Are Air Source Heat Pumps worth the outlay?

kaggi

We have an oil tank and combi boiler and are thinking about ASHP but there's a big outlay and were weighing up the pro's and cons.

Our current boiler is old and not really efficient but replacing that like for like would be much cheaper than installing a whole new system. We live in central Scotland so in the winter we often reach minus temperatures (-17 a couple of winters ago) and I don't know anyone who has one so looking for some honest opinions on whether this is a worthwhile investment and if it would work for us. We're in a semi-detatched house built in the mid 1940's and it's double glazed and well insulated if that makes a difference.

Cardew

There are hundreds of posts on this forum giving the pros and cons of an ASHP. You really should read and see how the various points affect your situation.


For me it is a no brainer - keep your old oil boiler as long as you can; especially with oil being as cheap as it is at the moment

Smiley_Dan

What boiler is it? Make and model.

Generally I'd keep running the boiler and invest in insulation and airtightness.

kaggi

I don't know the make and model of the boiler, it is in an outhouse and the way it has been out in means I can't see the details. It doesn't provide enough hot water to run a bath but it heats the house and gives enough water for showers so we were thinking it needed replaced at some point soon anyway. There is some kind of government incentive at the moment which is a consideration as I am not sure how long that will last, but as we don't actually know anyone who has a ASHP in Scotland we are unsure whether it would actually be worth while for us. There's so much information on here it is hard to see the wood for the trees.

Cardew

As you indicate it is difficult to 'see the wood from the trees' and certainly a firm installing an ASHP will not enlighten you to the downside of ASHPs.


Firstly with the present low price of oil(around 35p/litre) there will be little to choose between the running cost of a well installed* ASHP and a new oil boiler.


A big issue with an ASHP is that it needs to produce water at low temperatures for maximum efficiency- typically 30-35C(and oil boiler is up to 80C plus)


This has two major ramifications.


Firstly it is pretty certain that your existing radiators will not big enough and will need replacement.


Secondly, unlike oil CH, it takes a long time to bring the house up to the required temperature. Thus the system will need to run for long period - even 24/7 in colder weather.


In your semi-detached house there is a potential noise problem from the outside unit - you need to assess that issue by hearing one in situ - especially during the defrost cycle.


Do Scotland have a better or worse scheme(than England) for assistance from the Renewable Heat Initiative(RHI). That goes a long way to offsetting the high installation costs of an ASHP.


* experience shows this is not easy to achieve - Read the Energy Saving Trust trials.

Smiley_Dan

kaggi wrote: »

There's so much information on here it is hard to see the wood for the trees.

I'd say that's a sign you shouldn't be rushing into quite a major decision.

Take your time and learn about the possibilities. Also research the possibilities that reducing your heat demand brings. Not having to generate energy is preferable, IMO, to working out _different_ ways of generating energy.

Agree with Cardew.

Silent_Dancer

I also agree with Cardew. To install an ASHP is a considerable investment which at the present price of oil cannot produce a lower unit cost of heat than oil.