Venmar Air Exchanger - not condensing - recall program

[SKIN052]

Seeing allot of condensation in the house and have noticed that the Air Exchanger is not pulling out any moisture even though it seems to be running. Venmar apparently has a large recall on these units but I had no idea their was an issue until now. Worried I may be late submitting my claim, just did it this morning. Anyone have experience with these types of units. Is it a fix I can tackle myself if need be? Currently running a small plug in unit at the moment. Getting a bucket every 1 1/2 days.

 

[DickRussell]

If the unit is a HRV (just heat recovery), the only moisture removal will be from the cooling effect of incoming air on the outgoing air, and there would be a drain tube to get rid of that condensation. If the unit is an ERV (both heat recovery and moisture exchange), it also will transfer some moisture between incoming and outgoing streams, moving from higher to lower moisture content.

If you are getting condensation "in the house," which I presume means you see it on the inside of windows, then of course the interior air is too humid. In winter, this can happen if the house is very tight and either there isn't sufficient "natural" leakage of outside air into the house or the mechanical ventilation rate is insufficient to flush out the moisture added by human activity within. Increased ventilation rate will reduce interior humidity, provided the air outside is drier, of course, which it typically would be up there.

Then there is the matter of which type of exchanger is appropriate. A good summary can be found here: http://www.greenbuildingadvisor.com/blogs/dept/musings/hrv-or-erv

If your Venmar unit is an ERV rather than HRV, then transfer of moisture from outgoing (humid) air to the incoming air is working against you. I looked quickly to see if the moisture exchange can be disabled in a Venmar ERV, but I didn't find anything. Your user manual ought to cover that.

 

[SKIN052]

Thanks Dick. Basic Heat recovery unit with a drain tube. First year that we have had significant window condensation so i believe the unit is to blame. House is new construction, 2008 so fairly tight.

 

[DickRussell]

If it's the unit at fault, and humidity was controlled in the past, then I would suspect that either the internal blowers aren't moving any air in/out (failed motors or controlling circuitry isn't turning them on) or perhaps it's stuck in defrost mode, in which a damper is repositioned to block the incoming outside air while opening an inlet of interior air, the idea being to recirculate interior air to warm up the core and melt out the frost. It's easy to check for no air being moved; put your hand by the exhaust air hood outside, and you ought to feel air being moved out at a gentle rate. It also is just a visual check to see if the defrost damper is blocking the recirc air inlet or the fresh air inlet. Also, you should be able to hear the blower motor(s) running when close up. Reports of unit failure ought to describe what is failing.

 

[SKIN052]

Blowers seems to be moving air in the house and blowing it outside. Submitted a claim on the recall program after verifying from their website that my unit was one of the effected models. Received an email back stating that my unit was not affected. Waiting on another response. If no luck then I will start taking things apart.

 

[DickRussell]

Well, if the unit is exhausting interior air to the outside, then some ventilation is being done, and interior humidity is being flushed out, regardless of whether any heat exchange is going on or even if the incoming air is drawn through the unit or through the numerous air leaks in the exterior envelope of the house. Even a bathroom vent fan will do exhaust-only ventilation. I presume you did indeed feel air moving out the exhaust hood. I presume also that you checked to be sure the unit isn't simply recirculating interior air, which would not move any humidity to the outside. Perhaps you can set the ventilation rate on the unit to a higher setting.

Then you have to consider if any changes have been made to life style inside that would put more moisture into the air than before, like a lot of cooking going on, or laundry hung up inside to dry. You'd have to consider the possibility of something like a roof leak or foundation leak, creating a source of moisture that you didn't have before.

 

[maple1]

Are you sure there is absolutely no blockage in either the incoming air duct, or the outgoing air duct?

I found a problem with my Venmar a few years back- it sounded & appeared like it was working hunkey dorey, but the inside air wasn't getting exchanged. This was in the late fall, almost same as now. After a bit of detective work - I found the outgoing air duct (6" flex ducting) was completely blocked by about 4' of solid wasp nest just inside the outlet. Then I remembered that time a month or so earlier I was going by the duct outlet on the lawn mower & saw a couple wasps buzzing around. Anyway, I had to replace that ducting with new stuff. Ever since, once every season or so, I go outside with a small piece of paper & hold it against the inlets & outlets to make sure air is going in & going out. It should suck the paper onto the screen & hold it there.

Another possibility is dirty filters & exchanger. If the exchanger has never been washed, it could be plugged or partly plugged. They're pretty simple units - if the blower is running, it should be doing its thing. I also had to replace my blower unit a few years back - it started making noises that I could only hear when I was beside it. When I checked it out, it was really hot. So I unplugged in a hurry & started chasing Venmar. I think mine was under recall but they wouldn't help me - said it was too old. Part of the issue, I was also told, is I bought it on clearance, and it had been sitting around the store for like 2 years before they sold it. Anyway - good luck getting anything out of Venmar. They weren't helpful with me at all, I had to pony up for a new blower unit, couple hundred bucks or so. But it works good.

Do you have a humidity monitor to actually check what your humidity levels are? My windows will make condensation sometimes even when levels are good or on the low side. Sometimes that is a sign of tight windows with no air movement around them, rather than high humidity levels.

 

[SKIN052]

Thanks again guys. Will check again tomorrow for any blockages. Good idea using the paper.