Really sorry to read this @jswhite. 16kW is a large unit for 120m2 heated area, especially if you usually have diversity and only some rooms heated. You lose heat energy from heated to unheated space, so emitters in the heated spaces need to be larger and/or set to a higher setting or higher WC flow temperature to offset that, but that's still cheaper than heating space you are not using.

What was your former heating system and have you any idea of the energy requirement to heat it in kWh per year? That won't change regardless of what type of heating system you have. It only changes if you make some energy efficiency improvement in the building insulation and/or heat to a lower inside temperature. A 16kW unit implies very poor insulation levels, or the unit is oversized. Oversizing can be an issue if the minimum turn down means the ASHP ends up cycling on and off a lot in milder weather with lower heating load. Common misconception with installers is "if the ASHP is bigger than required it doesn't matter as it's inverter driven" That's true only within the min and max operating envelope of the unit chosen. ASHPs can turn down to 20-30% typically, but each time they start up they draw higher power for a while to catch up and offset the loss of temperature in the water circuit when they were off.

Right sizing the plant is important, but installers from the plumbing and CH trade have a legacy of throwing in 30kW gas combis to any size property. Old habits die hard and oversizing heat pumps because of ignorance or uncertainty about the correct unit capacity can be a costly mistake.

ASHPs don't save energy, heat is heat. But they will consume less energy because they are heat pumps, and systems should be 300-500% efficient on average. Good installers can better that. A lot of variables influence that of course. Less energy consumed does not necessarily mean less cost to run as electricity per kWh is around 34p/kWh on price cap tariff, and 10.3p/kWh mains gas. You'll only save money at current prices if the SCOP averages >3.4. In the longer-term, electricity will get better parity with mains gas on price per kWh, but not for a few years. All energy will be expensive in the new era, that's just the economic reality.

Can anything be done to better insulate the property? Whatever heating system you have, you'll pay a lot less if the fabric of the building can be properly insulated.

Standing losses from a modern well insulated system hot water tank are very low, around 2KWh per day typically at 60degC water storage for a 250litre cylinder, so a larger tank than needed isn't that inefficient.

You said the ASHP feeds into the hot water tank then the heating circuit? That's very strange if so, but easily fixed surely. It's just control valves and copper pipe. I found exactly that in my house when I bought it in 2012. The system boiler had a 2 way not a 3 way valve control between CH and HW, the 2 way valve opened to permit CH flow, but no valve controlled the thermal store flow, so it was charging whenever the CH was on. Water chooses the path of least resistance, which was most flow through the thermal store not the house radiators. Madness!

@editor 
I raised it with HIES and they dismissed it 'out of their remit' and 'my own fault for signing the contract'
The Ombudsman? No I cannot find a contact. When I requested email address from HIES I got the prejudged response that I would lose so not worth referriing my issue.

@jswhite, that’s just crazy that HIES would reply like that. As for the ombudsman, the industry is looking at forming an organization like this, but there’s no formal channel at the moment. MCS and HIES are supposed to be the main “protectors” in the system.

Posted by: @jswhite

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@editor 
I raised it with HIES and they dismissed it 'out of their remit' and 'my own fault for signing the contract'
The Ombudsman? No I cannot find a contact. When I requested email address from HIES I got the prejudged response that I would lose so not worth referriing my issue.

I would suggest that you write to your MP and ask him to request from Grant Shapps who you should contact for help with your predicament.

Posted by: @editor

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@jswhite, that’s just crazy that HIES would reply like that. As for the ombudsman, the industry is looking at forming an organization like this, but there’s no formal channel at the moment. MCS and HIES are supposed to be the main “protectors” in the system.

@editor what about RECC? Are they not a good organisation to raise issues through?

@gemiar, sadly, they too have been ineffective. They’re all toothless and frankly unwilling to ruffle feathers.  

But you have to give it a go… as mentioned in my other reply to you, I’d follow the complaint process. Sooner or later, homeowners must get adequate solutions and remedies to expensive, incompetent, bodged installations. I’ll help raise your case publicly with the powers that be through my channels, but to this point, they’ve remained weak and silent. 

Posted by: @editor

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@gemiar, sadly, they too have been ineffective. They’re all toothless and frankly unwilling to ruffle feathers.  

But you have to give it a go… as mentioned in my other reply to you, I’d follow the complaint process. Sooner or later, homeowners must get adequate solutions and remedies to expensive, incompetent, bodged installations. I’ll help raise your case publicly with the powers that be through my channels, but to this point, they’ve remained weak and silent. 

Maybe we should all write to our MP's and ask for an explanation as to why MCS and RECC are failing to protect consumers with regard to heat pump installations. I for one am quite willing to do so.

@editor thanks. I will definitely start the complaint and see where that leads.

it is very sad though that all the bodies that claim to provide protection for consumers can’t do so effectively when it comes to it. Perhaps they also need to be held accountable somehow.

Posted by: @derek-m

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Posted by: @editor

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@gemiar, sadly, they too have been ineffective. They’re all toothless and frankly unwilling to ruffle feathers.  

But you have to give it a go… as mentioned in my other reply to you, I’d follow the complaint process. Sooner or later, homeowners must get adequate solutions and remedies to expensive, incompetent, bodged installations. I’ll help raise your case publicly with the powers that be through my channels, but to this point, they’ve remained weak and silent. 

Maybe we should all write to our MP's and ask for an explanation as to why MCS and RECC are failing to protect consumers with regard to heat pump installations. I for one am quite willing to do so.

 

Absolutely- I think this is a great idea. I am willing to do this too! The organisations who provide guarantees or accreditation to the poor installers should also be held accountable.

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!

Posted by: @jswhite

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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!

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?