dogman Posted November 6, 2016 Share Posted November 6, 2016 I have been thinking about the location of the vent for our proposed MVHR. The property has a plant room that sits to the side of the house. I was intending to draw and vent at different sides of the house. The rear is south facing so we have a warm and a cold side to the house. The air sourced heat pump for the heating is to the rear of the plant room. I have two questions. Does it make a difference where to vent and draw. Did think that if i draw from the cold side it would help with summer cooling which is more important than heating Second part is that i would then be venting on to the heat pump or at least a couple of feet above. Was thinking of venting straight on to the back of the pump as the extracted air in mid winter will be a lot warmer than the outside air Any thought / advice please Link to comment Share on other sites More sharing options...
Dudda Posted November 6, 2016 Share Posted November 6, 2016 The extract and supply should be on the same side of the house so the wind pressure is the same. I'd be inclined to keep the duct lengths as short as possible as this is where heat is lost and more energy is used by the fans. Link to comment Share on other sites More sharing options...
PeterW Posted November 6, 2016 Share Posted November 6, 2016 The power of the fans in MVHR is negligible - if you feed it into the back of the heat pump you will have a real problem balancing the air flow as as the MVHR will create significant negative pressure. There isn't enough heat in the air coming out to be of any real benefit. If you read JSH blog there is lots in there about balancing the systems. 1 Link to comment Share on other sites More sharing options...
joe90 Posted November 6, 2016 Share Posted November 6, 2016 But where can you read JSHs blogs, they seem to have disappeared ( a bit like JSH)? Link to comment Share on other sites More sharing options...
PeterW Posted November 6, 2016 Share Posted November 6, 2016 42 minutes ago, joe90 said: But where can you read JSHs blogs, they seem to have disappeared ( a bit like JSH)? here ..?? Link to comment Share on other sites More sharing options...
dogman Posted November 6, 2016 Author Share Posted November 6, 2016 Ok read through JSH blog( thanks PeterW). Probably too much information and i got distracted by other things in the blog. So i think this is my plan On same wall (north east) min 2m apart. on cold side of dwelling away from heat pump away from prevailing winds keep ducts as short as possible and equal Next issue is that we will be using the radial duct systems with manifolds. Is it best to have the manifolds near to the MVHR and longer radial duct or reduce the radial duct length by putting the manifold close to the rooms to be vented i also found that JSH is active elsewhere. Link to comment Share on other sites More sharing options...
joe90 Posted November 7, 2016 Share Posted November 7, 2016 On 11/6/2016 at 19:53, dogman said: i also found that JSH is active elsewhere. Can you tell us where JSH is active please? Link to comment Share on other sites More sharing options...
Temp Posted November 7, 2016 Share Posted November 7, 2016 Our exit vent makes a bit more noise than the inlet so perhaps don't put it/them near your patio? Don't put the inlet down wind of your or a neighbours gas/oil boiler flue/bonfire location. Link to comment Share on other sites More sharing options...
DavidFrancis Posted November 8, 2016 Share Posted November 8, 2016 @dogman. As @joe90, I'd be interested to know where Jeremy Harris is now posting. Are you sure it is current? Link to comment Share on other sites More sharing options...
joe90 Posted November 8, 2016 Share Posted November 8, 2016 I think JSH is posting on an electronics forum which has nothing to do with building. Link to comment Share on other sites More sharing options...
volcane Posted November 8, 2016 Share Posted November 8, 2016 1 hour ago, joe90 said: I think JSH is posting on an electronics forum which has nothing to do with building. Shame, his input would've been very beneficial on a lot of recent discussions here, 1 Link to comment Share on other sites More sharing options...
dogman Posted November 8, 2016 Author Share Posted November 8, 2016 On 06/11/2016 at 19:53, dogman said: Next issue is that we will be using the radial duct systems with manifolds. Is it best to have the manifolds near to the MVHR and longer radial duct or reduce the radial duct length by putting the manifold close to the rooms to be vented Can i please bump this bit of my post before it becomes lost in the JSH discussion Link to comment Share on other sites More sharing options...
joe90 Posted November 9, 2016 Share Posted November 9, 2016 Well I intend putting the manifold next to the MVHR unit ( in a warm loft) and running radial pipes from there. I am lucky that the route to the lower floor is central to the house near the MVHR unit. Link to comment Share on other sites More sharing options...
dogman Posted November 9, 2016 Author Share Posted November 9, 2016 My MVHR unit will be at one side of the house so to get the manifolds centrally located or at least so that the radial pipes of an equal length will mean quite a long run of pipe between the unit and the manifolds. My current property the pipe between the unit and the manifold is about 1m. in the new house it will be about 6M Link to comment Share on other sites More sharing options...
Triassic Posted November 28, 2016 Share Posted November 28, 2016 According to JSHarris's last post, he's left and won't be back. His blog is being moved to mayflower.eu (it's far from complete). Link to comment Share on other sites More sharing options...
warby Posted November 29, 2016 Share Posted November 29, 2016 No this is Jermey's website@ http://www.mayfly.eu/ Link to comment Share on other sites More sharing options...
dogman Posted January 31, 2017 Author Share Posted January 31, 2017 I have had my designs back from my preferred supplier. My next issue is the supply outlets in the bedrooms. As we have a sort of room in roof (roof starts 1800mm from floor with a height of 2800 at the small ceiling) it is difficult to put the outlets in the ideal location ie in the corner furthest from the door I have the following choices in the vertical wall between two bedrooms in the flat roof above the windows or try my latest mad idea. Use the service void as a duct one side will be osb the other plasterboard my only worry is that i am looking to have some sort or active cooling so it may need to be insulated with some sort of thin insulation mhvr idea.pdf Is it a good idea? am i missing something. I can work around the battening. Comments please Link to comment Share on other sites More sharing options...
jack Posted January 31, 2017 Share Posted January 31, 2017 Does your supplier offer floor vents? We used these in the bedrooms, because we had similar access issues and didn't want to give up space just for MVHR duct risers. Not ideal from an air mixing point of view, I know, but we've been in a year and they seem to work fine. You install a unit like this (which can be cut down as required) then drop a vent on the top. We were able to put one in the preferred corner location in each bedroom. Probably saved about 10m of ducting, too. 1 Link to comment Share on other sites More sharing options...
dogman Posted January 31, 2017 Author Share Posted January 31, 2017 I did consider floor vents but wife not a fan of them. I have found that in our current house the vertical vents are noisier than roof vents. It could be the type of diffuser though It would be the easiest in the floor and as any noise is sent upwards it should help Link to comment Share on other sites More sharing options...
PeterW Posted January 31, 2017 Share Posted January 31, 2017 Hope you don't have small children who may find floor vents rather exciting to "post" things in to ...... Link to comment Share on other sites More sharing options...
jack Posted January 31, 2017 Share Posted January 31, 2017 Famous last words perhaps, but ours are old enough not to do anything like this. I don't they know that the vents are easily removed! Link to comment Share on other sites More sharing options...
Mikey_1980 Posted January 31, 2017 Share Posted January 31, 2017 Can you not run the ducts in the roof void before the insulation by MBC gets pumped in? Thats what we have done. 1 Link to comment Share on other sites More sharing options...
dogman Posted January 31, 2017 Author Share Posted January 31, 2017 @Mikey_1980 Had not thought of that, Was it standard 75mm flexible duct ? It would save on insulating pipe to avoid condensation Were they able to seal the vents enough for the air test?( didn't you have issues with yours) Link to comment Share on other sites More sharing options...
jack Posted January 31, 2017 Share Posted January 31, 2017 Could you run the duct on the inside of the airtightness membrane? You'd need to check routes, and whether it would be better to install the ducts before or after the membrane is installed, but it would certainly remove any airtightness issues. Link to comment Share on other sites More sharing options...
dogman Posted January 31, 2017 Author Share Posted January 31, 2017 That was my idea of using the service void on MBC homes. The air tight layer is the OSB inner skin for walls or the airtight membrane for roof this is then battened out by mbc as a service cavity Link to comment Share on other sites More sharing options...
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