Author Topic: VanEE 90h frost on Fresh Air to house flexible duct.  (Read 5683 times)

Offline super_coo

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VanEE 90h frost on Fresh Air to house flexible duct.
« on: December 09, 2014, 05:33:41 PM »
Hi,

I have a VanEE 90h air exchanger and when it’s really cold outside approx –10c or less the fresh air flexible hose seems to frost up and then melt dripping water on the floor.  Other times when it’s really bad water will drip from the system itself near the right handle to open the door.  The system is level all directions, I was told it was balanced airflow and the filters are cleaned somewhat regularly.  Also the damper works fine for the defrost cycle and the drain tubes are not clogged.
 
Any thoughts or ideas what I may try?

I've included a picture of the setup.
 

Thanks,
Sam

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Re: VanEE 90h frost on Fresh Air to house flexible duct.
« Reply #1 on: December 09, 2014, 06:22:53 PM »
Chances are the insulated duct that connects to the bottom left hand side port labelled, fresh air from outside, is compromised.  It doesn't look like it's very accessible, but start by inspecting that duct in the room.  If any sections have been taped, remove the tape and verify the flex duct under the insulation is not cut.  Check for any tears in the insulation or flex.  Also, pull back the insulation and make sure the flex is completely sealed to the HRV port.  Hopefully you can access the rest of the flex in the attic, but that duct appears to be travelling to the back or front of the building, most likely concealed by a bulkhead.  The problem is usually found at the exterior wall where the duct connects to the exterior vent.  That duct must be sealed tight to the exterior vent, otherwise it could be drawing in hot and cold air, which can cause the intake duct to ice up.  Depending on what floor you're on, you might be able to use a ladder and remove the exterior vent and see if things are connected and sealed.

It's hard to tell by the picture, but if you look at the right hand side ports, that the uninsulated ducts connect to, there are damper levers.  Are they secured in place with screws?  If not, it's unlikely that HRV is balanced.

Does the drain line have a p-trap installed like the one in the picture I attached?

Offline super_coo

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Re: VanEE 90h frost on Fresh Air to house flexible duct.
« Reply #2 on: December 12, 2014, 02:08:37 PM »
Hi thanks for the response.

It's not in the attic it's in the basement and quite easy to access I had cropped the original picture to hide my messy room haha

One thing I noticed the other night was that the chain that supports the unit to the ceiling some of the "extra" chain was caught between the top right corner of the door and I could see the seal was not making a tight seal allowing air in from that point.  What I can't say is that it's been like that for two years I may have just accidentally done that the other day.  And now the weather is above 0'c so I wouldn't have an issue under those conditions anyways.  The top right duct is the fresh air to building and that's the one that was getting frost/moisture on the outside.  It's the duct that's after the unit that is frosting up not before going into the unit.  Do you think it was happening on the inside of the duct as well?

I see the plastic dampers you mean and no they are not screwed in or marked.

My drain line does not have a p-trap but I thought that was only for smells?  Mine does not drain into the floor but instead into a plastic water jug that I empty when it gets 3/4 full.

Anyways I appreciate your help and I will keep my fingers crossed that it was the chain all along stuck in that top corner and I'll see what happens.
If not when it warms up next spring I'll replace all of the lines if I have to at that point.

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Re: VanEE 90h frost on Fresh Air to house flexible duct.
« Reply #3 on: December 12, 2014, 02:55:42 PM »
The door seal issue probably isn't the cause.

I have seen some weird things happen without the p-trap where a vacuum is created and prevents proper drainage.  It doesn't sound like you're having this problem.

Do the indoor ducts both connect to the return side of the furnace / air handler?

It sounds like the motorized damper is not closing 100% during a defrost cycle.  That might be allowing cold and hot air to mix and create condensation in the fresh air to building duct.

Depending on the age of the 90H you could try extending the defrost cycle.

Quote
4.1.2 SETTING EXTENDED DEFROST
The unit is factory set to normal defrost. In cold region (outside temperature -27 °C [-17 °F] and lower), it may be necessary to setup extended defrost. During the first 5 seconds of booting sequence, while the integrated control LED is GREEN, press on push button until the LED turns AMBER (about 3 seconds).

Quote
In a cold region, setup EXTENDED DEFROST by removing jumper JU1F on the circuit board

Offline super_coo

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Re: VanEE 90h frost on Fresh Air to house flexible duct.
« Reply #4 on: December 23, 2014, 01:47:04 PM »
Hi I'm back finally with more info.  I pulled back the insulation at the wall (fresh air into building) and the flexible hose was all wet/damp around there and the metal spline of the flexible hose was even rusted a little.  It was only held on by a cable tie that was really loose and the duct could slide quite easily on the metal duct that goes outside.  I put a bunch of foil duct tape thinking that would fix it and I checked again today and it's wet/damp again.  It's the very top left of the picture I attached.  Do you think if I replaced that insulated duct with new and put that caulking type stuff applied with a brush around the metal duct and then foil tape I might be ok?  Should the insulation on that end be taped down or anthing?  It's just butted up against the wall on that end but is foil taped where it goes into the unit.

The machine is just an air exchanger and is not hooked into anything else.
I'm pretty sure the damper seals well and I have already done the JU1F jumper in the past after reading about that in the manual.

Safe to say it's just that insulted duct causing my headache?
I wish I could buy only 4' instead of a 25' length!