Marko

Mines in the loft. No where else to put it really. Might end up ‘cladding’ the sides with PIR, at some point. On the coldest day we had last week, the temperature difference between the room extracts and supply valves was hovering around 0.3-0.5 degrees. There’s no insulation in the loft yet either, but ducts are lagged with 80mm ISO sleeve.

It’s currently-2 here. What’s peoples indoor humidity readings been like? We’ve had our system operational for around two weeks and I suspect various elements have been drying out over that time. We’re sitting at 55% at the moment.

Thanks for the insight. I’ve been looking at carbon filter solutions on here, seems most diy them. The house isn’t particularly airtight at the moment but it’s a work in progress Yes, I’d be looking at direct air with a duct to either outside or from under the suspended floor.

That window is north facing. No none else in the street seems to use their chimney. What do you reckon?

Thanks for info both. The intake, on the left is fairly close to the chimney so unsure what to do. Might be that smoke blows over and past.

I live in a standard terraced house, and my MVHR intake and extract terminals are located about four tile courses below the ridge on the side opposite the chimney. I am considering recommissioning the existing chimney for a wood-burning stove, and I am concerned about whether smoke might be drawn back into the house through the MVHR system. If anyone has dealt with a similar setup, I would appreciate any insights into whether its worth the hassle or not.

Am I right in thinking that going of Approved Document F, you go with the higher flow rate value of either paragraph 1.24 (A minimum rate of 0.3 litres per second per m2 of internal floor area)....or table 1.3 (Minimum ventilation rate by number of bedrooms (l/s)). In my case: Paragraph 1.24 requires meeting both 0.3 l/s/m² and the bedroom-based flow. For my area of 58.4 m², 17.52 l/s is needed by floor area, and 25 l/s by bedroom count (two bedrooms). So, I must use the higher value: 25 l/s. For boost, I was planning on upping these by 20%. How does all of this sound?

Fantastic. Very much appreciated!

Thanks Jack, I've gotten my head around the requirements now. I'd be very interested in hiring the anemometer. Do you have any ideas of timescales so we have something to aim for in terms of getting the last ducts ran?

Have most people here who installed their own systems also handled the commissioning themselves? I'm almost finished running the last few ducts and am starting to think about the next steps. My main question is about measuring the flow rate. If I can get my hands on an anemometer, do I simply divide the total flow rate by the number of intake or exhaust valves to calculate the flow per valve?

Thanks Mike 👍

I've gone through the BPCV instructions, and I can't find anything that specifically says whether the 75mm ducting needs insulation in a cold loft. I'm assuming it doesn't as long as you can place the ducts under the loft insulation. Can anyone confirm this? TIA

I've got the unit on the wall and had the roofers out to install the vent tiles. BPC just sent me their instructions and after reading through it I noticed they recommend that: 'roof vents must be installed at a higher level than the MVHR unit or condensation will form in the pipework' My intake vent is a lot lower than the unit. Is this critical before I get the roofers back out 🫣

I've just had the roof tile vents installed and going to start connecting the unit up. What has everyone used to make the connection from the spigot/adaptor on the vent tile to the PVC ducting from the unit? Presumably some sort of flexible connection to allow for the pitch of the roof?

Great, I’ve had a ‘preliminary’ design layout sent over that does give flow rates and basic intake and extract locations. They then say that they can provide full ventilation guide with more detailed information such as duct runs etc. No mention if it is deductible from total cost though. Just wondering if it’s worth paying the extra in the grand scheme of things.