Final plumbing "bowl/rim test"

[Ufar]

Hi,

I'm required to pass final plumbing air tightness test... or bowl test. i.e cap the roof vents, cap the main clean out. fill a traps with water... let the toilet bowl fill up slowly... in a air tight system it should hold water... i.e One inch of water column. Alternative be the manometer test in north central area. i.e U shaped tube pushed through the toilet and should rise up to 1" after air or water is run.

In my case it will only hold at 1/2 inch of water column any thing more the traps are blowing. I.e blub in the toilet that lets the air out.

We have tested the whole line by pumping with smoke (supperior smoke candle 3minute), tested further using peppermint test... (2oz perpmint pourd down roof vent, followed by hot water) could not smell any thing in the house. Confirmed it went through out the system... as once the main clean out was released could smell it.

So question is why do my traps blow before 1" inch of water column pressure is reached.

 

[Reach4]

How are you measuring the pressure? Is it a gauge, or open manometer? If it is a magic gadget, try sticking a clear tube down some water, and see if the measurement corresponds to the water level difference that you see.

If the open manometer (nothing to calbrate), and the toilet actually glubs, sounds to me like you would need a different toilet. This presumes that the bowl is getting properly refilled. See if you can get the water level to go higher by slowly adding another quart to the bowl.

 

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[Ufar]

No gauge, just open manometer. Cheap clear tubing with water in it in u shape some food coloring... then scale drawn on 2x4 and tubing mounted on it.

I don't think it is a problem with the gauge being accurate... as understanding is that when the toilet bowl is full of water it exerts one inch of water column pressure against the trap... in my case the bowl water always goes down to little over half and holds...

Before anyone else asks if their is a leak... I don't think that is the case as smoke test, the peppermint test, putting soapy water on all clean outs, etc etc... and the toilet holding water... but not the full 1 inch. BTW during roughing we did fill all pipes with water and they held for well over 18 hours... i.e filled the pipes up night before... went home had inspection in the morning.

We have changed all wax rings multiple times... plus it would not hold at 1/2 inch of water column pressure either. if it is a leak it should go down to zero... that only happens once we release the main clean out.

 

[Reach4]

One other possibility is to tilt the toilet forward some. Re-wax, of course, before dropping the toilet on your thick aft shims. That will raise the weir.

However if that toilet is old or needs a plunger now and then, I suggest that you take the opportunity to put in a new toilet that works well.

 

[Ufar]

@Reach4, ty for feedback... It is a brand new system, the toilets are new. All are elongated. Which could mean I would need less water in the bowl to get to 1inch water column pressure on the trap??

Just FYI... their are three separate bathrooms. Three toilets.

I was able to do a further test today... it held at close to 1inch... for longer period... I filled the toilet until the manometer reached 1" then stopped... which on the toilet was about 2 inches below the rim... after about 6-7 minutes one of the toilets bubbled and it dropped down to 1/2 inch . Not the full 15 minutes

 

[Reach4]

I filled the toilet until the manometer reached 1" then stopped... which on the toilet was about 2 inches below the rim

There must be a typo there. The water surface in a toilet bowl is way lower than 2 inches below the top of the rim on toilets I have seen.

Maybe you should ask the maker what the water seal depth should be on your model. Given your consistency, your inspector may be satisfied with 3/4 inch. I have not seen this topic discussed before.

 

[Ufar]

@Reach4 TY for the feedback. The inspection was passed.

The inspector this time around him self stop the fill on the toilet to about where it would hold... unlike previous inspector which kept water running until water was touching below the rim of the bowl. Inspector looked at it for 2-3 mins and said he will clear the infraction and you are good to go.