Installing air source heat pump and wet system increase value of property?

Ken2000

Hi, I live in the Scottish Highlands and don't have access to mains gas. As things stand, I've got storage heaters and am on a THTC tariff, which is fairly pricey and inconvenient. I'm looking to replace the heaters with a wet system and have an air source heat pump installed and make use of the government's RHI repayments. Firstly, does this seem like a sensible idea and secondly, is it likely to increase the value of my property? 

JJ_Egan

What does your local estate agent say .

Gerry1

How do the running costs compare to oil and LPG?  How reliable is the local electricity supply in the winter?  Is the property likely to appeal to people who are home all all day or vice versa?  Apparently heat pump solutions don't lend themselves to warming up a property quickly when returning to it, so local conditions and lifestyles may be as important as the basic engineering.

But with THTC, doing nothing isn't an option.

Mouldymeat3

There are many forms of air source, internal units, external units (like ours), heat recovery in loft spaces and hybrids of them all. We were obliged to have air source as a condition of our planning consent and here in Cornwall; it is adequate but it's not like a boiler replacement. North of the M4 it may be more marginal, the Coefficient of Performance falls sharply with a fall in ambient temperature- ours only just kept up with the Beast from the East- circa -5C. You need to read the full spec in the brochures to weigh up the costs, not just the headlines.

Grumpy_chap

It probably won't increase the value of the property

Cardew

Excellent advice from Gerry and Mouldymeat. There are plenty of threads about ASHPs on this forum and elsewhere on the web.

The climate in the Highlands varies - the West coast can be quite mild, but inland extremely cold. As said above, the performance in cold conditions drops off considerably.

The brochures paint a rosy picture boasting a COP of 4 or more(COP is a measure of performance - so an input of 1kWh giving a heat output of 3kWh gives a COP = 3.0). In England an overall COP of 3 is excellent and in extensive trials by the Energy Saving Trust(EST) few installations achieved that COP of 3.

Another issue is that it is neccesary to run the ASHP for very long periods - even 24/7. That is OK if you are home all day, but otherwise you are heating an empty house. You can't simply switch it on like a gas/oil boiler and the house is warm 30 minutes later.

Lastly the expertise of the installers is crucial - a poor installation can be a disaster. The manufacturers do not fit the heat pumps themselves, they just sell them to the installers and you have no guarantee of performance.

Obviously if your house meets the stringent insulation standards, RHI is very attractive and offsets the installation costs.

However with oil at the current low prices, oil CH is considerably cheaper to run than an ASHP even if you can achieve a COP of 3.0.

Guess what I would get if I lived in Scotland!! and yes I have owned a ASHP, albeit air to air and in the USA.

Mouldymeat3

I should, perhaps, have qualified my earlier post by explaining that we went to a self-build exhibition at Swindon where many systems were on show. We were lucky in that our local installer was well up on his game.

The calculation sheet for our tiny bungalow gave a requirement of 3.6kW for heating that's 86kWh/day at -2C.  We had a 5kW  inverter drive modulating unit installed with underfloor pipework under a 3 inch screed.

Edit: we don't have a bath so the only stored hot water is under-sink.

In the early days I tinkered with the room-stats but in the end left the bedrooms at 18C and living areas at 24C to allow the system to run generally 24/7 and let it do it's own thing. The worst electricity consumption so far has been 21kWh/day winter, 6kWh/day summer, average £10/week.

When we had LPG in the old bungalow, twice the distributor had to come out and decant from bottles because their lorry was out of action. There was no choice of tariff.

Oil systems now demand bunded tanks and certified installation and theft of fuel is a real thing.

The OP's choice may also be limited by Building Control as ours was.

Cardew

There is the world of difference between having an ASHP in a new property with excellent insulation and using underfloor heating, and  retro-fitting in an older house with storage heaters.

There is of course a case for retaining storage heaters as the savings in running cost with an ASHP or oil, will take many years to cover the installation costs.

Mouldymeat3

Cardew, you are, of course, quite right. I failed to emphasise the 6 inch cavity, 4 inch insulation batts and double quilt in the roof. As designed for us, the system is barely adequate. Our consumption is so low because the system cannot deliver any faster even with low-tog floor coverings. If any solar gain trips the thermostat it takes ages to recover. If we go away, we have to leave it running.

In the Highlands I assume the OP would need a hybrid system so the cost would be even more prohibitive. A village hall near us installed ground-source, multiple boreholes across the car park for a cost of tens of thousands. When the ambient air falls to +6C it reverts to oil. The bingo ladies sit in hats and scarves.

I had rashly assumed the OP was doing a complete refurb. His best return might be from improving insulation, reducing the draught up open flues etc.

matelodave

I'm guessing that Mouldmeats3's ASHP is undersized which seems to be a common theme - fit and undersized unit and the rely on the back-up/boost heater to deliver the shortfall which is a recipe for a not very warm dissatisfied customer and large leccy bills..  The system -both the ASHP and the heat emitters -  have to be properly sized to suit the heating requirements of the house and you do have to understand how to correctly operate the system - it does not perform like a conventional hot water boiler.

We have a 1986 bungalow 140sq.m with an overlay wet underfloor heating system. 12" insulation in the loft, indifferent cavity wall insulation and pre-2000 double glazing. The 11kw Daikin unit has kept us warm enough even when the outside temp has dropped down to -15  although I guess the back-up heater was in operation when that happened.

It does take a long time to recover the house temperatures so ours runs virtually 24/7 with a min of 17 overnight and around 19-20 during the day & evening but as we are at home all day it suits us.
The first time we went away (over an extremely cold December), I turned it right down and it to around 36 hours to reheat the place. e now set the holiday mode on the programmable stats to turn it back on 48 hours before we return so we come back to a toasty warm house.

I've disabled the back-up heater and we are still more than warm enough.Our total leccy consumption )heating, hot water, cooking etc) is around 7000kwh a year, some years a bit less and in the really cold winter about 2012/13 it went up to 8500kwh.

Whether it adds value or not is a moot point, but ours is now 10 years old, we've never paid anywhere near close to £1000/tr for our leccy and we've had nearly £5k back in RHI payments. We dont have mains gas which would be my preference but its easier and less trouble than oil or LPG. 

Gerry's comment about reliable leccy is a bit spurious as most heating systems (unless they are basic wood burning stoves) need leccy for the pumps, fans, valves and controls etc. 

Gerry1

matelodave said:

Gerry's comment about reliable leccy is a bit spurious as most heating systems (unless they are basic wood burning stoves) need leccy for the pumps, fans, valves and controls etc.

Agreed, you still need electricity. However, if you lived somewhere really remote at the end of an overhead line that might be brought down in a snowstorm and take a week or more to be repaired, you'd probably have an inverter/battery or even a small generator to keep the oil / LPG system going. You couldn't do that with an all-electric heating system, the property would soon become uninhabitable with the risks of burst pipes and even a danger to life without any form of heating.