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How would you rate the design, installation and efficiency of your heat pump system? Poll is created on Nov 06, 2022

  
  
  
  
  
  

[Sticky] Rate the quality of your heat pump design and installation

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(@bob77)
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I voted "generally good" although it would have been "very pleased" were it not for a fault on the indoor unit which can't be blamed on the installer - a faulty flow sensor meant it kept cutting out with water flow errors.

The actual system setup seems to be very well designed, we did have the advantage of fitting it as part of a whole-house refurb, replacing electric storage heaters and a gravity-fed immersion tank so all new plumbing. Underfloor heating throughout the ground floor, on two zones, and radiators in the three bedrooms upstairs (we kept the existing electric UFH and towel rail in the family bathroom).

Even during the recent cold snap when temperatures here got down to -8C overnight and stayed below zero in the day for four days straight, it was able to deliver a 50C flow temperature and kept the house pleasantly warm so I would say the heat loss calcs were done well. Unfortunately the last cold week coincided with having our floor laid so we had to turn the UFH off for four days!

Unit is an 8kW Daikin Altherma 3 R with an all-in-one 230 litre indoor unit. I hadn't realised quite how tall the indoor unit would be - it is in the airing cupboard which now doesn't have any storage space as it is fully taken up by the tank and plumbing!


   
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 mjr
(@mjr)
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Posted by: @jswhite

The last plumber said that ASHP should not have been fitted to a leaky old house like this because it had no chance of keeping us warm at an affordable price (even before the costs went up). He has recommended ripping it out and selling to someone who has a properly insulated new build where it might work.

There's nothing about being a leaky old house that makes ASHP necessarily impossible: it just costs more both to buy (bigger unit needed) and operate (more heat output needed). So that  comment sounds like:

1. the plumber hates ASHPs, possibly because the reduction in moving parts and near-universal addition of computer-control means less work for them and more for electricians and programmers; and/or

2. the plumber is proposing to install a much bigger burner instead, maybe a 28kW gas or oil unit to replace your 16kW ASHP? The house will still be leaky but that will be overcome by throwing more fuel at it, or to put it another way: pigs can fly if given sufficient thrust!


   
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(@jswhite)
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Joined: 2 years ago
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Hi Bob77 Your result sounds like the one I was looking for and your heat pump is half the size of the one that was fitted in my house. Can you tell me the area of your house and the daily cost when the temperature was so low?


   
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(@jswhite)
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@mjr 
That is the question that is difficult to answer for sure. What I got was an oversized system that was intended to keep rooms warm and without any concern for what it cost or whether we could afford it. There was a lot of voodoo around the numbers in the EPC (although the relevant footnotes pointed out they are not rigorous or specific or guaranteed in any way, just made up really). Then there was the voodoo around the MCS heat loss calcs. They may be relevant on a new build where very little heat is lost but on a leaky old house there was one set of numbers that were missing from the process and that was affordability. Could we multiply our heating cost by two or three times (before recent increases) until we could spend thousands of pounds worth of additional costs to plug the leaks.
The house is pre-1900 stone that was renovated in 1976 and again partly after I arrived in 1995. Apparently it is not suitable for cavity wall insulation. A large window would cost £3k to replace with triple glaze. There are no attics so extra insulation would have to be within the rooms. The info provided at the time listed about £25k of possible unsulation  remedies for a saving of less than £1k per year.
But the key problem here is that if I had insulated everything that was suggested the heat pump fitted would then be running inefficiently because it was vastly oversized.

The conclusion of any normal process like this was that this house, with the income of the owner, is not suitable for a heat pump.
I've had three solar panel companies come along who have assessed the house, the shadows cast by trees and other buildings and they have walked away, telling me it is not worth putting them on this house.
It never crossed the heat pump company's tiny mind to say such a thing, just take the money and run, knowing that not being able to afford the system meant that I was also not able to afford to sue!


   
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cathodeRay
(@cathoderay)
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Posted by: @mjr

There's nothing about being a leaky old house that makes ASHP necessarily impossible: it just costs more both to buy (bigger unit needed) and operate (more heat output needed).

I agree, that's the point I always made, including the second part, ie I knew full well an old leaky building costs more to heat, whatever the fuel.

I think some installers are just rather rigid, they have been taught not to put ASHPs in old leaky buildings, and haven't thought it through (it means a lot of our housing stock 'isn't suitable' - and where does that leave us?).

All the installers I approached claimed to be heat pump installers, and none said what I need is a stonking great fossil fuel system. They just didn't have an answer except no heat pump for you, because, as I say, I think they were rule bound.

Part of me wanted to show that this rule was nonsense, and in many ways I have shown that it is indeed nonsense: I have a fully working DHW system, and heating that works as long as it is mild or only moderately cold. My bills are always higher than for a comparable size well insulated home, but that always has been the case, and always will be. It is part of the price paid, literally, for living in an old attractive building.

The reason the system fails in cold weather is down to the heat pump output being marginal, and that happened for two reasons: (a) Freedom's heat pump calculator being over-optimistic about the 14kW using output, and the ugly impact of grant deadlines: at the key time, Freedom only had a 14kW unit in stock, it had to be that, if I was going to meet the grant deadline. The original design had a 16kW unit, had the grant deadline not been imminent, then I would have waited for a 16kW unit, but as the Freedom calculator showed the 14kW was OK, if marginal, and the grant deadline was imminent, I ended up with the 14kW unit.

Since then there has been the 'discovery' that the 14kW and 16kW (and 12kW unit for that matter) unit are identical in hardware, the only difference is in the positions of a certain set of three dip switches, which use software to limit the 16kW capable unit to either 14 or 12kW. The mystery is why Freedom don't know this and suggest it as the solution, or if they do know it, then suggest it as the solution.

The reason I didn't up the output during the cold spell was because I realised it was probably not the best time to do it for the first time, in case something went wrong, leaving me with no heating when I needed it the most. I'll do a brief dry run in mild weather (once Christmas and New Year are past, again, not a time to have your heating pack up) and if it works, then know I can put it in place again in future cold spells.

There might be a bit of a silver lining, I am not sure: running a 14 rather than a 16kW unit might save me a few pennies, but maybe not. They are the same unit, both a 14 and a 16kW unit will have the same (lower) output in milder conditions, and so, being the same unit, I think their running costs would be very similar, if not identical, with the 16kW only costing more when it gets to output levels above what the 14kW setting can achieve.      

Midea 14kW (for now...) ASHP heating both building and DHW


   
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(@jswhite)
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Joined: 2 years ago
Posts: 24
 

@mjr 
You are right that the last plumber has suggested an LPG  boiler instead. It would still leak heat but it would not suffer inefficiency from being used on one or two rooms - that is what we did with oil and we were warm, but with a heat pump it would make it recycle and the cost would go up.
The plumber is quite prepared to replace the DHW tank, which is not a thermal store, just hot water, with one that is a more efficient thermal store. But his point is that the running costs may well be very little different from the present set up, saving a pound a day out of twenty or thirty is of no use.
His point is that selling the ASHP, which would be good for a larger house with good insulation, might cover the cost of changing to LPG.

I really wanted an environmental break from burning anything to keep warm and it would be a set back to do it this way but half way through a second winter of being cold in a world that is careering towards environmental disaster, our discomfort is feeling very much like an empty gesture.


   
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(@derek-m)
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Posted by: @mjr

Posted by: @jswhite

The last plumber said that ASHP should not have been fitted to a leaky old house like this because it had no chance of keeping us warm at an affordable price (even before the costs went up). He has recommended ripping it out and selling to someone who has a properly insulated new build where it might work.

There's nothing about being a leaky old house that makes ASHP necessarily impossible: it just costs more both to buy (bigger unit needed) and operate (more heat output needed). So that  comment sounds like:

1. the plumber hates ASHPs, possibly because the reduction in moving parts and near-universal addition of computer-control means less work for them and more for electricians and programmers; and/or

2. the plumber is proposing to install a much bigger burner instead, maybe a 28kW gas or oil unit to replace your 16kW ASHP? The house will still be leaky but that will be overcome by throwing more fuel at it, or to put it another way: pigs can fly if given sufficient thrust!

Why not do something to improve the energy efficiency of the 'leaky old house', then you may even be able to install an unsuitable heat pump.

 


   
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(@jswhite)
Trusted Member Member
204 kWhs
Joined: 2 years ago
Posts: 24
 

@derek-m 
Which inprovements do you suggest?
Solar panels, tried but told too many shadows cast on available roof
Sub floor insulation  - we put in an ufh system in the kitchen before the heat pump was installed, with proper subfloor kingspan. There is only a small area of flooring that has no insulation.
Flat roof/sloping roof - no flat roof. One sloping roof fully insulated, kingspan between rafters and full sheets across rafters. One roof has rockwool and would save some heat loss but the cost is more than Kingspan, it would need replastering too.
Wall insulation - the price is eyewatering and there are issues on stone house removing condensation.
Solar Water heater - that might save us some money heating water but it makes the installed system rather redundant with its 210 litre water tank

The image is from the hilarious Energy Performance Certificate (reduced instruction set i.e. guessed at) suggesting that for a cost between £16000 and £31000 I can save £786 a year.
Any other insulation suggestions would be appreciated.

Suggested insulation
This post was modified 1 year ago 2 times by jswhite

   
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(@derek-m)
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Joined: 3 years ago
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Posted by: @jswhite

@derek-m 
Which inprovements do you suggest?
Solar panels, tried but told too many shadows cast on available roof
Sub floor insulation  - we put in an ufh system in the kitchen before the heat pump was installed, with proper subfloor kingspan. There is only a small area of flooring that has no insulation.
Flat roof/sloping roof - no flat roof. One sloping roof fully insulated, kingspan between rafters and full sheets across rafters. One roof has rockwool and would save some heat loss but the cost is more than Kingspan, it would need replastering too.
Wall insulation - the price is eyewatering and there are issues on stone house removing condensation.
Solar Water heater - that might save us some money heating water but it makes the installed system rather redundant with its 210 litre water tank

The image is from the hilarious Energy Performance Certificate (reduced instruction set i.e. guessed at) suggesting that for a cost between £16000 and £31000 I can save £786 a year.
Any other insulation suggestions would be appreciated.

Suggested insulation

Are the savings shown based upon present installation cost and energy prices? Can you get any form of grant to help with the cost?

You have somewhat of a unique situation, which at the present time means that your home is going to be expensive heat whatever fuel source you use.

Draft proofing can often be beneficial at modest cost, and there are also quite cheap forms of secondary glazing which may prove of use.

 


   
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(@jswhite)
Trusted Member Member
204 kWhs
Joined: 2 years ago
Posts: 24
 

@derek-m 
The saving will be from before the energy price increases but if they are even three times higher that is still too little for too much cost.
We were warm with an oil boiler but often only heated one or two room and then took the edge of other rooms for half an hour before using them, like bathroom for showers. Oil cost us £500 in the year before lockdown. I'm currently paying £112 a month personally plus £66 top up, to heat one room with an oil filled electric heater and no hot water in the taps.

We blocked the windows with kingspan and a whole sheet goes across the door and that kept us reasonably warm.
With the heat pump on I spent £900 between January and March this year and that was before the prices increased, so it went off and stayed off.

I sound like a terrible Jeremiah moaning on about this but we live in a nice place, are very comfortable for most of the year, and there are many worse off, so the issue is that a bunch of 'experts' have made our situation worse by foisting on us a device that demands that we waste heat in rooms we do not use. They should have been professional and walked away like the solar panel salespeople.


   
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 mjr
(@mjr)
Prominent Member Member
1941 kWhs
Joined: 2 years ago
Posts: 304
 

@jswhite actually, yours sounds like one of the few uses where a twin-pump solution might have made sense. A single pump causes you problems in that switching off the other rooms reduces the system capacity far below efficiency, but if you had a smaller pump that could be used for most of the time for heating the two rooms and hot water, with a second pump to reinforce it in the coldest weather, you might have been in a better situation than even if you do get a dirty burner again. After all, running an oversize gas burner well below its optimal range isn't efficient either. So it's not so much that it was unprofessional to sell a heat pump system as it was that they seem not to have listened and sold you the wrong one, one that doesn't fit your need at all. But hindsight is wonderful and you are where you are and I sympathise and hope you find a good route out.


   
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(@derek-m)
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Posted by: @jswhite

@derek-m 
The saving will be from before the energy price increases but if they are even three times higher that is still too little for too much cost.
We were warm with an oil boiler but often only heated one or two room and then took the edge of other rooms for half an hour before using them, like bathroom for showers. Oil cost us £500 in the year before lockdown. I'm currently paying £112 a month personally plus £66 top up, to heat one room with an oil filled electric heater and no hot water in the taps.

We blocked the windows with kingspan and a whole sheet goes across the door and that kept us reasonably warm.
With the heat pump on I spent £900 between January and March this year and that was before the prices increased, so it went off and stayed off.

I sound like a terrible Jeremiah moaning on about this but we live in a nice place, are very comfortable for most of the year, and there are many worse off, so the issue is that a bunch of 'experts' have made our situation worse by foisting on us a device that demands that we waste heat in rooms we do not use. They should have been professional and walked away like the solar panel salespeople.

If you only wish to heat one room then maybe you should consider an Air to Air ASHP, which would be much cheaper to run than your present Air to Water heat pump.

I agree that your installer should have discouraged you from installing an ASHP in your situation, but once the decision was made they would have to design and install a system for the full property, since future owner's would not want a system that could only heat one room.

 


   
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