Trombe walls and MVHR

[MikeSharp01]

We have about 30m² of matt black vertical hung tiles on our south wall and I have been wondering if there is any mileage in making this into a Trombe wall and ducting the air into / through the MVHR at appropriate times. My research into the subject has led me to put this question into boffins corner because there are some 'views' out there and I know, cos I can read and once you put something onto the internet it has a habit of being there for a long time, that both @SteamyTea and @joe90 have had some input into such ideas in the past HERE (2010 ish). Interestingly the WWW is well furnished with opinion but very little science. Perhaps there is not much but I wonder if anyone has any pointers to the / any new science or technology in this space? Clearly there will be costs both financial and thermodynamically but if it can be controlled, IE you can switch it in and out as required, the question comes down to the positive or negative effects / efficiency on / of the MVHR unit when feeding it with warmer air and the engineering of the wall to avoid build up of nasties like fungi. I think I can see that just feeding it into the supply input will mean any heat produced will mostly (depending upon the efficiency of the MVHR heat exchanger) come out again immediately in the exhaust air - however the remainder is a (the) contribution. I have also read that injecting the air so heated into the exhaust line before the MVHR, where its temperature is above that of the house's exhaust air, might be a way forward as this air's heat will then be added (in some proportion - heat capacity, volume, T delta, humidity dependant) to the naturally aspirated air coming into the MVHR system for supply to the house. Controlling all this won't be simple though I suspect. Given all this, and the fact that since our fellow forum members were talking about it 7 years back and it still is not mainstream, it sounds like a non starter but I wonder if the world has moved on around it enough to make it possible / feasible! (PS I appreciate that the basic laws of thermodynamics have not changed.)

[SteamyTea]

6 and a half years on, not much has changed.

 

What you are talking about here, I think, is an active system to pump in a bit of warm air when the temperature behind the tiles is higher than the internal air (or high enough to be useful).

 

The first thing to work out is the resource you can use i.e. the total tiled area, the amount of air that can be passed behind it (the m³/min or kg/s), the expected temperature rise from some local weather data (try weatherunderground for a station with a solar meter).

 

As for connecting it to the MVHR, I would think that plumbing it in after the exchanger would be the way to go.  It may make the balancing a bit strange, but you would be pumping in fresh heated air, so the heat exchanger may be rather redundant during those times.  Think of it as a positive ventilation system.

[joe90]

I do remember being interested in this but think I came to the conclusion that it was little return for a lot of work and headache. I am having a large "sunspace" that will probably overheat (if it's ever sunny in Devon?) in summer and I may try to use its heat once I get to know what I have got to play with.