Tilda Posted June 21, 2022 Share Posted June 21, 2022 Hi all, After being disappointed with various places quotes mandating I bought all the kit through them, I decided to DIY it myself. I've got a basic idea from a couple of places and am hitting 11 extract ducts and 11 supply ducts. I have a Brink Renovent Excellent 400 unit which will be loft based. 180mm insulated foam duct to extract and supply vent, venting to outside via: https://www.ubbink.com/en-gb/product/roof-terminal-insulated-ub48-180mm-black Inside, 2x 90 degree foam bends to point tubes downwards. Supply - into a 90cm radial silencer - https://www.ventilationland.co.uk/product/20468/round-silencer-diameter-180-mm-length-900-mm-100-mm-insulation.html then into 14 port manifold: https://www.bpcventilation.com/quiet-vent-14-port-distribution-box-vertical radial ducting to house into plenums I found from a polish company on ebay which seem okay. nuair room vents which I got cheap on facebook! Extract wise - from the unit no silencer planned but a 90cm downwards stretch of foam duct to an identicle manifold and then as above to the rooms. Questions 1) Does this sound okay? Anything missing? 2) Will the silencer be enough, there's options for 5 or 10cm thick sound insulation, does it make a difference? 3) The majority of ducts will be in loft so I'm planning on either/both individually insulating them and bulking up my loft insulation over the top. Okay? 4) Drainage pipe ?do I need a 'dry' ubend or a normal ubend? 5) Does cheap vs expensive 75mm ducting make a difference? Anybody send me a link or reply with a decent place to get cheap ducting? 6) I'll need to switch kitchen extract for recirculating one, but does anybody recommend a decent filtered extract for kitchens? Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 21, 2022 Share Posted June 21, 2022 Hello. Has a competent MVHR designer designed your MVHR system? If so, could we have a look at the design please? The reason I ask is because the designer will probably have answered questions 2, 3 and 4. 11 extract ducts the same number of supply ducts seems a bit out of kilter to me. We have a good few supply ducts and 3 extracts. The extracts have twin hose piping. How much work have you done on air-tightness in the property? Link to comment Share on other sites More sharing options...
JohnMo Posted June 21, 2022 Share Posted June 21, 2022 A house layout may also help, long runs may need to be doubled up. Have worked out flow rates? Link to comment Share on other sites More sharing options...
Roundtuit Posted June 21, 2022 Share Posted June 21, 2022 Sounds like too many extracts unless you have a lot of 'wet' rooms. The air needs to flow through the house, not just out of a feed and back up an adjacent extract. Generally I think you can just extract in toilets/bathrooms/utility/kitchen, and feed to every habitable room. As above, a plan would help. (Don't forget a 10mm gap under all of your internal doors is required to get the air flow 😉) Link to comment Share on other sites More sharing options...
JohnMo Posted June 21, 2022 Share Posted June 21, 2022 Assuming you are using around 50% the capacity of the brink 400, so around 200m3 flow (suitable for 600m3 house volume), that only 18m3h average flow per inlet and outlet, which sounds wrong. Link to comment Share on other sites More sharing options...
Tilda Posted June 21, 2022 Author Share Posted June 21, 2022 (edited) I had a plan from BPC and lindab. I didn't progress with a paid-for plan because everybody insisted that I buy everything from them! Floor area is about 200sqm Lindab quoted for 11 supply and 12 extract with a trickle rate of 59.1l/2 Airtightness is work in progress as its a retrofit, but planning to make baby steps with this once MVHR in in. I attach a plan. The extracts are 3 bathrooms upstairs, utility, kitchen, WC downstairs. The downstairs part of the house is tricky as theres no easy route down into the WC/utility but can just squeeze two ducts down through the ensuite. A 7th question - do i need the fancy insulated roof vents, or are the flat type tile vents enough? https://klober.co.uk/ventilation/roof-vents/universal/p/universal-20k-tile-vent Edited June 21, 2022 by Tilda Link to comment Share on other sites More sharing options...
Tilda Posted June 21, 2022 Author Share Posted June 21, 2022 2 hours ago, ToughButterCup said: Hello. Has a competent MVHR designer designed your MVHR system? If so, could we have a look at the design please? The reason I ask is because the designer will probably have answered questions 2, 3 and 4. 11 extract ducts the same number of supply ducts seems a bit out of kilter to me. We have a good few supply ducts and 3 extracts. The extracts have twin hose piping. How much work have you done on air-tightness in the property? So I've quoted in number of ducts in my original post - you're right a number of them are doubled. Link to comment Share on other sites More sharing options...
JohnMo Posted June 21, 2022 Share Posted June 21, 2022 Some initial comments Kitchen/diner only needs an extract. Move supply and extract points away from windows and doors. You could remove extract from landing Make use of coanda effect supply and extract valves. These throw the air across a room at ceiling level, may make duct routing easier. You could remove a supply from the snug as all supply air in the lounge and family will travel through the snug prior to being extracted. 8 supply 6 extract. Anything outside the heated envelope has to be insulated. I have attached a layout drawing I got from Fresh R for our house. There are only two supply points and three extract points (200m2 floor area) so some food for thought. They have looked at the way the air would flow through the building and simplified. I didn't go that route, because Brexit was just happening at that time. Link to comment Share on other sites More sharing options...
Tilda Posted June 21, 2022 Author Share Posted June 21, 2022 2 hours ago, JohnMo said: Some initial comments Kitchen/diner only needs an extract. Move supply and extract points away from windows and doors. You could remove extract from landing Make use of coanda effect supply and extract valves. These throw the air across a room at ceiling level, may make duct routing easier. You could remove a supply from the snug as all supply air in the lounge and family will travel through the snug prior to being extracted. 8 supply 6 extract. Anything outside the heated envelope has to be insulated. I have attached a layout drawing I got from Fresh R for our house. There are only two supply points and three extract points (200m2 floor area) so some food for thought. They have looked at the way the air would flow through the building and simplified. I didn't go that route, because Brexit was just happening at that time. Thanks John, very interesting - did they offer a design only package? Link to comment Share on other sites More sharing options...
JohnMo Posted June 21, 2022 Share Posted June 21, 2022 No, the layout is specifically for the Fresh R units, but can't see why it can't be adapted to other units Link to comment Share on other sites More sharing options...
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