ᐅ Mechanical ventilation with heat recovery for indoor air quality

Hello everyone,

Maybe it’s a silly question, but I’ll ask it anyway.

We are considering installing a mechanical ventilation system with heat recovery in our new build.

Now I have the following question:

I once read that to ensure the system works as efficiently as possible, you shouldn’t use the traditional method of airing out (turning off the heating and opening all the windows), since the mechanical ventilation takes care of the air exchange and regular airing only wastes energy. That seems reasonable to me.

But how does it work in summer? Here we often keep the patio door open all day. In that case, the system doesn’t seem to make sense.

Is it possible to switch off these systems somehow (and ventilate manually as needed)? After all, you wouldn’t want to blow warm air inside during summer either.

wadi1982 schrieb:
Hello everyone.

Maybe this is a silly question, but I’ll ask it anyway.

We are considering installing a mechanical ventilation system with heat recovery in our new build.

Now I have the following question:

I once read that to keep the system as efficient as possible, you shouldn’t do the usual shock ventilation (turning off the heating and opening all the windows) because the mechanical ventilation takes care of air exchange and normal ventilation just wastes energy.
That sounds reasonable to me.

But what about in summer? We often keep the patio door open all day then. In that case, the system doesn’t really make sense.
Is it possible to switch these systems off somehow (and ventilate manually)? In summer, you don’t really want to bring in warm air either.

Hi Wadi,

We keep our mechanical ventilation system with heat recovery (Vaillant) running during summer as well (using an F6 filter against pollen).
We see the following benefits:

• Less pollen in the house (we suffer from hay fever)
• Moisture removal after showering or bathing without needing to open windows
• Fewer flies and other insects indoors because we keep the windows closed and only open the patio door briefly when going out or in
• Some cooling effect in summer when the cooler night air is drawn in (of course, not comparable to an air conditioner)

Completely switching it off is only possible by unplugging.
However, you can program time intervals for when the system should run at full capacity. In summer, we set the ventilation to run roughly from 6:30 to 7:00 am and from 10:00 to 10:30 pm.

Best regards

Andy

Thank you for your quick response.

If it’s possible to at least program times there, that would work.

I’ve been used to having the patio door open in the summer since I was a child. Habits are hard to change.

Hi,

Yes, I’m familiar with that habit from my parents’ house as well. They also stay active every summer by chasing mosquitoes and flies...

In any case, we are very satisfied with the mechanical ventilation system with heat recovery.

Regards

Andy

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I do have some questions right away.
We just had an appointment with a salesperson.

He advises against mechanical ventilation systems with heat recovery because, according to him, these systems

1. Require a lot of maintenance (about 200 € per year)
2. Can develop mold inside the system due to the cold supply and warm exhaust air.

What are your experiences with this? Does anyone else have experience with this?

wadi1982 schrieb:
This is how you save on the gym

I do have some questions though.
We just had an appointment with a salesperson.

He advised against the mechanical ventilation with heat recovery system because, according to him, the units

1. Require a lot of maintenance (about 200 € maintenance per year)
2. Could develop mold inside the system due to the cold incoming and warm outgoing air.

What are your experiences with this? Has anyone else dealt with this?

Hi,

1. Maintenance: In our case, the mechanical ventilation with heat recovery is serviced together with the gas boiler. When we moved in (March 2011), we signed a maintenance contract with our heating technician.
The first service is due around March 2012 – I think it costs about 100 euros?
Operating costs (besides electricity) come from filter replacements. The filters should be changed twice a year – costs are around 35 euros, or 50 euros for the F6 version (for allergy sufferers).

2. Honestly, I haven’t really thought about that. I just briefly googled but found no reports regarding hygiene issues or mold growth in Vaillant mechanical ventilation with heat recovery systems.
I’m not really an expert on mold, but doesn’t it usually occur when there is no fresh air supply? (like in bathrooms if they aren’t ventilated properly)
And with mechanical ventilation, air is continuously exchanged.

Regards

Andy