Hi,
I built a two-storey house with a ducted heating system (upstairs and downstairs), the installer only installed a single return air grill downstairs.
Unfortunately, since we moved in, every time we turn on the heating unit, it created a whistling noise on the return air grill area. The installer suggested me to clean the air filter more regular, which I have done this.
After a further check, they suggested me to have an additional return air grill upstairs (to have better air return flow).
They said there is no disadvantage of having this additional return air grill, apart from better airflow and no whistling noise. They said that normally they installed a single grill on double storey house as it is more cost-effective for them, although having two return air grills are better.
What do you guys think? can you see any potential issue by having two grills on upstairs and downstairs?
Thanks heaps!
The whistling is caused by the amount of air moving through that space.
You're options are, make the inlet larger or install a 2nd one elsewhere to spread the air return.
OR
turn the fan speed down on the unit, but this might not be an option (even if your controller doesn't have a fan speed, there is a setting on the unit)