MVHR and fire safety

[Bramco]

I would ask this of our MVHR supplier but he's in 'fit and forget' mode, as in not responding to voice or email.....

 

The question we have, is whether the position of the fire dampers on the inlet and exhaust for the MVHR should both be within the plant room from a fire safety perspective.  Due to various reasons, the inlet is within the envelope of the plant room but the exhaust damper is outside the envelope.  The dampers are designed to spring shut at temperatures just above 70C, so you could imagine that one might trigger but the other one not. We're a bit concerned that if they don't trigger at pretty much the same time, then there's the potential for fire to spread. There isn't any gas in the house, or open fires or log burners, so the chance of fire is pretty small but nonetheless....

 

Anyone any expertise in this area? Are there any standards that should be adhered to?

 

Simon 

[Mike]

There's no requirement for fire dampers on a regular domestic MVHR system. The low air flow of isn't going to feed the fire with much additional oxygen, and keeping it running may help a little in venting some of the fumes, which are often a more immediate problem than the flames. I suspect that the biggest danger for MVHR in a fire would be fumes given off from meting plastic MVHR pipes, rather than anything else.

[mike2016]

What I'm hoping to do is link up the AICO smoke/heat detector network to home assistant and have a power circuit via a Shelly Relay I can turn off to kill the MVHR unit in the event of a fire. So at least the MVHR fans aren't spreading the smoke. I would like an intumescent vent in each room but not sure if they are compatible with the system I'll be using. BPC have some here you could consider:

https://www.bpcventilation.com/metal-fire-protection-valve-supply