MVHR vent location

[dogman]

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 

 

 

[Dudda]

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.

[PeterW]

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. 

[joe90]

But where can you read JSHs blogs, they seem to have disappeared ( a bit like JSH)?

[PeterW]

  On 06/11/2016 at 14:42, joe90 said:

But where can you read JSHs blogs, they seem to have disappeared ( a bit like JSH)?

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here ..??

[dogman]

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.

 

 

 

 

 

 

 

[joe90]

  On 06/11/2016 at 19:53, dogman said:

i also found that JSH is active elsewhere.

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Can you tell us where JSH is active please?

[Temp]

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.

[DavidFrancis]

@dogman.  As @joe90, I'd be interested to know where Jeremy Harris is now posting.  Are you sure it is current?

[joe90]

I think JSH is posting on an electronics forum which has nothing to do with building.

[volcane]

  On 08/11/2016 at 10:40, joe90 said:

I think JSH is posting on an electronics forum which has nothing to do with building.

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Shame, his input would've been very beneficial on a lot of recent discussions here,

 

[dogman]

  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

 

Expand  

 

Can i please bump this bit of my post before it becomes lost in the JSH discussion

[joe90]

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.

[dogman]

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 

 

[Triassic]

 

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).

[warby]

No this is Jermey's website@ http://www.mayfly.eu/

[dogman]

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.pdfFetching info...

 

Is it a good idea?  am i missing something. I can work around the battening. Comments please 

 

 

[jack]

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.

[dogman]

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

 

  

[PeterW]

Hope you don't have small children who may find floor vents rather exciting to "post" things in to ...... 

[jack]

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!

[Mikey_1980]

Can you not run the ducts in the roof void before the insulation by MBC gets pumped in? Thats what we have done.

[dogman]

@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)

[jack]

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.

[dogman]

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