SteamyTea

Air Source Heat Pumps Do Not Work

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Time over time, I read on here that ASHPs are no good for old houses.

Can we stop this nonsense.

ASHPs, or any heating system, if it has a too lower power output, will struggle.  That is what power means.

So rather than say an ASHP will struggle, or is the wrong thing to install, tell the true story.

The true story is that it may be cheaper overall to install a gas or oil boiler, or a much larger, or even two, ASHPs.

 

And could everyone stop getting temperature, energy and power confused, they are different thing.

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Precisely

 

Years ago I bought a 1930's semi detached house with 9" solid walls.  It had a large storage heater in the living room.  That proved woefully inadequate to heat the room in winter even at it's maximum setting. So I had to light the coal fire, use a fan heater, or later I installed a gas fire (much later I installed central heating)

 

But that does not mean "storage heaters don't work" just because that one heater was inadequate for that particular room in that particular house.

 

I think the REAL issue is there are bands of installers going around fitting poorly designed / sized ASHP systems that then turn out not to work properly and it is those poor installs that get "heat pumps" a bad name.

 

I know perhaps half a dozen houses with an ASHP and they were all designed properly and working well.

 

Perhaps it is time for the law to state clearly that someone designing a heating system should warrant that it will work in all normal weather conditions for the house and it's location.

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25 minutes ago, ProDave said:

Perhaps it is time for the law to state clearly that someone designing a heating system should warrant that it will work in all normal weather conditions for the house and it's location.

That was the case if a MCS installer did the job. The system had to supply 99% if the time.

So 3.65 days if the year you may need supplementary heating i.e. a fan heater.

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23 minutes ago, SteamyTea said:

That was the case if a MCS installer did the job. The system had to supply 99% if the time.

So 3.65 days if the year you may need supplementary heating i.e. a fan heater.


Can someone tell @zoothorn that!!,!

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I completely agree... I have a 4kw ASHP that I did no calcs for and to be fair is woefully undersized for the job as it turns out. But I bought it cheap whilst drunk from ebay on a whim, a year before I fitted it. It’s perfect for my downstairs UFH, just too small for my rads upstairs (on very cold days upstairs is about 19*c tops). It also does my dhw with a bit of support from the immersion. 
 

My house is partly 300 year old stone and crud walls (no insulation), and partial new build (to basic building regs level of insulation). We have 2 lots of bifold doors, 3 patio doors, 2 chimneys, so the place is a little drafty (certainly compared to the builds on here).
 

My total energy usage for a year is about 7000kwh. (My wife and I both work from home, and both my wife and daughter would like the house to be about 35*c if they had their way).


So I guess I am saying that even in the ‘wrong’ type of house and being incorrectly sized, I still think it’s a great solution and would definitely do it again. I am however keeping an eye out for a higher kw unit to upgrade when I can. 

Edited by Gav_P
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I also have a 4KW ASHP but with my level of insulation and draught proofing it works well, yes er indoors would like it warmer but it’s a constant 20-21 downstairs and 19-20 upstairs which is fine (IMO). I am sure if I ran it longer higher temps could be reached. 

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1 hour ago, ProDave said:

...

Perhaps it is time for the law to state clearly that someone designing a heating system should warrant that it will work in all normal weather conditions for the house and it's location.

 

There's a conflict of interest that will prevent that. And a powerful one at that. The designer is often the installer. Many threads on BH attest to that.

 

It's the elephant that stalks this discussion board. In plain sight.

 

Absolutely bloody right Dave.

Edited by ToughButterCup

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But to us self builders that designed it ourselves (like me) we have no one to blame (except @jeremy cus I copied him 😱).

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26 minutes ago, ToughButterCup said:

The designer is often the installer. Many threads on BH attest to that.

Isn't that mixing up skill and qualification/accreditation.

I have the skills to calculate heat loss, but no certification to prove that.

But if there was a way for the equipment manufacturers to say 'show us your workings' then they should not be able to sell the wrong component knowingly.

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1 minute ago, SteamyTea said:

Isn't that mixing up skill and qualification/accreditation.

I have the skills to calculate heat loss, but no certification to prove that.

But if there was a way for the equipment manufacturers to say 'show us your workings' then they should not be able to sell the wrong component knowingly.

There is a growing trend for you to need qualifications and need to join some form of "competent persons scheme" before anyone will believe you know how to do it and indeed allow you to do it.  AND STILL THEY GET IT WRONG.

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7 minutes ago, ProDave said:

There is a growing trend for you to need qualifications and need to join some form of "competent persons scheme" before anyone will believe you know how to do it and indeed allow you to do it.  AND STILL THEY GET IT WRONG.


Is this not what happened to @zoothorn ?.?

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5 minutes ago, joe90 said:


Is this not what happened to @zoothorn ?.?

It would appear so.

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17 minutes ago, ProDave said:

AND STILL THEY GET IT WRONG.

Yes, and the blame often goes to ASHPs, not the sizing of them.

This is the whole point of this topic, it is to stop this happening.

So everytime we see someone say something like "I thought of an ASHP, but they are no good in old houses" or "I know someone that has one, and it is rubbish", maybe my favourite "they are not there yet", which I have no idea what it means.

it should always be pointed out that they will work if they the design size and installation is correct.

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I have a neighbour with an old house that has an ASHP and it works well, but it is 4 times the output of mine and their house is colder, but as outdoor types they don’t mind.

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I'm guessing many old houses have 25, 30 or even 40kw boilers and may need them in cold weather.

 

Are there ASHP that will deliver say 30kW at a COP of at least 3 when it's 0-5C outside?

 

Do you have to buy two 15kW units?

 

 

 

 

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My old 1930's house ended up with central heating and a 70,000 btu gas boiler which is about 20kW  You can certainly get an 18kW ASHP

 

But to work best, it would have needed a serious amount of work to dig up all the floors to install insulation and UFH.

 

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2 hours ago, Temp said:

I'm guessing many old houses have 25, 30 or even 40kw boilers and may need them in cold weather.

 

Are there ASHP that will deliver say 30kW at a COP of at least 3 when it's 0-5C outside?

 

Do you have to buy two 15kW units?

 

 

 

 


Yes there are. Usually 3 phase but they can easily cope with big old houses. Most boilers though are sized for the DHW supply (combi) or rapid recharge of a cylinder hence why you see boilers of 21KW or more in small houses. 
 

This is one example - 25kW and that’s pretty standard to have twin fans etc. 

 

http://www.earthsaveproducts.co.uk/product/classic-air-source-heat-pump-25kws-phase-3/

 

4 hours ago, ProDave said:

think the REAL issue is there are bands of installers going around fitting poorly designed / sized ASHP systems that then turn out not to work properly and it is those poor installs that get "heat pumps" a bad name.


Thats what happens when governments give free money away and you get the bandwagon jumpers who then go bust 18 months later. Mark Insulation was a big example of this - started in cavity wall, went into renewables then when the money stopped flowing in 2015 they went pop... 

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Trust me, effin great oil boilers don't work if the heat is pi$$ing out through every wall, around every window and the gaps in the floor and ceiling. 

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35 minutes ago, Onoff said:

Trust me, effin great oil boilers don't work if the heat is pi$$ing out through every wall, around every window and the gaps in the floor and ceiling. 

100% In our old cottage during winter we would have the oil heating going and I would still be chucking wood into the burner like a stoker on the Titanic. 

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41 minutes ago, Onoff said:

Trust me, effin great oil boilers don't work if the heat is pi$$ing out through every wall, around every window and the gaps in the floor and ceiling. 


No, but at least you can feel the heat radiating at you from red hot radiators (even tho it disappears just as quickly).

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14 minutes ago, joe90 said:


No, but at least you can feel the heat radiating at you from red hot radiators (even tho it disappears just as quickly).

 

Not when you've broken the bleed key off and won't be changing it until this weekend you can't!

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6 hours ago, Gav_P said:

I am however keeping an eye out for a higher kw unit to upgrade when I can. 

Why not find another smaller one, then plumb that in for upstairs and the DHW.

And it is kWh, not kwh.

4 hours ago, ProDave said:

But to work best, it would have needed a serious amount of work to dig up all the floors to install insulation and UFH.

Probably not the best way to go with an old house, more radiators would be easiest, and cheapest.

4 hours ago, Temp said:

Do you have to buy two 15kW units?

Probably not, but having two smaller ones could work out cheaper and give more options.

 

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I would be interest to know how efficient air source heat pumps are in well insulated new builds.

 

Over the course of year how many months of the year are they used for providing heating? 

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5 minutes ago, Thedreamer said:

I would be interest to know how efficient air source heat pumps are in well insulated new builds.

 

Over the course of year how many months of the year are they used for providing heating? 

Ours runs about 6 months of the year, October to March usually.  Annual heating cost about £250

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7 minutes ago, Thedreamer said:

I would be interest to know how efficient air source heat pumps are in well insulated new builds.

 

Over the course of year how many months of the year are they used for providing heating? 

The efficiency is not set by the type of building, it is set by the load cycle.

So the question is wrong really.

 

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