jfb Posted February 1, 2021 Share Posted February 1, 2021 I’ve got an issue with mould growth in a Brink Mvhr unit. The extract fan has considerable mould on it. None in the ductwork/ manifold before it. The extract vents upwards (not ideal I know no) to a pitched roof cowl. So I presume the wet warmer air is condensing near the roofline and coming back down into the Mvhr unit. The ductwork is all insulated/eps ducting. the unit has been installed for about 5 years. I had the same problem when I last took it apart for a proper clean and I had to remove similar mould from the fan. I can see some mould in the heat exchanger on the extract side as well. given that both supply and extract go upwards through the roof can anyone suggest anything to help with the situation? More insulation around the duct to roof cowl? Link to comment Share on other sites More sharing options...
Olf Posted February 1, 2021 Share Posted February 1, 2021 Can you check if the extract fan is actually working at all? At its nominal revs it should be hard for the mould to grow to thick layer (especially at the tips of the blades, having the highest linear speed) and there should be some 'streaks' of the airflow along the surface - and I can't see either. If it's dead, then it acts as flow restrictor only, stopping 'dirty' air from being expelled. Link to comment Share on other sites More sharing options...
Stones Posted February 1, 2021 Share Posted February 1, 2021 I had a similar issue when my Vent Axia was located in our cold loft (albeit insulated). I think that was part of the problem, the other being the drain (including the one at the base of the exhaust fan chamber) blocked with build up of gunk / biojelly, that caused condensate overflow onto the fan blades which in turn threw cold water into the exhaust vent chamber and all over the fan blades. I've since moved my unit into the heated envelope where it was originally meant to go and that has vastly improved things - don't seem to get mould growth now Link to comment Share on other sites More sharing options...
jfb Posted February 1, 2021 Author Share Posted February 1, 2021 26 minutes ago, Olf said: Can you check if the extract fan is actually working at all? When I get a chance I’ll check it is still working - interesting I had assumed it is working but I guess it is possible it’s not. Link to comment Share on other sites More sharing options...
jfb Posted April 12, 2021 Author Share Posted April 12, 2021 On 01/02/2021 at 12:02, Olf said: Can you check if the extract fan is actually working at all? So i finally had a look and both fans appear to be working. No mould in the duct from the Brink unit to the extract terminal. I noticed that there is some standing water in a small section - in the second picture there is a small section to the left of the EPS upstand (so to the left of the drain and nearer the back) with no route for the water to go anywhere. When the heat exchanger is in place this section is separated from the fan with the mould issue. Any ideas? Link to comment Share on other sites More sharing options...
Marvin Posted April 28, 2021 Share Posted April 28, 2021 did you find the answer to this problem? Link to comment Share on other sites More sharing options...
jfb Posted May 11, 2021 Author Share Posted May 11, 2021 not yet! just in discussion with my original suppl;ier Link to comment Share on other sites More sharing options...
jack Posted May 11, 2021 Share Posted May 11, 2021 On 12/04/2021 at 16:04, jfb said: I noticed that there is some standing water in a small section - in the second picture there is a small section to the left of the EPS upstand (so to the left of the drain and nearer the back) with no route for the water to go anywhere. When the heat exchanger is in place this section is separated from the fan with the mould issue. I think there's design flaw with these Brink units. Mine has the same issue with standing water in a non-draining area. There's some discussion here: The solution for me was to fit a strip of flexible plastic between the inverted channel on the heat exchanger and the foam ridge that it slides onto. The edge of the plastic extends past the foam, which kicks any condensation out away from the foam itself. That stops it trickling down the foam and tracking to the undrained area. Brink must be aware of this issue, as they send someone out to fix it over three years after installation. Their fix involved aluminium tape, and basically ripped off the first time I removed the heat exchanger! As for your mould issue, once mould gets into this foam, I suspect it's going to be hard to kill off. I think a few rounds of scrupulous cleaning coupled with the application of some anti-mould compound (gel bleach perhaps?) might work? Link to comment Share on other sites More sharing options...
jfb Posted May 12, 2021 Author Share Posted May 12, 2021 18 hours ago, jack said: The solution for me was to fit a strip of flexible plastic between the inverted channel on the heat exchanger and the foam ridge that it slides onto. The edge of the plastic extends past the foam, which kicks any condensation out away from the foam itself. So you mean something like a thin bit of corex (or thinner I guess as its already tight fitting the heat exchange in) that extends over to the side with the drain? (the right side of the unit in my picture). That makes some sense. I noticed another problem over the winter. I could hear the fans working hard and when I looked I found that the insect mesh on the ubbink roof cowl had iced up. Crazy that I was recommended a cowl with insect mesh that is far from accessible. Anyway I think I will have to try and remove the insect mesh in situ and rely on the MVHR filters to stop this happening again. Appreciate the help Jack. Link to comment Share on other sites More sharing options...
jack Posted May 12, 2021 Share Posted May 12, 2021 23 minutes ago, jfb said: So you mean something like a thin bit of corex (or thinner I guess as its already tight fitting the heat exchange in) that extends over to the side with the drain? (the right side of the unit in my picture). Thinner than that. I think mine was some leftover DPM plastic, so quite flexible. Mine is something like this: The strip extends a bit longer at both ends of the guide, and is bent up so nothing can drip off the end. Link to comment Share on other sites More sharing options...
jfb Posted May 12, 2021 Author Share Posted May 12, 2021 Thanks for the diagram. Very helpful 1 Link to comment Share on other sites More sharing options...
jfb Posted May 13, 2021 Author Share Posted May 13, 2021 On 11/05/2021 at 14:57, jack said: I think there's design flaw with these Brink units Jack - couple more questions! My installation involves both supply/extract ducts terminating upwards into two pitched roof cowls. I know now that ideally the ducting would slope down to the main in/out penetrations but that wasn't really feasible here. Is it possible that is compounding the issue with condensation tracking down from the roof cowl? (my ducting is all insulated EPS ducts all inside the thermal envelope and there isn't really any sign of mould in these ducts its just in the unit itself) Having made the fix to yours have you been able to confirm that it is working in your case? Cheers John Link to comment Share on other sites More sharing options...
jack Posted May 13, 2021 Share Posted May 13, 2021 1 hour ago, jfb said: Is it possible that is compounding the issue with condensation tracking down from the roof cowl? (my ducting is all insulated EPS ducts all inside the thermal envelope and there isn't really any sign of mould in these ducts its just in the unit itself) I suppose that's possible, although I also have upward-terminated EPS ducts on the cold side, and I've never noticed any condensation in them. In general, if it's cold enough for condensation, it's usually fairly dry, but I suppose if it's cold and humid (eg, when it's raining) it could potentially be an issue. I just haven't seen any evidence of it in my own installation. 1 hour ago, jfb said: Having made the fix to yours have you been able to confirm that it is working in your case? I haven't noticed any issues, although to be fair, it was so rarely we had the problem that I wouldn't want to read to much into that! Link to comment Share on other sites More sharing options...
jfb Posted May 13, 2021 Author Share Posted May 13, 2021 Ok thanks Jack Link to comment Share on other sites More sharing options...
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