Savage87

whenever I used couplers or elbows on semi rigid ducts, they came with rubber gaskets on the inside and I used acrylic sealant and aluminum foil tape, a bit of overkill but it works.

I'm interested in the answer as well, I have just balanced my system which was installed 4 years ago and the house is a bit leaky. I think there a bit too much ventilation TBH with current building regs. I had it set to 25-50% less and it was fine for years, boosting only when there was high humidity in the kitchen or bathroom.

my unit Nuaire unit has a humidity sensor on it, but it's basic. I have another humidity sensor is the bathroom which is connected to an ESP controller and it boost that way. You are overthinking it, the boost switch can be done via so many wireless options you just need to decide what would work best for you. I also boost via another ESP controller via wifi. @Ajn could you please let me know what model sensors are you using for temp, humidity and CO2? I'm currently using some DHT22's, BME280, BME680 and Xiomi BLEs

I was considering the Domus unit to begin with and in the end I found a good deal for a Nuaire MRXBOXAB-ECO2 with a display added later on. This unit is more or less the same as the Domus one. I have gove through the same journey that you are about to go on back in 2019. If you haven't already seen it, have a look at this: Good luck, feel free to ask any questions.

Just as follow up, I had both fans replaced under warranty and also had the unit removed from the wall and hanged to the rafters as there was a considerable amount of noise to the neighbours, I could only hear it a bit in the landing at night and it didn't bother me as much. Now the unit is silent.

In my opinion, you should have been tinkering with ideas before a major renovation. You most likely have extractor grills for the bathroom and kitchen and possibly some in line fans. Answer to your first question: chimneys need to vent at the top and bottom, not necessarily in the middle. If you success in making the house more airtight you will need to think of a solution to introduce more ventilation(with heat recovery) either decentralised or centralised. Good luck!

I have a condensate trap (as a collar) on the extract pipe just above the mvhr and another hole at the bottom of the unit. Hope it helps..

you would have both extract and supply go on boost as @JohnMo said, it's a balanced system and whenever the speed of one fan increases the other one should follow so you don't get differential pressure. You could have it the just the extract boosts but there might be a disadvantages to it, not sure.

I'm getting smoke coming in via my supply roof vent from 2 houses away. So, be very careful.

I have these fitted on my concrete tile roof, there is another model to use for slate depending on slate size. Do a search for Manthorpe Slate Vent 300 x 600mm / 500 x 250mm.

Johnny I have done exactly what you are doing, I designed and installed my own MVHR, used different parts from different suppliers and it's all OK. When you first turn it on, for a couple of day you will hear it, unless it's on it's lowest setting but you(your wife) will get used to it and ignore it. In my case I would have had the next size unit just so I can run it at a lower setting and be able to use more boost when needed. Good luck!

I was looking at one of those split air con units, I would have liked to fit the whole thing in the loft, but after doing a bit of research, it's a bit tricky to install it ithe loft. I'll keep on looking... Another thing that I thought about was to some how use the componets from an small old fridge/freezer to get the cooler temperature. Crazy right?

Thanks @Dudda/@SteamyTea ! I already have bluetooth temp sensors dotted around the house and in the loft, these are connected to and ESp32(EspHome) and I do all my data logging through Home Assistant and InfuxDB/Grafana. I was hoping to find a solution to run some cool air in the supply distribution box, I'm not looking to cool the house significantly, just to lower the temperature down by a couple of degrees when the house overheats and like I said in my first post, I was looking at one of those heating/cooling coil boxes. If i wanted to heat the air I would have connected it to the boiler, but If want to cool the coil I'm not sure how to get the lower temperature.

@tonyshouse the house in question was built in 1910 and it's a mid terrace house, I'll have to check if it got a building physics model ? Jokes. I'll have to think about putting the MVHR to sleep, it's not going to be an easy decision.. ?

Side tracking a bit, does anyone know if you can install a split aircon unit and the outside unit to be fitted in the loft ?! ?

At about 18:00 outside temp in the shade was about 24 and temp inside was 27, temp in loft is about 30 degrees

I'm not sure what's the main cause for the solar gain is, I think there a mix of things but the house is fully insulated. At this stage I'm looking for an air conditioning solution. I understand this might not be the best way to look at a solution for the problem.

the problem is partly from the heat gain in the loft there the mvhr is, the intake and exhaust are on the roof. So it's bringing a bit more hotter air. The unit is boxed in and insulated but I'm not sure how much of a difference that is making.

Sorry to jump on, I'm having the same problem. The summer bypass in not doing much or better said nothing at all, I'm getting 27 degrees inside. I'm a bit desperate for a solution for confortable summers.

Hello everyone, It's summer again, yuppy! It's the second summer with the MVHR which has a summer bypass but the house is still getting to about 27 degrees inside. Does anyone have a solution to cool the house down? I was looking at integrating something like this but not sure where I would get the lower temperature from? https://www.bpcventilation.com/cold-water-duct-cooler-range

The way I done it (in the UK): I searched for the filter size that I needed, then I got the code for the filter and googled it and it came up with the car model it's used for, them I looked for a carbon cabin filter for that car model, 2 days later I had suzuki swift filter delivered.

Wow! Must a cost you half the mvhr install, all because of neighbours that live in the past.. Does the cleanbox have an additional fan?

great post @woodman please add some photos I have the same problem with one of my neighbours and their log burner. It's not as bad anymore but at times, depending what they were burning it was coming in thick. I done a lot of research, like you, but I didn't want it to be a permanent fixture to the system. I only wanted to use the extra filtration in the winter months. In the end I bought a filter box and a car carbon filter to fit in the box. This website helps you find car filters based on the required dimensions https://www.wixfilters.com/Lookup/FilterBySize.aspx If you are worried about the MVHR being to loud at night you might be able to turn it down within certain hours. Do you know at what percentage were your fans set before and after you changed the filters?

I would like to add this link as it has a lot of useful info

a bi tricky to check it at the moment, it's on the roof.. near the ridge. I will check it soon just to rule it out.