A heat pump system will typically have an efficiency of 300%, which if using electricity at the standard rate still brings it down to a nominal
5p/kWh. If you take into account the other running and service costs, plus the cost of the initial installation, is it a really economical?If the user is an enthusiast and willing to get their hands dirty, then of course it is a different matter.
No mains gas is a requirement to get the RHI(*) and pretty sure to get the RHPP capital cost help as well. For GSHP the RHPP is £1250, ASHP t o water £850.
Not a bad idea, ground source would be best but rather disruptive to the garden (if it's big enough) or you can drill bore holes. Trouble is to fit to a conventional HW/CH system you need a more expensive two stage heat pump.
There are implications relating to the electricity supply. If you need 2
0 odd kW of output that implies at least 6 kW of input on top of whateverload is already present. This is also a relatively long term load, unlik e a shower for example. If you only have small (but common) 40 A supply that is only 9.2 kW...
(*) No defiante figures for the RHI payments but the range is 6.9 to
11.5p/kWHr for air source and 12.5 to 17.3p/kWHr for ground source.
Admittedly it was 8 years ago but business was booming then and I am in central London: WB 24 combi, replacing cast iron lump, including modifications to gas and water pipework, was about half that.
So I'd say too much.
I have one in my main room, which is also my office. I use it to heat just the office when working at home. It's been running today. Running cost seems to be very low. I installed it myself about 7 years ago, and it cost £400 at the time (B&Q, but they don't sell them anymore). It has probably well paid for itself by now, but only because it was a self-install. It will likely need a gas topup sometime over the next year or two (it's drawing less power than it did originally), which costs about £100 (and you can't legally DIY that anymore).
A professionally installed system would never have paid for itself during it's likely lifetime.
Yes.
Bill
Did those calculations include RHPP and RHI?
3 phase for a silly little 4 kW compressor? Naw, it will have soft start. Might cause a little dip on start but nothing serious.Two stage heat pump to interface with the conventional plumbing.
Weather doesn't have a great effect on GS, AS can drop off a heck of alot between 0 and 5 C due to the collector icing up and energy being reuired to de-ice it. Once you get below freezing things improve again.
Agreed.
I don't think you need to do as much as you think these days. But ideally one would want UFH rather than coventional rads. Pondering about a heat pump for the currently E7 storage heated cottage, rads can be sized to take into account a low circulating temp but I don't think 50C would cut it, not up here with a gale blowing... Space is also a problem, and heat pumps are not the smallest or quietest of things.
Firstly, many thanks for that comprehensive answer. We have a 27kW combi boiler. There are 14 radiators plus a towel rail. Because the pipes between the boiler and the kitchen and the wetroom are very long we have a 2 litre 'instant hot water' electric gadget. This feeds separate taps to the main system. We are on a north-facing slope and get incredibly strong cold winds from the north and east.
Bill
yes.
in short if its a new build and you can design the house around it, its very worth doing (until you get a power cut)
But like insulation, retrofitting it to existing houses is sometimes not that simple.
Its a 210 l one too. With a solar coil.
I have seen cheaper ones but I can't decide which are better than the others from the data sheets available.
Some time last year, I did some basic calculations of comparison costs. I took my bills, electric and oil, and the electric and gas bills of a flat near London. In each case, I worked out what the additional cost would be for a kWhr. Electric near London: 15.02p Gas near London: 4.83p Electric in East Anglia: 12.63p Oil in East Anglia: 5.58p
Maybe this helps.
just cuddle up next to Sizewell B...
Too far away....
Oh dear dense
Your spell checker got it wrong not once but twice
what can be going on ?
Dennis - I'm not taking the piss or anything here
Just look for the one which meets your spec which gives you the longest warranty
That's all
Thanks Adam, but I have a good bloke near here. I only got Calor out because they enclosed a flier with the gas bill promising that they would give me a new boiler at a fantastically cheap price. Clearly this was not true.
Bill
What you do will need to do (if anything) will depend on what you actually want to achieve...
Unless a boiler is very inefficient[1] and your gas bills also very high, then there is not usually much if any cost benefit to be had changing one working system for another. Obviously if the boiler is on its last legs and needs replacing, then its a difference situation.
Changing a system to achieve better performance or new capabilities is another possibility. If for example you wanted more hot water performance, then you could look at adding a unvented cylinder to the existing setup (just because the boiler is a combi, does not mean it can't also heat a hot water cylinder like any other boiler!)
Fitting better controls, or adding weather compensation would also lower bills and improve comfort without too much extra expense.
Yup a problem I can relate to...
If looking for "things to do", its often worth taking a step back and seeing if there are any "low hanging fruit" cost savings to be had elsewhere. i.e. it may cost less to improve insulation than to make the heating work better.
[1] Look up the model here:
You should have seen the price before they gave you a discount! ;-)
(Note that a "like for like" combi change is easily DIYable for someone with a bit of practical ability - that brings the price for a new high end boiler down to around a grand, which may change the outlook somewhat)
There is the running costs subsidy to take into account. More than covers electricity costs I think.
I'm not exactly an expert plumber, but had no problems changing my boiler, although I do have all the basic plumbing tools like a pipe bender, etc. Found it very satisfying.
Many installers will simply do things the easiest and quickest way - regardless of what it looks like - even when charging a high price. My brother's installation has surface mounted pipes running along a wall when with a little more work they could have routed them under the floor.
How good is that service, John? Our boiler doesn't seem to appear there (Glow-worm Flexicom 24 HX).
[ I must say that the interface doesn't inspire confidence : it looks like an amateur creation from the 90s! ] [[Hope I haven't trod on any toes there.]]John
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