Could any any one please tell me what this. It was on the outside wall behind the condensing unit
Thanks
That appears to be a heat recovery system to supplement the water heater. Works by capturing excess or available heat from the a/c system when it is in use.
Thank you Micheal, that is exactly what I thought it was (NOT!!)
I have never seen one before
I’ve seen a few in my area and will see if I can find a more descriptive site for reference. Try: http://www.heatharvester.com/Heat_Rcovery_System.htm