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Old 09-25-17, 02:49 AM   #23
DEnd
Apprentice EcoRenovator
 
Join Date: Nov 2011
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Quote:
Originally Posted by ecomodded View Post
NiHoaMike that would be a easy install plug it and let it run , where do see the heat gains coming from ? is it in the refrigeration cycle ?

The issue is the heat doesn't stay in the house. You are basically adding energy to the air and it will move as fast as it can outside the house. A major path of this energy escape is the stack effect. And that combined with outdoor air temps is what determines how well your unit will be able to add heat to your house cost effectively.

Basically the unit works because of the Delta-T (difference in temperatures) between the inflitrated air and the unit's exhaust air. At some point when the inftrated air is still a bit warmer than the discharge air it effectively becomes a house exhaust fan with a resistance heater attached (all electrical devices are in effect resistance heaters). Where the point of cost effectiveness is depends entirely on how much leakage your house has. Remember the stack effect pushes out warm air and pulls in cooler air that then needs to be heated. That cooler air accounts for between 30% and 66% of the BTUs needed to heat your home. Fans can easily overpower your stack effect, so when you end up pulling more than ~2.7 times the amount of natural air infiltration then you are automatically at the point of it's cheaper to use resistance heat. But that's not the actual point it doesn't become cost effective. Where it looses cost effectiveness (against resistance heat) is at the point where the recoverable BTU's in the infiltrated air is less than 2.7 (or whatever the COP of your unit is) times the amount of BTUs to bring that air up to room temperature.
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