MVHR warming incoming air on 100% bypass ! Zehnder Q350

[FarmerN]

 

 

The display on my Zehnder Q350 shows the incoming air at 17.5 C but air entering rooms at 20 C.

Seems odd to me, is this normal or do I have a problem?

Set on 100% bypass ,cool temperature profile, Bypass on Auto.

Surely the air should be coming in at outside temperature?

5am and still 17.5 outside in a rural area.

[SteamyTea]

What temperature is the air in the room?

 

You could switch the fans off and see what happens.

[FarmerN]

Unit Currently showing

Extract air 25 C                        from rooms

Outside Air 21 C                       into unit

Supply  Air  22.5                      into rooms

 

Bypass 100%

230 CuM /Hr for a 210 Sq M bungalow

Edited 2 hours ago by FarmerN

[MikeSharp01]

1 hour ago, FarmerN said:

The display on my Zehnder Q350 shows the incoming air at 17.5 C but air entering rooms at 20 C.

It is still coming through the fabric of the house so maybe it's picking up heat from the ductwork etc?

[FarmerN]

The figures are all taken from the MVHR unit display

I presume the sensors are all in the unit within plant room. I am not aware of any remote sensors.

[SteamyTea]

46 minutes ago, MikeSharp01 said:

coming through the fabric of the house

That is a good point I had not considered.

If the main pipework is in the loft, which may be 40°C or more, then, even with insulated ductwork, it can easily heat up.

[MPH243]

I have the Q450 the sensors are all in the unit, 1 each side of the heat exchanger on both supply and extract.

 

Mine is the same 100% bypass, I can't connect to mine to show the figures but was the same as yours earlier. I think it's probably the fan warming the air. The bypass takes it over the top of the heat exchanger to miss it.

 

I think if you look this afternoon it goes into reverse and closes the bypass when outside is warmer than the house.