Heat Pumps - post here.

Latro

Just don't fall for claim that to run HP you need excellent insulated house.
I'd claim the opposite. If you have passive house level of thermal envelope don't get heap pump and definitely not GSHP. It will never pay back for itself.
Heat loss is heat loss, regardless of heating system.
If you lose almost 0 heat you can run anything to compensate for that near 0 loss. In these cases the cheaper the system the better imo.

Water John

You still have Building Regs to pass.
If you want to run a small log stove, all day, that's fine.

Latro

Water John wrote: »

You still have Building Regs to pass.
If you want to run a small log stove, all day, that's fine.

I wouldn't consider running log stove of any size in any house a cheap solution unless you have free supply of fuel and even then all the labor involved... oh well that would't be for me but I'm sure some people would enjoy.

Water John

I was sort of joking originally but I just see ceramic stoves on The Great House Revival. It absorbs a good bit of the heat and lets it out gradually. So the house would be warm in the morning.

RedPandaDan

Hi Folks,

So I've been informed that my gas boiler is on its last legs and needs to be replaced. I've been looking at A2W heat pumps and was wondering if they are worth fitting to a small existing house? I wouldn't be in a position to install under floor heating, can they be used with rads?

House built in 2000
3 Bed Semi
80 m² total
D1 BER

Most stuff I've found about them online talks about the savings in large houses. Would anyone have a rough estimate how much it'd cost?

Thanks in advance!

If your house isn't extremely well insulated and air tight then you'd be far better off getting a modern 98% efficient gas Boiler, your old one is probably 70% that will save you 28% right there + change provider and you could save even more.

A HP is very expensive and the true life remains unknown, 10 years I hear, there's no pay back if that's the case.

A brand new build I'd say fair enough.

So if it were I, than I'd probably get a good efficient boiler and put the rest into insulation.

RedPandaDan

Deleted User wrote: »

If your house isn't extremely well insulated and air tight then you'd be far better off getting a modern 98% efficient gas Boiler, your old one is probably 70% that will save you 28% right there + change provider and you could save even more.

A HP is very expensive and the true life remains unknown, 10 years I hear, there's no pay back if that's the case.

A brand new build I'd say fair enough.

So if it were I, than I'd probably get a good efficient boiler and put the rest into insulation.

Thanks Mad_Lad, appreciate it.

No bother, I'm no expert so just offering my opinion , perhaps maybe get professional advise as to what is the best way to go, it might also be better electronic controls to go with your new boiler if you get one.

Carrickbeg

[Deleted User] wrote: »

If your house isn't extremely well insulated and air tight then you'd be far better off getting a modern 98% efficient gas Boiler, your old one is probably 70% that will save you 28% right there + change provider and you could save even more.

A HP is very expensive and the true life remains unknown, 10 years I hear, there's no pay back if that's the case.



A brand new build I'd say fair enough.

So if it were I, than I'd probably get a good efficient boiler and put the rest into insulation.

New gas boiler is the one for you. Heat pumps for A rated homes and work best with UFH.

SeanHarty

Deleted User wrote: »

No bother, I'm no expert so just offering my opinion , perhaps maybe get professional advise as to what is the best way to go, it might also be better electronic controls to go with your new boiler if you get one.

Use to work in the technical office of a large heating and plumbing merchants and your spot on in this case a high efficiency boiler is the way to go.

Shefwedfan

I seen mentioned earlier on another forum about Air to Air heat pump. Longer term I want to move from oil and was looking at air to water but it is retrofit and don't want to change radiators.

I was thinking of swapping to air to air. Does anyone have any experience of these systems?

SeanHarty

Shefwedfan wrote: »

I seen mentioned earlier on another forum about Air to Air heat pump. Longer term I want to move from oil and was looking at air to water but it is retrofit and don't want to change radiators.

I was thinking of swapping to air to air. Does anyone have any experience of these systems?

Do you want to change from oil for a cost saving measure for tree hugging on?

Best value for money for someone with oil is a efficient boiler and their cheap now and off the shelf.

Retro fitting a heat pump system CAN BE an expensive exercise

Shefwedfan

SeanHarty wrote: »

Do you want to change from oil for a cost saving measure for tree hugging on?

Best value for money for someone with oil is a efficient boiler and their cheap now and off the shelf.

Retro fitting a heat pump system CAN BE an expensive exercise

Your wisdom is great.....oh wise one.....

Expensive you say? I thought they would have just installed free of charge....with a few trees in garden so I can hug them

SeanHarty

Wasn't trying to take the piss out of you or anything, I have a degree in renewables so if anyone's a tree hugger it's me...


But with my degree and years experience working in the heating and plumbing industry selling these things I guess I would know a thing or two..

But please do plant the trees. The rate we are cutting them down is shocking.

Carrickbeg

Im told that the COP of heat pumps for heating hot water as oppose to space heating is 2.
Is this correct?

MOTM

Carrickbeg wrote: »

Im told that the COP of heat pumps for heating hot water as oppose to space heating is 2.
Is this correct?

How long is a piece of string?

Look for test results to EN16147 or Ecodesign technical documentation showing nWh efficiency from the supplier / manufacturer.

However, space heating efficiency in heatpumps (particularly for lower temperature applications such as underfloor heating) will likely be better than water heating efficiency as hot water is required at highter temperatures.

o1aa

Hi guys,

I have the air to water system installed by Dimplex and trying to figure out the hear curve.
People are saying to have it on low rather than high. Not sure what's meant by it?? I've attached my heat curve below, could someone explain to me what the numbers mean? I'm so confused! Also would love to hear some insight on the heat curves that worked in your houses! Thanks a mill.

o1aa

o1aa wrote: »

Hi guys,

I have the air to water system installed by Dimplex and trying to figure out the hear curve.
People are saying to have it on low rather than high. Not sure what's meant by it?? I've attached my heat curve below, could someone explain to me what the numbers mean? I'm so confused! Also would love to hear some insight on the heat curves that worked in your houses! Thanks a mill.

haven't a clue what all that means but just curious as to what type of house the A2W system was installed, older house, very energy efficient ?

Cost including installation and what was involved ?

Water John

Could be wrong but my reading of the first one is that when the outside temp is very low, the output side is 45C, but as outside temp goes above 0C it tapers down to a 40C output.
The second simply tells Total Operating Times for the Compressor, the time for space heating, the time the compressor is producing hot tap water, the number of hours the back up electric heating element had to come on, to boost the compressor.

o1aa

@Mad_Lad it's a new house in the estate. A2 rated.

Water John wrote: »

Could be wrong but my reading of the first one is that when the outside temp is very low, the output side is 45C, but as outside temp goes above 0C it tapers down to a 40C output.
The second simply tells Total Operating Times for the Compressor, the time for space heating, the time the compressor is producing hot tap water, the number of hours the back up electric heating element had to come on, to boost the compressor.

Thanks a lot for this! And why would the compressor come on to produce hot tap water? I thought I the water goes below certain degree that I set it at, the heat pump(starts working outside) and heats up the water to go to desired level.

I've been told that the compressor shouldn't run more than the heating , as this costs money. In my case the compressor is working more. Any idea why?

And when does the backup heater start working ?

I'm c a newbie in this and it's not so statight forward as heating up the house with gas!

Water John

Not an authority of HPs. The back up heater only comes on in very cold weather to supplement the HP. Usually HPs have a split system. The main one heats water to 40/45C for space heating either under floor or rads. A second unit takes water to 55/60C for tap/shower water.
The higher temp you take water to the less efficient the unit is. So the unit doing the space heating operates at a better efficiency (COP) than the tap water heating.

Condenser

Water John wrote: »

Not an authority of HPs. The back up heater only comes on in very cold weather to supplement the HP. Usually HPs have a split system. The main one heats water to 40/45C for space heating either under floor or rads. A second unit takes water to 55/60C for tap/shower water.
The higher temp you take water to the less efficient the unit is. So the unit doing the space heating operates at a better efficiency (COP) than the tap water heating.

This is incorrect. The system is not split. If you have ufh downstairs and rads upstairs the heat pump will heat the water to the temp required by the highest temp system meaning your overall COP will drop. So if you use rads that need 45c and your ugh needs 30c your efficiency is dictated by the need to satisfy the radiators and will drop performance by at least 35%.

The heat curve also needs to be set up to reflect your heating system so if your rads need 50c when it's 0c outside in order to heat the house then you set it to reflect this. If you have ufh alone 30c might be sufficient at 0c and 25c might be sufficient at 15c.

Regarding back up immersions, they tend to come on far more regularly in systems that require high temps such as radiators, have small hot water tanks usually less than 300l and air to water systems where lower outside temps put much more pressure on the system and defrosting is an issue.

GraceKav

Hi all, Hoping I have this in the right spot - we're just going out to tender on a new build which will have a heat pump - we've had conflicting advice about whether or not we should keep this as a PC sum item - Thoughts? Thanks.

Wearb

GraceKav wrote: »

Hi all, Hoping I have this in the right spot - we're just going out to tender on a new build which will have a heat pump - we've had conflicting advice about whether or not we should keep this as a PC sum item - Thoughts? Thanks.

Have a read here https://www.askaboutmoney.com/threads/warning-all-the-pc-provisional-sum.166542/

Carrickbeg

GraceKav wrote: »

Hi all, Hoping I have this in the right spot - we're just going out to tender on a new build which will have a heat pump - we've had conflicting advice about whether or not we should keep this as a PC sum item - Thoughts? Thanks.

Get your heat loss calculations done for your house and then get a properly sized system to meet your needs...

GraceKav

Wearb wrote: »

Have a read here https://www.askaboutmoney.com/threads/warning-all-the-pc-provisional-sum.166542/

Thanks Wearb, I think I've read this before but good to have a refresher as its been a while. I may have misunderstood the engineer as it sounded like they were planning to let the builder spec the heat pump which I wasn't happy with for all the reasons detailed in that article and more. We're sitting down to go through the full tender and construction drawings (which we have commissioned in full) next week and fingers crossed I've just misunderstood them. Just wanted to get a sensecheck that if I haven't misunderstood them, I'm not being unreasonable in wanting to spec 100% the heat pump and the supplier/model etc for the builder.

AnswerIs42

Does anyone have their heat pump installed upstairs or in the roof? We are thinking of installing it in the gable wall upstairs so it would mean maintenance guys would need a ladder or scaffolding (Health & Safety reasons??) to service it from the outside. I'm trying to see if their are other issues with keeping the heat pump off the ground floor that should be factored in.

John.G

KCross wrote: »

OK, I'm familiar with all those metrics. They are available on the main screen of the system as well. There isn't a great deal of benefit to being able to see them from the app to be honest.

Once the system is running and stable the way you want it it is fully automatic and there is no real requirement to remotely access it.

Even if you changed some of the settings it takes time for the system to "rebalance" so doing it from the app doesn't buy you anything really.

It should be free, tbh.

Do any of the ASHP manufacturers display the time on defrost cycle(s) and the compressor energy required since defrosting has such a huge effect on the COP/SPF of the installation or has any user any data/info on this?.

Latro

I retrofitted 9kW A2W in to my house last month.

I will post here how it goes once the heating season starts.
So far we use it to heat DHW 280L tank.
Water temp 45 degrees, at the moment cost according to the manufacturer app is 12-15 cents per day. 2 adults+1 child.

The target is to have constant 20-21 degrees throughout the day. The heating window initially is going to be from 7am to midnight with downtime for the night to avoid low external temperatures.

Some stats:
2 storey detached house with attached garage(heated), in total around 200sqm heated surface. Finished in 2013 to pre 2008 regs. Timber frame.
Ground floor: open plan, office, utility, toilet, garage.
First floor: 3 bedrooms, 2 en suite, bathroom, TV/play room, hot press, small walk-in wardrobe.

Insulation:
-walls 6 inch fibreglass
-slab: no idea here since I bought the house at near builders finish state and never had opportunity to see whats in it.
-attic: initially there was 10(4+6) inches of fiberglass, upgraded with another 2 layers of 6 inch of the same in criss-cross pattern. In total 22 inches. Heh I know, a lot, but it is relatively cheap material and easy to DIY.

Windows: known brand PVC, double glazed.
Ventilation: traditional holes in the walls, I'm contemplating upgrading to heat recovery, maybe next year, depends on this season heating bills.

Steel, double Radiators: 8 fairly large downstairs and 6 of the same upstairs plus 4 towel rails in total.

Fingers crossed it is enough. If not I will add few more as this option would be far cheaper than going underfloor at this stage. Also easy DIY-able with timber frame.

3 zones for heating: ground floor, 1st floor and DHW tank. No zone thermostats at all, TRVs on all rads.

Heat pump: 9kW, monoblock, inverter, single phase with cooling option and desktop PC or android phone loging/monitoring/operating bells and whistles.
One of the latest model of big, known brand.

John.G

Latro wrote: »

I retrofitted 9kW A2W in to my house last month.

I will post here how it goes once the heating season starts.
So far we use it to heat DHW 280L tank.
Water temp 45 degrees, at the moment cost according to the manufacturer app is 12-15 cents per day. 2 adults+1 child.

The target is to have constant 20-21 degrees throughout the day. The heating window initially is going to be from 7am to midnight with downtime for the night to avoid low external temperatures.

Some stats:
2 storey detached house with attached garage(heated), in total around 200sqm heated surface. Finished in 2013 to pre 2008 regs. Timber frame.
Ground floor: open plan, office, utility, toilet, garage.
First floor: 3 bedrooms, 2 en suite, bathroom, TV/play room, hot press, small walk-in wardrobe.

Insulation:
-walls 6 inch fibreglass
-slab: no idea here since I bought the house at near builders finish state and never had opportunity to see whats in it.
-attic: initially there was 10(4+6) inches of fiberglass, upgraded with another 2 layers of 6 inch of the same in criss-cross pattern. In total 22 inches. Heh I know, a lot, but it is relatively cheap material and easy to DIY.

Windows: known brand PVC, double glazed.
Ventilation: traditional holes in the walls, I'm contemplating upgrading to heat recovery, maybe next year, depends on this season heating bills.

Steel, double Radiators: 8 fairly large downstairs and 6 of the same upstairs plus 4 towel rails in total.

Fingers crossed it is enough. If not I will add few more as this option would be far cheaper than going underfloor at this stage. Also easy DIY-able with timber frame.

3 zones for heating: ground floor, 1st floor and DHW tank. No zone thermostats at all, TRVs on all rads.

Heat pump: 9kW, monoblock, inverter, single phase with cooling option and desktop PC or android phone loging/monitoring/operating bells and whistles.
One of the latest model of big, known brand.

Its not clear to me at least but have you upgraded your house insulation (just) before you installed the HP and what form of heating are you converting from?.
It will be very interesting to see how fast the house will take to heat up after being off from midnight to 0700 each night bearing in mind that you will now have ~ 30 deg rads with ~ 50% output of the 50 deg rating.
The best of luck with your installation.