Quote:
Originally Posted by tinco
Hi people,
I was thinking about the idea of reversing the flow through the heat exchanger every N minutes, to regulate the moisture content of the air. It's an appealing idea, but I could not come up with a design that does not require at least 4 actuators. 2 for switching the air supply/exhaust on one side, 2 for switching them on the other sides and a pretty clunky maze of canals. The actuators are pretty costly, especially when you buy them in a store instead of on ebay. Am I missing some clever design idea that requires less actuators?
Has anyone ever built this idea, is it applied in commercial HRV units?
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I have seen HRVs that have reversible DC fans.
The reversing work is done with electronics.
In these HRVs the core has enough thermal mass, that:
1. a 'charge' of indoor air is blown out, thus warming the core,
2. there is some dwell time for the core to absorb the heat from the charge
3. a 'charge' of outdoor air is drawn into the core, to be warmed
4. there is some dwell time for the core to release heat
5. REPEAT
If you are able to work with a micropressor like Arduino (or similar), the timing and duration can be finely optimized, depending on the thermal mass of the core, etc.
The Arduino can be also programmed to continuously vary the fan speeds, and ramp-up or ramp-down rate, to maximize efficiency.
Best,
-AC_Hacker