Pocster Posted January 30, 2017 Share Posted January 30, 2017 (edited) Hey all So how do you deal with this and MVHR?. Because in theory (and I suspect practise) the MVHR could spread cooking smells throughout the house; yes? I presume you do not want MVHR vent above hob/hood? Thanks in advance! Cheers Edited January 30, 2017 by pocster Monday; can't type correctly Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 30, 2017 Share Posted January 30, 2017 13 minutes ago, pocster said: Hey all So how do you deal with this and MVHR?. Because in theory (and I suspect practise) the MVHR could spread cooking smells throughout the house; yes? I presume you do not want MVHR vent above hob/hood? Thanks in advance! Cheers It's always a bit of a challenge! The MVHR cannot recirculate cooking smells though, as it only ever delivers fresh air from outside to the rooms in the house with air feeds, so the cooking smells still go outside via the extract side of the system (fresh air in and extract air out are kept separate in MVHR). You can't easily plumb a hood in, because there's a risk that oils and fats will clog the ducts, filter and heat exchanger on the extract side of the MVHR, plus the hood extract rate will over-power the MVHR and cause it to run out of balance (more air being sucked out than is sucked in). The simple fix is to use a recirculating cooker hood, one with decent filtration, and allow the kitchen MVHR extract (which is the highest extract rate of all of them) to remove the remaining smells. if need be, you can add a boost button in the kitchen to increase the MVHR fan speeds on demand, as you might in a shower or bath room. Link to comment Share on other sites More sharing options...
joe90 Posted January 30, 2017 Share Posted January 30, 2017 I concur with Jeremy above and this is what I have planned for our new build. Link to comment Share on other sites More sharing options...
Pocster Posted January 30, 2017 Author Share Posted January 30, 2017 (edited) Thanks guys. What about one of the new hobs; where the extraction is built in and at hob level??? Or does it not make any difference? i.e. any extractor must be a filter type rather than vented type? Edited January 30, 2017 by pocster Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 30, 2017 Share Posted January 30, 2017 Not sure, TBH. They were outside our budget range when we were looking, plus SWMBO had already decided on the induction hob. There's one model that we could have fitted in our island (where the hob is) that sucks down, filters and then blows out at a lower level. Still expensive, I think, and hard to retrofit if you have stone work tops, I should imagine. Link to comment Share on other sites More sharing options...
Pocster Posted January 30, 2017 Author Share Posted January 30, 2017 Yeah this is the type I mean. I guess Im thinking it could still create an air imbalance for the MVHR; but does that matter just for an hour of cooking? Cheers Link to comment Share on other sites More sharing options...
dogman Posted January 30, 2017 Share Posted January 30, 2017 Some info from BPC who a lot of members have used https://www.bpcventilation.com/blog/the-cooker-hood-conundrum 1 Link to comment Share on other sites More sharing options...
Pocster Posted January 30, 2017 Author Share Posted January 30, 2017 25 minutes ago, dogman said: Some info from BPC who a lot of members have used https://www.bpcventilation.com/blog/the-cooker-hood-conundrum Yeah I looked at that!. I *think* I'll ask then about the hob 'down' extractors and see what they say. Link to comment Share on other sites More sharing options...
PeterW Posted January 30, 2017 Share Posted January 30, 2017 There was a thread on the very nice downdraft extractors a couple of weeks ago Link to comment Share on other sites More sharing options...
Pocster Posted January 30, 2017 Author Share Posted January 30, 2017 Just now, PeterW said: There was a thread on the very nice downdraft extractors a couple of weeks ago Yeah; it is nice! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 30, 2017 Share Posted January 30, 2017 48 minutes ago, pocster said: Yeah this is the type I mean. I guess Im thinking it could still create an air imbalance for the MVHR; but does that matter just for an hour of cooking? Cheers No, it won't cause any issues at with the MVHR, as it's not changing the air flow at all. They suck from surface level to remove cooking smells, vapour etc, filter the air then blow it back out into the kitchen, with the smells and vapours etc mostly removed. Most use a mixture of washable filters to trap oil and fat vapour, plus an activated carbon filter to remove most of the smells. The manufacturers would like you to always fit new filters, but on the conventional recirculating hood we have in our old house I found that the two filtration units were easy to clean/rejuvenate. The mesh oil and fat filter cleaned up well by just sticking it in the dishwasher and the activated carbon filter was just carbon granules between two bits of stainless mesh. I found that it was dead easy to take one of the mesh sides off and bought a big bag of activated charcoal granules very cheaply (the stuff is used in pond filters). empting the carbon out and filling the filter with fresh stuff was clean and easy to do, and a fraction of the price of replacing the filters. I still have a bag of activated carbon I bought several years ago, left over. 2 Link to comment Share on other sites More sharing options...
Pocster Posted January 31, 2017 Author Share Posted January 31, 2017 15 hours ago, PeterW said: There was a thread on the very nice downdraft extractors a couple of weeks ago So what stops condensation and moisture build up occurring in the MVHR pipework? Link to comment Share on other sites More sharing options...
Crofter Posted January 31, 2017 Share Posted January 31, 2017 3 hours ago, pocster said: So what stops condensation and moisture build up occurring in the MVHR pipework? Because the MVHR ducting is the best ventilated part of the whole house! 1 Link to comment Share on other sites More sharing options...
Pocster Posted January 31, 2017 Author Share Posted January 31, 2017 Hmmmm ive had bathroom extractors with the flexible ducting get moisture build up in them and then sag . Making the problem worse . Link to comment Share on other sites More sharing options...
jack Posted January 31, 2017 Share Posted January 31, 2017 Bear in mind that bathroom extractors don't have air being continuously extracted through them 24/7. 90+% of that time the air is not damp, so there's plenty of opportunity for any condensation to dry out. Link to comment Share on other sites More sharing options...
gravelld Posted January 31, 2017 Share Posted January 31, 2017 Well, air *is* extracted through them continuously, just not enough ;-) Link to comment Share on other sites More sharing options...
Pocster Posted January 31, 2017 Author Share Posted January 31, 2017 24 minutes ago, jack said: Bear in mind that bathroom extractors don't have air being continuously extracted through them 24/7. 90+% of that time the air is not damp, so there's plenty of opportunity for any condensation to dry out. This one did. It was an expensive fan that runs constantly and supposedly adjusts depending on the humidity. You see my concerns for this issue with MVHR. Link to comment Share on other sites More sharing options...
jack Posted January 31, 2017 Share Posted January 31, 2017 33 minutes ago, pocster said: This one did. It was an expensive fan that runs constantly and supposedly adjusts depending on the humidity. You see my concerns for this issue with MVHR. Maybe, but MVHR is a different proposition. The lowest level of extraction should be more than enough to dry out the ducts between steamy situations (oo er missus). Link to comment Share on other sites More sharing options...
joe90 Posted January 31, 2017 Share Posted January 31, 2017 I would suggest that if a fan was running 24/7 and there was still condensation within the pipe then something else is wrong, you mentioned sagging, that will produce pools of water, just a thought. Link to comment Share on other sites More sharing options...
TerryE Posted January 31, 2017 Share Posted January 31, 2017 You can't extract air with a cooker hood in a house with MVHR. You still need a recirculating hood though because this will remove the vast bulk of oil and particulates in its filters. The de-greased air will then be removed by the normal MVHR extract duct(s) in the kitchen. 1 Link to comment Share on other sites More sharing options...
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