Posted by: Scott McCullough | March 13, 2013

HRV

With the electrical and plumbing work going on we’ve been working on getting the HRV (Heat Recovery Ventilator) equipment and ducts installed.  We settled on Zehnder, who have a rep in Greenland, NH.  Initially we weren’t sure if it would be affordable for us, but since their system seemed to be fairly easy to install there would be significant savings if we did it ourselves.  The pricing for the parts came to equal the parts and labor of a Lifebreath system with conventional metal duct work.  But in the end by putting in our own labor to install the Zehnder system, we would benefit from the most efficient and reliable ventilation system available.

My father and uncle were generous enough to come up north with a cargo van and drop everything off from their warehouse in Haverhill, MA.

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I got familiar with the parts and started by installing the register boxes throughout the house in their appropriate locations.  There were instructions on how to install the HRV itself and the controls, but virtually nothing to show how to connect all the pieces and parts together.  But thankfully there were installation videos showing how the Zehnder HRV is installed with the Comfosystem distribution system.

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The Comfotubes are what make the install so simple as compared to conventional rigid metal duct work.  They are similar to vacuum hoses except a bit larger at just under 3″ in diameter.

Above you see the silencer boxes which collect all the tubes into one plenum that would be attached to the HRV itself.

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After the registers were all installed, all necessary holes were drilled through framing and floors, and the HRV was hung in the basement along with the silencer boxes, we started running the tubing throughout the house.  It started out as a wrestling match to get the tubing to cooperate with the turns we were trying to make.  After some practice we got the hang of it and were making progress.  Each register has either one, two or three tubes going into it depending on the required CFM.  And they are all homeruns, meaning there are no main lines or branch lines.  So in the end we had a good sized web of tubes in the basement that we eventually organized.

The install videos made it all look pretty easy which makes sense since they are professional Zehnder installers.  And once I got going it was, though inserting the tubes into each register box was frustrating every time and never got easier as I went.  I lubricated the tube with the o-ring and the receiver just like the videos recommended, but I always had to haul on the tube as hard as I could to budge the o-ring the tiniest bit.  I understand an air tight fit is necessary, but we’re not in outer space.

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It’s a little tight in that corner of the mechanical room, but that’s just how things had to be.  The radiant heat system takes up some room so the HRV got squished into the corner.  I still need to get the exhaust and intake ducts to the exterior and get power to the HRV, but that can wait a little while.  With the tubes in, we can go ahead with getting wall boards installed on the second floor.

Overall I would not discourage anyone from installing a Zehnder/Comfosystem ventilation system themselves.  Just make sure to do the proper planning in getting the tubes throughout the house, especially if you are working with a timber frame.

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Our curious pup was checking things out on Sunday!

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