MVHR external vent placement?

[Alan Ambrose]

To avoid collision with my PV panels and Velux windows, is there any reason why I shouldn't put my MVHR external vents under the gable soffits using terminals like these?

 

Ventilation Tile UB19 Slates 500mm x 250mm (NJ) Anthracite | Ubbink

 

Also, can I use these, this time on the top of the roof, for SVP vents rather than 110mm pipe? For various reasons, mainly aesthetics, but again I want to avoiding shading my PV panels.

 

[Nickfromwales]

4 hours ago, Alan Ambrose said:

To avoid collision with my PV panels and Velux windows, is there any reason why I shouldn't put my MVHR external vents under the gable soffits using terminals like these?

 

Ventilation Tile UB19 Slates 500mm x 250mm (NJ) Anthracite | Ubbink

 

Also, can I use these, this time on the top of the roof, for SVP vents rather than 110mm pipe? For various reasons, mainly aesthetics, but again I want to avoiding shading my PV panels.

 

I fit these, not too tall tbh. 

 

Put the SVP elsewhere? Or out horizontally at the top of a gable maybe? Done that a few times too. 

[Mike]

6 hours ago, Alan Ambrose said:

is there any reason why I shouldn't put my MVHR external vents under the gable soffits using terminals like these

Not sure what you man by 'under', but first check that they can support the required airflow rate

 

6 hours ago, Alan Ambrose said:

can I use these, this time on the top of the roof, for SVP vents rather than 110mm pipe?

No problem, provided they respect the distances from windows required by the Building Regs.

[Kelvin]

Maybe too late. But if you have detached garage and can extend the waste pipe to it you can take the SVP up through the garage roof. We have a dog bath in the garage and a washing machine so it was easy enough for us to do it. No penetrations through the house roof. 

[Alan Ambrose]

@Mike - I was meaning here (below) and yes, the MVHR calcs say a 180mm diameter vent (i.e. 25,000 mm^2) gives 2.3 m/s on boost and the UB19 is 22,000 mm^2 - so 'close enough for government work'. 

 

 

@Kelvin - that's clever, but we don't have any waste running from the garage, and it's also some distance away.

[Mike]

37 minutes ago, Alan Ambrose said:

the MVHR calcs say a 180mm diameter vent (i.e. 25,000 mm^2) gives 2.3 m/s on boost and the UB19 is 22,000 mm^2

And Ubbink have a 180mm pipe / duct adapter to suit?
 

 

19 minutes ago, Alan Ambrose said:

I was meaning here

So you'd screw the tile upside down (sideways?) - I guess physically that could work, provided you can get the duct connections within the space. However if upside down then the upturned cowl would be liable to collect snow / leaves / other debris which might cause a maintenance problem, and you'd also need the exhaust duct sloping back towards the MVHR unit (it couldn't fall towards the vent as otherwise there's a risk that the upturned cowl would collect condensate too), but that may not be a problem to achieve. Sideways would probably be preferable.

 

However, what's the problem you're trying to solve & why are you trying to avoid regular wall terminals?

 

[torre]

If fixing to the underside of the soffit can't you use a simpler cover, just a plain grill or a bull nose?

It sounds harder to run the ducting to the soffit versus out of the gable end right next it.

[Post and beam]

22 hours ago, Nickfromwales said:

I fit these, not too tall tbh. 

I have a pair of these spare if anyone wants them.  Free to a good home but buyer collects

[Nickfromwales]

2 hours ago, Post and beam said:

I have a pair of these spare if anyone wants them.  Free to a good home but buyer collects

Bought two last week lol. 

[Nickfromwales]

18 hours ago, torre said:

If fixing to the underside of the soffit can't you use a simpler cover, just a plain grill or a bull nose?

It sounds harder to run the ducting to the soffit versus out of the gable end right next it.

Would need to be a big soffit!!

[MikeSharp01]

3 hours ago, Post and beam said:

I have a pair of these spare if anyone wants them.  Free to a good home but buyer collects

Shame I bought two of these 3 months back ready for the roofer to fit!!!!

[Dave Jones]

On 03/11/2025 at 12:03, Alan Ambrose said:

To avoid collision with my PV panels and Velux windows, is there any reason why I shouldn't put my MVHR external vents under the gable soffits using terminals like these?

 

Ventilation Tile UB19 Slates 500mm x 250mm (NJ) Anthracite | Ubbink

 

Also, can I use these, this time on the top of the roof, for SVP vents rather than 110mm pipe? For various reasons, mainly aesthetics, but again I want to avoiding shading my PV panels.

 

 

I did exact same as I didnt like the look of the little chimneys. Problem I had they are not big enough and throttled the air flow (MVHR complained about restricted air flow) so had to ditch the plan.

[Nick Laslett]

On 03/11/2025 at 12:03, Alan Ambrose said:

Also, can I use these, this time on the top of the roof, for SVP vents rather than 110mm pipe? For various reasons, mainly aesthetics, but again I want to avoiding shading my PV panels.

 

You have an STP, just use AAV for SVP stack. 

[Alan Ambrose]

@Nick Laslett I thought that BC required one 'proper' SVP vent, no? 

[Nick Laslett]

3 hours ago, Alan Ambrose said:

@Nick Laslett I thought that BC required one 'proper' SVP vent, no? 

@Alan Ambrose, it is a very long time since I looked at this (2021), but I believe if you are on an STP, then all the house vent stacks can be on AAV. The STP has a vent to the outside. Mains drainage may have different requirement.
 

I had my drainage design drawn up by Ingent Drainage. All the documents submitted to my BCO by my Architect show only AAVs, and when I had the first fix inspection, that is what he saw installed. 
 

Unlike a lot of my build, this is one area where my Architect handled the process, liaised with Ingent Drainage and presented me with a finished design. I had no input. 
 

I’m sure there is a much earlier discussion here about AAVs that corroborates the design I was given. 
 

https://www.bpfpipesgroup.com/media/73916/Air-admittance-valves-for-domestic-properties-v2-Jan-2024.pdf

 

Some other links:

 

 

 

 

 

Edited yesterday at 22:23 by Nick Laslett