How do I know if Heat Recovery Unit is working as it should?

[Switchornot]

We renovated our house recently, complete upgrade and got a Vent Axia Sentinel Plus Heat Recovery system installed as part of the renovation. It was commissioned by the installer a month or so ago. Is there any way that I can test that it is working properly?

It seems to be completely silent (which isn't necessarily a bad thing!) at all times. Even after showers, I don't hear any noise from the units in the bathrooms. The condensation on mirrors and in the room in general doesn't seem to clear very quickly. I expected to hear some noise at least after a shower when I would expect the unit needs to work a bit harder but that is not the case.

Anyone got any experience with one of these units or know anyway for me to test that it is working properly?

Thanks.

 

[Zenith63]

I self-installed a couple of these in my house recently. They are fairly quiet, although when they detect humidity (which not all models will by the way!) and ramp up if I listen carefully I can hear them in the bathroom that is close to the unit, further away rooms are virtually silent.

If you take a look at the unit the screen will tell you the percentage of total power the fan is running at, default is 30% in normal mode, 50% when humidity is detected. You could also pop off a vent cover and try to hold a piece of paper across it, it should be obvious if air is flowing.

 

[Micks'r]

As @Zenith63 said, use a tissue to check at the ceiling valve.

Another way: Locate the condensate drain and check that there is some water coming out. The amount of water will depend on what's happening inside the house and the outdoor temperatures; basically the more moisture producing activities and cooler outdoor temperature the more water will be coming out. If it is dry then there is no heat tecovery happening and the system needs to be checked.

How long roughly for the condensation on mirrors to clear?

 

[Switchornot]

Thanks @Zenith63 and @Micks'r for the responses above. I will try the two solutions you have mentioned. The unit is in the attic and it shows that it is operating towards a normal airflow of 30%. Next time the shower is running, I will go up and see if I can hear it working harder.

I am not 100% sure where the condensate drain is but I can check with the installer. I do see water dripping out the back of the outdoor air to water heat pump every now and again but not sure if that is related or not (as you can tell, I am not a DIY expert!).

I would guess that it roughly takes 4-5 mins after the shower is switched off for the condensation on the mirrors to clear.

 

[Zenith63]

Thanks @Zenith63 and @Micks'r for the responses above. I will try the two solutions you have mentioned. The unit is in the attic and it shows that it is operating towards a normal airflow of 30%. Next time the shower is running, I will go up and see if I can hear it working harder.

What size is your house and do you know the exact model of the unit? Did you get a design document for the install by any chance, it might list the location of each vent along with how much air each room required. The installer should have balanced the system using the fan speed and aperture size on each vent to deliver the correct level of ventilation to each room - it's pretty darn unlikely that the default setting of 30% fan speed exactly matched your home so I'd be suspicious balancing was not completed correctly? Having said that I did not balance mine properly either, but if you've paid for it you would want it done right.