Leaking Vent Axia help needed

yoyo

Hi folks,

I first spotted damp patch on the ceiling just before Christmas. Today, I discovered where this on/off leak was coming from. See attached photos for details.

Basically where that green tape in photo 2 has a gap, water seems to be coming out. Checking the tape is Gerbrand 586, and this seems to be air tight taps. I did a bit of a bodgery job with some duct tape which seems to have sorted the leak. I will get back later if it has not.

Is the solution to this simply buying some air tight tape like Gerbrand 586 and just redoing the vent pipe connection, or is there more to it that might need it serviced?

10-10-20

In my mind it's not an issue for tape to fix in the first place. I presume that this an exhaust outlet to the external vent? Is that vent fitted at the eves or the roof?

Any humidity that collects within this pipe should flow away from the heat exchanger, so that pipe probably needs to be pointed down with a consistent slope away from the exchanger. Adding additional insulation to the pipe or correcting any gaps near to the exchanger will improve matters too.

yoyo

https://www.boards.ie/discussion/comment/121838122#Comment_121838122

Thank you for the advice. The vent goes directly to the roof. I'm not sure if it's inlet or outlet. Both pipes are actually quite tight with one squeezed in under the problem one.

Here are some better photos of them:

Since taping it up there hasn't been any leak, but also as I said this issue is not consistent.

Buffman

Is there any drain pipe on the MVHR Unit?

It is entirely possible that the leaking air duct was causing condensation to form outside the unit and this was causing your damp spot issue. It may have be an 'on/off leak' as the condensation would only form in certain temperature/humidity conditions. Duct tape is exactly what's used to fix small air leaks like this, hence the name.

The air ducts are always a tight squeeze with these MVHRs, you have 4 large air ducts all attached in the same small area in a tight enough attic so space is always at a premium.

Has the MVHR been serviced recently? If not, it'd be no harm to do the filters and check inside for any excessive moisture/dirt/other issues.

yoyo

https://www.boards.ie/discussion/comment/121842031#Comment_121842031

Cheers Buffman,

Never had the unit formally serviced but I replace the filters every 6 months. In the house 6 years now. I'm leaving a bowl under where it leaked and I will monitor that. Hopefully the issue was just lack of duct tape. Bone dry this morning up there when I checked.

There is a condensate drain and I can confirm it is connected. No water is escaping at that point. The attic is tight so I don't really have much access around the machine. I did find this guide online, is it worth doing? https://www.ifixit.com/Guide/How+to+clean+the+Vent-Axia+MVHR+Cell/24911

Also I read online people suggesting condensate drain can form a jelly type substance and not work properly. Does the cell need to be removed to access condensate drain? I don't really think the drain is blocked though as even with daily showers/cooking etc. it doesn't happen a lot. I only noticed it just before Christmas, but thinking back now I did notice a on/off dripping sound for a while (I assumed it was outside around dormer frame, so at the time thought nothing of it!)

keno-daytrader

I had a similar problem with mine, and I have mine in our plant room which is heated.

There wasn't enough insulation around the inlet pipe where it enters the unit, as in your picture. Yours maybe the opposite as yours in in a cold attic. So maybe it's your outlet pipe.

My solution was to strip away all the wet insulation (under the silver/aluminium tape). Rewrap the outlet with insulation, don't wrap it really tight as the insulating properties is the amount of trapped air within the insulation wool. I used aluminium tape to wrap the insulation then airtight tape to seal the piping to the unit.

Tape wouldn't fix my problem because the water was still condensing on the cold inlet pipe and soaking wet insulation. The water will still condense and it will find a way out.

Once the pipe was fully insulated, no more condensation. I was surprised at how soaking wet the insulation was. Even a small gap in insulation made a ton of condensation.

Or you could get lucky and the water will find its way to the bottom inside of your unit and out the condensate drain after new tape. But since mine was at exterior of the unit i had to use the above approach.

10-10-20

https://www.boards.ie/discussion/comment/121844281#Comment_121844281

That's the exact opposite to what the original poster is experiencing as you rightly pointed out. In your case the air in the plant room was warm and moist and the incoming air was cold, so the condensation was caused on the exterior of the feed pipe. In his case it's most likely that the warm and moist air is coming out of the exchanger and through the cold attic so it's causing condensation on the interior of the pipe. More insulation might help reduce that, but others were pointing out that the unit might need to be serviced and perhaps the heat exchanger surfaces are coated in dust and slime-moulds making them less likely to catch moisture and cause it to build-up in the pipe. Those slime-moulds can also build-up and block condensate drain-pipes, etc.

dbas

If that vent goes to the roof, could it be rain getting into the duct?

Check the roof vent and try straighten that duct as much as possible if that is the case.

If that's the exhaust duct from the unit I can't see another reason why moisture would be there. Is the filter wet?

keno-daytrader

On my vent axia the front panel comes off to access the heat exchanger, it even pulls right out. You can also access the drain, I poured a few cups of water down and looked outside at the drain pipe to make sure it was clear.

yoyo

https://www.boards.ie/discussion/comment/121844672#Comment_121844672

It's quite possible alright. It started happening when it was snowing, maybe the snow melting was finding its way back inside the unit? It's a 3 story house so there's no way I'm going up there to check! If I need to get someone out to look at it I will. Hopefully the tape will solve the problem fingers crossed. Not checked it today but have a basin under it so will know if it leaks again!

Also I'll check if filter is also damp, that would prove water getting down from the roof then?

yoyo

https://www.boards.ie/discussion/comment/121844838#Comment_121844838

Yes I might do this. Unfortunately attic is very tight I'm not sure I'll even be able to remove the heat exchanger as water tank is situated pretty near the unit. I'll give it a go at some stage anyways!

Does the heat exchanger need to be removed to access the drain?

keno-daytrader

https://www.boards.ie/discussion/comment/121846066#Comment_121846066

I didnt have to take the heat exchanger out on mine to see the drain.

yoyo

https://www.boards.ie/discussion/comment/121848287#Comment_121848287

Thank you! I will definitely remove the cover soon and check it out!

spose

Moisture in the pipe shouldn’t be a problem. It should just drain back to the unit and out the waste. It’s not an issue with the drain line either, the whole unit including fans would need to fill up for it to be coming out the top and usually they leak out the bottom. My guess is one of the connections on that pipe isn’t right and that’s how it’s getting out

yoyo

https://www.boards.ie/discussion/comment/121881735#Comment_121881735

Thanks Spose,

There has been no further leak since I duct taped the pipe (but then again, it was always an on/off issue). I'm hoping by taping the pipe where the gap was will fix the problem. I doubt the whole unit was full of water I agree, as only the right side had the issue (water dripping down through the opening in the vent pipe). I am keeping an eye on it regularly (including just now), but the bowl I left under it hasn't a drop of water thankfully.

Been a lot of heavy rain since raising this thread, and no evidence of water which suggests to me the issue was more probably condensation in the pipe leaking out due to lack of proper taping and sealing pipe to spigot.

yoyo

A further update to this saga. Been checking regularly over the last few days the bowl I put under the unit and it has been dry. This evening however a different story, unfortunately. About 50ml of water collected and unit dripping. I decided to open it up and take a look inside. Here is what I found.

The filter was absolutely dry except for the corner. The water was trickling like before where the ducting meets I think the spigot? Here is a picture for reference (blue lines roughly path water was taking):

I decided to take off all the duct tape and couldn't see any gaps of not while doing so since I patched it up (although obviously water was leaking through the tape somewhere!).

I had a feel of the pipe and noticed where it was bent horizontally a bit cooler than other sections, so the condensation was happening further up. I then checked where pipe is leaving to the roof, and I faced this!

The ducting to the roof has a massive gap as the photo shows! How sloppy a job was that!

Armed with my duct tape I did a job at it so hopefully this will help:

I also checked the condensate drain, popped the little rubber cap off and hardy any water came out, so I guess the drain is draining away properly.

I'm hoping I've identified the cause of the issue now! But I'll keep monitoring it!

10-10-20

https://www.boards.ie/discussion/comment/121994719#Comment_121994719

So the gap was just in the insulation or was it a hole in the pipe? Can't tell from the images.

Bear in mind that last night was cold after a horrendous day of rain, so the RH would have been very high anyway and the dew-point then rose as it cooled down - so if it was ever going to condense and drip then last night was the time for it.

yoyo

https://www.boards.ie/discussion/comment/121996086#Comment_121996086

Sorry for not clarifying more clearly, the pipe had a massive gap/hole as the installer never taped the pipe up properly. He just caught some of the pipes insulation with the tape, but if you look closely in this image you can see at the gap the black plastic from the roof vent showing:

It was dry up at this point but I could feel the pipe was a bit cold further down which I'm guessing was the condensation drenching the insulation material.

I'm hoping this will solve it! :) 🤞

yoyo

From feeling around the pipe I'm noticing now it doesn't feel as heavy and cold. So it looks like it is drying out and there has been no further leaks. I hope sealing the above gap with duct tape has sorted it out!

I bought some of the below tape which I will wrap around the duct tape as this is how it was originally done. Not sure if it makes much difference:

https://www.screwfix.ie/p/diall-insulation-board-tape-silver-45m-x-50mm/4806v