MVHR Duct Routing

[Andrew]

I'm trying to get my head around how the MVHR ducting should be routed. We're planning to have the MVHR in a downstairs plant room. Running the ducting into the first floor trusses (these are 253mm metal web joists) is straightforward and I guess the ground floor can be easily covered with ceiling terminals.  Most of our upstairs rooms have fully vaulted ceilings and I'm struggling to work out how the ducting would make its way to the appropriate sloped ceiling. Do the terminals need to be in the ceiling? Is it possible to route the ducting up through stud walls and terminate in the stud wall? I'm really not a fan of boxing in, so would really like to find a way to route the cables through the fabric of the building.

 

These are probably stupid questions and I confess I'm not fully up to speed with MVHR yet. I've asked for quotes from a couple of the MVHR suppliers which will hopefully give me a bit more to work with. 

 

Thanks.

[Jeremy Harris]

We have vaulted ceilings and I didn't bother to try and get the MVHR ducting up them at all.  We have low walls either side of the upstairs rooms and I just ran the ducting up from the floor to wall mounted terminals in those low walls.  This works fine, with the terminals around 4ft off the floor.

 

In the bathrooms I fitted a small false ceiling in the highest corner and ran the MVHR extract ducting along that. 

[Andrew]

3 minutes ago, JSHarris said:

We have vaulted ceilings and I didn't bother to try and get the MVHR ducting up them at all.  We have low walls either side of the upstairs rooms and I just ran the ducting up from the floor to wall mounted terminals in those low walls.  This works fine, with the terminals around 4ft off the floor.

 

Thanks Jeremy - it's the getting up through the floor into the wall bit I can't visualise. Are those internal or external walls? Is it just a case of drilling through the centre of the stud attached to the floor and then taking the duct up through the internal wall? 

[Big Neil]

If you didn't have Vaulted ceiling, i assume the easiest thing to do where it wouldn't 'look' like boxing in, would be to run them up the back to say the airing cupboard into the space above and then just board over so it is a false wall , such that it wasn't obvious?

[Jeremy Harris]

9 minutes ago, Andrew said:

 

Thanks Jeremy - it's the getting up through the floor into the wall bit I can't visualise. Are those internal or external walls? Is it just a case of drilling through the centre of the stud attached to the floor and then taking the duct up through the internal wall? 

 

They are internal stud walls with just a storage area behind, so the ducts run up inside the storage area to the wall-mounted terminals.  It would have been easy enough to just fit the slimline oval semi-rigid duct inside the stud walls though.  Someone here has used that I seem to remember, and posted photos of the ducting inside the wall.  The oval semi-rigid ducting is 51mm x 138mm, so will fit in spaces where the round stuff is just too big.  IIRC there are adapters to allow conversion from the oval section to the round section stuff.

[Andrew]

1 hour ago, JSHarris said:

 

They are internal stud walls with just a storage area behind, so the ducts run up inside the storage area to the wall-mounted terminals.  It would have been easy enough to just fit the slimline oval semi-rigid duct inside the stud walls though.  Someone here has used that I seem to remember, and posted photos of the ducting inside the wall.  The oval semi-rigid ducting is 51mm x 138mm, so will fit in spaces where the round stuff is just too big.  IIRC there are adapters to allow conversion from the oval section to the round section stuff.

 

I did see the oval stuff and wondered if it would go through stud walls fairly easily. Thanks again - I can see how this could work now. 

[jack]

We have floor outlets in the bedrooms for our MVHR system. They seem to work fine 

[Gone West]

4 hours ago, Andrew said:

I'm trying to get my head around how the MVHR ducting should be routed. We're planning to have the MVHR in a downstairs plant room. Running the ducting into the first floor trusses (these are 253mm metal web joists) is straightforward and I guess the ground floor can be easily covered with ceiling terminals.  Most of our upstairs rooms have fully vaulted ceilings and I'm struggling to work out how the ducting would make its way to the appropriate sloped ceiling. Do the terminals need to be in the ceiling? Is it possible to route the ducting up through stud walls and terminate in the stud wall? I'm really not a fan of boxing in, so would really like to find a way to route the cables through the fabric of the building.

 

These are probably stupid questions and I confess I'm not fully up to speed with MVHR yet. I've asked for quotes from a couple of the MVHR suppliers which will hopefully give me a bit more to work with. 

 

Thanks.

We have vaulted ceilings and took the ducting up through the stud walls upstairs. We also have 250mm metal web joists and used 125mm ducting rather than a manifold system. The rectangular ducting we used was 204mm x 60mm.

 

 

 

 

[Pocster]

Can I ask a stupid question 

Though it’s obvious to see the ducting / pipework / cables in stud wall with one side open . How do you plasterboard the other side with certainty of not sticking a drywall screw through something ..... ???

[Onoff]

11 minutes ago, pocster said:

Can I ask a stupid question 

Though it’s obvious to see the ducting / pipework / cables in stud wall with one side open . How do you plasterboard the other side with certainty of not sticking a drywall screw through something ..... ???

 

You mark on the floor/ceiling where your studs/joists are and only screw on the centreline.

 

Another way is if you've any redundant windows,  you can make permanent inspection ports...

[Pocster]

Just now, Onoff said:

 

You mark on the floor/ceiling where your studs/joists are and only screw on the centreline.

 

Another way is if you've any redundant windows,  you can make permanent inspection ports...

I might have some redundant windows somewhere ; let me take a look ........ ?

[Pocster]

7 minutes ago, Onoff said:

 

You mark on the floor/ceiling where your studs/joists are and only screw on the centreline.

 

Another way is if you've any redundant windows,  you can make permanent inspection ports...

Anyway !

So should pipes ( like hep 20 ) be attached to the stud or loose ? . If attached then you are next to a vertical stud so chance of a screw hitting it is greater . If loose I assume the pipe work could move and jolt when water pressure changes .

[Jeremy Harris]

28 minutes ago, pocster said:

Anyway !

So should pipes ( like hep 20 ) be attached to the stud or loose ? . If attached then you are next to a vertical stud so chance of a screw hitting it is greater . If loose I assume the pipe work could move and jolt when water pressure changes .

 

All pipes and cables must be secured with the appropriate clips (and that means metal or fire-resistant cable clips from now on - the old plastic ones and plastic cable ties have been outlawed in the 18th Ed).  Those clips need to be at the right spacing too, in the case of pipes to stop movement when taps or valves turn off and in the case of cables the spacing is supposed to be as per the regs.

[Pocster]

11 minutes ago, JSHarris said:

 

All pipes and cables must be secured with the appropriate clips (and that means metal or fire-resistant cable clips from now on - the old plastic ones and plastic cable ties have been outlawed in the 18th Ed).  Those clips need to be at the right spacing too, in the case of pipes to stop movement when taps or valves turn off and in the case of cables the spacing is supposed to be as per the regs.

Thanks .

So would it make sense to add a vertical stud in between the ‘ real’ ones / just so pipes/cables can be clipped to that . Then when plasterboarding simply ignore screwing into the extra stud . That sensible ? . I just think of all the cables and pipes with thousands of drywall screws the inevitable will happen otherwise .

Edited February 12, 2019 by pocster

[Jeremy Harris]

23 minutes ago, pocster said:

Thanks .

So would it make sense to add a vertical stud in between the ‘ real’ ones / just so pipes/cables can be clipped to that . Then when plasterboarding simply ignore screwing into the extra stud . That sensible ? . I just think of all the cables and pipes with thousands of drywall screws the inevitable will happen otherwise .

 

All our cables and pipes are just clipped to the side of studs or the sides of the 50 x 50 counter battens on the external wall inner faces.  As an added precaution I did run aluminium foil tape on the studs/battens where the cables/pipes are clipped, in the hope that it will make them easy to detect with a cable finder (not sure whether it does or not, though).

 

I also took loads of photos of every location where there are pipes and cables running down walls, so that I have a reference as to which side of the studs/battens they are clipped to.  I've also got a load of small, powerful, neodymium magnets, plus a few fixed to the end of pencils, that are very handy for finding the buried plasterboard screws.  As the plasterboard screws are pretty much in the centre of the studs/battens, I can be pretty sure that it's safe to put any fastening inline with them.  I still isolate the power to the relevant circuit before screwing anything in to a stud/batten that's got cables running down the side though, as I got caught out when drilling a hole for a wall light years ago.  I discovered that drilling through a cable makes a hell of a bang and totally buggers up the end of a masonry drill.