Quote:
Originally Posted by AC_Hacker
I'd go for the very smallest size de-humidifier compressor I could possibly find... see how it works out, you'll really learn a lot. Then scale it up if you need.
-AC
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Any idea what sort of COP the de-humidifiers achieve? Looking at this table:
http://ecorenovator.org/forum/conser...hanger-14.html
The efficiency of the best units seem to be about 4x those of the worst.
At first glance, I think that running the heat recovery ventilation part efficiently (and quietly) is probably going to conflict with running the heat-pump part efficiently. Having lived with a heat recovery ventilator in the past, and taking into consideration the way my house is used, I'm guessing that on average (during the heating season) the unit for my house is probably only going to run at an average of 50 m³/hr or so (a lot of the time there's no one in the house during the day, only a bit of humidity being generated by house plants, and maybe drying clothes in the "drying cupboard" which I'll place next to the HRV unit).
Playing with that recair calculator, if I build a unit to work at 300 m³/hr peak, but only run it at 100 m³/hr normally, then when it's running at the 100 m³/hr figure, it'll use something of the order of a quarter of the power to run the fans vs. the peak flow (which is a significant saving - maybe 60 watts), but the losses in the exhaust air will drop to about one eighth of the peak-flow amount (an even more significant saving - maybe 200 watts). The factor of 3 gain (from transferring only a third of the amount of air) is multiplied by the considerable improvement in the heat recovery core's efficiency which results from passing air through it more slowly.
So intelligent control software could be conservative about turning the fans up (if I get a bit of condensation on the windows occasionally, that's OK in many cases, so long as it doesn't sit around long enough for building materials to get damaged, and mould to start growing etc.).