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View Full Version : How to calculate for scaling an air heat pump install?



ohansen
06-03-2009, 07:00 PM
Hi all,

how would heating engineers normally go about doing their calculations with regards to sizing an air heat pump install (such as Daikin Altherma or Mitsubishi Ecodan) for heating and hot water?

This would be for a new property, standard Barratt-type box, four bedrooms, two livingrooms, appx. 160m2 living area. All radiators, no underfloor heating sadly. Solar hot water and a 5kW woodburning stove are the only other heating sources.

Thanks in advance!

ohansen
18-03-2009, 12:25 AM
No hints anyone, are these trade secrets ;-) ? I've had a few ASHP proposals ranging from 8-15kW and it would be great to get some overall ideas, just making general assumptions about a property that's built to current building regulations/standards, no better, no worse. And how would one generally take into the calculations:

1) Potentially adding a ~5kW woodburning stove for the livingroom, maybe with air ducted around the house
2) Potentially installing a HRV which I believe could recover the equiv. of 1.5-2kW heat
3) Potentially keeping the 20kW gas boiler that I hate with a vengeance, just for the few ultra-cold days per year
4) Potentially installing a 4m2 solar panel hot water system, with a 300l twin-coil cylinder or Daikin solar kit
5) Definitely fixing some of the cold-ish bits in the house with extra insulation

It buggers the hell out of me when I speak to heating engineers/companies that want to sell stuff, that they have an "all or nothing" attitude. I don't feel a religious need to integrate my new woodburning stove with my new ASHP, and I don't feel an irrestistible urge to integrate the two with my new HRV. How come suddenly the TRVs on my radiators (radiators which I comfortably run below 55 degrees) have become no good?

So, a bit of venting there, but I'd like to be able to get out of this with some sensible high-level calculations and arguments so any hints would be extremely welcome!

brunstar
20-03-2009, 12:15 AM
at the end of the day there must be no guessing and same as air con a heat LOSS must be carried out for each job otherwise you will be guessing and the system may not work!