Can PVC joints used on a furnace or water heater exhaust be leak tested with soap or a solution like a gas pipe?

Im guessing no, since its not under pressure. How would you test for leaks in such a case?

well, they are sealed combustion so therotically if you capped one pipe outside you could pressurize from the other. just how much pressure the whole internal system would take before causing any damage would have to be answered by the manufacturer.

So no bubble then with one side open under normal operation?

Capping both ends the the gas would run for about 2 seconds before it trips the safety...



Edited 2 times.

The only leak test then is if you die or not of carbon monoxide poisoning?

no, you install a hard wired CO detector.
truthfully, if you cut nice clean, square joints. prime and glue them properly, you will have no leaks.

You basically answered your own question when you said "there is no pressure to do a soap test", which means there is also no pressure to cause a leak.

So its impossible for a leak to occur in a vent because their is no pressure? ... but what about leaking drains? Please elaborate.

HJ- I ask very respectfully, I really have learned a lot from your replies here and I am a total novice.

Water HAS a "pressure" so it may leak from a bad connection, but not necessarily so. It depends on how the pipe is situated and how poorly the connection was made.

They could be tested if you tested it the same way as a pressure test for a vent, but keep in mind that if you had any doubt, you could simply wrap the joints in silver ducting tape. One roll of tape could do about 100 joints I am guessing, and the price of equipment would probably be the equivalent of about 500 rolls of tape. So unless you already had the test balls, pump, gauges, etc. you would be better off just getting a roll of silver tape as added insurance. I couldn't find a definitive answer about the set point of pressure switches in furnaces, but it appears that the pressure of the combusting exhaust gasses plus about .9 inches of water column are all the pressure that are in the system to begin with, but as it is open on the end, I don't know what the working pressure would be, but it wouldn't be much.

Sheetmetal flue piping for gas appliances aren't required to taped/sealed. They are only slip fitted and 3 screws to keep them from pulling apart. I don't see the need to be concerned with pressure testing PVC flues.