ᐅ Advantages and Disadvantages of Ventilation and Exhaust Systems

What is wrong with dry air? -> Irritation of the mucous membranes in the nose. For infants (we currently have a second one here), a humidity level of 60% is best. In winter (regardless of the type of heating), this is naturally very difficult to achieve. Therefore, we need to humidify the air anyway. Our little one is affected by this (he snores quite loudly). Higher humidity would be beneficial for him and us.

kaho674 schrieb:
Yes, if I keep the windows open all the time, do I need to turn off the ventilation system? Otherwise, it’s pointless and just uses electricity, right?

Exactly... as soon as a room has an open window, the designed airflow throughout the house no longer works properly. However, the electricity consumption at the lowest setting is really quite low. In summer, you usually turn off the system during the day anyway... in winter, it stays on until it gets too cold in the rooms at night.

A ventilation system can regulate the humidity inside the house. On one hand, it removes moist air. Water then condenses inside the system and drains away.
Result: The air becomes drier (which is good in summer).
We also purchased an enthalpy exchanger with our system. It works in principle the same way, but it re-humidifies the incoming air slightly... so the dry winter air is somewhat improved.
Of course, this only works within certain limits... but a 10% difference more or less makes quite a difference.

What type of system do you have?
I assume you don’t have an enthalpy exchanger. With one, you would also have moisture recovery, and it would still operate efficiently at lower temperatures without needing a preheater. Typically, you can replace the standard heat exchanger in a system with an enthalpy exchanger.

Der Da schrieb:
What is actually a myth, at least from my observation, is that the mechanical ventilation with heat recovery heats the other rooms when the fireplace is burning.
I checked in spring... outside temperature -5°C (23°F), fireplace running at full power, supply air temperature in the system 15°C (59°F). But the rooms upstairs had 18°C (64°F) room temperature... so it does not heat. And if it does, the effect is minimal...

Well, if your mechanical ventilation with heat recovery draws in the warm air (heated by the fireplace) and uses up to 90% of the heat from that air to warm the supply air, then indirectly the fireplace is also heating the other rooms through the supply air—am I missing something here?

Doc.Schnaggls schrieb:
Well, if your mechanical ventilation with heat recovery draws in the warm air (heated by the fireplace) and uses up to 90% of that heat to warm the incoming fresh air, then the fireplace indirectly heats the other rooms via the supply air – or am I completely missing something here?

It strongly depends on the outside temperature. I gave the example from last spring. At that time, with an outside temperature of -5°C (23°F), my supply air temperature was 15°C (59°F)... warmed by the fireplace that was burning at full power... But 15°C (59°F) was still lower than the current room temperature... so in fact, it’s not heating but cooling.

However, the exhaust air intake is not located above the fireplace, but in the kitchen 4m (13 feet) away.
And personally, I consider that 90% figure to be a bit of marketing spin.

The fact for our house (KFW55 standard) is that waste heat is definitely utilized, but it’s not enough to provide actual heating. You end up using less gas... now, you could argue whether all of this is properly defined and labeled.

Der Da schrieb:
The fact with our house (KFW55) is that the waste heat is certainly utilized, but it is not sufficient to heat with it. You just use less gas for heating... one can argue whether all of this is correctly defined and named.

OK, now I also understand what you mean.

Then I expressed myself incorrectly – I meant that the air heated by the wood stove is preheated through the mechanical ventilation with heat recovery.

It is clear that this alone is not enough for heating.