Quote:
Originally Posted by Xringer
One other crazy idea that crossed my mind was to skip using a coil and fan in the attic.
Maybe try using some of that radiant floor heating hardware up there.?.
Perhaps direct contact with sun warmed roof lumber would work.?.
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The difference between direct heat extraction and using refrigeration cycle for heat extraction is that refrigeration cycle allows to use low heat for "producing" high heat. If you just try using attic heat directly you are limited to what you have right now when it is hot. As soon as temperature in attic equals or even a bit higher to temperature at the place you want to heat up your "heating" system will stop working. You need temperature difference to make it work. Heat pump will keep pumping heat even when attic temperature is lower than temperature were you need it.
Also you probably want to attach pex with plates to roof plywood but how?? Nail it from inside and damage the roof??? OK you can use very short nails but you already have hundreds of nail sticking out from plywood.
Let's see how this can work very well with refrigeration system:
1. Summer time is self explanatory it is super hot there and you just pump heat to your tank. This also will keep your attic cooler and help your AC.
2. Winter time gives you enough heat (depends on your sun exposure) during day time and your system can extract this heat efficiently. But during night time when it is cold there your heat pump system is down and you use (if you need at all) elements.
To control this system when to work and when use elements is super easy you can just install very basic even mechanical thermostat. Many mechanical thermostats have 2 pairs of contacts NO and NC. One pair will control your heat pump system and the other one will turn on/off your elements.