Heat pump cost to run

[eaton]

I'd personally a
Ways do both, one whole house and then one with rad output needs for every room , I'd then compare, I'd still always go with the rad/underfloor output totalled, if you do each rooms heat loss and add it up it might come out a bit differant to a whole house, also some people design certain rooms to differant temps, ie bathrooms, hall, beds etc

 

[slingshotjim]

Ok I get you, The bedrooms are 19, living 21 etc understood, I used the estrust one that assumes 19.2 average I think, to be fair just needed a ball park and Im in the park now I think! Still dont quite get the consumption being massively different, perhaps when Ive finished the ufh in all the rooms maybe the 11kw wont be able to keep up and the temp wont be able to be reached in the rooms? But at the moment got about a quarter left to do so the 11KW probably not as far out as it sounds after the calcs . Like i ve said its the bills, just had the last one, oct nov dec was £700...... Saying that thats total , inc hot water all lighting, cooking washer tumble etc etc, and its a big house with not the best ufh kit because of the insulation underneath or lack off.... my bills will be about £2500 a year praps maybe thats that . Most of the people with ashp s seem to be in mega insulated new builds with other forms of solar and back boilers etc... maybe just expecting too much praps,

 

[eaton]

If you just want a rough est and this is rough use this

70 watts for refurb, 50 watts for new build, 100watts no insulation,
181m2

So for eg 70 watts x m2 181 divide by 1000 = kw

So 70x181/1000=12.67 kw, that's the size of the unit, this really is a rough way of doing a heat loss but hope it helps! I'd est you need around a 13-14kw pump, from this rough guide, 11kw heat pump does sound borderline but I don't know how good your insulation, windows are etc, If you was using above info of 12.6kw and you had an 11kw I'd say there is a back up heater installed or needed

 

[eaton]

This is easier, again I don't use this or the heat pump but it's a quick idea, you'll have to match your area with outside temp

[DLMURL]http://www.heatking.co.uk/pdfs/Heatking_Heatloss_Calculator_Guide.pdf[/DLMURL]

 

[slingshotjim]

Thanks for that, that link Id be at about a 15Kw , your rough guide 13Kw, my calcs that I did carefully following all the guides , measuring everything twice inc the windows etc I get 22Kw... Mmmmm .Hard to get it right thats for sure,

 

[eaton]

It's called experience lol

 

[slingshotjim]

Ha, no substitute fella. Trouble is I dont know anyone that Id trust to come and do the job properly now Ive seen all the bodgers at my house! Its hard when your relying on someone for something you dont know a lot about, learning quick mind... No doubt there are good lads out there and if you can help with someone in the N/west (Preston) Area then great.... If anyone wants some race motorcycle instruction round Oulton Park...... Jim...

 

[eaton]

I'll have an ask on another forum

 

[slingshotjim]

Thanks, Jim

 

[MattWeth]

Ha, no substitute fella. Trouble is I dont know anyone that Id trust to come and do the job properly now Ive seen all the bodgers at my house! Its hard when your relying on someone for something you dont know a lot about, learning quick mind... No doubt there are good lads out there and if you can help with someone in the N/west (Preston) Area then great.... If anyone wants some race motorcycle instruction round Oulton Park...... Jim...

Heat loss and system sizing is a tricky thing - as eaton says, it's part calcs, part experience. I'm struggling to see why there's such a disparity between your calculated losses and the 'rules of thumb' methods that eaton posted but without seeing your property and your calcs, it's difficult to see where the problem lies.

My gut feeling (and it's only a gut feeling, so as they say, it's worth what you paid for it !) is that your HP sizing probably isn't a million miles out, but there could be other issues which are causing inefficient running. This could include things like poor insulation which falls outside the calcs, draughts, poor system design (component selection, layout, piping, installation etc) or none of these and perhaps other things! My other gut feeling is that as discussed earlier, your underfloor installation isn't suited to HP use and that you might be better off with different emitters (high efficiency HP rads, fan coil units etc).

What I would say though is that I definitely wouldn't throw more money at the problem and start swapping things around until you've got a proper handle on what's happening with your system. However, it might be worth throwing a couple of hundred quid at an independent consultant who can do some calcs and take a look at your installation - the Chartered Institution of Building Services Engineers would be a good place to start.

So you build race bikes? - Excellent! My racing days are over (I used to proddy race Yam LC's a long time ago) but I live in Cheshire and go past Oulton on my 'quick flirt out' route. These days I tour, mess with old bikes and display astonishing incompetence at trials (at 45 I don't bounce as well as I used to!).

Matt

 

[peteheat]

Hi,

I fully agree with Mattweth, get the house surveyed by a professional I had reason to look at that suppliers products and like eaton I was far from impressed.

One option I did not see mentioned (I read all five pages) is the possibilty of making the system Bi-vallent that is to install a back up boiler to the underfloor system, I am thinking of wood pellet (for the green energy) or even an oil boiler.

As the outside temperatures drop you can expect your heating bills to increase possibly to the point where for a short time the heat pump will run at full output and still not provide sufficient heat for your home, the back up system can come on and assist the heat pump during such cold spells.

I got so tired of telling potential customers to spend the money on the heat loss calculations that I stopped all advertising for heat pumps and removed all links about them from our web sites because the consumers were getting so much conflicting information from other suppliers / installers it was making us look like the bad guys.

There is no joy in having consumers coming back telling me I was right because they are sure to have told a lot of people that heat pumps don't work or are too expensive to run, thankfully I can point to a few where they both work and heat large homes at very reasonable cost.