MVHR installation help! Please

[AppleQueen]

Hello!

I have come to a problem that I don’t know how to get around with my DIY installation. I have a wooden beam above a doorway (see picture) and in order to supply the side of the house through the doorway (both ground and first floor) I will need to get 15 of the 75mm pipes through here. I can’t manage this without seriously weakening this wooden beam. There is no other route to the other side of the house.

i have attached the floor plans, the purple line is where the wooden beam is and the purple circles are where I’m struggling to reach.

Does anyone have any ideas/suggestions??

Can you attach another distribution box to the first distribution box so I only need to get one pipe through?

I have contacted BPC who I ordered through for some help but not heard back yet.

Thank you in advance!

[crispy_wafer]

When confronted with a steel that split my house into two in the floor void, I had to replan, moved the unit to the loft, built in a cupboard in one of the bedrooms and drop the pipes to the ground floor through the void at the back of said cupboard.  Is there any opportunity for you to do similar?

[Mike]

48 minutes ago, AppleQueen said:

Can you attach another distribution box to the first distribution box so I only need to get one pipe through?

You could certainly feed 2 separate manifolds, one for each side of the beam.

[BotusBuild]

This is what I had to do, through a 200mm concrete wall!!

Unit in plant room

Two x 180mm feed and extract pipes

Tees of the above to two distribution boxes on one side of the wall, and the 180mm go thru the concrete to two more distribution boxes

[Russdl]

It would be a long route but can you go up into the loft along the loft and then down on the other side of the beam?

We did the same as @crispy_wafer and ran a lot of our pipes down behind a cupboard whose main job in life is to hide those pipes. 
 

How come you need to get 15 pipes through there? Are you double ducting each room? Seems a bit over the top if you are. 

 

Just looked again on a bigger screen and I see that indeed you are having two runs to most of the supply and extract valves. 4 runs in total to the dining room. Some of the valve positions look a bit odd as well. The kitchen for example, why is the valv not in the far corner of the room away from the outside door?

Edited November 1 by Russdl

[AppleQueen]

6 hours ago, crispy_wafer said:

When confronted with a steel that split my house into two in the floor void, I had to replan, moved the unit to the loft, built in a cupboard in one of the bedrooms and drop the pipes to the ground floor through the void at the back of said cupboard.  Is there any opportunity for you to do similar?

Yes this is a possibility, I would then only need to get 4 pipes through that wooden beam. We have a dressing room under the loft that I was going to use for the pipes to upstairs anyway. I didn’t really want to vent to the roof if possible but might need to! Thanks

[AppleQueen]

5 hours ago, Mike said:

You could certainly feed 2 separate manifolds, one for each side of the beam.

Thanks for the info. So would I need some kind of splitter coming off the unit to feed to two distribution boxes? Then I could have a small distribution box for the rooms left of the hall and another for the rooms right of the hall. Or would two separate units be better with one in the loft above bedroom 2?

[AppleQueen]

5 hours ago, BotusBuild said:

This is what I had to do, through a 200mm concrete wall!!

Unit in plant room

Two x 180mm feed and extract pipes

Tees of the above to two distribution boxes on one side of the wall, and the 180mm go thru the concrete to two more distribution boxes

Yes I think this is what I’m imagining! Did you get this from bpc? Thanks for your help! The pictures are really useful

[AppleQueen]

4 hours ago, Russdl said:

It would be a long route but can you go up into the loft along the loft and then down on the other side of the beam?

We did the same as @crispy_wafer and ran a lot of our pipes down behind a cupboard whose main job in life is to hide those pipes. 
 

How come you need to get 15 pipes through there? Are you double ducting each room? Seems a bit over the top if you are. 

 

Just looked again on a bigger screen and I see that indeed you are having two runs to most of the supply and extract valves. 4 runs in total to the dining room. Some of the valve positions look a bit odd as well. The kitchen for example, why is the valv not in the far corner of the room away from the outside door?

Thanks for your help!

We have vaulted ceilings in the hall with exposed beams so can’t run anything up there. 
I was also thinking it looked like too many ducts - the rooms are large but not ridiculous and the dining room has fairly low ceilings. Maybe I should ask BPC to look at that again. Also I’m not sure why the downstairs bathroom and plant room need double ducts - I was just going to put them in there because I do what I’m told…

the kitchen is difficult because again it is vaulted with exposed beams so I told them I couldn’t run anything in the ceiling. I actually think I’m going to have to put those extract ducts just outside the kitchen into the dining room where the column is on the plan because I can’t find anyway to get them into the kitchen otherwise. I have also asked BPC to redesign this if possible.

[Mike]

12 minutes ago, AppleQueen said:

So would I need some kind of splitter coming off the unit to feed to two distribution boxes?

Yes, as per @BotusBuild's photos.

 

9 minutes ago, AppleQueen said:

Also I’m not sure why the downstairs bathroom and plant room need double ducts

It's not required to vent the rooms, however you appear to have 8 ducts pumping air into the ground floor, and you need to pump that same amount of air out from somewhere. If you have only 4 extract pipes, the airflow in them will (on average) therefore have to be twice as fast, and that speed could be more than recommended to avoid noise. You'd need the calculations to know if that's so, but it's possible.

 

17 minutes ago, AppleQueen said:

I actually think I’m going to have to put those extract ducts just outside the kitchen into the dining room where the column is on the plan because I can’t find anyway to get them into the kitchen otherwise.

You do need extract directly from the kitchen, but away from the hob, and ideally on the far side so that the air flows across the room. As a compromise a wall-mounted vent could work (in the kitchen-dining room wall), unless you want to make to make a feature of a suspended metal pipe & vent.

[Sparrowhawk]

27 minutes ago, AppleQueen said:

I was also thinking it looked like too many ducts - the rooms are large but not ridiculous and the dining room has fairly low ceilings. Maybe I should ask BPC to look at that again. Also I’m not sure why the downstairs bathroom and plant room need double ducts - I was just going to put them in there because I do what I’m told…

Did you pay them for a design or is this their free one? I found the free one wrong on many counts, and it's worth doing your own if you have the skills to.

[AppleQueen]

2 hours ago, Mike said:

Yes, as per @BotusBuild's photos.

 

It's not required to vent the rooms, however you appear to have 8 ducts pumping air into the ground floor, and you need to pump that same amount of air out from somewhere. If you have only 4 extract pipes, the airflow in them will (on average) therefore have to be twice as fast, and that speed could be more than recommended to avoid noise. You'd need the calculations to know if that's so, but it's possible.

 

You do need extract directly from the kitchen, but away from the hob, and ideally on the far side so that the air flows across the room. As a compromise a wall-mounted vent could work (in the kitchen-dining room wall), unless you want to make to make a feature of a suspended metal pipe & vent.

Do you think a wall mounted vent here where I’ve put the blue cross would work? Facing into the kitchen? Thanks

[AppleQueen]

2 hours ago, Sparrowhawk said:

Did you pay them for a design or is this their free one? I found the free one wrong on many counts, and it's worth doing your own if you have the skills to.

Ah I didn’t know there was a free/paid for option. I just asked for the correct materials and this is the plan that came back.

[Russdl]

The plan looks wrong to me, but I’m far from being an expert so hopefully someone will chip in with better guidance 👍🏻

[Mike]

40 minutes ago, AppleQueen said:

Do you think a wall mounted vent here where I’ve put the blue cross would work? Facing into the kitchen? Thanks

If it's not too close to the hob it could.

 

Another possibility may be to run concealed ducting boxed in over the top of the kitchen cupboards, if you have any, to give more flexibility.

[Sparrowhawk]

10 hours ago, AppleQueen said:

Ah I didn’t know there was a free/paid for option. I just asked for the correct materials and this is the plan that came back.

 

A paid MVHR design service isn't cheap (c£1k) but will provide things like:

• calculations of flow rate in ducts e.g. how fast the air is moving (too fast is audible) and the pressure drop (too high means the MVHR has to work too hard)
• work out how to best route the ducts around the house
• use the calculations to assess the size of ducts you need and which runs need to be doubled up
• position the supply/extract valves in sensible places (this is not a high bar to meet )

They do like to be involved before build starts though, to iron out problems like "there's a beam where all the ducts need to go"

 

You are where you are, and my first thought is what does changing to 90mm ducting do for the number of ducts you need? If you use the Frankische 90mm duct which has ~half the pressure loss per m of the others, you can push a single duct to longer runs than would normally be advised. You're still restricted by the volume of air you need to move though.

 

But - what does your structural engineer say about cutting holes through the beam? How many at each diameter are you allowed?

 

10 hours ago, AppleQueen said:

Do you think a wall mounted vent here where I’ve put the blue cross would work? Facing into the kitchen? Thanks

 

I don't. With what looks to be an open plan setup, the air will mostly go from the supply vents straight to the extract vent, creating a dead space in the kitchen. I've tried to show that with arrows on the picture below.

[dpmiller]

1 hour ago, Sparrowhawk said:

 

A paid MVHR design service isn't cheap (c£1k) but will provide things like:

BPC do everything except work out the duct routes...

[Sparrowhawk]

26 minutes ago, dpmiller said:

BPC do everything except work out the duct routes...

Hmm, my layout guide from them was like the one shown here, "X marks the spot" and a number for one run or two. Did yours cover more than that, like flow rates per room?

[dpmiller]

2 hours ago, Sparrowhawk said:

Hmm, my layout guide from them was like the one shown here, "X marks the spot" and a number for one run or two. Did yours cover more than that, like flow rates per room?

Yes. IIRC there was a nominal fee attached but this was discounted off the order.

[BotusBuild]

21 hours ago, AppleQueen said:

Did you get this from bpc?

The materials and initial design comes from them, but I got fed up arguing and adapted it to what I knew would work for what I had.

Their free design was minimal as already expressed, but I had some experience with ventilation already, so k ew of some of the gotchas of vent locations etc

Edited November 2 by BotusBuild