Hi all looking to find a way to reduce my winter fuel costs, I had seen some ASHP's apparently spending a lot of time defrosting but then I see claims of 2.0 for COP even at -1C so maybe there not so bad.
in the UK the cold spells are also periods of near 100% humidity. It puzzles me how an ASHP could function in those conditions. Once one gets frozen over it just won't defrost if the ambient temp is below 0C, so its stuck until the weather warms up. Do the systems supplied in the UK have a thawing cycle, or something?
in the UK the cold spells are also periods of near 100% humidity. It puzzles me how an ASHP could function in those conditions. Once one gets frozen over it just won't defrost if the ambient temp is below 0C, so its stuck until the weather warms up. Do the systems supplied in the UK have a thawing cycle, or something?
This is the dreaded "defrost cycle" where the heatpump works in reverse to heat the external unit thus de-icing it. Of course the effect is to reduce the effective COP and dramatically reduce the heat delivered into the house! Quantifying this aspect is what concerns me
Our Solar system is 2.5kWp, so we only use the ASHP on the sunny days, so there is an initial hit where it gets going then it is just topping up. According to the smart meter still cheaper than turning on the Combi on bright days.
When I put the ASHP in the house, and a smaller one in my office, I gave up with the websites and just went to see a couple of local installers, they can normally get more detail out of the manufacturer. Following a few discussions both my systems are Daikin and haven't missed a beat in the years they have been installed. Follow up on any references they give and ask the owners how they get in, it's the only way to really know how a system performs.
I don't think the models Daikin sells in Hong Kong have a defrost function. You have to do really dumb things to get a radiator to freeze over there. In the UK its not even hard to get an air con to freeze over on a hot rainy day in summer, but I have no experience of heat+cool air cons in the UK providing winter warmth.
I remember the extremely high humidity in HK,but as they were working as aircon it was the indoor units that were in danger of freezing up, as you say I cannot recall any particular defrost arrangement, just the usual condensate drain.
The best temperature increase you can expect (measured between outside air and the air coming through the registers) is about 20F or so.
At the peak of summer I typically spend about $20 a month in electricity running the AC for a ~2300 sq-ft house, a small price to pay IMO.
Did you miss a zero there? Good grief, Charlie Brown, I spend that much when it's 70F outside! Must be a better breed of electrons they sell around these here parts.
For me the primary use is air conditioning in the summer. People say it's not really necessary up here and very few have AC, but for the month or two of hot weather we typically get in a year it's totally worth it to be able to sleep in comfort rather than laying on top of the sheets sweating.
For me the primary use is air conditioning in the summer. People say it's not really necessary up here and very few have AC, but for the month or two of hot weather we typically get in a year it's totally worth it to be able to sleep in comfort rather than laying on top of the sheets sweating.For that purpose I have a large tree in front of my house where our bedroom is.
Hi all looking to find a way to reduce my winter fuel costs, I had seen some ASHP's apparently spending a lot of time defrosting but then I see claims of 2.0 for COP even at -1C so maybe there not so bad.