Air source heat pumps in the news again

[Ric2013]

We get worked up on stuff that isn't necessarily relevant. The first floor of my extended 2-up 2-down has draught problems I need to address, but it's a hell of a lot better than it was. The ground floor, however, is now very tight. The ground floor has been insulated even though the APC didn't consider it an issue.

The ground floor can be kept to temperature with 1.4kW and that includes heat losses to the first floor due to no interfloor insulation. I don't heat with an ASHP, but I probably could if I could get the first floor up to scratch (some very poor quality DIY timber frame on the extension).

Yet what I'd be encouraged to do is insulate the small section of poorly constructed cavity wall which would probably lead to damp issues (there are mortar bridges in the cavity) and save hardly any energy and fit solar thermal and PV (despite having only the roof area for one of the two).

Within a home... sensible insulation. Draft proofing. Get rid of damp issues first. Then learn to ventilate the house on a daily basis. Not very sexy, is it? But for the cost and materials involved, it certainly beats ASHP.

 

[John.g]

From a running cost point of view then a HP with outside/flow temps of 0C/45C will give a COP of 2.48 which around here would be very competitive with oil and increasingly with gas.
One think to bear in mind though is that a 15kw HP isn't the same as a 15kw oil/gas boiler as a 15kw boiler will always give 15kw ouput but a 15kw HP will give 14.5kw at outside/flow temps of 7C/35C but under the above conditions of 0C/45C "only" 9.8kw, this is because the "thermal input" from the compressor motor is only 3.5/4kw.
However, like it or not, they will be increasingly more common especially with new builds/increasing levels of insulation which leads to lower flow temps = higher COP= more competitive, also smaller units. They are being installed here in a very large proportion of new builds, some have a separate HP for hot water production, others just heat the hot water to ~ 40C which is boosted once/week to 60/65c with a immersion for legionella protection.

 

[gpbeck]

Over reaction Jim.

The Gas Man will take a hiatus from gas boiler installs for a period of time.

ASHP's will be installed on thousands of homes, by companies that have secluded Government Contracts to install these systems.
All tax payers will be contributing to these systems being installed.

When, in 2, 3 or 4 years, these systems become too much of an issue for the homeowner or the Goverment Funded company that installed them, the company will close or go bankrupt, leaving the home owner to contact their local Gas Man to re-install a gas boiler ( at the home owners own expense )

[ In a Nutshell ]

Scandal, public enquiry, demands for compensation.

 

[RoryD]

I'm getting so sick of the media and tories plugging ashp's like they are the solution to all our heating needs.

Latest news today, £5k grant towards the cost of replacing a gas boiler with an ashp. What a joke.

Every ashp system I've worked on and installed runs the heating at 40 degrees, great for a new build with fantastic insulation and underfloor heating but just simply wouldn't work in most of the houses in England.

Why is this never mentioned in the media?

Air source should be the last thing we do not the first, the first should be insulation and upsizing pipework.

Just think of all them new builds, built in the last 30 years with microbore pipework, some barely run on gas boilers nevermind air source.

It makes me wonder what other things the tories pretend to know what they are talking about

I think one of Boris' mates manufactures ashp's....

ASHP's will work if installed correctly in any property. As you rightly point out the pipe sizing and insulation is critical to that.It's always been the case but installers themselves are neglecting to do that...even before the tories came in to encourage migration. In a few short years we are going to be reliant on Russian Gas. They have been proven to use this as a weapon - Ukraine - so we have to find alternatives. It is also environmentally cleaner. I think this place is great to share professional views and advice. My experience is that things get messy when we start getting political mate. What needs to happen is that installers should be more honest when quoting, fitting and 'effing off' will have the system working but it will cost a fortune to run if pipework isn't upgraded. This is good technology.

 

[jim843]

I’m glad this is being discussed.

My home was built 1890. End terrace. Totally unfit for modern living! I’ve spent last 7 years renovating as best I can: insulation in loft, under floor, etc. But walls are solid in a few places. There wasn’t a damp proof course so I fit one where I could.

I have solar panels and would love to reduce carbon emissions but based on what I’ve read a heat pump will not work well in a house like mine.

To me the solution is insulated render but I imagine the cost on a 3 storey would be unaffordable.

Plus my back wall backs onto the neighbours yard. Can’t imagine they’d be happy if I remove 200mm from their already tiny yard with thick insulation!

 

[jim843]

ASHP's will work if installed correctly in any property. As you rightly point out the pipe sizing and insulation is critical to that.

In your opinion would a heat pump work in my home (see above for more detail).

Built around 1890. Solid walls to front and rear. High ceilings. Draughty!

 

[pewe]

ASHP's will work if installed correctly in any property. will have the system working but it will cost a fortune to run if pipework isn't upgraded. This is good technology.

What would pipework have to be upgraded to in order to work efficiently?
For example we have 10 radiators (about 60,000 BTU) on a 15mm piped circuit run from a gas combi boiler.
Someone tried to talk us into installing an electric combi, with solar panels to run it in the daytime and batteries to run it in the evening.
From comments I've read whilst trying to do some research, it appears that at a cost of over £12,000 plus installation it would not be a wise expenditure without upgrading insulation, and the size of all the radiators first.

 

[gmartine]

^^^ I'd like to see a working example of that and interrogate the owners, you'd need a decent array of solar panels to do everything as well as a large battery pack or it'll cost you a fortune to run as well.

I watched this a while ago and can't remember the numbers but in principle it utilises many of the same things you may need cept we don't know how he heats his house.

 

[John.g]

I know the thread title is ASHPs but there is no mention of storage heaters which are powered from renewable energy, one would think that they could play some even small part.
Some of them like the Dimplex Quantum can actually retain heat unlike the old ones where it leaked away during the day.

 

[Ric2013]

What would pipework have to be upgraded to in order to work efficiently?
For example we have 10 radiators (about 60,000 BTU) on a 15mm piped circuit run from a gas combi boiler.
Someone tried to talk us into installing an electric combi, with solar panels to run it in the daytime and batteries to run it in the evening.[....]

Okay. Electric combi/PV combination and ASHP are different. The ASHP will work better at low flow temperatures, so you need thicker pipes and bigger radiators to give the same heat output with cooler water. With PV and electric combi, you have no particular need to reduce the flow temperature (in a nutshell).

I hope I'm not being political in questioning the technical validity of proposed solutions. I'm trying not to be, but I suppose we all have our biases. There is a sense in which renewables will push the output of the grid up at certain times of day and conventional power stations (especially nukes) are not easy to shut down and restart quickly, plus they may be running idle to give the grid some excess capacity for cloudy and calm moments, advert breaks (kettles!), etc. So may as well run ASHP under such conditions on houses where they are suited, and retrofitted improved insulation etc to existing stock may make a lot of it suited to ASHP. Not all of it - I agree!

What's the deal when it comes to high RH, however, as is typical in the British climate? The above charts ignore R.H. which can be 80 - 90% in the U.K.. My understanding of the problems C.A.T. (West Wales) had with its heat pump was that it (obviously) increased the R.H. of the outside air to dewpoint where it hit the evaporator and then, since the evaporator surface was below 0°C, frost formed instead of the condensate just dripping off. At which point, either they needed to use a defrost resistive electric heater coil to defrost the evaporator, or the ASHP no longer worked. This, at C.A.T., was dropping the C.O.P. to below 1. Is there a way of avoiding this? My feeling is that there probably is not, and that the sensible thing to do in this case is to avoid installing a defrost coil and switch to conventional resistive electric heating (or gas etc) in such circumstances, reserving the A.S.H.P to the warmer months of the heating season. If there is a better alternative, I would genuinely like to hear it. I would be open to fitting an ASHP even on my own house if I thought it would work well.