Jolo

Thanks for the replies -- but just to be clear, it's definitely not the internal ducting, as I've mentioned earlier we've done every check possible. The extract ducts suck and the supply ducts blow. The ducting is still visible so it's easy to follow each pipe to its destination vent. We've tested with just a single pipe connected to each port on top of the MVHR unit, eliminating the internal ductwork entirely. It's definitely not external cross-flow either: We followed the supplier's guidelines, he's happy with our inlet and exhaust locations The bloke from Brink was satisfied with them The odour transfer is too strong and immediate to be happening outside anyway So the problem is definitely inside the unit, there is no doubt about that. However, my question this time was just about what the humidity should be for an MVHR unit that was working properly. Thank you John, that's good to know! Thanks Mike, that's useful information. But nothing changes regardless of the speed, because the unit is just blowing a mixture of fresh and stale air into the house. So when showering, the bedrooms and living room are getting some of the steam blown in. Not yet! This is one of the reasons I'm getting annoyed with Brink, they go weeks without any progress or updates. (Also, the odour transfer is so strong that anyone with half a nose can detect the issue. Spray a bit of deodorant in the bathroom and a few seconds later it arrives in the living room.) I'm now considering starting to send legally valid complaints to the supplier, in the hope that he'll get Brink to up their game. It's been three weeks since I let them know that the new exchanger didn't fix the problem.

Update... there is no update! I'm a bit disappointed with Brink and the supplier, to be honest. I don't get any progress unless I push for it, and there seems to be no answers forthcoming. The latest "news" is that it's been passed to the R&D department to figure out what might be causing the issue. One question for those with experience of such systems -- should the MVHR system help regulate the moisture inside the house? I ask because we've had really high moisture levels indoors, like 80 - 90% RH sometimes, which is surprising to me. Windows covered in condensation in the morning, even though we're running the unit at around 0.45ach. We're not doing anything weird like hour-long showers or running a commercial kitchen! I've taken to opening the window vents, which helps a lot with the humidity but of course defeats the purpose of the whole MVHR system!

Oops, I missed your reply somehow! It's a radial system. Small house, really simple, the ducting is mostly still visible so it's all been checked a dozen times. We've even tested it with just an elbow and a metre or two of ducting on the extract and supply ports, and the problem still exists, so it's definitely not a problem with the internal ducting.

Oh 100% Here's a photo from during our installation

Thank you @Mike that's useful info! I discovered last night that despite my best attempts to cover the metal box, some condensation is forming in awkward to cover places, so I might take the plunge and get a proper one. I do like DIYing stuff, but with the time and money I've spent on trying to insulate a metal box, I could have gotten the proper one!

Can I ask where you bought that, Mike? I wanted something already insulated, but couldn't find where to buy one! Ended up using a metal one and covering it in Armaflex, which does work but it was a faff

Yeah it's a bit confusing! Easy to read them as directional, which they're not. Just imagine the main unit in the loft of the little house, and it makes a bit more sense. Regarding brands, they're also sold in Germany by Wolf (also owned by Ariston) as the CWL-2. Knowing the various names helps when comparing prices on filters etc! Well I'm glad it's not just us DIYers who have to think carefully about it!

Sounds pretty idyllic! (Though I'm surprised you don't get a lot of flies in the filter) I only just had enough space -- I hadn't planned to add a pre-filter, so luckily there was a gap big enough between two other ducts to fit the box in. If the gap was a few centimetres narrower I couldn't have done it!

I'm surprised that ventilation systems don't come with a pre-filter like this, really -- or at least, that the're not more common. Sure, the unit has a filter inside it, but on mine this comes after the temperature sensor and the pre-heater, meaning that these components get covered in dust, and probably flies too. Also it's nice to protect the fancy expensive fine filter with a cheaper one!

@JohnMo Thanks, and yep we crossed off 1, 2 and 3 already, this was pretty much my thinking process when the problem occurred. I'll let the supplier decide whether to try a regular exchanger, but as I mentioned I'm sure it's not that, as the odours transfer even when the extract air isn't flowing through the exchanger. So it can only be number 4 (which is also my conclusion) and as you say, not something I can fix myself, it's for Brink or the supplier to do.

I've checked the bypass by watching it through the port, as it's right below the top of the unit. It's working correctly, but even if it wasn't I don't think it would account for the leak, as the both routes just diverge then meet again anyway -- one route goes through the exchanger, and the other one goes around the back. They're both parallel routes, which converge again before the extract/exhaust fan. So I suspect the leak is either before the bypass valve (although I can see in there via the port on the top, and it all looks fully sealed), or after the two routes converge again, somewhere before or after the extract/exhaust fan. I think it must be the latter, but I can't see much of anything in this area without taking stuff apart, which I'd rather leave to Brink for now as it's all still under guarantee!

Wow, that filter really is doing its job well! That colour change really is astounding.

This is one reason I chose the ERV exchanger -- it cost an extra 500 euros or so, but if I'd chosen the regular exchanger then I'd have probably spent more than that getting a plumber out to install a drain line, which would have been a pain as there's no suitable point near the unit. It would have involved drilling through two brick/concrete floors and adding a connection directly to the main soil pipe leaving the house. Plus I'd read (I think on here) how some people had uncomfortably dry houses in the winter with a regular heat exchanger, and figured that that, plus the plumbing challenges, made the extra unit cost worth it. For us, the decision about whether to buy any MVHR at all was mostly about comfort! We use so little gas in this house that savings on heating bills never really came into consideration, it was always about living comfort (including indoor air quality). Wow that really is a thin exchanger material! I had no idea there was such a futuristic thing in our cupboard I guess it's true that there could be manufacturing issues with the exchangers, but we've also tested the problem with bypass mode on, and the problem persists. I'm not sure how other units do it, but on the Brink Flair 200/225 left-hand model, when bypass mode is on the extract air is routed directly to the exhaust port, so it doesn't go through the exchanger at all. The incoming air still does pass through the exchanger, though. Although thinking about it, there must be a point at which the extract->bypass channel and the extract->exchanger channels meet just before the exhaust port, so I guess there's a possibility for some back-flow into the exchanger from there..? Anyway, just thinking out loud, that's something for the other thread really!

Everything is definitely connected properly, I've checked it all about a thousand times, and the bloke from Brink checked it too. I've not gotten around to boxing in any of the ducting yet, so it's really easy to see what goes where, and follow it to its destination. We've also tested the issue by disconnecting the house ducting from the unit entirely, and just putting two single internal ducts on the top -- one on the extract port, one on the supply -- to prove that the problem exists purely within the unit, so it can't be due to anything wrong inside the house. Incidentally, I've also tested by sniffing at the exhaust duct, and the smells do also come through there, so it's definitely mixing air streams inside the unit. (If I'd somehow mixed up the exhaust and supply ports, the smells should only come through one of the "blow" holes, not both!) I'm hoping to hear back from either Brink or the supplier in the coming days, I think they're planning to do a smoke test. I'll keep this thread updated!

Thank you @JohnMo and @Nickfromwales for your fast and clear replies, much appreciated 👍 It's good to know that I'm not losing it! The unit was manufactured earlier this year, and it's only been installed and running for a couple of months, so I'm hoping there'll be a quick resolution.

Not sure whether to start a new topic or resurrect this one after 4.5 years, but as I have the same problem I suppose it's best to comment here... But I need a bit of a sanity check from those with experience of MVHR systems! We have a Brink Flair 200 unit (it's the Dutch version, the same as the UK Flair 225, but without the screen) with enthalpy exchanger, and have noticed the same issue as described here. Except it's not just kitchen odours, but even less pleasant ones..! To rule out our internal ducting, we even tested it by disconnecting the house entirely and just attaching two lengths of ducting to the unit. Smells which are sucked into the extract duct (shower gel, cream cleaner, coffee, whatever) come out of the supply duct almost immediately. It's really noticeable and strong. It's also not due to cross-flow outside -- Brink came out earlier this week and had a look, our installation is within spec. (Plus the effect is too strong and immediate to be external.) They swapped the exchanger core for a replacement, but the problem persists. (Not a surprise, as the smells also transferred with bypass mode on.) Their next plan is to do a smoke test. I'm pleased that Brink seem to be taking this seriously, and the company that sold me the unit has been helpful. Am I right in thinking that this just shouldn't happen? This isn't normal with MVHR or ERV, right -- nobody would want a ventilation system which spreads smells around the house! I clearly have a defective unit, right? Some seal must be missing or loose, otherwise this just wouldn't be occurring. Both my supplier and the man from Brink said they've never experienced this before, just my luck to get the one defective unit! I wonder what model MVHR @readiescards has/had which exhibited this same behaviour?

Ah that's interesting, I'd been wondering if something like this existed! I'd been pondering how our Flair will behave when the outside temp drops and the built-in pre-heater turns on. I know this is a heat exchanger protection thing, rather than a room temp thing, but I'm not sure if it uses a ton of electric, as it's just a resistive heater as far as I know. But because we have radiator pipes running past our unit and ducting, I'd wondered if it was possible to merge them somehow... Purely speculation though -- I'm trying to resist fiddling with the MVHR any more and concentrate on other stuff, such as boxing in the green ducts!

I agree -- if you can stop the sun from hitting the glazing, that makes a massive difference in the summer! External sun shades are really common here in NL and we've gradually had them added to all the windows. One room that was previously a hot box from June to September became a comfortable shady space. Back on the original topic -- although we only turned it on at the end of the summer, having the MVHR in bypass mode helped a lot too, drawing out all the hot air and bringing in cool night-time air. It meant we could close the windows without suffocating (it can be noisy around here even at night due to a big road not far away).

Yeah, estimates for our 80m2 house (supply and install) came in about that price, so for somewhere over 5 times larger that just sounds too good to be true.

It's definitely not a light bit of DIY! I would certainly consider having a company in to install it in our next house, instead of self-install. Though I'm happy with the results, it was a lot of work.

Are you asking about their air distribution system or their MVHR units? Their Ubiflux Vigor units are rebranded Brink Flair units (as far as I know both companies are owned by Ariston, so they're sibling companies, and stuff is cross-branded in different countries -- the Ubbink ducting is branded Brink in France, for example). Like JohnMo I've also used their distribution duct (the green ribbed stuff, Air Excellent) and the grey foam main ducting (the weirdly spelled Aerfoam), along with their distribution boxes and vent terminal adaptors. I also used their wall and roof penetrations for the external connections, and everything fitted together neatly and easily. Had no issues with it (as a first-time self-installer), although the Air Excellent is difficult to undo if you want to make changes -- once they're connected, they're pretty solid! This is a good thing, of course. While it's possible to ease the plastic clip back out, it's tricky in confined spaces. (Funnily enough, if you look at photos of Air Excellent installations in Poland, they use a metal clip which goes around the adaptor, instead of a plastic one which goes inside. The metal one looks easier to remove, though I've never handled one so that's just a guess!) It sounds like you're having it installed by a third party though, so I doubt all that is much of a concern to you! It's solid stuff, and is very widely used as far as I can tell, so it's a sound choice IMO.

It's a DEC International flexible silencer non-woven, Ø 100mm, 1m long. (Pretty cheap, about 25 quid?) I used Ubbink Air Excellent distribution box adaptors to connect the semi-flex ducting to the silencer, as I have several spares of these (I'd accidentally over-ordered when ordering the parts for the distribution boxes!). https://www.ubbink.com/int/products/ventilation/air-excellent-ventilation-ductwork/duct-adaptors/air-excellent-ae48c-dbox-adaptor/ The ducting clicks into it as designed, and I've used aluminium tape to attach the silencer onto the adaptor. I guess a cable-tie might also be a good idea, I might add one before I put the cupboard ceiling back on. The outer diameter of the adaptor matches the inner diameter of the silencer fairly well, so it fits together pretty neatly. At the vent end of the silencer I did the same thing in reverse, though this was only necessary because I have a Vent-Axia UniflexPlus wall vent in the bedroom, and the design of the ducting connector means it needs the semi-flex duct to be air-tight. If I'd used another brand of ducting at the bedroom (such as the Ubbink Air Excellent ones) then the end of the silencer would just slip over the vent adaptor and be taped on, as the air-tight design on those would allow that simpler connection.

I do have a multi saw which I love to use, as it happens That's definitely an option, although cutting the new floor is my 2nd choice, even though that might well be the easiest way to do it! It's probably because the floor is new, and the skirting boards are old, so they feel less valuable and fragile. (So that's more of a psychological issue than a DIY one!) The cornflake box cardboard trick is a genius move, thank you for that! I'd been wondering how we'd get a small but consistent gap, that's the perfect solution.

Directly opposite the gap is very generous -- maybe 20 to 25mm, because there's a wood and plasterboard build-out. The plasterboard doesn't go right down to the concrete floor, but stops about 20mm above it, so the floor tension springs are against the framing. Are you thinking that this gap might make up for the lack of a gap on the other side? (If I can get away without cutting, that would be wonderful!) Most of the room has about 15mm gap, which is a bit big, but I've got quarter-round to cover that.

Thanks for the reassurance! But the section I'm concerned about is regarding the width of the plank -- I've highlighted it on this photo. The side of the plank is pretty much right up against the skirting board, maybe 1mm gap, if any. I think my only option is to try and cut off the skirting board. (Either that or trim the side of the plank.)