MVHR Outlet/Inlet Close to ASHP?

[Barney12]

Hi All

 

I'm considering moving the location of my inlet and outlet vents. Its a better location because its protected from the strong winds on the west elevation. 

However, the one downside is that its on the same elevation and location that the ASHP is planned for. 

I assume there is a possibility that the air is cooler in this general area but would it be enough to cause a problem with the MHRV? 

Here's a rough sketch:

 

[jack]

No, I don't think so. The MVHR blows air away from the wall due to the fan, so the cold air will tend not to hang around against the wall. Ambient air is sucked into the back from all directions. Unless the whole area is a confined space (eg, a corridor that doesn't get any breeze), I'd be surprised if there's much overall impact.

 

Even if the area is slightly cooler due to the ASHP, it shouldn't have much impact on the MVHR.  At 80% MVHR efficiency, and, say, 2 degree lower temp (due to the ASHP) at the outdoor MVHR inlet, the supply temp inside will be at worst 0.4 degrees lower than if the MVHR wasn't there.

 

 

 

[Barney12]

17 minutes ago, jack said:

No, I don't think so. The MVHR blows air away from the wall due to the fan, so the cold air will tend not to hang around against the wall. Ambient air is sucked into the back from all directions. Unless the whole area is a confined space (eg, a corridor that doesn't get any breeze), I'd be surprised if there's much overall impact.

 

Even if the area is slightly cooler due to the ASHP, it shouldn't have much impact on the MVHR.  At 80% MVHR efficiency, and, say, 2 degree lower temp (due to the ASHP) at the outdoor MVHR inlet, the supply temp inside will be at worst 0.4 degrees lower than if the MVHR wasn't there.

 

Thanks Jack.

[Jeremy Harris]

I can confirm this, as our MVHR inlet is on the wall directly above the ASHP.  There is no change at all in the inlet temperature of the MVHR when the ASHP is running less than 2m below.  It was one of the things I was concerned about, but there was no easy way to position either the MVHR intake or the ASHP somewhere else, so I decided to just fit it and then check to see what happened, with the fall back plan being to fit external MVHR intake ducting under the eaves if need be (this is on the hidden rear elevation, where the retaining wall is located).  As it happens I didn't need to do anything at all.

[Barney12]

7 minutes ago, JSHarris said:

I can confirm this, as our MVHR inlet is on the wall directly above the ASHP.  There is no change at all in the inlet temperature of the MVHR when the ASHP is running less than 2m below.  It was one of the things I was concerned about, but there was no easy way to position either the MVHR intake or the ASHP somewhere else, so I decided to just fit it and then check to see what happened, with the fall back plan being to fit external MVHR intake ducting under the eaves if need be (this is on the hidden rear elevation, where the retaining wall is located).  As it happens I didn't need to do anything at all.

 

Thanks Jeremy

[Barney12]

In a related question: what have people decided on for grilles?

 

BPC have supplied me these: https://www.bpcventilation.com/exterior-grille-s-steel-louvered-cowl

 

They look to be good quality but are erm a little "industrial".

 

Is their any disadvantage to going for just a plastic flat louvre style grille?

 

 

[PeterW]

9 minutes ago, Barney12 said:

Is their any disadvantage to going for just a plastic flat louvre style grille?

 

Only that the amount of free air flow may be reduced. Watch for the ones with flaps as to be honest they may not be needed as they will be permanently open...

[ProDave]

2 hours ago, Barney12 said:

In a related question: what have people decided on for grilles?

 

BPC have supplied me these: https://www.bpcventilation.com/exterior-grille-s-steel-louvered-cowl

 

They look to be good quality but are erm a little "industrial".

 

Is their any disadvantage to going for just a plastic flat louvre style grille?

 

 

I have used that type and more than one person has commented they look cool and contemporary.