High temp air source heat pumps?

katie279 · 3 Sep 2022 at 07:25

Ok guys,

Now I'm all solared and batteried up, I'm now looking at heating.

I know low temp heat pumps are pretty controversial at the moment, dubious in terms of ROI and very disruptive to both your house (rip the place apart for new radiators, insulation) and your lifestyle (plan your heat 24 hrs in advance!).

However these high temp ones are now being released in the UK, which are just straight swaps for your oil/gas boiler and look pretty compelling.

Has anyone got any experience/ thoughts on these? After oil has risen from a £230 bill to around £1000, I'm keen to free myself from that and love the idea of heating through solar/cheap electricity rates using batteries....

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katie279 · 4 Sep 2022 at 08:22

Take that as a no then....

Gonna investigate these more - seem to be eligible for government grants/rebates too, so that'd be extra £7500 potentially off.

Need to try and work out how many KW my heating would be in winter...!

HungryHippos · 4 Sep 2022 at 08:49

I could do with a heat pump that directly replaces a combi boiler in function, so no hot water tank, or a small integrated one in the unit that allows enough water for a shower or w/e.

What would traditionally be my upstairs boiler tank cupboard is instead just storage, but it's a little too busy in there now to add a water tank really unless it's small. That cupboard has my inverter/battery on the left, boxed in shower controls for the en-suite at the back, and also pipework for the existing CH system on the right.

See pic: https://i.imgur.com/vonvpDA.jpg

Removing gas supply and going full electric would be good, especially if done efficiently with off-peak and solar, but there are still too many costs and challenges at the moment I think.

Will wait a bit, see if costs come down and better solutions come along, if my boiler outright dies I will re-consider, but it's about 10 years old and has been solid, should carry on for a bit.

Apparently removing gas supply also has a cost, you have to pay them to take it out to save on paying standing charge, and from what I read it wasn't cheap.

katie279 · 4 Sep 2022 at 08:58

Ah makes sense - I think oil is a bit simpler as we've naturally got no 'mains supply ' needing plumbed out, just a big tank outside.

Have sent a few emails around, so will see what comes back!

HungryHippos · 4 Sep 2022 at 09:02

Yes if you have the space then it seems like it's sort of going nicely hand in hand with the other systems you have, and not having to pay to remove a gas supply is a bonus (honestly this seems like a scam cost to me!).

I have a multi-split AC setup 3 internal units one external, it's not a central heating system but uses the same refrigerants mentioned, R32.

Considering scheduling them to heat the house a little overnight on the cheap Go electric rates in the winter, although the impact may dissipate a bit by the time I actually wake up, it should in theory give a better baseline heat. New build house so keeps heat in pretty well.

katie279 · 4 Sep 2022 at 09:05

HungryHippos said:
Yes if you have the space then it seems like it's sort of going nicely hand in hand with the other systems you have, and not having to pay to remove a gas supply is a bonus (honestly this seems like a scam cost to me!).

I have a multi-split AC setup 3 internal units one external, it's not a central heating system but uses the same refrigerants mentioned, R32.

Considering scheduling them to heat the house a little overnight on the cheap Go electric rates in the winter, although the impact may dissipate a bit by the time I actually wake up, it should in theory give a better baseline heat. New build house so keeps heat in pretty well.

Yes, I'm even mulling adding a third battery to cover this.. ie charge for cheap or store solar from previous day and discharge during day to heat as required.....

Macro · 14 Apr 2023 at 18:17

Did you ever get anywhere with this? We've had our PV panels (4kWh) and Batteries (11kWh) installed along with an Eddi unit to heat the hot water cylinder before sending the rest to the grid on what will be Octopus Flux once we get it sorted. We seem to be more or less covering the house needs for electricity at the moment (April) with PV during the day and batteries charged from PV during the day carrying us through the evening and night. I expect we'll have some surplus in the summer and need to charge the batteries from Octopus Flux at night during the winter.

Our 25 year old Oil fired boiler which runs the heating and hot water tank could do with replacing, I was thinking of a new higher efficiency Oil Burner but then thought perhaps I should think about Air Source Heat Pump and take advantage of the voucher scheme. The house is 25 years old, reasonably well insulated with modern double glazing and a Wood stove in the living room for spot heating in the winter.

I noticed Octopus are doing their own Heat Pumps in the scheme along with a detailed site survey. Like the OP I also noticed elsewhere info about High Temp Heat pumps. I've asked Octopus to give us an estimate, hopefully they're reasonably reputable so should give us a good starting point.

I'm interested to get anyone else's view and experience; I hear some stories about horrendous electricity bills and permanantly cold houses and others who are happy and are saving vs Gas/Oil. I guess it very much depends on the house and if you're a "put a jumper on" or "whack up the thermostat" sort of family.

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b0rn2sk8 · 14 Apr 2023 at 22:25

Consider an air to air system, cheaper to install, can be ducted into the loft so no wall units on upper floors, can heat hot water cylinders, fast reaction times and more efficient than air to water.

Macro · 15 Apr 2023 at 15:59

It'd be interesting to hear from anyone who has gone down the Air source heat pump route what their experiences are with running costs and how warm the house is etc.

Freefaller · 15 Apr 2023 at 16:54

I'm interested too as we're looking at removing gas if we go ahead with our extension. We have a modest solar array, batteries and hot water diverter so in terms of electricity I'm happy to take the hit. That said we spend so little on gas anyway we may just leave it, but just thinking about it from a sustainability perspective.

b0rn2sk8 · 15 Apr 2023 at 18:07

Macro said:
It'd be interesting to hear from anyone who has gone down the Air source heat pump route what their experiences are with running costs and how warm the house is etc.

It’s been correctly installed, it should cost slightly less to run and there should be no difference in terms of how ‘warm’ the house is.

The issue as always is the retrofit cost.

Coran · 15 Apr 2023 at 22:09

I had an ASHP installed about a month ago and I’ve got some extra monitoring going in over the next month which will give me an accurate COP reading (ratio of heat energy out to electricity in).

I should then be able to adjust a few settings (e.g. lowering flow temperature to radiators) and see how much it improves performance. I’ll also get my heat pump onto https://heatpumpmonitor.org/ which provides a bit of a comparison by heat pump size, brand, building type and so on. There’s not yet enough data on there to draw many conclusions but they’re all real examples showing the efficiency that can be achieved.

b0rn2sk8 said:
It’s been correctly installed, it should cost slightly less to run and there should be no difference in terms of how ‘warm’ the house is.

The issue as always is the retrofit cost.

I think this sets slightly unrealistic expectations. You’re right that it should just work but, if you want the system to run very efficiently, you’re going to need to gain an understanding of how it works, adapt to it and tweak settings to maximise performance. I’m happy with my installation (it heats the house) however, based on electricity usage, I can see that the heat pump turns on and off a lot which is not good for efficiency so is costing me more unnecessarily.

Re the switchover, to help assess how big a retrofit challenge you have, you can reduce the temperature your gas boiler is running at (no idea what control you have for oil boilers!). If you turn this down to 40-50C and your house is still heating up well, you should be fine without major adjustments. Anything you do such as increasing radiator sizes will just improve efficiency (by letting you run even cooler).

Macro · 15 Apr 2023 at 23:39

Good info thank you. I have a setup similar to Freefaller so in essence I have a minimal electricity bill currently. I’d be swapping an oil fired boiler which costs us c£1000 in oil a year for heating/hot water (pre hot water Eddi solar diverter).

I guess I’m happy to go for ASHP, swallow the install costs and contribute to the environment as long as the house warming and annual running costs are nett neutral compared to oil.

katie279 · 16 Apr 2023 at 16:21

Hey all - I looked into this in some detail and posted in various forums to get expert views and the like. The short of it is, I'm leaning towards holding fire for a year or two as it appears the whole heat pump technology (especially high temperature ones) are just too new and constantly evolving - think of it like buying the first iphone....

I'm really keen to wait for a straight swap heat pump that can reach high temperatures if required (ie so I don't need to plan 24 hours ahead when I want to be warm!) - there are several on the market now, but they're very much first editions and have a few reported bugs, so I'm going to wait for at least the '2nd editions' of these and then jump onto the bandwagon!

Freefaller · 16 Apr 2023 at 16:50

With our underfloor heating (wet system) heat pumps make sense but they are a compromise elsewhere... The advantage of underfloor heating is that it uses a trickle of energy to stay warm once it's up to temp. Gas is still better for heating radiators unfortunately for us. However it would be nice to go to single energy source, however as you seem to have alluded to the technology just isn't quite right yet.

Rroff · 16 Apr 2023 at 16:58

As I've mentioned before a load of people around where I'm living took advantage of some grant thing (specific to the area - not really sure details as we moved here after the scheme expired) to have heat pumps installed, those with ground source seem fairly positive but those with air source I've heard a lot of negativity about.