Hello everyone,
we are building a KfW 70 house, which is economic even without a mechanical ventilation system.
Now, like many others, we are uncertain whether we really want to install a mechanical ventilation system. It has been planned, but the prices quoted are quite high... A decentralized system also seems to be similarly expensive due to the number of rooms and additionally causes quite a few holes in the nice facade...
Our heating engineer, who also installs ventilation systems, suggested installing fans in the exterior walls of the wet rooms (guest toilet and bathroom). These would be controlled by a switch and/or humidity sensors to extract the moist air from the rooms.
Additionally, a cooker hood with exhaust ventilation is recommended for the kitchen.
What do you think about this?
From a cost perspective, it does seem to be considerably cheaper.
we are building a KfW 70 house, which is economic even without a mechanical ventilation system.
Now, like many others, we are uncertain whether we really want to install a mechanical ventilation system. It has been planned, but the prices quoted are quite high... A decentralized system also seems to be similarly expensive due to the number of rooms and additionally causes quite a few holes in the nice facade...
Our heating engineer, who also installs ventilation systems, suggested installing fans in the exterior walls of the wet rooms (guest toilet and bathroom). These would be controlled by a switch and/or humidity sensors to extract the moist air from the rooms.
Additionally, a cooker hood with exhaust ventilation is recommended for the kitchen.
What do you think about this?
From a cost perspective, it does seem to be considerably cheaper.
There are heating and ventilation companies that offer a 10-year warranty... but only if you sign a maintenance contract.
Of course, you always have a 2-year warranty / guarantee.
So, if everyone is on vacation, where would the moisture come from?
Once the building is properly dry after the construction phase, the moisture usually comes from the occupants...
Unless you have damp walls, but that is a different issue.
Of course, you always have a 2-year warranty / guarantee.
So, if everyone is on vacation, where would the moisture come from?
Once the building is properly dry after the construction phase, the moisture usually comes from the occupants...
Unless you have damp walls, but that is a different issue.
fragri schrieb:
I’m not sure if the operating costs are really that negligible.
After all, the ducts of a mechanical ventilation system with heat recovery also need to be cleaned, right?
I read in a report that a poorly maintained mechanical ventilation system can become a breeding ground for germs.
Filters also need to be replaced quite often.
I think it’s realistic that annual costs of around 200 to 300 € (about 220 to 330 USD) can easily add up—excluding electricity!
Best regards,
Frank Here’s a brief comment from me.
Before our consultation in Berlin, I had a long phone conversation with someone who has a mechanical ventilation system with heat recovery. When I asked about maintenance and cleaning of the ducts, she said her husband changes the filters, and even after years of operating the system, they found almost no contamination inside the air intake ducts (she had apparently checked, and there was nothing inside). So, she doesn’t see a reason to hire a company for cleaning.
Since this contradicted the information I had read before, I followed up with the ventilation office in Berlin. They confirmed that the system owner can change the filters themselves and that the intake ducts are usually clean (I assume the filters are located directly at the air intake connection). However, normal household dust (which leads to the typical dust bunnies) gradually contaminates the exhaust ducts. These can apparently only be cleaned by a specialized company, which means ongoing maintenance costs.
Has anyone here who has had a mechanical ventilation system with heat recovery for a long time ever checked the exhaust ducts and can confirm, qualify, or completely reject this statement?
You often find contradictory information on this topic. On the one hand, there are opinions from supporters of mechanical ventilation systems (usually users themselves), and on the other hand, from critics. Personally, I find it very difficult to filter out the correct information. I have come to the conclusion that ventilation is useful, but after weighing the information I had, I decided in favor of a decentralized system.
@f-pNo
I completely agree... if anything, it should be a decentralized system without all the ductwork.
If a system extracts humidity from the rooms, moisture can also condense and accumulate inside the ducts, for example if the system is installed in a cooler room. Then mold might develop inside the ducts instead of on the walls.
I completely agree... if anything, it should be a decentralized system without all the ductwork.
If a system extracts humidity from the rooms, moisture can also condense and accumulate inside the ducts, for example if the system is installed in a cooler room. Then mold might develop inside the ducts instead of on the walls.
N
nordanney3 Dec 2013 13:43fragri schrieb:
@f-pNo
I completely agree... if a system is used, it should be decentralized without all the ductwork.
If a system extracts humidity from the rooms, moisture can condense and accumulate inside the ducts, especially if the unit is installed in a cooler space... This can lead to mold growth inside the ducts rather than on the walls. If there is mold inside the ducts, then your mechanical ventilation with heat recovery (MVHR) system is the least of your concerns.
The unit itself has a condensate drain.
D
DerBjoern3 Dec 2013 13:55fragri schrieb:
@f-pNo
I completely agree... if anything, it should be a decentralized system without all the ducts.
If a system extracts humidity from the rooms, moisture can condense and collect inside the ducts if, for example, the system is located in a cooler room... Then mold might form in the ducts instead of on the walls.Controlled mechanical ventilation and ductwork should be installed within the heated building envelope. That way, no condensation occurs. Condensation may only happen in the heat exchanger, which is designed for that purpose...
No, it cannot, because the mechanical ventilation system with heat recovery should be installed within the building envelope (otherwise, this is considered a construction defect). As a result, the dew point is never reached inside the ducts, so no moisture forms there—only at the heat exchanger itself.
And anyone worried about the supposedly enormous operating costs clearly has no idea what the inside of a ventilation unit looks like and what kind of expenses are involved.
Here is an example of the operating costs:
Electricity: between 20 and 150 watts depending on the airflow, so about 50 W on average (since systems rarely run at full capacity), which corresponds to roughly 100 euros per year for almost continuous operation, 24 hours a day, 365 days a year.
Filters: 1 square meter (sqm) F6 filters are widely available (from ventilation companies, sanitary suppliers, filter manufacturers) for around 30 euros. The quantity needed depends on the ventilation unit but typically lasts 5 to 6 years, so about 5 euros per year for filters. Let’s say 10 euros if additional filters are also installed in the supply and exhaust valves, etc.
Duct cleaning (required with regular filter changes, approximately every 10 years): about 500 euros for a “standard” single-family house.
So, total annual operating costs come to around 160 euros — definitely cheaper than renovation due to mold damage caused by insufficient ventilation.
Decentralized systems should, however, only be installed in rental buildings or during modernization projects. Why settle for a partial solution when the complete, finished product is available?
And anyone worried about the supposedly enormous operating costs clearly has no idea what the inside of a ventilation unit looks like and what kind of expenses are involved.
Here is an example of the operating costs:
Electricity: between 20 and 150 watts depending on the airflow, so about 50 W on average (since systems rarely run at full capacity), which corresponds to roughly 100 euros per year for almost continuous operation, 24 hours a day, 365 days a year.
Filters: 1 square meter (sqm) F6 filters are widely available (from ventilation companies, sanitary suppliers, filter manufacturers) for around 30 euros. The quantity needed depends on the ventilation unit but typically lasts 5 to 6 years, so about 5 euros per year for filters. Let’s say 10 euros if additional filters are also installed in the supply and exhaust valves, etc.
Duct cleaning (required with regular filter changes, approximately every 10 years): about 500 euros for a “standard” single-family house.
So, total annual operating costs come to around 160 euros — definitely cheaper than renovation due to mold damage caused by insufficient ventilation.
Decentralized systems should, however, only be installed in rental buildings or during modernization projects. Why settle for a partial solution when the complete, finished product is available?
Similar topics