365.

In theory, my results are nonsense, I am happy to enjoy the actual results.

I do think the constant temperature requires less energy to maintain heat at a steady level, over time the fabric of the house including the mass concrete floor act as a heat sink evening out the heavy loads required to be heating the house up with typical on/off heating cycling of a traditional system.

As a retired person, at home most of the day, it is impossible to put a price on the pure comfort of it. I hate to think what it would cost to achieve the same result using my old regime.

Latro

mrawkward wrote: »

I have a 1970's big windowed bungalow as was spending around €4K per annum on gas (modern condensing boiler with rads) electricity and some solid fuel. I added an extra layer of attic insulation, active air vents and an 8Kw AWS heatpump and ancillary DHW tank/controls. Mar 2017-Mar 2018, total energy spend €1429 with the comfort of 21C 24/7/365.

In theory, my results are nonsense, I am happy to enjoy the actual results.

I do think the constant temperature requires less energy to maintain heat at a steady level, over time the fabric of the house including the mass concrete floor act as a heat sink evening out the heavy loads required to be heating the house up with typical on/off heating cycling of a traditional system.

As a retired person, at home most of the day, it is impossible to put a price on the pure comfort of it. I hate to think what it would cost to achieve the same result using my old regime.

And that's what I'm trying to say.
If you spend 2-3k on oil right now you should spend considerably less switching to HP unless there is some serious fundamental flaw with the system design(too small radiators), installation or settings(too high flow temperature).

On the other hand if you make effort to build excellent performing passive house why would you invest into expensive heating system at all. Just get earlier mentioned kitchen oven or hair drier like device.
Forget about spending all the money on underfloor or even 20 rads with all piping and a bunch of other devices needed for that kind of system. It just doesn't make sense.

The less energy you house looses the less of a factor the energy cost becomes. If you lose almost zero energy it desn't matter how much it costs to compensate it.

mrawkward

mrawkward wrote: »

I have a 1970's big windowed bungalow as was spending around €4K per annum on gas (modern condensing boiler with rads) electricity and some solid fuel. I added an extra layer of attic insulation, active air vents and an 8Kw AWS heatpump and ancillary DHW tank/controls. Mar 2017-Mar 2018, total energy spend €1429 with the comfort of 21C 24/7/365.

Interesting, so your house isn't that well insulated then ? did you install underground heating ?

We've a 80's bungalow with a sort of attic conversion, roof was never raised and it was more of a space for the kids for the previous owner and a play area/bedroom though it can't be officially classed as a bedroom. So insulation in the roof could be better.

We could do eventually replacing the windows with low U type as the old ones are dirt and poorly fitted.

Eventually I hope to raise part of the roof and make a few rooms up there, the potential is huge as the house sits on 1 acre.

The Heating is a over sized 35 Kw oil boiler , it's huge and our plumber can't understand why they installed something so large but it heats the rads fast and they're nuclear to touch but the rads are the really old inefficient type that barely throw out any heat.

If we were to install a heat pump we'd have plenty of space for geothermal but whether I'd want to uproot the garden is another matter probably not.

If we had a feed-in-tariff system we could install solar PV and run HP and export all the excess in the brighter warmer months and import it back in winter to heat the house but I would fear the heat pump would have to run far more than it should shortening it's life.

Our other problem is the conservatory which sucks heat out of the house even with the door open so I would rather knock that and make it a proper functional room rather than a messy storage space in Winter to dry clothes.

I would even consider spray foam for the attic, I've always heard great things about this, seals every gap and air tight.

To do it right of course I'd need to gut the house but since we have no mortgage taking out a loan to do all this is not very appealing but neither is using over 3 tanks of Oil either.

External insulation is a huge cost too, also having sealed up the chimney makes a huge difference to draughts, it sucks air through the sitting room door and causes a large draught and sucks the heat out of the house with it.

Latro

Deleted User wrote: »

Interesting...

Looks like your house has massive heat loss. It will be expensive to keep warm on anything. If I were you I'd start with serious insulating plan first and then work from there. Perhaps that's all you need.
Think about insulation as a heating system with life span of the house that works for you every moment whenever it's cold outside and once installed the running cost is zero.

fergallyons

Hi guys,

Delighted to find this thread and really hoping for some guidance. I posted elsewhere and got an all mighty roasting about the accuracy of BER ratings (not what I was looking for). Any feedback would be greatly appreciated.

Our situation:

We bought a house 15 months ago. It is 15 years old, C1 BER, approx 3000 square feet with the attic converted. It was pretty cold when we moved in and has been a struggle to heat it effectively or efficiently! The boiler is on its last legs and the misses was looking for a new stove in the kitchen and with these combined costs I decided to look at alternatives and have arrived at the possibility of an air to water heat pump.

Steps so far:

Since moving in we have taken a number of measures to improve the house. We have insulated the attic, pumped the walls, installed an insert stove and blocked up the second chimney (all bar the wall pumping have been done since the last BER.)

Since then we have had an SEAI advisor out to assess our house for suitability to install a heat pump. We are waiting for confirmation next week but he feels confident that we will be under the cut off point of 2000km heat loss.

We have already had Unitherm in Galway come out to assess our house. We will be retrofitting this system through our current heating system (we don't have underfloor heating and putting it in now would be nuts expensive). Many of the radiators in the house are oversize for the rooms so we have been advised we won't need low temperature aluminium radiators in many rooms. There are currently 20 radiators in the system and will be looking at replacing about 8... Is it ok to have both types of radiators in the same system?

Questions:

So I suppose we are just looking for some guidance overall. Everyone who has an air to water system says they are delighted with it (but none we have spoken to have it installed without underfloor heating). So is hooking it up to the current radiator system a runner and if so is it ok to have a mix of radiator types? .....Note that we intend going with Uniterm as they have a lot of experience in the market and only work with fitters they have used over a long period of time.

For our size house, a need a 16kw Daikin has been recommended based on the assessment done (approx 8000 plus vat). In recent weeks there has also been a suggestion of a new Hitachi system coming out in January that operates at higher water temparatures and may be more suitable to an all radiator system (its about 1000 more expensive than the Daikin). Any feedback on these systems or any other recommendations?

We have been dealing with Unitherm because they are in this game a long time, are trusted and have a cousin working for them. I appreciate that they may be a little more expensive but have a good reputation. Is there anyone else reliable and cheaper? We are based in Clare.

Finally, any other thoughts? This is a significant amount of money that we don't overly have so really want to get it right.

Thanks in advance

I'll certainly be interested in this as we would not be in a position to install underfloor heating either.

A few Solar PV panels could go a long way to supplying power but the issue is that when you need it the most in the colder months there's a lot less solar energy. Wind energy is probability expensive. A FIT would allow to export in Summer and import back in winter, shame we don't have this.

All our rads would need replacing and it's an old skool system of all rads run on the same ring and not independent back to manifold in the hot press, I don't know if this really matters.

Latro

Latro wrote: »

Looks like your house has massive heat loss. It will be expensive to keep warm on anything. If I were you I'd start with serious insulating plan first and then work from there. Perhaps that's all you need.
Think about insulation as a heating system with life span of the house that works for you every moment whenever it's cold outside and once installed the running cost is zero.

The conservatory is causing a lot of heat loss really, we'd be far better off turning it into a useful room.

Walls were pumped but the attic could do with a lot more insulation really but the half assed attic conversion would prevent much better insulation.

Wartburg

Deleted User wrote: »

I would even consider spray foam for the attic, I've always heard great things about this, seals every gap and air tight.

If you´re happy with 2-3 air changes per hour and a frightening fire safety for your building on top, please go ahead.

sydthebeat

Wartburg wrote: »

If you´re happy with 2-3 air changes per hour and a frightening fire safety for your building on top, please go ahead.

Expand on this please.

Or else you're just seagulling

Tefral

sydthebeat wrote: »

Expand on this please.

Or else you're just seagulling

I've had this done on my house recently.

I took a handful of the off cuts and used one of those long gas flame lighters for candles. It took a about 20seconds of direct naked flame for it to catch fire and then it went up in a puff of the thickest blackest smoke.

I got a bit of a fright to be honest, so I did it again and timed it. I then got an off cut of the insulated board Xtratherm XT-MF. I set fire to that also. Literally not even a second of a difference and that did the same.

So its no more or less flammable in my uncontrolled experiment than standard house insulation. (The 12.5mm board gives 15mins of fire protection)

John.G

Latro wrote: »

I don't quite get it why people claim here that in order to have heat pump to work properly you need to have passive spec house or near that.

It simply doesn't make sense to me.

So let me elaborate for a minute.
I need to invest large sum of money into insulation, hrv, air tightness etc get everything designed and commissioned by experienced and expensive specialist and then it will allow me to invest even larger sum of money into complicated, 20 grand worth of GSHP system that has to be replaced almost throughout after 15-20 or maybe even 10 years if you are unlucky?

If you have passive house wouldn't it make more sense to simply turn on lets say something like a 2000W kitchen oven with open door at 220C for 2-3 hours a day? 2000W run for 3 hours would cost you less than 1 euro per day.
Free heating system and the 20k euro kept in bank for 20 years will give you a nice return too

But on a more serious note. Why people think that there is some kind of secret magic behind running heat pumps. They are heating devices like oil, gas or anything else. Oh well the only "secret" is that you should not to try and produce too hot water with them if you want them run reasonably cheap. To compensate for low water temperature in the system you need large radiator and that's why underfloor is preferred for that because it is one big radiator.

There is a heat loss and heat gain. To keep the temperature constant at your desired level you need to compensate for the loss.
Switching from oil to HP or vice versa will not magically make your house warmer.
If you burn 2000L of oil per winter that means your heat loss was 20.000 kWh multiplied by your boiler efficiency(70-80%?) over that period.
With water to air heat pump you will probably get average efficiency of around 2.7, so to produce lets say 16.000kWh worth of heat that you need would cost you 16000/2.7 mutliplied by 0.15 euro (price of electricity per 1 kWh).

There you go. To produce 16k kWh worth of heat on oil will cost you around E1400. To produce 16k kWh on air to water heat pump will cost you E890. You save 510 a year at today's fuel prices. Life span of oil burner, life span of HP, service cost, comfort, future fuel prices? Answer for yourself.

If you go through 3000L of oil per winter the savings should be even bigger with the HP but if you only burn lets say 200L of oil during the winter with the passive house why would you invest into expensive HP at all?

Or, maybe, to put it another way (same result):
Yearly Saving = House Kwh requirement x ((gas or oil cost per Kwh/Blr.Eff.)
- (elec cost per Kwh/SCOP))

Wartburg

sydthebeat wrote: »

Expand on this please.

Or else you're just seagulling

1. Air Tightness
You do not get the same air tightness performance by installing spray foam without any additional air tightness strategy, because you still have plenty of uncovered gaps in and around the spray foam insulation areas. Think about all the uncovered joints between different timber junctions or the joint between your wall plate and the block.... The new built houses, I tested with spray foam only so far, were all ending around 3 ACH. As a comparison: the house were I live at the moment, does not have any window tapes or membranes and didn´t get down light covers when I tested it, ended in 2.3 ACH.
My absolute favourite, that shows the "air tight weakness" of the spray foam insulation in an inadvertent way can be found here:https://www.fusioninsulation.com/air-tight-sealing--air-barrier-membranes.html The same simple and clear structure with an air tight membrane (installed in a standard way) will definitely end in 5 times less air changes or even better.

2. Fire Safety
On the paperwork, the most spray foam products are rated as B2 (or class E, coming from the new standards). That means that the fire should automatically quench off within a few seconds. I tested plenty of cut offs, coming from the hardened spray foam so far. Some of them quenched off as described, other ones have been constantly burning until I had to extinguish them. They all created plenty of black smoke whilst they burned. Recently I had a homeowner, who got the house spray foamed before the weekend. When I returned the week after I noticed they burned all the off cuts of the spray foam at the back of their house over the weekend. Beside the fact that this isn´t a great idea regarding environmental pollution, I would start considering, what protects the installed spray foam insulation in my attic, to prevent the same result in for my building in the worst case.

Carrickbeg

Question regarding heat pumps

If a heat pump is 12KW - 16KW does that mean that it is using your all the electricity in your house?

I was told before that u cant run two electric showers in ur house because the are 9kw each and that exceeds the electricity supplied?

antoinolachtnai

Carrickbeg wrote: »

Question regarding heat pumps

If a heat pump is 12KW - 16KW does that mean that it is using your all the electricity in your house?

I was told before that u cant run two electric showers in ur house because the are 9kw each and that exceeds the electricity supplied?

No. That is the heat output, not the electricity input.

Carrickbeg

antoinolachtnai wrote: »

No. That is the heat output, not the electricity input.

So if the COP is 4 a heat pump will use 4kw to produce 16kw?

Water John

Correct.

Wearb

Water John wrote: »

Correct.

But am I correct in saying that the COP changes depending on temperature difference and therefore (at low temperature times) it will take a lot more than 4Kw to produce 16Kw

Water John

Yes. It could be nearer to 3:1 in very cold weather. Thus 16 divided by 5 = 5+ Kw needed.

Carrickbeg

Like most things in life everyone's opinion on this is different. I went to a heating "expert" for advice on a heating system for my build and he was dead against the heat pumps and he reckoned the true COP was closer to 2 in Ireland with our 8 month winters. But on the flip side of that anyone I've met with a heat pump is happy with them.

Wearb

Water John wrote: »

Yes. It could be nearer to 3:1 in very cold weather. Thus 16 divided by 5 = 5+ Kw needed.

Do they not go even lower than that, e.g. COP of 2 in extreme conditions?
I am not trying to trap you here, I don't know enough about them and am curious.

Water John

If you check the detail spec on a HP. There are usually 2 COPs. One at lower temps, obviously not used in promotion.

Carrickbeg

Wearb wrote: »

Do they not go even lower than that, e.g. COP of 2 in extreme conditions?
I am not trying to trap you here, I don't know enough about them and am curious.

Everyone is curious about these things...id like to think ive a strong interest in all things property related and last year was the first time I heard of the air to water heat pumps...I had heard of the geothermal ones.

I think they have only become a runner since the insulation regulations have increased so significantly on new builds that houses now require very little heat to heat them.

Water John

The main ones like Mitsubishi and Daikin would claim efficient working down to -20C.
Yes the higher insulation spec and building envelope sealing lowers the heat demand. But that applies to all heat systems.
A2W are now plug and use, easy to install.
Don't forget the the heat recovery system, which is a necessity if the build is well sealed. Cost about €5K, very low running cost. This is a necessity, not an optional extra as some would suggest. Needed for air changes and healthy living conditions.

Latro

Wearb wrote: »

But am I correct in saying that the COP changes depending on temperature difference and therefore (at low temperature times) it will take a lot more than 4Kw to produce 16Kw

No, the maximum input will not change. The output will decrease.
For example 16kW pump will effectively become 12kW.

Water John

There may be a direct top up heating element to make up the diff.

Carrickbeg

Are these like the VW cars that said you get 50miles to the gallon when really they only did 35?

Water John

In fairness, We rarely have severe low temps. Read the small print on the COP. It's 7C to 35C.
Most people have low electricity bills. There are other threads where posters have put up their usage.

Latro

Carrickbeg wrote: »

Are these like the VW cars that said you get 50miles to the gallon when really they only did 35?

As with any product with efficiency involved. They use tricks to make it look better than they really are. You need to meet certain perfect conditions to get the efficiency claimed by the manufacturer.


The best way is to do your own research with healthy dose of skepticism and make your mind on your own.