My water heater pilot went out when the furnace started in 2005. Because it also had a leak I replaced the water heater, but to no avail. I could watch the pilot go out, and a candle only inches away did not flicker, so it didn't appear to be draft related. I finally replaced the gas regulator and that solved the problem. It was a 4 year old Maxitrol 325-5AL meter. Now, seven years later I have the same problem again. I have a hard time believing that the regulator would be such a problem area, usually they just work forever. Does anyone have any ideas why this would begin happening again?

Prior to 2001 I had a different regulator, but had to go to the Maxitrol 325-5AL because my service was upgraded to 2 psig. Downstream (35' of 1" pipe) I have the 40K BTU water heater and an 80K BTU furnace, so the 325-5AL should not be underspec'd. A new 2 psig leg goes the other way and has 4 regulators at each appliances, 22K BTU clothes dryer, two 170K BTU tankless heaters and a ~50KBbtu range top.

Hi Bill

Is this a Closed combustion chamber water heater? If it is, then there is a good chance that your air intake has gotten slightly clogged. Here, a simple cleaning and vacuum at the air intake should resolve the issue; this may require a heavy duty cleaning if you have the honeycomb filter system in place.

A call to the manufacturer's technical department may prove useful here for best result!

Mark

Mark,

Thanks for your suggestion, but it is a conventional Richmond WH, #12G50-40F; the only perk is piezo ignition.

Interesting that 7 years ago when I first fixed it by replacing the gas regulator it was winter so I thought it was temperature related. Now the garage where the regulator is, is in the 90s.

Any other suggestions Mark?

Thanks, Bill

Furthur diagnoses now points to the vent limiting device on the gas regulator in the garage. I removed this device from the regulator and the furnace no longer causes the water heater pilot to go out. Seven years ago I replaced the whole regulator, which solved the problem, but now it looks like only the limiting device needed replaced. Is it common for the vent limiting device to fail, or is it getting plugged up with dust or insect debris? Can or should these be serviced? If the unit were outside it would only need a vent protector; it is not practical to move it outside, but would it be normal to run a line from the regulator vent hole to the outside and just put a protector on it?

I have a new vent limiting device on order, but I'd like to put a permanent fix in.

Have they checked the actual pressure and flow to determine if there is enough gas to properly supply both units.

We have had to replace gas pipe size more times than I can remember when we installed ( commercial ) hot water systems,

11 years ago the previous Maxitrol 325-5AL regulator was added because the service was upgraded to 2 psig. The old .5 psig downstream (35' of 1" pipe) load is a 40K Btu water heater and an 80K Btu furnace. So on the failing leg, the pipe size and the Maxitrol 325-5AL control seem far from underspec'd. A new 2 psig leg, about 45 feet long, .75" flexible SS line, goes the other way and has 4 regulators at each appliances, 22K BTU clothes dryer, two 170K BTU tankless heaters and a ~50KBbtu range top. No active load was on the 2 psig leg when observing the problem.

Things fail.. simple as that. You should be able to purchase a new vent limiting device... super cheap and easy to swap out.

You can also pipe these to the outside, but if it is not a requirement then there should be no need, too.

Mark