Can you have MVHR in house with internal garage?

[Ruggers]

Is it possible to have MVHR fitted to a new self build if you have an attached/internal garage?
If so how do you get a good seal on the fire door separating the house & garage. The garage would have 50mm cavity wall insulation and would have a 60mm insulated door but these still pass air. The room wouldn't be fitted with any supply or extract vents from the MVHR.

I struggle to find any internal decent door sealing systems in the uk, but when I've visited Austria they have excellent seals between internal doors with a triple rebait and a rubber seal fit into a groove.

 

[ScottishGasMan]

A properly fitted fire door should be pretty well sealed in the first place so doubt there would be any additional requirement. As for the MVHR, I've seen a lot of new builds in the last 18 months with them fitted inside an internal garage so would imagine its ok to do.

 

[JohnD]

how do you get a good seal on the fire door

The door linings ("frames") for fire doors usually have a groove, into which an intumescent strip is fitted.

You can get an intumescent strip which includes a sort of draught-strip as well, it is like brush-bristles intended to prevent smoke passing through the gap round a door, prior to it getting hot enough for the intumescent strip to expand and close the gap. I've used them when I think there is a particular risk of draught. They also muffle noise a bit more (fire doors are very good for that).

If your door was fitted without them, it might need to be planed down a bit before re-hanging. Lift-off fire hinges make it relatively easy to adjust the door fit.

It's possible to groove the edges of the door, but this is more work than using the grooved linings.

https://www.ironmongerydirect.co.uk/search?SearchText=intumescent+strip

fire-only strip

fire and smoke strip



The Austrian door and lining design is not the same as the UK one.

 

[Ruggers]

Ive not seen the lift off fire hinges, good idea as they are a fair weight. Do you mean fitting the intumescent strip into the casing instead of routering the door edges? It'll have to have a good seal from what i'm told because a couple of people who have fitted MVHR told me every slight hole in the house can be picked up when they do the negative pressure test.

 

[JohnD]

yes, the door linings come ready machined with the grooves. I don't recall the depth. Illustrated example https://www.wickes.co.uk/Wickes-Softwood-Fire-Door-Lining-32-x-132mm-x-2-05m/p/205862
If you have not bought yours yet, you could ask the supplier. You usually choose the strips to match the width and depth of the grooves, looks neater that way (applied after painting white) and will stay cleaner with no gap to hold dirt. You can also get an intumescent white sealant, it looks rather like silicone sealant, easy to use. And you inject pink expanding fire foam (also intumescent) between the frame and the wall after packing and screwing, it fills the gap and also sticks them firmly into place. These are intended to block the passage of smoke and flame, but they will also seal draughts and (in your case) air movement. I don't know if there is a special threshhold available, it was not required on mine. Usually air enters the room through the gap under the door (e.g. a bathroom with extractor fan).

The brush sticks out a bit and brushes against the door as it closes, I'm not a joiner but they knew how to fit them. if you have closers, the brush slows the door down at the point of shutting, so you may need a greater closing force. Some closers can be adjusted for speed and force. If you shut them manually you may not notice it.

Strip with rubber fins
https://www.ironmongerydirect.co.uk...mescent-strip-10x4x2100mm-white-pack-5-767380

The hinges are very strong and heavy, and have a bronze lubricated bush. Very free-swinging and easy to lift the door off and back (fire doors are very heavy)

https://www.ironmongerydirect.co.uk/search?SearchText=lift+fire+hinge

You can also get stainless ones, more expensive. Various brands but probably all the same. The pin is pointed and shortened to make it easier to lift the door on.

 

[Ruggers]

The brush sticks out a bit and brushes against the door as it closes, I'm not a joiner but they knew how to fit them. if you have closers, the brush slows the door down at the point of shutting, so you may need a greater closing force. Some closers can be adjusted for speed and force. If you shut them manually you may not notice it.

Yes i had this problem fitting my current door, it was hard to get the door closer pressure correct to allow the door latch to click shut as the stips were fouling the casing. Thanks for the info, i will try one of them casings when i get to this point, i'm currently just working out what options there are.

 

[stem]

One of the principles of MVHR, is that the 'intake' and 'extract' airflow is balanced to maintain a neutral pressure inside the house to help prevent air entering or leaving the building through other means than via the heat recovery process. So it actually reduces the risk. There would be more chance of air transfer to a garage in a house without MVHR when windows were open on a breezy day.

Regardless of the method of ventilation, as well as being fire resistant, garages are usually unheated and uninsulated in which case the door from the garage to the living area is considered as being external and insulated and draft proofed accordingly, so as regards airflow would be the same as any other external door or windows.