Low Supply Temps

[TheMiddle36]

Hello!

 

I've a Zehnder Q350 in the new build which we've recently moved in to. I connected it to the ComfoConnect app which allowed me to see what's going on with the temps.

 

I'm barely getting above 15degs supply and only 16degs extracted, but all the bathrooms and kitchens are between 18 - 20.

The unit is located in the loft, however the ducting seem fairly well insulated save for some spaces where the ducting bridges the studwork. Pictures attached, could this really drop the temps by that much??

 

All the filters have been changed this week too. 

The house isn't massively warm, I need to start another thread about the temps the Nibe Heat Pump is able to generate to the UFH, but it's certainly not helping that the MVHR is supplying such cold air.

 

Any advice on what I could look in to next?

 

Thanks in advance,

Nick

 

[ProDave]

Do you have an independent and reliable thermometer?

 

IF the extract air is only 15.4 degrees then it seems reasonable that the supply air temp is a little lower than that at 14.1 degrees.  What that shows is the heat recovery is working well and most of the heat from the extract air is getting transferred to the supply air.  With no heat recovery the incoming supply air would be a chilly 0.8 degrees and you WOULD notice that cold air coming in.

 

So on the face of it, nothing to worry about here, other than perhaps why does it only think the extract air is only 15.4 degrees when you think the rooms are warmer?

[TheMiddle36]

Thanks Dave,

 

Fortunately we do have a reliable thermometer and I’ve been logging the temps in bathrooms, ensuites, kitchen and utility. 

 

One bathroom, seldom used, is markedly colder but i’m still surprised the extract temps recorded by the MVHR are so low. 

 

Im thinking to add extra insulation to the gaps show in the pics and work on warming *all* the rooms that the MVHR will be extracting from.

 

Does the fan speed make much of a difference to the supplied temps? Should the rooms where air is extracted from have doors kept closed with a good seal to make sure they only get the warm/humid air (as opposed to the cooler air that’s being supplied back in)

 

Thanks,

Nick

[ProDave]

It is important that there is airflow between rooms.  Fresh air is supplied to living rooms and bedrooms, stale air is extracted from bathrooms, kitchens and utility rooms.  Doors should be trimmed to allow airflow under the bottom even when shut.

 

The extract comes from a number of rooms, and if one is unused and unheated, that will lower the overall extract temperature as that is in effect the average of all the extract rooms temperatures.

[TheMiddle36]

Hmm, Ok, there’s the first thing then.

 

We had a draughty porch, which doesn’t have any MVHR terminals so bought a foam strip to close the gap between floor and door... And had some left over so sealed the doors to the kitchen and utility too. These are usually left ajar mind you.

 

Whats the best way to cover up an extract duct, to see if the unused bathroom is bringing the temps down? A plastic bag type cover?