I’m looking at enhancing the COP of an EAHP cylinder by preheating the air coming into its ducts with a solar thermosiphon or similar. What I’m wondering is whether or not there are any devices that can be fitted to a duct to smooth the temperature variations over the course of the day.
I’d guess it would be a heat exchanger with a storage medium placed at the hottest part of the duct, but haven’t been able to find any products. I recall seeing this alluded to by an aerovoltaics installer but can’t find it now.
Does anyone know if this exists and is generally available? If not, same question but for DIY instructions!
It looks to me as though you risk ending up with a system that nobody knows how to support. I have abandoned a few solutions that for greatly added complexity might yield a few Watts more. For the house to be usable for your heirs/purchaser you need to adopt the ancient adage of KISS (Keep It Simple, Stupid).
Having said that, if you have solar thermal then you could preheat the incoming air using a normal wet heater for a warm air heating system. But then why not use the heater to heat your house, and thus indirectly, the exhaust air.
True enough: I have considered the supportability of the system and have resolved to at the very least draw it and explain the components.
In this case, what I’m trying to do is attain a higher than ambient input temperature as close to 24/7/365 as I can to drag the COP of the unit towards 4 or so.
There are two steps to that, in my mind: first, drag the air temperature up by placing a fan assisted thermal syphon over the inlet on the roof (since we’re south facing). Supposedly this can boost intake temperature by 25C above ambient. Then, in deference to the pump’s maximum intake temperature (43C) try to buffer some of that heat for when the sun doesn’t shine, and in so doing make sure the inlet temperature never exceeds that 43C threshold.
I’ll admit this is a bit complicated, though. Really fighting myself over attempts at low-tech DIY tweaks and just doing things that are known to be wise (and sane)
Update: after searching for how I’d do it DIY, I found… one product. It appears to be made by a French company, and works with aerovoltaic panels:
Looking at it, it might just be… a heat exchanger filled with something that melts at roughly 25C. Could be lard for all I know. If I’m understanding it correctly though, it isn’t electrical in nature and charges/discharges as a consequence of the material’s properties.
Still, it exists! Quizzing them on what temperatures they expect on either side of it from their aerovoltaic panels, and whether they’ll sell me it without the panels. Wish me luck!