Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 09, 2025 ...

Double sink

September 22, 2014, 02:43:59 pm

I'm having trouble  draining the kitchen sink. The water being drained from one sink tends to back up into the empty sink.
I replaced the vacuum break under the bathroom sink, but that did not help.
I'm wondering if I install a vacuum break on the drain line under the kitchen if it would help this problem?
Does anyone else have this problem? Would installing a vacuum break alleviate this problem? Any comments?
Thanks in advanced.

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Re: Double sink

Reply #1 – September 22, 2014, 03:22:28 pm

Tom, we found a vacuum breaker on the drain in the kitchen area too. Had to pull out some drawers to find it. We replaced it because of odor. Bought one from Lowes; still had odor. Replaced it with one from FOT; no more odor.
If your vacuum breaker does not open to relieve negative pressure in the drain system or if there isn't one, it could cause slow draining.
Dick

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Re: Double sink

Reply #2 – September 22, 2014, 03:25:24 pm

Check for restricted p-trap.  Sink drains are connected before the trap.

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Reply #3 – September 22, 2014, 03:57:09 pm

 yopu can also take it apart and reverse the rubber flap, it does work.
JohnH

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Re: Double sink

Reply #4 – October 20, 2014, 02:38:46 pm

I finally got around to checking trap in kitchen sink and changed vacuum break for sink. Didn't help matters.
Guess I'll try a vacuum check valve from FOT when I get there. Didn't try reversing flapper because I damaged the valve trying to remove it.
Thanks to everyone for your suggestions.

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Re: Double sink

Reply #5 – October 20, 2014, 02:57:19 pm

Sounds like a restriction in the drain line, like was previously mentioned the p trap may have a clog in it. I would take it off and check for a blockage

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Re: Double sink

Reply #6 – October 21, 2014, 08:02:05 am

The valve is an AAV (air admittance valve} it lets air in and is not supposed to let air out. Its to prevent the trap from being siphoned when the sink is drained. It will not have any effect on the sink draining. There is atmospheric presser in the room allowing the sink to drain. If the sink drains slow it is because of a blockage.

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Re: Double sink

Reply #7 – October 21, 2014, 11:08:12 am

 My understanding of the  vents is that they are there firstly because the vent pipe could not be run thru to the roof and secondly to allow air in so that water can drain out of line. Without one (or the roof vent) a vacuum is created that will hold the water back somewhat and not drain as fast as with one. It also prevents odours from eminating back into room that would normally go out the roof. The trap will hold a water block not matter what the situation is. One thing that must be correct is that the under counter vent has to be above the water line in sink or you stand a good chance of water coming out of the vent should you have a large blockage in drain line, and water always wants to find the easy way out and it also automatically tries to be level in the system.
JohnH

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