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Thinking about an air source heat pump in Aberdeenshire

stevebrockie3 · 2021-08-04T07:44:37Z

Hi Everyone, so glad to have found this forum!! We live in Aberdeenshire, off the mains gas grid and currently heat the home and hot water via LPG. We only moved in last November and estimate we'll need to fill the LPG tank twice a year, at a cost of about £2k in total (been notified of two price rises since November amounting to about a 30% increase). We have had a quote for a 17Kw Grant ASHP and replacement radiators. Cost is about £14k, but with government cashback and RHI payments, would only be about £3k cost to us, so we're fine with that.The issue is I don't know what to believe with ASHP, read some horror stories, then some success stories. Our neighbour built his house 2 years ago and has a Samsung ASHP and says its brilliant - but that is modern insulation with minimal heat loss. Our house is 30 years old, so hardly ancient but not insulated to modern standards. The house is 176sqm, 1.5 storey so the upstairs is in the loft space effectively. We have underfloor insulation (50mm) under our timber raised floor. We have 75mm loft insulation (being replaced with 300mm insulation once the bats vacate (another story!!)). The walls are cavity walls with the following composition - 100mm block, 50mm air space, 100mm inner block, 25mm air space, 50mm solid insulation, 75mm glass wool insulation between studs, 10mm plasterboard - so not bad, but not up to modern standards as I say. We had a bad winter this year, -10oC at times and about 2 foot of snow, so an extreme example, but the house struggled to get to 20 degrees unless we put on our wood burner stove and when the heating went off, overnight the temperature plummeted down to about 14 in some rooms, so heat loss very much evident. I am told with ASHP that as it is "on all the time" then you won't experience those drops and once it reaches that desired temp it shouldn't have to work so hard to maintain it, again, unless extreme temps outside. The windows are the originals, PVC frames and double glazed, but we know some of them are drafty, so we are considering replacing these at the same time. Both external doors are just timber so could do with being replaced, front door opens straight into hallway, no vestibule, so that probably isn't helping with heat loss either. From what I've read on forums, the bigger the Kw of your pump, the more likely you are to have a success with ASHP, my installer that has quoted me said they are over compensating by installing a 17Kw (said I'd get away with 13Kw) - but in their opinion you should install bigger/stronger than what the uValues calculation suggests - perhaps I should be encouraged by that, that they are giving it serious thought. They seem professional enough, have been doing renewables for over 15 years, so it isn't some plumber who's just jumping on the bandwagon. I am really keen to hear honest opinions, taking our circumstances into consideration and especially from anyone who's circumstances sound similar to ours. Thanks and take careSteve

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Air Source Heat Pumps (ASHPs)

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CeeBee

(@ceebee)

Eminent Member Member

Joined: 5 years ago

Posts: 10

05/08/2021 1:47 pm

@stevebrockie3

Hi,

We had a Vaillant ASHP 12kw fitted last October. We have a big old drafty cottage on the Yorkshire coast and had no choice but to install before we could do any other work. The majority of the house cant be insulated as its chalk,cobble, mud etc with no cavity only in a later extension. We have the whole pipework replaced and triple rads fitted. It worked lovely in the winter reaching 20degrees which was sufficient however it was costing about £300pm! Once we realised we lowered the heat and turned some rads right down. It also cut out in -2 temp, but they claim thats because it needs a bigger cable (we had problems with the fitters you can see on another thread).

I now take the meter reading everyday to check and we use about 5 units a day at the moment in total (not just hot water), we have had new windows and doors fitted and kingspan on many of the internal walls. More to do, but expecting it to perform much better this winter.

Look us up on facebook 'bramley manor cottage' and you'll see if the size is comparable to yours.

We need solar panels but neighbours are whinging about everything so far and we are running out of money so not sure when that will happen but id imagine it would then be really economical.

Good Luck

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Brendon Uys

(@heacol)

Noble Member Contributor

Joined: 4 years ago

Posts: 415

07/08/2021 1:55 pm

@stevebrockie3, If your installers are MCS certified, they have to do a room, by room calculation that takes your current build, insulation levels, ventilation and room temperatures (21 in the living areas and 18 in the bedrooms) in to account. Ask them for this, they have to give it to you with your quotation and with this there should be a radiator schedule for every room. In addition to this, ask the installer for manufacturer's evidence that the chosen heat pump will supply the required heat at the design temperature or duty point (usually between -1 and -5 depending on latitude and altitude). They should also be able to supply you with performance and running cost estimates, do not be afraid to interrogate these thoroughly, good installers will welcome it. If the installer struggles with this, get another installer.

If your installer is not MCS certified, get another one that is, as you will not be able to claim the RHI grant.

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Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 3849

01/12/2021 3:53 pm

@stevebrockie3, did you end up committing to an air source heat pump?

Get a copy of The Ultimate Guide to Heat Pumps

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stevebrockie3

(@stevebrockie3)

Active Member Member

Joined: 4 years ago

Posts: 5

Topic starter 01/12/2021 5:39 pm

@editor hi Mars, no we didn’t in the end. We’ve decided to grin and bear the extortionate LPG costs for another winter then will look into Biomass in the spring. Meanwhile we’re replacing all the windows and beefing up the loft/eaves insulation and will put in composite front/back doors as the old timber doors have to be a major contributing factor to the heat loss.

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