Standing condensation water in new MVHR exchanger

[runcyclexcski]

I've installed a new small Boulder MVHR unit and been running it for about a week. It's been around freezing all week, so it was a good chance to check its performance, both in terms of heat-recovery and in terms of condensation. The unit is an older (2x cheaper) version of this:

 

https://ventilationmegastore.co.uk/products/all-products/mvhr-units/auto-bypass-pre-heat/dhv-15b-bph/

 

The drainage hose has remained completely dry for the whole week, even though the quarter of the unit receiving the cold air showed plenty of condensation on the outside, which dripped down about a cup worth (I kept wiping the floor underneath). Since the absence of water in the drainage hose did not make sense, I opened the unit to see what was going on.  I found that the bottom condensation pan was also completely dry. When I pulled out the exchanger, out poured the condensate water, about 2-3 cups worth. This water never made it down into the pan. I do not think the unit was intended to be installed "vertically" which (in prinicple) would allow for the condensate to run off the exchanger faster by gravity -- since this would make the bottom pan vertical, too. It looked as if every plastic channel of the exchanger was "pan-shaped", with water accumulating in every "sub-pan" and not draining out. Perhaps if there was twice as much water in the exchanger (say, a pint), some of it would drain. But it appears that with this design the unit would always have standing water in the cube, which does not sound proper.

 

I know zero about MVHRs, and I bought this unit w/o any research. Based on my new (very limited) experience, I would rotate the cube 90 degrees with respect to the bottom pan (within the unit). Are there units designed like this? Are there units with the exchanger working better for condensate run-off? I do not know... Teflon-coating? A spout in each "fin" to allow run-off? Metal exchangers for better heat conductance? Also, it would make sense if the outside of the unit (at least the respective quarter of it) was insulated on the outside, to prevent the outside condensation. Clearly, none of the above is implemented in this unit, so buyer beware, I guess. 

 

Many thanks in advance! I apologize for weekly postings on this :).

 

 

Edited December 14 by runcyclexcski

[Mike]

3 hours ago, runcyclexcski said:

the quarter of the unit receiving the cold air showed plenty of condensation on the outside

Is the unit installed the correct way round? Condensation would be expected in the section that exhausts to the outside air - warm moisture-laden internal air sheds water when it's cooled by the incoming air.

 

On the air intake side the cold external air is warmed up, so can hold more moisture, therefore condensation is unlikely.

[runcyclexcski]

The condensation on the outside of the unit is due to the ambient humidity in the room coming into contact with the unit outer metal housing (cooled by the cool incoming air from the inside). I humidify the flat to 45% artificially. The condensation inside the unit, as you say, should be due to the outcoming air coming into contact with the incoming air, and that's the condensate that I can't seem to drain

 

For now, I have tilted the unit by about 5 degree, so that water drips down out of the exchanger and flows towards the spout at the bottom better. Interestingly, the spout is right next to the internal electronic box as well, does not loook like proper placement

[runcyclexcski]

Correction: the exchanger internals are made of aluminum foil, not plastic, I was wrong about that.