# Air to Air Heat Pumps



## goosebump (22 Jan 2018)

I've seen a lot of info about Air to Water Heat Pumps recently, and new SEAI grants (€3,500) are becoming available for these in a couple of months.

However, there is also going to be a grant for Air to Air heat pumps (€600).

These are basically inverted fridges. They try to cool down the air outside (like a fridge) and the heat generated is transferred inside. If you've ever been on a package holiday to Spain, the A/C unit on the wall of your apartment is one of these. They can do both cooling and heating. Apparently, they are ideally suited to Irish climate for heating, because air is moist and temperatures never fall too far below zero.

The COP score is between 3-5 depending on size of unit, which means for every 1 unit of energy you put in, you get between 3-5 units of heat energy out.

I am thinking of getting one of these for an extension that I have. There doesn't appear to be too many suppliers to residential customers. These guy seems to know what he talking about:

http://heatpumps.scanhome.ie/

Has anyone any experience of these that they could share?


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## Fire away (23 Jan 2018)

I know a friend who has air to water system and electric bill is massive 300e a month. System cost close to 20k to install also. It'  a big house but that is crazy money for a new house


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## Anniekate (7 Mar 2021)

Can anyone recommend a good reliable heat pump. Any comments about Vitocal Heat pump by Weissman. Are they any good?


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## Coldwarrior (8 Mar 2021)

Anniekate said:


> Any comments about Vitocal Heat pump by Weissman


Not sure about their heat pumps but Wiessman make great boilers so I'd expect their heat to also be good quality.


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## noproblem (8 Mar 2021)

For the pump to be totally efficient it's advisable to get your house or desired project technically assessed. In short, its air tightness, insulation, draughts, windows, chimneys (if any) etc. When people say it's costing them a fortune in electricity to run the heat pump I can assure you they didn't properly do their homework before going ahead with the work. Goosebump; This is a quickish answer to your query but very relevant.


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## Anniekate (8 Mar 2021)

Thanks Coldwarrier & noproblem for your advice. Good to know that their boilers are great. My house has been assessed and what is recommended is a 5k Vitocal by Weismann for my house. Its a semi D with  4, bedrooms


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## Zenith63 (8 Mar 2021)

Anniekate said:


> Thanks Coldwarrier & noproblem for your advice. Good to know that their boilers are great. My house has been assessed and what is recommended is a 5k Vitocal by Weismann for my house. Its a semi D with  4, bedrooms


Out of interest what does an assessment like this look like and who/where do you get one done?  Is it an actual test (ie. seal the doors, pump in air and see how quickly it escapes) or more like the BER?


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## Anniekate (8 Mar 2021)

I had assessment done with a retrofit company to measure heat loss when a full insulation job is done e.g attic insulation, floor insulation external insulation ( in my case). A BER would then be achieved and the idea in order to achieve a BER rating to B2 at least for houses built before 2011.


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## Micks'r (8 Mar 2021)

Anniekate said:


> I had assessment done with a retrofit company to measure heat loss when a full insulation job is done e.g attic insulation, floor insulation external insulation ( in my case). A BER would then be achieved and the idea in order to achieve a BER rating to B2 at least for houses built before 2011.



So no air tightness test?


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## Anniekate (8 Mar 2021)

Not yet


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## Jazz01 (8 Mar 2021)

@Anniekate 
From my understanding, unless your home is air tight, the air to heat pump wouldn't be recommended as a means to heat the home. Maybe as part of the retrofit you are doing, they will be performing this air-tightness? It's difficult to do in existing houses, but I guess not impossible.

The installation of all that insulation needs to be coupled with allowing enough ventilation flow in through the house and out again, so there will need to be a mechanical ventilation system running too. 

All this costs money, so depending on your budget, it may / may not be feasible to implement everything. I recently saw on a RTE program (think it was EcoEye?) of a deep retrofit performed on a home, where the costings came to ~ €75K in total, then the applicable grants brought it down to around €50K. The owner did not go through in detail what was done, but at a high level, was the external insulation, new windows, doors, attic insulation and the air-to-heat system. Brought the house to an A rating (A2 or A3 I think).

(_The air to water heat system I have in my own home is a Daikin system, double fan - think you were asking about the types in a different thread_)


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## Zenith63 (8 Mar 2021)

Anniekate said:


> Not yet


OK thanks.  I'm in a similar position to you, I'd love to move to a heat pump but only if it makes sense to do so.  In the case of my home it would fare relatively well on a BER assessment (Xmm of insulation in the walls, Y insulation in the floors).  The problem is when I started to do some DIY renovations I found areas where the insulation was missing in the walls, where the plasterboard had a gap of up to 100mm to the floor which was covered with the skirting board, gaps in the concrete floor covered by wooden floor etc etc.

With the quality of much building in Ireland, I think an air tightness test (not assessment) is essential before considering a heatpump.


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## noproblem (8 Mar 2021)

As far as I understand it and in a common sense way, it is at the end, when all work has been completed that the air tightness test is carried out. In order to satisfy the grant criteria, etc and get the rating to the A standard it must meet the standard as set out. It's strict and is done properly. By the way, anyone thinking they can get a survey carried out for free, you can't.  However, if you deal with the company that carries out the assessment for you the cost will be allowed off the final price. 
On another note and nothing to do with any of the above, as regards getting estimates for any building work etc, is a common enough thing to get from handymen, builders, etc, and doesn't cost anything.  But, if you want a detailed quotation for work then most qualified builders and tradespeople are beginning to charge for them because they are now getting Quantity Surveyors to price the work and (naturally enough) passing on the cost. You'll certainly see it if you ask a builder to quote a price for building a house or similar. It gets rid of the "tyre kickers" as they say.


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## Zenith63 (8 Mar 2021)

noproblem said:


> As far as I understand it and in a common sense way, it is at the end, when all work has been completed that the air tightness test is carried out.


If you were doing a big renovation that would make sense. In my scenario I’m wondering about adding the heat pump to a house that is already at a decent BER but without doing other renovation work, so the air tightness test would be to validate what is already in-place and make sure it is suitable for a heat pump install.


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## Micks'r (8 Mar 2021)

noproblem said:


> As far as I understand it and in a common sense way, it is at the end, when all work has been completed that the air tightness test is carried out.


This is flawed logic in the sense that in order to know what  / where to address from an air tightness pov, an initial test is paramount imo. Yes, by all means have a second one at the end for input into the BER assessment but it is generally too late then if unknown leaks are doscovered when all finished etc are in place.


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## Hooverfish (9 Mar 2021)

Micks'r said:


> This is flawed logic in the sense that in order to know what  / where to address from an air tightness pov, an initial test is paramount imo. Yes, by all means have a second one at the end for input into the BER assessment but it is generally too late then if unknown leaks are doscovered when all finished etc are in place.


Is the airtightness test not just an indication of the overall situation, rather than showing where any issues are? I've always thought fix the obvious problems, then do tests that actually identify where issues lie (I'd love to know more about these), do work, retest for overall airtightness? Or are there different types of tests?


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## Micks'r (9 Mar 2021)

Hooverfish said:


> Is the airtightness test not just an indication of the overall situation, rather than showing where any issues are? I've always thought fix the obvious problems, then do tests that actually identify where issues lie (I'd love to know more about these), do work, retest for overall airtightness? Or are there different types of tests?


The issue I find frequently when doing the surveys / tests is that the "obvious" problems to the client are rarely the main issues leading to somewhat wasted effort & resources by the client.
You are correct in that the official air tightness test does give an overall result which represents the air tightness of the building. However, not simultaneously investigating the cause of the leakage when set up to carry out the depressurisation of the building is, imo, a wasted opportunity to garner maximum information from the test (and value for money).


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## dem_syhp (10 Mar 2021)

We got a full deep retrofit including a heat pump to take house from a D2/3 to a A2.  However, I'd argue we've gained most of the benefit from the insulation and new windows.   I would not be rushing to get a heat pump.
- Not cheaper (so far the bills are more expensive - I'm basing this on energy used not cost.  But I'm not comparing like with like due to working from home, and haven't had a full year yet.  For reference we've heating set to 16-18 degrees, lower the temperature at night and have a solar panel.   I suspect that the hot water is set to come on more than we need and when I get time I'll do a bit more investigating - though we were strongly recommended not to change the settings for it)
- Radiators are physically quite a bit bigger for use with heat pump, with small rooms its quite a big difference.
- We've had issues with our water since upgrade (problem with differences in pressure from heat pump? /  an installation/design problem, or something historic in our system that only happened when we upgraded - 4-6 months later still working with installer on root cause) This is a risk with any building work that there are problems.
- Less flexible (heats up slower.  They say that this means houses don't go through the swings of being too hot / cold, but I'd put most of the differences down to the insulation versus the heating - if you try and heat it quicker its more expensive, most efficient at a steady heat)
- More of a design issue, but one to consider, if a zone is balanced, but the rooms aren't you still end up with cold/hot rooms -  we'll probably be able to tweak this over time, but not as easy as before.

If we'd got the insulation done and not upgraded heating, we'd have a system where rooms heated up quicker at a lower cost.   We got a grant, so the extra cost of the heat pump was somewhat offset, but I'm really not so sure yet that it was worth it to us.   I'm interested to see how the costs work out over summer.  We'd figured we were doing the under floor insulation, etc... so while everything's up, do it all at once.   I certainly wouldn't consider it outside of this.  But maybe ask me next autumn what I think.


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## _OkGo_ (10 Mar 2021)

dem_syhp said:


> - Not cheaper (so far the bills are more expensive - I'm basing this on energy used not cost. But I'm not comparing like with like due to working from home, and haven't had a full year yet. For reference we've heating set to 16-18 degrees, lower the temperature at night and have a solar panel. I suspect that the hot water is set to come on more than we need and when I get time I'll do a bit more investigating - though we were strongly recommended not to change the settings for it)



That cannot be correct. If your home has genuinely gone from a D2 to A2, your energy use should be a fraction of what it previously was regardless of the type of heating system. Are you excluding the fact that with a heat pump you are now electricity only and have no gas bill??

It sounds like you are not using your heating system properly or you were poorly advised during the renovation. Generally it does not make sense (cost/benefit) to have both a heat pump and solar panels. Heat pumps are an extremely efficient way to heat water particularly during summer months when air temperatures are higher and the COP is high. Your heating system should not really come on during those months particularly in an A rated home, its usually the opposite, trying to get retained heat out of the house in summer months. So your electricity usage should be very low at a time when your solar panels can generate an excess.

Solar panels are not as effective during winter months when your heat pump is actually heating your home so they are generally wasted cost and effort. They over supply in summer months and massively under supply in winter months. They make more sense when combined with gas heating


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## Coldwarrior (10 Mar 2021)

_OkGo_ said:


> Generally it does not make sense (cost/benefit) to have both a heat pump and solar panels.


They probably have photovoltaic panels, which would make more sense with a heat pump (offsetting the electricity the heat pump uses) than the solar tubes for hot water.


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## Coldwarrior (10 Mar 2021)

_OkGo_ said:


> That cannot be correct. If your home has genuinely gone from a D2 to A2, your energy use should be a fraction of what it previously was regardless of the type of heating system. Are you excluding the fact that with a heat pump you are now electricity only and have no gas bill??


I would guess they are comparing with the previous year, where they may have been at work out of the house most of the day with the heat off, to now where they are wfh and the house is maintained at a level comfortable temperature all the time?

dem_syhp am I correct? Otherwise I'd be surprised that the units of energy needed hasn't dropped a fair bit.


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## _OkGo_ (10 Mar 2021)

Coldwarrior said:


> They probably have photovoltaic panels, which would make more sense with a heat pump (offsetting the electricity the heat pump uses) than the solar tubes for hot water.



The same applies to PV. In a highly efficient A rated home, the only heating required during summer months (and late spring/early autumn) should be for water. If you need 8kWh of energy to heat water, your PV system needs to be sized to supply 8kWh during summer months. The same amount of heating with a heat pump can be achieved using 2.25kWh of electricity, of which a lot can be done at very cheap night rates

Basically your heat pump should not be running off an oversized PV as it is more economical and energy efficient to just use the grid. During winter months, the same PV is contributing very little to electricity, maybe 2-3kWh per day so it is not a good investment along with a heat pump.



Coldwarrior said:


> I would guess they are comparing with the previous year, where they make have been at work out of the house most of the day with the heat off, to now where they are wfh and the house is maintained at a level comfortable temperature all the time?


WFH should only be a small contributor (5-10%) especially if it is A-rated. Going from D to A rated should have slashed the energy use so it is more than likely behavioral changes or incorrect use of the system (wrong settings, constant fiddling)


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## Micks'r (10 Mar 2021)

_OkGo_ said:


> That cannot be correct. If your home has *genuinely* gone from a D2 to A2, your energy use should be a fraction of what it previously was regardless of the type of heating system. Are you excluding the fact that with a heat pump you are now electricity only and have no gas bill??


This, imo, is the flaw of the whole BER system for rating a dwelling especially when it comes to the heat retention characteristics, in that the rating achieved (BER) is a result mainly of a box ticking exercise rather than any kind of in-depth investigation.

I expect this flaw to come more to the fore when a lot of heat pumps are installed replacing convention heating systems and are found to be not up to the task (either very expensive to run and/or not able to deliver the heat when very cold) because the BER cert cannot be relied upon.


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## dem_syhp (10 Mar 2021)

Yes, sorry, photovoltaic panels, so yes, I'd absolutely expect costs to be lower in the summer (hence the comment, I can't really say for another 6 months how things will fare).

We still have a gas for cooking, albeit very low energy usage, but still have standing charges.   [I know we can change, but for now things are staying as they are]

Yes, I agree we've someone in the house all the time, which wasn't the case a year ago, so I can't compare like with like.   But I've no reference to how much other peoples bills have gone up with someone working from home.

Our yearly gas bill before, for heating + hot water, was about 500 Euro, this is based on the last two years - This was without shopping around as our figures were low, and shame to say on askaboutmoney I just didn't.    But our most recent electricity bill (for two months) was in excess of 220 Euro (Estimated reading, but I'd the actual kWh used for the billing period month and just calc'd out difference).  I didn't really expect our bills to go down, but hadn't expected it to go up....which by the time I've included summer it may not.  I can only go on the data I currently have. 

As has been suggested behavioral change is part of the problem....but its not one we want to make.    (lack of research on our part before).    How we previously liked to live is to turn on the heating when we were cold.  So if actively working around the house - say working out, DIY, cleaning, moving around that is, I'd rarely need much/any heat.  If sitting down, on the computer, in front of the television, I want a warmer room.   I don't want a warmer room all the time - but that's how the set up is designed to run -I know its bad practice to be messing with it, so I don't..... but it doesn't suit me (yet!  Maybe I'll go all soft and will want the additional heat  ).

I'm not saying they're not efficient, I'm saying, so far, based on 4-6 months, the jury is out as to which way I'd go if given the choice again.   The house is way more comfortable, we absolutely had rooms that were never comfortable, but that's the insulation.


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## _OkGo_ (10 Mar 2021)

dem_syhp said:


> So if actively working around the house - say working out, DIY, cleaning, moving around that is, I'd rarely need much/any heat. If sitting down, on the computer, in front of the television, I want a warmer room.


That is one of the downsides to A-rated homes. Once you get used to the constant temperature, any level of moderate activity can suddenly make you feel very warm. 


dem_syhp said:


> but it doesn't suit me (yet! Maybe I'll go all soft and will want the additional heat  ).


I can confirm that's exactly what happens 

My advice to get the most out of the system:

Change provider every year for the cheapest rates
Switch to a day/night rate if you have a night meter
Do not let the room temperatures drop at night, it is very cheap to heat at night on the lower rates.
Do set your bedrooms lower all day so they are not uncomfortable at night even if heating comes on
Keep all doors open especially within the same heating zone to maintain the constant temp. (We benefit from a south facing living room with large windows that effectively keeps our stats at temperature during daytime even in winter so very little additional heat required)
Check the temperature on your water tank and reduce it until the water temperature is comfortable. This is often a big mistake and waste of energy with heat pumps. To maintain a good COP, the water tank should be set as low as possible. It makes no sense to have really hot water coming out of taps that you then use the cold mixer to cool. There is a balance too between how low you can drop the temp and having enough water for all residents to shower etc.
Similarly, the output temperature for your space heating is just as important. Dropping the temp by a few degrees means the systems stays on for longer but runs more efficiently
Finally, if you do make changes to stats or other temperature settings. Let it 'settle' for a few days before adjusting again until everything feels comfortable
You won't really see the impact of any of the above suggestions until next winter as your summer usage should be very low anyway



dem_syhp said:


> I'm not saying they're not efficient, I'm saying, so far, based on 4-6 months, the jury is out as to which way I'd go if given the choice again. The house is way more comfortable, we absolutely had rooms that were never comfortable, but that's the insulation.



 That is probably where you frustration lies. As you already had gas, you didn't really need a heat pump. They would both be as effective at heating your home. Heat pumps are not necessarily better than gas, they are just another option in A-rated homes. Their benefits rapidly disappear if homes are not A-rated. Personally, I would be quiet annoyed with whoever spec'd your home to have gas, PV and a heat pump, it makes no sense.


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## dem_syhp (10 Mar 2021)

Thanks @_OkGo_ for the suggestions.   Many of them we're already on our way to learning - I'm quite sure I'll be able to get back down to where we were, but I suspect it will take a bit of monitoring!


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## Coldwarrior (11 Mar 2021)

_OkGo_ said:


> Check the temperature on your water tank and reduce it until the water temperature is comfortable.


Just on this, the temp of the tank should be brought up to 60 C at least once a week to prevent any legionella bacteria growing. Not sure if the heat pumps have a mode for this (I think some do? ), if not then a 7 day timer immersion could be used to give it a quick blast of a higher temperature.


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## RobFer (11 Mar 2021)

_OkGo_ said:


> That is one of the downsides to A-rated homes. Once you get used to the constant temperature, any level of moderate activity can suddenly make you feel very warm.
> 
> I can confirm that's exactly what happens
> 
> ...


I guess hypothetically if carbon taxes are radically increased, this person's system may gradually become easier to justify financially.


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## mike2017 (11 Mar 2021)

If it's vented, yes legionella is a risk
It it's unvented my understanding is no air can get into system so no risk of legionella
Interestingly as the thread is about Air to Air, Kore had a recent Daikan seminar online (youtube has a copy) and air to air systems can't heat water, air to water can. They are working on a system to deliver this next year as apartments would find this combination useful. They do supply heat emitters than can cool or heat which is interesting and can be mounted up high out of the way (with their A2W models). 
If retrofitting A2W watch out for microbore - not compatible with that piping so more mess.


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## Foreveramber (20 Mar 2021)

_OkGo_ said:


> That is one of the downsides to A-rated homes. Once you get used to the constant temperature, any level of moderate activity can suddenly make you feel very warm.
> 
> I can confirm that's exactly what happens
> 
> ...


Do you have to leave all the doors in the same heating zone open? I'm thinking of replacing my Grant's oil burner replaced with the air to water heat pump but it wouldn't suit me to leave all doors open


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## _OkGo_ (20 Mar 2021)

Foreveramber said:


> Do you have to leave all the doors in the same heating zone open? I'm thinking of replacing my Grant's oil burner replaced with the air to water heat pump but it wouldn't suit me to leave all doors open


The 'keep the doors open' comment is in relation to passively keeping an even temperature in A-rated homes. Not specifically for a heat pump but it all helps. Basically there is no point letting some rooms overheat by closing doors while sunlight is streaming in and your heating system is on bringing a room up to temperature at the other side of the house.

From your other post, a heat pump is probably not a good option for you until you have addressed all the heat loss issues ( in particular the convective heat loss) as pointed out by @Micks'r. Heat pumps are only a part of the overall heating system. Putting one on an old house is a bad idea unless all heat loss issues have been addressed.


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## roker (21 Mar 2021)

Anniekate said:


> I had assessment done with a retrofit company to measure heat loss when a full insulation job is done e.g attic insulation, floor insulation external insulation ( in my case). A BER would then be achieved and the idea in order to achieve a BER rating to B2 at least for houses built before 2011.


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## David_Dublin (18 Apr 2021)

_OkGo_ said:


> That is probably where you frustration lies. As you already had gas, you didn't really need a heat pump. They would both be as effective at heating your home. *Heat pumps are not necessarily better than gas, they are just another option in A-rated homes. Their benefits rapidly disappear if homes are not A-rated*. Personally, I would be quiet annoyed with whoever spec'd your home to have gas, PV and a heat pump, it makes no sense.



Is the above pretty much undisputed?

We're planning an extension and refurb job. We're gas at the moment, but need to replace boiler, and extension part of house will be UFH. Wondering if we should plan to stay gas, or run as A2W.

Other downstairs rooms may also be UFH as they are draughty suspended floors, old house, so a good opportunity to cut joists and pour concrete. So would make sense to go UFH in that case.

Some people I talk to are adamant that A2W is the way to go. Elsewhere I read thats only for A rated, and even then running costs can be high. I'm just so confused! Also, we have decent rads upstairs, so going A2W would mean changing these to alu ones.


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## Micks'r (19 Apr 2021)

Comparing gas or oil fired ch to a heat pump system is like comparing apples to oranges. Yes, they are both heating systems just as apples & oranges are fruit but that is really where the comparison ends. 
The main function of a heating system is to supply heat to the house at a higher rate than the heat is lost from the house. 

High temperature heating systems such as gas / oil were developed for houses with a high heat loss rate. These systems work well because they are capable of delivering large amounts of heat energy in a short period of time. They can deliver heat at a higher level than the house loses it so the house heats up.

Low temperature systems such as heat pumps are used to deliver a much lower level of heating over a much longer period of time. Therefore they work best when married to low temp distribution systems such as uf, high thermal mass buildings and also where the heat loss from the house is very low to start off with. Also they are designed to be running constantly so the house doesn't swing madly from cold to hot to cold etc but rather stays as a constant comfortable temperature.

The issue (confusion) arises when you try to shoehorn a hp system in a house with high levels of heat loss. You end up with v high electricity bills or not being able to heat the house or in some cases both!

This is why it is vital that before a hp is considered, serious attention must be paid to the significant reduction of the heat losses in the first place.


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## David_Dublin (19 Apr 2021)

Micks'r said:


> Comparing gas or oil fired ch to a heat pump system is like comparing apples to oranges. Yes, they are both heating systems just as apples & oranges are fruit but that is really where the comparison ends.
> The main function of a heating system is to supply heat to the house at a higher rate than the heat is lost from the house.
> 
> High temperature heating systems such as gas / oil were developed for houses with a high heat loss rate. These systems work well because they are capable of delivering large amounts of heat energy in a short period of time. They can deliver heat at a higher level than the house loses it so the house heats up.
> ...



Thanks Mick. I've a good understanding of the above, all makes sense.

In my case, though we most likely have sufficient thermal mass in the ground floor floors, the issue I have is that when undertaking a big refurb, including new windows, doors, insulation, airtightness measures, I don't know if the result of this work will deliver a house suitable for hp, i.e. what the heat loss will be and how much running a hp will be/how effective it will be.

I know what the likely answer to this is: make it so, only go for hp if the result will support efficient use of hp by engaging with the right professionals and design for a specific BER rating. Maybe that is my answer.


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## noproblem (19 Apr 2021)

Anniekate said:


> I had assessment done with a retrofit company to measure heat loss when a full insulation job is done e.g attic insulation, floor insulation external insulation ( in my case). A BER would then be achieved and the idea in order to achieve a BER rating to B2 at least for houses built before 2011.


Hopefully you got this done with one of the companies on the SEAI list? You will pay for this and it's quite substantial, but if you chose the company to do the work they'll allow you this cost against the overall job. The quotation they give is very, very, detailed and the company I saw and was involved with on behalf of my sons job in Dublin really knew what they were doing. It wasn't a quotation given with a quick look and a few figures.


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## Micks'r (19 Apr 2021)

David_Dublin said:


> I know what the likely answer to this is: make it so, only go for hp if the result will support efficient use of hp by engaging with the right professionals and design for a specific BER rating. Maybe that is my answer.


Yeah, this is it really. Concentrate in doing the best job you can on the building fabric and then how the place is heated becomes a much simpler problem to solve.


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## David_Dublin (19 Apr 2021)

Will probably avoid risk, do as good a job as we can and stay with gas heating. Seems like a sensible choice for a 100 year old house that we're not going to be overly focused on air tightness.


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## Leo (20 Apr 2021)

David_Dublin said:


> Seems like a sensible choice for a 100 year old house that we're not going to be overly focused on air tightness.



Only choice in that case!


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## Coldwarrior (20 Apr 2021)

_OkGo_ said:


> The same applies to PV. In a highly efficient A rated home, the only heating required during summer months (and late spring/early autumn) should be for water. If you need 8kWh of energy to heat water, your PV system needs to be sized to supply 8kWh during summer months. The same amount of heating with a heat pump can be achieved using 2.25kWh of electricity, of which a lot can be done at very cheap night rates
> 
> Basically your heat pump should not be running off an oversized PV as it is more economical and energy efficient to just use the grid. During winter months, the same PV is contributing very little to electricity, maybe 2-3kWh per day so it is not a good investment along with a heat pump.


Just on this about the PV solar again, I'm hopefully soon going to be moving to a new build (A2 or A3 BER) that'll have an air to water heat pump, underfloor heating downstairs and radiators upstairs. I'll be working from home most of the time and will probably go for an electric car the next time I change cars. The house won't come with any solar panels as standard, though I was considering asking the builder to install PV. From what you've said it sounds like it may not be worth it, is there any merit to installing PV in this case?


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## Zenith63 (20 Apr 2021)

Coldwarrior said:


> Just on this about the PV solar again, I'm hopefully soon going to be moving to a new build (A2 or A3 BER) that'll have an air to water heat pump, underfloor heating downstairs and radiators upstairs. I'll be working from home most of the time and will probably go for an electric car the next time I change cars. The house won't come with any solar panels as standard, though I was considering asking the builder to install PV. From what you've said it sounds like it may not be worth it, is there any merit to installing PV in this case?


The merits of installing PV panels are the same whether you have a heat pump or not to be honest.  The point _OkGo_ is making is that PV will not be generating electricity at the times your heat pump needs electricity, so putting up PV thinking it will provide free electricity to run your heatpump does not make sense.

So you just need to look at your electricity usage and ignore whether there is a heatpump there or not and see if PV makes sense.  The conclusion you'll likely come to is that it has a payback of somewhere between 6-10 years depending on whether you go for a battery or not and assuming you get a good price.  If you plan to stay in the new house for 10/15/20 years then that payback period is fine and you'll be saving a decent few quid on electricity bills.


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## Clonback (15 Feb 2022)

dem_syhp said:


> Yes, sorry, photovoltaic panels, so yes, I'd absolutely expect costs to be lower in the summer (hence the comment, I can't really say for another 6 months how things will fare).
> 
> We still have a gas for cooking, albeit very low energy usage, but still have standing charges.   [I know we can change, but for now things are staying as they are]
> 
> ...


Whats your current views on heat pumps given you have 12 months experience?


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## roker (17 Mar 2022)

Jazz01 said:


> @Anniekate
> From my understanding, unless your home is air tight, the air to heat pump wouldn't be recommended as a means to heat the home. Maybe as part of the retrofit you are doing, they will be performing this air-tightness? It's difficult to do in existing houses, but I guess not impossible.
> 
> The installation of all that insulation needs to be coupled with allowing enough ventilation flow in through the house and out again, so there will need to be a mechanical ventilation system running too.
> ...


That is the contradiction, we have vents in the walls and windows etc to prevent condensation and mold and we are told not to have leaks to run a heat pump


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## newirishman (17 Mar 2022)

roker said:


> That is the contradiction, we have vents in the walls and windows etc to prevent condensation and mold and we are told not to have leaks to run a heat pump



Thats why you put in a proper heat recovery ventilation and stop using those dreadful holes in walls.


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## Ryan (19 Mar 2022)

It’s not as simple as taking out your oil or gas boiler and installing a heat pump, you’ve got to do some upgrades to make the house more efficient nd in some cases the cost outweighs the benefit. You are better off getting a new more efficient oil or gas boiler


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## dem_syhp (16 Apr 2022)

Clonback said:


> Whats your current views on heat pumps given you have 12 months experience?


Our usage of electricity has gone from approx. 1000kw per annum, to 2000kw per annum.   We have solar panels, so the real usage has probably gone up to 2800kw per annum.  This is for a two person, 3 bed room terraced house.  Previously we both worked outside of the house, but now there is someone working from home all the time so not comparing like with like.   We previously would have used approx 5kw of gas in addition to the electricity (price per kw for gas far lower than electricity and not comparable).    My numbers aren't perfect, the previous ones are based off averages (but these' tended to be correct, rarely a big change when I did a reading.   Current numbers are based off summer and winter averages - not exact.  We still have a gas bill as we use it for cooking, although, clearly our usage is far lower, but we still have all of the standing charges and usage of approx. 600kW per annum - 9m cubed * conversion factor * 6 bills (I've based this off the last 4 months, but they're winter when we'd use the oven a bit more.  )

We did a full retrofit, insulation windows, walls - the house is far more comfortable.   But the house would be far more comfortable if we'd done all of the upgrades without the heat pump - but that's not how the grant worked.   

We naturally prefer to keep a cooler house - 16 to 18 degrees.   A notable amount of the energy we've used has been over night when temperatures are low to prevent it freezing.   Maybe comparing bills for someone who keeps a house warmer there would be a more noticeable difference. 

We didn't do the upgrade for cost savings - our bills were always low, but front of the house wasn't comfortable, even with the heating on (even as people that don't mind a cooler room).  It was to future proof the house and make the front rooms usable - we're pleased we did that.   But if I wasn't doing a full upgrade, upgrading the heat pump would be the very very very last thing I'd do.  I think that we need to move away from fossil fuels, I think we need to move away from Gas.  But when I look at the operation mode for the month of Jan, the freeze stat was 18% of the time, and heating was 23.8%, with water at 4%.    That minimum level of having everything off, with a heat pump, is quite high in the winter time.  Where as from now till November it will hardly kick in at all.

In hind sight we should have put more panels up (We went with what was recommended, I didn't think we could put more, I think we could have).   Moving to electricity for cooking is likely to happen for us, but just not sure when, and I may need to convince someone else to give up gas cooking.   The difference in comfort in the house is huge from improvements in the insulation.  I can't tell with the bills as we've someone home more now, so its probably just offset it.


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## newirishman (16 Apr 2022)

dem_syhp said:


> […]   Moving to electricity for cooking is likely to happen for us, but just not sure when, and I may need to convince someone else to give up gas cooking.   The difference in comfort in the house is huge from improvements in the insulation.  I can't tell with the bills as we've someone home more now, so its probably just offset it.


few years ago I installed both a gas hob and a induction hob. (Half/half so to say).
The gas one rarely gets used at all. Don’t think I’d bother with gas hob again, induction is great.


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## David_Dublin (16 Apr 2022)

Are the controls for nduction hobs not very fiddly? I've only cooked on them a coupe of times, but the controls seemed to be very finicky, sometimes not responding to touch for example. I prefer the look of induction hob over gas, but love the simplicity and visual of gas.


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## noproblem (16 Apr 2022)

newirishman said:


> few years ago I installed both a gas hob and a induction hob. (Half/half so to say).
> The gas one rarely gets used at all. Don’t think I’d bother with gas hob again, induction is great.


I'd be the complete opposite


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## roker (21 Jul 2022)

noproblem said:


> For the pump to be totally efficient it's advisable to get your house or desired project technically assessed. In short, its air tightness, insulation, draughts, windows, chimneys (if any) etc. When people say it's costing them a fortune in electricity to run the heat pump I can assure you they didn't properly do their homework before going ahead with the work. Goosebump; This is a quickish answer to your query but very relevant.


You are not making the system more efficient, you are making the house more efficient . So no matter what heating system you have you will save energy cost.
Correct me if I'm wrong but
the heat pump is running 3 motors, fan, compressor,  circulating pump. All requiring energy


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