Noise from unde bathroom sink when flusning the blacwater tank.

[Elliott & Vicky]

Starting a few months ago, when I flush the blackwater tank I can here a whistling sound from under the bathroom sink. Since the same time, when we use the fan while taking a shower, we get a septic smell in the bathroom. Anyone know how to solve these problems? We've had the Redwood since 2013 and never had these problems before.

[Garyl53]

There is an air valve under the sink at the top of the black drain pipe usually. This allows air in to help the sink drain work. It might be worn or damaged resulting in the whistle and smell. You can get them at a local hardware store usually. The exact name of the device escapes me at the moment.

[NW Snowbirds]

Actually, it is a vacuum breaker valve located in a loop from the black water rinse line and is underneath of the sink. I believe that the purpose is to prevent siphoning of black water out of the black water rinse line when disconnecting from the external water source. Your vacuum breaker valve may be defective and if you turn on the fan in the bathroom with the door closed it could possibly be sucking some bad smelling fumes out of the vacuum breaker valve. The smell could also be coming from the vacuum breaker on the sink drain which goes into a gray tank. The smell in the gray tank can be almost as noxious as the smell in the black tank considering all the things that are flushed in the gray tank from the sink, etc.

[atom ant]

It looky like this on our 2014 Redwood 36RL, on top of the blue Pex.

[Elliott & Vicky]

Any idea where I can get one of these?

[r time soon]

These can be found on Amazon and others. Google is your friend. B&B molders 571 VAC CHK Vacuum Breaker, Valterra A10-3050 1/2" mpt check valve/ vacuum breaker. Some have bypassed altogether but I would recommend replacing for the reason it is there in the first place. So water drains out of the line and doesn't freeze and to not allow water to enter from the black tank if it were to ever get that high.