ERV and musty bathroom smell
Hi all – I have a broan ERV installed. It takes air from kitchen and bathrooms to outside, and brings in air to the rest of the rooms. My bathrooms have had a musty, kind of a construction smell to them. I’ve been using dehumidifiers to keep it around 50%, but the smell persists. I just got a whole house dehumidifier installed which takes air from the middle of the house, dehumidifies it and adds it to the air that distributes around the house.
I’m noticing my master bedroom isnt getting air circulation as expected, the humidity is 10% higher than the other rooms which got me thinking.
I’m wondering if the outgoing air from the bathrooms is pulling air from the drains and other open plumbing like sinks, rather than pulling air from the other rooms? Is it necessary to cover or block shower drains, sinks when not in use so the ERV doesn’t pull air from those areas? Should the ERV pull from a different location rather than the bathrooms?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
An ERV or any HVAC equipment can't create enough negative pressure to suck air through a typical P trap. If you drains are smelling, you have a plumbing problem.
Musty smell in bathrooms are generally water leaks somewhere or missing air/vapor barrier details on the exterior walls.
Bathroom door usually have a reasonable undercut, your ERV draws in air through this. If you've installed a gasketed bathroom door, than you do need a jumper duct to the hallway.
As for your bedroom, it sounds like a balancing issue. Get a budget anemometer from an on-line retailer and check if you get the expected airflow. Sometimes (always?) the HVAC tech skip the balancing step so you get more airflow some rooms than others.
Akos, thanks for the response. I'll get an anemometer. The ERV tech mentioned that far rooms don't get as much CFM because they are the last on the line. Seems like there are several ways to remediate that. Would you mind explaining options for balancing?
Thanks
I'm no expert, but you basically put dampers on the rooms receiving "too much" airflow to encourage more airflow to make it to the rooms at the end of the line. We can't reduce friction in the ducts without upsizing ducts but we can add artificial friction and backpressure with dampers. In general you should install big ducts to reduce overall friction and then you can always impose additional friction through dampers to control where the airflow goes.
brilliant