jack

That's a good idea. A lot of members don't look at the Introduce Yourself sub-forum, so you'll generally get more and better advice if you post in the right sub-forum.

Welcome to BuildHub, that looks like an interesting project.

Welcome! I wouldn't worry about getting things wrong. Most of us aren't in the building trade, and even those who are started knowing nothing. Post a pic, use your own words (all in the correct sub-forum of course!) and you'll generally get the help you need.

Yeah, with the full spec sheet, it's easy enough to find the right bearing from whatever manufacturer. From what I've read, it's worth spending a bit more on SKF branded bearings (still only a tenner a pair - enough for a single motor).

Sure, MVHR manufacturers see it that way. But many MVHR units (at least those from Brink and Paul) use similar EBM Pabst motors that are certainly serviceable based on the many reports of people replacing bearings in them. I don't know much about bearings, so I'd be concerned about whether non-dimensional parameters such as loads, duty cycle, or tolerances might be relevant. I'd therefore much rather get the right spec (if it's available) than estimate based solely on measurements. I think I'm going to start a pinned thread pulling together bearing information for different MVHR models that people have encountered. Might be a useful resource given these things inevitably fail and are much cheaper to replace than the motor as a whole.

Thanks @ProDave Is there a reason you took your own measurements rather than contacting the MVHR or motor supplier and asking them for the bearing specs?

I'd do that with something like a plumbing component that I can get locally, but I have no idea what sort of bearing supply places are near me. Seemed just as easy to start by seeing whether anyone else had dealt with the issue given that I know quite a few people have these Brink units installed.

I disagree with those who say all rooms need to be the same temperature in a Passivhaus class dwelling. For example, it's generally fairly easy to maintain lower temperatures (during winter) in upstairs rooms. We have no heating in the bedrooms and it's naturally 2-3 degrees cooler upstairs than downstairs at this time of year. The coldest ground floor room in our house is the TV room. It's the only room with carpet - the rest of the ground floor is polished concrete, which is much better at transferring heat. As well as using different pipe spacing, you can throttle down the flow rate to rooms where you want less heat. You won't get massive temperature differences, but even a couple of degrees can be noticeable. All that said, I agree with those who say you're overthinking it, especially as far as the challenges you think will arise out of using off-peak energy. Our slab temperature has varied by a total of 1.2 degrees over the last two months, with a typical daily fluctuation of about 0.2 degrees. That's with an extremely simple control setup in Loxone that doesn't even take into account outside temperature (the ASHP does weather compensation).

Thanks for that. I did find that (and a few other similar videos) yesterday, but it has a different motor. I suspect most of them use the same bearings but I'd rather not risk it!

I've figured out the motor (EBM Pabst R3G190-RG19-22 (previously R3G190-RC05-09)), but can't find out anything about the bearings. It seems Brink would prefer you buy a new motor for several hundred quid rather than replace the bearings. Thanks Nick. I've shot off emails to EBM Pabst and the UK supplier, but am not particularly expecting a positive reply (if any) before the new year anyway. If you know someone who could give you the necessary info, that'd be great. There's no particular rush, thanks!

See if you can find recycled railway ballast. We used it under our raft foundations. Make sure you get the cleaned version.

The fans on my 9 year old Brink Excellent 400 have been slowly getting noisier, so I'm going to replace them. Our unit is installed in such a way that it's going to be a complete bear to get to the motors so I can replace the bearings. I'd therefore like to order the bearings before I take the unit apart, so I can do the whole job on the same day. Does anyone happen to know what size and number of bearings Brink uses on these units? I could contact Brink, but I expect they're closed until the new year, and I can't find anything about it online. @Nickfromwales, is this something you've encountered? Thanks.

Yes, I think some of them can. In my case, even 2 x 7 kW car chargers and the ASHP pump running flat chat on top of ordinary background loads wouldn't take me anywhere near the limit.

Diversity.

If they did calculations, then they ought to be able to present them and explain their maths. You've paid for it, so demand they show their working. 40 kW is 166 A. Like you're planning, I have a "big house all electric" (290 m2, 5 kW ASHP, 7.2 kW car charger, 3 ovens + induction hob) and my very conservative electrician was more than happy with our existing 100 A supply.

What are you running that could possibly consume 40 kW given you're talking about a max 7 kW heating system? Are you planning something like a 22 kW charger for a car?

@GTM_88, I've moved your original post to the underfloor heating subforum, as it's turned into a heating discussion rather than an intro. You're likely to get more input here, as a lot of members don't monitor the Introductions subforum. There's a link to the new thread location in the Introductions subforum, so people who've already replied can find the thread easily.

Welcome to BuildHub. What a great intro! As you've seen, lots of our members enjoy getting back to first principles when it comes to working with things like UFH, MVHR, ASHPs and the like, especially where there's a novel angle (like UFH in a boat).

Hi Joe BuildHub is a strictly non-commercial forum. As such, the sharing of business names, websites, and email addresses isn't allowed. We've therefore deleted the rest of your post, which read as an ad for the business you work for. That said, we do welcome members who work in the building and related trades. The way to approach it is to take a long term view of your membership. Share knowledge and offer advice based on your skills and experience. Once people realise that you know what you're talking about and might be able to help them solve their problems, they'll find you via the private messaging system. Plenty of members have had business through the forum with this approach, without falling foul of the "no commercial posts" rule. It just requires taking a slightly longer view. Good luck.

This is slightly different. I thought from your first post that you'd paid for them and were going to re-use them. It's probably still fine to do what you've done. It's hard for a company that isn't trading any more to sue you for copyright infringement!

Submit them. If they find out and complain, and can explain why what you're doing is in breach, they can threaten to sue you for damages. IANAL, but presumably damages are realistically likely to be no more than the original charge for the report (or their current charge for the same, not that that's relevant if they're no longer trading).

Welcome to BuildHub. There are definitely at least a few BuildHub members who used 200+ mm concrete slabs in a raft construction. More common is a nominally 100 mm reinforced slab on a raft with 200-300 mm of EPS underneath. However, by the time you factor in a 300mm deep ringbeam, 200 mm deeper reinforcement ribs and 200 mm deep reinforcement areas for structural walls, the average thickness is actually much higher than the nominal 100 mm would suggest. Overall, the performance of a flat 200 mm slab probably isn't that far off a 100 mm slab with all the extra deep bits. Try these two Google searches for more info: https://www.google.com/search?hl=en&q=250mm slab raft site%3Abuildhub.org.uk https://www.google.com/search?hl=en&q=200mm slab raft site%3Abuildhub.org.uk

Summer bypass also takes into account the outdoor air temp. The settings on ours let you set the exterior temp above which the summer bypass will operate (if the indoor air temp is higher than the outdoor temp). Ignoring summer bypass, MVHR tries to maintain any temperature difference that exists between the inside and the outside. If you have the heating on in winter, or the cooling on in summer, such that you've pushed your house temperature up or down in a direction that makes it more comfortable than the outside temperature, then you want the MVHR operating in its normal (non-bypass) mode. It will stop your hard-won heat/coolth from being lost to the outside through ventilation. In summer, when the temperature outside drops below your house's internal temperature (in the evening, say), but is still above a threshold temp, the summer bypass kicks in. Instead of operating to maintain the temperature difference, the MVHR ejects warm air from the house and draws in cooler air from outside. Nothing special happens. Assuming it's cooler inside than outside because of the operation of the UFH, then the MVHR will try to maintain that temperature difference. Some people turn down the ventilation rate when it's very cold or hot outside. That reduces energy losses due to the large temperature difference between the inside and outside. It also reduces how much moisture is taken out of the air in winter. Overventilation when it's very cold can result in very low humidity inside.

That's the plan, in conjunction with screens in at least the bedrooms to encourage stack ventilation (assuming I eventually manage to fix the electric rooflight opener - yet another thing on the to-do list).

I didn't get much mould for the first few years, but as time's gone by, I get increasing amounts building up every year. You've reminded me I need to do my annual clean. If I remember, I'll drop a photo (if it isn't too disgusting!) into the thread.