Heat recovery system

[Marnhullman]

I have a heat recovery system in my flat. There are ventilation bosses in the kitchen and both bathrooms that are ducted to a single fan located in a cupboard in the hall.

I understand that ventilation is important but the b....y fan runs all the time and is quite noisy. It's particularly noticeable at night and makes it difficult to sleep.

Would it be okay to fit a timer to the fan so that it only runs at the prime times e g. a couple of hours first thing in the morning, an hour at lunchtime and an hour in the evening. This would allow the wretched noise to be eliminated during the nighttime?

Grateful for any advice.

 

[Roddy Young]

These can be very annoying at night - at 3.31am...........

Many of these have some kind of controller which allows you to change the running speed; some even have a built in clock.
The controller might be wall mounted or on the front of the HRV unit itself.

Ours is a Vent-Axia unit and we have set the running speed down to 35% at night (9pm to 7am).
The rest of the time it's only at 50% because there is "boost" of 75% activated by pressing a button on the control.

What make is your HRV system? Can you find info on the maker's website?

 

[Marnhullman]

Thanks.

It's a Vent-Axia system.

There doesn't appear to be a timer but I have now emailed VA technical department for advice.

Regards

 

[Roddy Young]

Our house was built 10 years ago. Relatively airtight, it does not have trickle vents in the windows.

Our neighbours installed a very smelly woodburner and local farmers sometimes spread smelly things around.

Officially, we cannot stop these smells being sucked into the house by switching the HRV off.
The HRV system does the mandatory ventilation and so must always remain on.

Despite that, we have been known to switch OFF the mains to the HRV for a few hours.
(The mains has to be OFF in any case when its filters are being changed.)

Please keep us updated on any reply from Vent-Axia. (I found them pretty helpful in the past.)

On a positive note: the HRV does keep the house dry by removing steam after cooking or showers, etc.
It does that 24/7, even if we're not at home to open windows.

 

[Marnhullman]

Ah, interesting; you mention a filter that needs changing. I'm not aware that my system has a filter- will investigate.

I don't expect a reply from VA until after the weekend so check back then.

Best regards

 

[big-all]

just a though
have you tried cleaning around the fan as a build up off dust and rubbish can multiply noise several fold

 

[Agile]

Watch out for condensation if you turn off the fan!

 

[Marnhullman]

It'll only be turned off overnight so condensation shouldn't be a problem bearing mind the vent ducts are only in the bathrooms and kitchen!

 

[John D v2.0]

If it's really heat recovery the would be inlet vents in either the hall or the bedrooms/living room. Perhaps you'd is just a constant extraction system?
At night is when the walls get colder and you spend longer breathing condensation air with the doors shut, so it's not a given that it isn't needed at night. Also you need to maintain the air quality for carbon dioxide

 

[muggles]

Ah, interesting; you mention a filter that needs changing. I'm not aware that my system has a filter- will investigate.

I don't expect a reply from VA until after the weekend so check back then.

Best regards

Sounds like it needs a good service. Should be virtually silent in operation if installed, set up, and maintained correctly

 

[Marnhullman]

John D - yes, I believe it is a constant extraction system. That is how it was described by the builder when I bought the flat 7 years ago. The flat is a rental property and I'm only staying here between lets so have only just become aware of the noise.

Muggles - I've looked on the VA website and the unit I have is no longer available but its technical description is still there. The unit is described as a sealed unit that needs no servicing and there's no mention of a filter.

Will await feedback from VA - hopefully.

There is a switch adjacent to the unit labelled MHVR which I've tried turning off, as I assumed it was the power for the unit and although it did stop the fan initially the unit started again, some time later, which suggests there's an additional power supply.

Anyone familiar with how these units are wired and are supposed to operate?

 

[Marnhullman]

Reply from Vent-Axia:

"Have you tried adjusting the humidity sensor to make it less sensitive as this may be the reason the unit is boosting at night?

Please see attached instructions which show where the humidity adjuster is positioned in the unit, to make the humidity sensor less sensitive turn the adjuster towards the plus so you raise the set point. Please ensure you isolate the fan from the power before removing the cover.


You could add a timeclock to the unit but then you would need to add the condensate drain and ensure it is trapped away as the fan will be used intermittently this will be required."

Have made an adjustment and the unit is running at a much lower rate. I may have overdone it and shall take another look tomorrow.

Regards to all.