Plumbing pressure relief

Lynnmor wrote:

Gdetrailer wrote:

Lynnmor wrote:

mobeewan wrote:
Accumulator tanks are now required at the hot water outlet pipe of water heaters on residential construction and when replacing WHs in existing homes.

I believe that is local codes, it wouldn't make sense for those on a well with an open system that has no check valve after the tank.

A "properly" installed water well WILL have a check valve at the pump.

Never want water to flow back into your well.

My well driller put a check valve above the submersible pump down the well.. I have an additional check valve between the pressure tank and well head for good measure.

Correct, the check valve(s) is on the PUMP side of the tank, not on the HOUSE side. The tank has the air pocket to keep pressures from going too high. What I said before is correct.

I was giving a bit more complete explanation on a HOME well system which lead into the fact that the OPs TOILET VALVE actually may be at fault similar to what I ran into.

Something else also, unless the water heater is heating the water to high enough temps to create steam I highly doubt that it will cause enough pressure without an air pocket to cause the toilet to start leaking unless there is a FAULT at the toilet..

The T&P valve IS there to relieve WATER PRESSURE in the event of over water heater overheating..

From HERE

In a standard water heater, the water is heated by a gas burner or electric elements. As the water reaches temperatures between 120 and 140 degrees Fahrenheit, both the water and the water heater's metal tank expand. Some expansion is normal, but too much expansion is unsafe. When the temperature reaches 210 degrees or the pressure reaches 150 psi (pounds per square inch), a properly functioning T & P valve opens and expels hot water and steam through the discharge tube.

One would really need to put a pressure gauge on the system and monitor the pressure to see what is really happening rather than making a bunch of guesses..

OP could even have a faulty pressure switch on the water pump but in reality the toilet should not leak even with CITY water pressures up to 100 PSI or better (yes, city water CAN get there).

Under NORMAL conditions with RV water heaters I have seen T&P valves "weep" some even with a newly filled water heater tank. And that may be partly due to a small air pocket but also have to consider RV water heaters operate at a much higher temp, of 135F to even 140F..

As far as the check valve goes on the inlet of the water heater, it should have had one from factory, even my 1980s TT HAS ONE.. Of course, with the factory check valves they use the cheapest ones they can get their hands on which are typically the plastic body with inline spring and plunger and the plunger has a rubber gasket that fails.. I changed mine to a all brass swing check valve for more reliability and much quieter operation (that plastic valve would "sing" when water was moving and DW didn't like the noise).

And yes, I would agree that some expansion tank may be nice to have as it will buffer the water pump but it is most likely not the fix or issue here.. I suspect the issue IS the OPs toilet water valve..