MVHR Making A Gurgling Sound

[deptfed]

The MVHR in my 4-year old flat has started making an intermittent gurgling noise in the outlet pipe below it, which is loud enough to be heard through the vents in the rooms. It tends to be more noticeable during the day rather than the evening/night, and doesn't happen every day.

I've attached a video as the sound is hard to explain - it sounds like a gurgle of water in the pipe. If you block the pipe coming down from the MVHR unit with a finger then a) the noise stops and b) your finger gets wet.

 

Does anybody know what could be causing this and if there's a simple fix?

 

Model = Titon HRV1.25 Q Plus Eco

TP406HMB

[MJNewton]

That's the condensate pipe which exists to enable the condensation that forms as a result of lowering the temperature of the extracted air to be expelled. The pipe should be connected to a trap and not via a tundish as in your case. That air break means that the slight vacuum that forms inside the MVHR unit will be sucking in air from the room and, if there's just the right amount of condensate built up in the base of the unit, cause it to gurgle as the air passes through.

 

I'd suggest removing the tundish and making a connection directly between the grey pipe and what appears to be a waterless trap below. If you can help identify the latter I can suggest a more exact method (as it's all down to pipe/fitting sizes). When connected directly to the trap it won't allow any air to be admitted and the gurgling will stop.

 

Edit: From that quick glimpse it looks like it's a Hepworth HEPvO waterless trap with a BV1/21 tundish adapter on it. If so, that adaptor looks to have a 15mm 'pipe like' interface to it so, if you removed the black tundish, you could connect the two 15mm ends together using a short length of suitable-sized hoses and jubilee clamps. Others might be able to suggest other methods, which might include 15mm pushfits at either end but you'd have to see how well one would attach to the tundish adapter (I suppose if it has a 15mm OD like a plastic pipe does then it'd be fine).

Edited January 5, 2022 by MJNewton

[MikeGrahamT21]

Oh dear, someones fitted that wrong!

 

Its basically sucking air up via the tundish, and therefore bypassing the heat exchanger, with it being cooler weather you'll have condensate, which is where the gurgling is coming from.

 

Get rid of the tundish, and connect straight into the trap.

 

Ideally it should be a water filled trap, with a good bend to it to prevent this. Once fixed, you'll also recover more heat too.

 

For a very quick fix, tape the hole up in the tundish, but it must be airtight to stop that noise from happening. If it still does this after, then the airless trap doesn't like negative pressure.

Edited January 5, 2022 by MikeGrahamT21

[MJNewton]

8 minutes ago, MikeGrahamT21 said:

Ideally it should be a water filled trap, with a good bend to it to prevent this. Once fixed, you'll also recover more heat too.

 

I thought a waterless trap was generally recommended, so as to avoid the issue of a dry trap during the summer months which could cause drainage smells to enter the system?

 

Quote

For a very quick fix, tape the hole up in the tundish, but it must be airtight to stop that noise from happening. If it still does this after, then the airless trap doesn't like negative pressure.

 

You say quick fix but actually I quite like that idea as a permanent fix in this instance. The negative pressure will be minimal, certainly nothing like what the trap would have to deal with in a many plumbing systems.

[MikeGrahamT21]

8 minutes ago, MJNewton said:

 

I thought a waterless trap was generally recommended, so as to avoid the issue of a dry trap during the summer months which could cause drainage smells to enter the system?

 

 

You say quick fix but actually I quite like that idea as a permanent fix in this instance. The negative pressure will be minimal, certainly nothing like what the trap would have to deal with in a many plumbing systems.

 

Good point re. waterless trap. Mine recommended a water trap (Vortice), and the boiler also drains into the same trap, so in my case I don't think there will be any drying out.

[deptfed]

Thanks all for the responses! I've added a couple of photos here to show the whole set-up as the trap below seems like it could be relevant.

 

From reading the suggestions I think I will try taping it up first (seems like no harm in trying the quick fix), and if not then I'll have a go at creating a solid connection like @MJNewton suggests.

[MJNewton]

Yeah, a few wraps of duct tape as @MikeGrahamT21 suggested would work well I expect, and if black I don't think anyone would be any the wiser!

[Barnacles]

Apologies for being late to the party on this one. I have the same Titon unit in our house and had the same problem with the gurgling sound the first time it got really cold after installing it. I don't think it will be such a big problem for you as you have a fair drop of pipework for the condensate water to escape under gravity. I have a shallow fall on my pipework and hadn't properly sealed the condensate outlet pipework. In my case the extract fan managed to suck water up into the fan and destroyed it. At £220 for a new one I was kicking myself pretty hard about that one.

 

Some duct tape around the tundish will probably suffice for now but longer term I would certainly seal the pipework completely.