dnb Posted October 20, 2021 Share Posted October 20, 2021 I am drawing up the duct routes this week ready for some 1st fix progress and I have two options for MVHR. Reading the threads here it looks like there is a requirement to separate the intake and exhaust of the MVHR by 2 to 3m and keep them on the same (ideally sheltered) wall. Both of my options achieve this, but does it make a difference if the separation is vertical or horizontal? Option 1 has vertical separation with the intake low down on the wall (apprx. 3m above ground) with the exhaust just under the eaves at around 6m above ground with up to 2m horizontal separation. Option 2 has both intake and exhaust at 6m above ground. Horizontal separation can be up to 10m but the easiest option gives approx 5m. Option 1 presents some inconveniences to other bits of infrastructure so unless there's a compelling reason for vertical separation I would prefer option 2. I would very much like to know what anyone else has done. Link to comment Share on other sites More sharing options...
Blendworth Posted October 20, 2021 Share Posted October 20, 2021 I dont fully understand your issue but things to note, For vertical separation, exhaust wants to be above FAI (fresh air intake) to reduce the chance of recirculation. Horizontal separation, if I remember correctly, the minimum recommended separation is 1.5mtr. Try and avoid having the FAI n a area where pollutants will be absorbed into the building, and also avoid area where any external 'hot-sports' of air may be brought into the building, eg intake within the recess of the south facing roof may lead to hot air being drawn into the building. Zehnder make an approved external combined stainless steel intake & exhaust terminal that allows both to be routed out the building directly adjacent, well below the 1.5mtr minimum separation. Link to comment Share on other sites More sharing options...
Blendworth Posted October 20, 2021 Share Posted October 20, 2021 Just a thought, have you read the Domestic Ventilation Compliant Guide? Link below domestic_ventilation_compliance_guide_2010.pdf (publishing.service.gov.uk) Link to comment Share on other sites More sharing options...
dnb Posted October 20, 2021 Author Share Posted October 20, 2021 2 hours ago, Blendworth said: I dont fully understand your issue but things to note, Thanks. The external terminal examples do help a bit. Not sure I have an actual issue. It's more about what solutions other people have employed and me thinking about an optimal solution - does vertical separation help with anything or does it make no difference, and figuring out if there's a sensible maximum for horizontal separation. I'm not short of space. The ventilation guide looks useful. 1 Link to comment Share on other sites More sharing options...
Adam2 Posted October 20, 2021 Share Posted October 20, 2021 I'd expect the further apart they are over the min then the more pipe you'll need and more insulation on the pipe. Not sure if there is any benefit unless you have specific local conditions that mean >1.5m is necessary as surely if they state 1.5m then that is sufficient to work as designed for most situations. Mine will be 1.5m as this is all I can accommodate - will use a hooded vent grill that I can use to direct flow direction a bit. Link to comment Share on other sites More sharing options...
Faz Posted October 20, 2021 Share Posted October 20, 2021 I can take a pic of mine tomorrow if you want - got 2 massive extract ducts popping out of the anonymous side of the building. Massive things! Link to comment Share on other sites More sharing options...
Iceverge Posted October 20, 2021 Share Posted October 20, 2021 6 hours ago, dnb said: Reading the threads here it looks like there is a requirement to separate the intake and exhaust of the MVHR by 2 to 3m and keep them on the same (ideally sheltered) wall. Both of my options achieve this, but does it make a difference if the separation is vertical or horizontal? I installed one of these as I wanted to keep the ductwork tidy inside the house and have minimal run of "cold" ducts inside the thermal envelope. https://www.proair.ie/products/proair-fex-terminal/ In essence it is a bracket for 2 ducts and a cover which ensures no interference of airflow. However I recently left the cover off for about a week while I was painting the house. This left two 160mm ducts separated by only 50mm. All through that time we didn't notice any difference. When I cooked a curry I thought maybe we might get a whiff in the bedrooms but zero/nada. The space behind our house is very open with no nearby buildings. I haven't seen interference between ducts in real life. I imagine that if you are not venting into a small enclosed alcove there's little risk of ever suffering from intaking much exhaust air. Happy to stand corrected by anyone with any evidence of it happening. 1 Link to comment Share on other sites More sharing options...
Adsibob Posted November 8, 2021 Share Posted November 8, 2021 On 20/10/2021 at 15:29, Blendworth said: Just a thought, have you read the Domestic Ventilation Compliant Guide? Link below domestic_ventilation_compliance_guide_2010.pdf (publishing.service.gov.uk) Thanks. The “system 4” of that document relates to MVHR. On page 45 it states that the minimum horizontal distance between extract and supply on the same facade of a building is only 300mm. That seems very low to me. Link to comment Share on other sites More sharing options...
Coanda Posted October 30, 2023 Share Posted October 30, 2023 On 20/10/2021 at 13:32, Blendworth said: also avoid area where any external 'hot-sports' of air may be brought into the building, eg intake within the recess of the south facing roof may lead to hot air being drawn into the building. Would that necessarily be a bad thing? Link to comment Share on other sites More sharing options...
Adsibob Posted October 31, 2023 Share Posted October 31, 2023 16 hours ago, Coanda said: Would that necessarily be a bad thing? Ask that question again during the height of summer. Link to comment Share on other sites More sharing options...
Coanda Posted October 31, 2023 Share Posted October 31, 2023 What is this summer thing you refer to? I live in county Antrim. 1 Link to comment Share on other sites More sharing options...
Adsibob Posted October 31, 2023 Share Posted October 31, 2023 7 hours ago, Coanda said: What is this summer thing you refer to? I live in county Antrim. I think even there you are not immune from a hot summer’s day. Only last month you had a few: https://m.belfasttelegraph.co.uk/news/northern-ireland/official-heatwave-to-be-declared-in-ni-as-experts-predict-when-soaring-temperatures-will-peak/a1117229642.html Given climate change, summers will only get warmer. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 31, 2023 Share Posted October 31, 2023 2 minutes ago, Adsibob said: Only last month you had a few: https://m.belfasttelegraph.co.uk/news/northern-ireland/official-heatwave-to-be-declared-in-ni-as-experts-predict-when-soaring-temperatures-will-peak/a1117229642.html As nice as some of the weather was, it is down to the definition of a heat wave. It is the number of days (3) above a threshold temperature. It also varies from place to place. So my heatwave is not the same temperature as your heatwave. https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/temperature/heatwave 6 minutes ago, Adsibob said: Given climate change, summers will only get warmer. But not as much as winters will. I was thinking of starting a thread about climate change as the opportunities it may bring. Shall do it now. Link to comment Share on other sites More sharing options...
Adsibob Posted October 31, 2023 Share Posted October 31, 2023 2 minutes ago, SteamyTea said: also varies from place to place Obviously. Otherwise the Sahara would be experiencing heatwaves every day of the year. I think of a heatwave as unusually hot weather that lasts long enough it begins to get bothersome. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 31, 2023 Share Posted October 31, 2023 (edited) 9 minutes ago, Adsibob said: Obviously. Otherwise the Sahara would be experiencing heatwaves every day of the year. I think of a heatwave as unusually hot weather that lasts long enough it begins to get bothersome. I don't want to derail this thread, so started another. Edited October 31, 2023 by SteamyTea Link to comment Share on other sites More sharing options...
Coanda Posted October 31, 2023 Share Posted October 31, 2023 1 hour ago, Adsibob said: I think even there you are not immune from a hot summer’s day. Only last month you had a few: Yes we had a few nice days. But you have to allow for headlines and clickbait. Nowadays every gust of wind has a name and storm warnings every few weeks. There hasn't been a decent storm in this area for 20 yrs. Anyways I apologise. It was I who drifted off topic lets return to MVHR. I shall add a summer bypass if and when needed. Link to comment Share on other sites More sharing options...
Mr Blobby Posted January 22 Share Posted January 22 On 31/10/2023 at 21:53, Coanda said: Nowadays every gust of wind has a name and storm warnings every few weeks. There hasn't been a decent storm in this area for 20 yrs. There has now 🤨 Link to comment Share on other sites More sharing options...
Adsibob Posted January 22 Share Posted January 22 41 minutes ago, Mr Blobby said: There has now 🤨 Really? Hardly felt it down here. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 22 Share Posted January 22 22 minutes ago, Adsibob said: Really? Hardly felt it down here. Was pretty good wind yesterday, had stronger ones in the past, but as soon as the windspeed is over 40 MPH, then it makes things rattle. Think we hit around 55 MPH for a few hours in the evening. Link to comment Share on other sites More sharing options...
Coanda Posted January 22 Share Posted January 22 1 hour ago, Mr Blobby said: There has now 🤨 Yip. My bin blew over and a fence that was falling down is now down. To be fair it was as bad as I've seen in a long time. Link to comment Share on other sites More sharing options...
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