UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

richardc1983

DD137 wrote: »

I'm not sure if it can be turned down or not, trying to insulate the cupboard isn't a bad idea but at some points the whole room vibrates. Its an Ecodan
Are there any online resources to learn more about how they work? Google doesn't come up with much. I'd like to take a radiator off the wall to paint behind it for example but have no idea how to refill / pressurize the system after reconnecting it

Plenty of manuals can be found online for the ecodan and it is a very high end and configurable system as well.

Your best bet is to ring Mitsubishi Ecodan for some advice. Lots of info and manuals on here...

https://les.mitsubishielectric.co.uk/homeowners/ecodan-owners

colesadam

Hi, we have been talking to our local supplier for about 6 months and hummed and harred about the best solution - we are going to take an old oil boiler out of our 1990s conversion of a 18th/19th century brick byre, as we are short of space we want to put an ASHP on and in the adjoining garage. After seeing how my partner responds to the cold weather I don't think we can live with low temperature flow radiators and so we will need to install an HT system. The supplier quoted us around £16k for supply and installation of a Daikin Altherma HT system but this is now apparently discontinued so he is suggesting a Hitachi, which I presume is the Yutaki S80. Anyone know how this compares to the Daikin?

Part of the installation cost was running an insulated pipe outside the house rather than pull up the internal floors - how well does this work in practice? I can see how the heating circuit can work with antifreeze in it but what about the hot water supply? He has suggested a recirculation pump to get round the lag created by adding around 7m of pipe from the hot water cylinder to the original boiler site - but does this not just waste the heat in the pipe continuously?

Hae to say I'm finding the amount of decisions to be made for the huge up front cost to be fairly stressful....

Cardew

colesadam wrote: »

Hi, we have been talking to our local supplier for about 6 months and hummed and harred about the best solution - we are going to take an old oil boiler out of our 1990s conversion of a 18th/19th century brick byre, as we are short of space we want to put an ASHP on and in the adjoining garage. After seeing how my partner responds to the cold weather I don't think we can live with low temperature flow radiators and so we will need to install an HT system. The supplier quoted us around £16k for supply and installation of a Daikin Altherma HT system but this is now apparently discontinued so he is suggesting a Hitachi, which I presume is the Yutaki S80. Anyone know how this compares to the Daikin?

Part of the installation cost was running an insulated pipe outside the house rather than pull up the internal floors - how well does this work in practice? I can see how the heating circuit can work with antifreeze in it but what about the hot water supply? He has suggested a recirculation pump to get round the lag created by adding around 7m of pipe from the hot water cylinder to the original boiler site - but does this not just waste the heat in the pipe continuously?

Hae to say I'm finding the amount of decisions to be made for the huge up front cost to be fairly stressful....

Why a heat pump for a 18th/19th century brick byre?


Oil fired CH with an external boiler?? - under half the cost to install??

colesadam

No I appreciate the cost difference, but we don't want to install another fossil fuel boiler. We especially don't want oil though we did consider LPG as a stopgap until either heat pumps become cheaper or something else comes along - also I know LPG is a bit more expensive than oil but our oil tanks is also at it's end of life so would need replacing anyway and so LPG with a rented tank would be the cheapest option up front.

BillSenior

I am interested in finding out more about hybrid systems with air source heat pumps combined with oil boiler. I have a high efficiency Grant oil boiler which is only a few years old which provides heating and hot water in a detached house.

There are some hybrid systems being offered by B-Snug(backed by Shell) and EDF which appear quite interesting as much of the installation cost is expected to be offset by RHI payments. Both use Samsung heat pumps and PassivLiving app.

Does anyone have any actual experience with the installation and running of any of these? I am interested to know whether savings are actually made on fuel costs.

Many thanks

matelodave

You would need to do your sums very carefully as well as ensuring that your system (not just the heat pump, but the rads, hot water tank and plumbing) will achieve what you want.

Heat pumps are designed to run at low flow temperatures of around 35 degrees so the system has to be capable of keeping the place warm with low temperature radiators/heat emitters. As soon as you crank up the temperature the costs raise rapidly.

Most heatpumps are spec'd at 7 degrees outside/35 degree inside an you should get a COP of around 3-3.5, however when the temp drops or you want hotter flow temps then the COP will drop. If you pay 15p/kwh for leccy then a COP of 3 will cost you 5p/kwh so you really need to work out whether it it's cheaper than oil, especially when you take into account the cost of the ASHP and any heating mods that might be required.
The RHI is based on the heat requirement of your home and if you are contemplating a hybrid system you'll need to install heat meters so be able to measure how much heat the ASHP produces, so you may not get anything like the RHI that some sales people suggest you might.

inet_user

We're worried our LPG tank doesn't meet the latest regs, and we can't find anywhere on our small plot that would meet the regs so I'm pondering alternative systems.



We have a ~10yr old LPG boiler, with underfloor heating downstairs and radiators upstairs (that we only really use for one or two rooms). Our hot-water comes off the LPG boiler at the moment, but there is also an immersion.



Given we have the underfloor heating, it seems like an air-source heat-pump might be a viable option? I'm wondering if the running costs would be close enough to make it worth getting someone to come and quote for an install.



I guess there are going to be a lot of variables, but the install prices I've looked at seem to assume you're installing underfloor heating as well so are very expensive - a straight swap of the boiler for the heatpump should be relatively straightforward I guess?

Cardew

inet_user wrote: »

I guess there are going to be a lot of variables, but the install prices I've looked at seem to assume you're installing underfloor heating as well so are very expensive - a straight swap of the boiler for the heatpump should be relatively straightforward I guess?

I suspect it might not be straightforward


An ASHP should run at low water temperatures; 30C -35C is optimum. An LPG boiler runs at much higher temperatures.


Almost certainly your upstairs radiators will need to be considerably bigger and an investigation carried out on the suitability of the underfloor heating at such low temperatures.

matelodave

If you've already got underfloor heating have a look at you flow temperatures (not necessarily the boiler temp). Most u/f systems have a bypass/mixer valve to reduce the flow temp around the u'f part of the system whist leaving the higher boiler flow temps to heat the radiators and hot water.

Bear in mind what I said above, you ideally dont want a flow temp much above 40 degree when using a heatpump. Also be aware that at low flow temps the unit has to run a lot longer than a conventional boiler to heat the place although you should already be used to a lower flow temp if you've got u'f heating.

It's certainly worth considering especially when compared with the cost of LPG but you might need to increase the sizes of the upstairs radiators and get used to cooler hot water (is your present boiler a combi or do you have a hot water tank.

A fair proportion of the cost might be recovered from RHI payments - our Heatpump cost us around £7.5k (including the hot water tank) some 10 years ago and we'll get around £5.2k back as RHI payments. We are are on a single rate tariff (E7 wont suit us) costing 12p/kw and we have a deemed COP of 2.5 = 4.8p/kw although I reckon it's a bit better than that. Our total leccy consumption is just under 7000kwh/year of which about 3500kwh is for heating and all the rest is for lighting, cooking, washing and hot water (which also comes from the heat pump).

Get some quotes but dont be seduced by fantastic savings or excessive RHI claims - do you own homework as well so you know what you are being offered and can also compare systems from different vendors. Do a few sums youself (including detailed heat loss calculations) so you know roughly what size unit you'll need.

An undersized unit will need to use the backup/boost heater to produce enough heat, will cost a lot more to run and probably still wont keep you warm whereas an oversized unit will cost more up front and may not be running at optimum efficiency.

As in all heating things, make sure that your insulation is a good as you can get it - you'll need an up to date Energy Performance Certificate EPC and the system must be installed by an MCS registered installer to be able claim RHI

inet_user

thanks - looks like it might be viable, our underfloor runs at <40 degrees already (it has its own control), and we have the radiators upstairs fairly cool as we have young kids. We have a hot water tank - so I suppose the heat pump works better with the tank?