Can you add a mini split coil into an existing HRV system?
Hello,
We built a new home in 2019. It is super insulated and has triple pane windows. It has a combination of electric baseboard and in-floor heat, and an HRV system for ventilation. At the time, we thought that natural ventilation would look after our summer cooling, but the on the worst days of hot, humid weather in Quebec, we wish we had put in some cooling.
My question is this: Is it possible to install a mini-split air to air heat pump with a coil inserted into the existing main supply duct of the HRV system? The coil would be placed just where that supply duct exits the HRV unit, but before it branches into smaller distribution ducts. The coil would be connected to the exterior heat pump. The idea is that it could add some cooling (in summer) and heat (in winter) to the air already being distributed by the HRV ductwork. Is this possible?
We have considered getting a couple of separate mini-splits with the wall mounted units, but we would like to use the existing HRV system for more central and balanced distribution.
Any thoughts on this would be appreciated. Thanks!
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Replies
I would look into installing a slim duct mini split using your existing erv ducting, assuming the ductwork is big enough. The smaller units put out 300 - 400 cfm, so it’s possible your existing ductwork might be big enough. A high static pressure unit might be needed.
You would need a central return for the air handler and then reroute your hrv supply to the return. I think this is more feasible then trying to hack a coil into your hrv ductwork.
Another option is a Minotair unit (https://www.minotair.com/minotair-pentacare-v12_us/), but it can be difficult to find these and can be quite expensive.
If you put it in the HRV duct you have to check that the added air friction (static pressure) does to impact the HRV's ability to move air. You would have to rebalance your HRV after as well.
Depending how open the homes floor plan is just put a ductless mini split in the living room.
The HRV will move the cool air around.
That is what I did in my passive house to get a bit of colling and reduce the use of electric resistance heaters in the winter.
Even cheaper would be to buy a $1,000 portable air conditioner and make a frame to mount it in your tipple pane window if they are not the typical outward opening casement or double hung frame type.