Petrochemicals Posted March 10, 2023 Share Posted March 10, 2023 Having just done my system, why is it recommended to have a feed in the dwelling rooms and extract in the wet rooms, why not a feed to the halls and extracts in the rooms? It seems more logical. All the room stale air is instantly extracted, rather than wafting through the house. One large distribution box The noise in the extracts is lower because the air is travelling toward the noise. Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 10, 2023 Share Posted March 10, 2023 This is a wheel which does not need to be re-invented! 1 hour ago, Petrochemicals said: The noise is present in a badly designed and executed installation. Zero or near-zero audibility on my installs is a No.1 priority. Link to comment Share on other sites More sharing options...
Iceverge Posted March 10, 2023 Share Posted March 10, 2023 4 hours ago, Petrochemicals said: Having just done my system, why is it recommended to have a feed in the dwelling rooms and extract in the wet rooms, why not a feed to the halls and extracts in the rooms? It seems more logical. There's no saving in materials as you'd need to extract from every room so no reduction in ductwork. Good systems are inaudible. Extracts can make plenty noise too if done wrong. With all your ducting running off one of the MVHR fans you'd need an MVHR unit roughly twice the size as the job of shifting air is normally split 50/50 amountg the 2 fans, not 90/10 or 95/5. Link to comment Share on other sites More sharing options...
JohnMo Posted March 10, 2023 Share Posted March 10, 2023 This is a system design for our house, although I couldn't get the correct rates to keep building control happy. But could see no real reason why it wouldn't have been a good working system. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 6 hours ago, Nickfromwales said: This is a wheel which does not need to be re-invented! is present in a badly designed and executed installation. Zero or near-zero audibility on my installs is a No.1 priority. That's a bit rude and unbelievable. How do you stop the machine noise then. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 3 hours ago, Iceverge said: There's no saving in materials as you'd need to extract from every room so no reduction in ductwork. Good systems are inaudible. Extracts can make plenty noise too if done wrong. With all your ducting running off one of the MVHR fans you'd need an MVHR unit roughly twice the size as the job of shifting air is normally split 50/50 amountg the 2 fans, not 90/10 or 95/5. You would save on the distribution box, but I would say you would have even more duct work than normal. The point about the fan may be it. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 2 hours ago, JohnMo said: This is a system design for our house, although I couldn't get the correct rates to keep building control happy. But could see no real reason why it wouldn't have been a good working system. A few more extracts may have done it. Link to comment Share on other sites More sharing options...
Kelvin Posted March 10, 2023 Share Posted March 10, 2023 By comparison here’s ours: Link to comment Share on other sites More sharing options...
Iceverge Posted March 10, 2023 Share Posted March 10, 2023 I reckon if you ran an MVHR unit without any ducting in a central room in a compact house and left all the doors open then you'd have acceptable air quality. Otherwise just make sure you have a good unit, large enough ducting and an appropriate silencer. You can DIY one if needed. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 1 hour ago, Iceverge said: I reckon if you ran an MVHR unit without any ducting in a central room in a compact house and left all the doors open then you'd have acceptable air quality. Otherwise just make sure you have a good unit, large enough ducting and an appropriate silencer. You can DIY one if needed. The best silencer I have found is a flexible one from a cannabis garden shop, bent around, it works much better than the straight one. I come to believe bends in the duct work are good, not bad, I think flexible ducting must be pretty good at sound attenuation too. But I followed the manufacturers advice, rigid for as far as was reasonable then semi rigid, it transmits sound like shouting down a long stiff pipe. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 2 hours ago, Kelvin said: By comparison here’s ours: Imagine all of those ducts where extracts and you had additionally 2 large or very large in the case of your ground floor imput vents in your hall/ landing, maybe in the far far side in your living room. It seems that you would get the fresh air and the extracted air would have far less distance to travel. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 10, 2023 Author Share Posted March 10, 2023 1 hour ago, Iceverge said: I reckon if you ran an MVHR unit without any ducting in a central room in a compact house and left all the doors open then you'd have acceptable air quality. Otherwise just make sure you have a good unit, large enough ducting and an appropriate silencer. You can DIY one if needed. Not sure what you mean, would it not just go across the top of the unit? Link to comment Share on other sites More sharing options...
Iceverge Posted March 11, 2023 Share Posted March 11, 2023 3 hours ago, Petrochemicals said: The best silencer I have found is a flexible one from a cannabis garden shop, bent around, it works much better than the straight one. Like this one? Had one, it wasn't great. 3 hours ago, Petrochemicals said: Not sure what you mean, would it not just go across the top of the unit? Some for sure but not all. The best analogy I can think of is squirting cordial into a glass with a straw and sucking out beside it. Almost all of it will still be diluted in the water, very little pure cordial will be left. Link to comment Share on other sites More sharing options...
Petrochemicals Posted March 12, 2023 Author Share Posted March 12, 2023 On 11/03/2023 at 01:00, Iceverge said: Like this one? Had one, it wasn't great. Some for sure but not all. The best analogy I can think of is squirting cordial into a glass with a straw and sucking out beside it. Almost all of it will still be diluted in the water, very little pure cordial will be left. Like that yes, a bit more heavy duty, it works for me to a degree, it goes straight into the unit and is bent at a weird 90 angle insulating the outflow from the machine, it enables a low flow rate to be inaudible for night time, the extracts are now noisier than the inputs. It isn't perfect but much better than the straight through silencer, I'm not sure that did anything really. Tell me more of your silencing solutions please as the boost level is still a bit noisy over the TV(supply side) when it is switched on for after dinner extract. Link to comment Share on other sites More sharing options...
Iceverge Posted March 12, 2023 Share Posted March 12, 2023 https://forum.buildhub.org.uk/topic/23724-diy-mvhr-acoustic-silencer/#comment-366744 1 Link to comment Share on other sites More sharing options...
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