gas supply/gas valve problem(s)?

icheat

I have two Burnham P206 series 2 gas boilers (one for space heating, the other for DHW). Recently I have noticed two issues:

1. On some occasions one or both of the gas supply valves (Honeywell SV9500 2600) will continue to click every few seconds even after boiler ignition. The flame seems fine, its just that the relay is mis-behaving somehow. This goes on for a couple of minutes and then stops (the clicking, that is).

2. When both boilers are firing, the gas supply is noticeably diminished (just visually---the flame is markedly decreased).
(I have to check the supply piping to make sure it is adequate, but I haven't noticed this problem in the past. You can see the piping in the images).


I will most likely have a professional come and check things out (I'm not sure I want to mess with gas myself ) but I was hoping that someone might have some thoughts so I can be better informed.

Thanks in advance
AC

BobC

I just had the gas company out for a similar problem. The gas pressure seemed lower than it should be, when they checked they found the pressure dropping by 3" when the boiler kicked on. They reamed out the pipe that goes out to the street and are going to replace the pipe from the incoming main to the gas meter on Wednesday.

It sounds like you might have a similar problem, you might need the gas company to check out their piping.

Bob

icesailor

They have test ports on the gas valves so you can check the pressure when it is running. Just like oil burners.

Wonderful discoveries can be made with a manometer or a digital negative gas valve meter.

BobC

That is how I knew to call the gas company. The gas pipes in this area are probably 80 years old and I have neighbors who have had pressure problems and they had to run new feeds into the houses.

I hope my gas pressure is steadier when they are done.

Bob

icheat

Thanks Bob and Ice:

You called it---checking the pressure on the street-side of the meter gives 5" pressure with no load dropping to 2" when the boiler fires. The gas company is installing a new line from the street tomorrow.

BobC

The gas company replaced my line yesterday and everything is much happier.

Bob

Abracadabra

I've seen 80+ year old gas lines collect water in sags in the line. A 6" low pressure gas main now becomes a 3" low pressure gas main. Guess what happens to the pressure at everyone's furnace when morning rolls around and everyone switches out of nighttime setback? Had a 2,000,000 PowerFlame burner that had a flame on it that looked it was from a turbo torch. Of course the power burner would eventually blow out the flame and it'd cycle over and over. Had to videotape it to provide proof to the gas company since the pressure would be fine when they'd come out at their convenience around noon every day to check it out. They ended up supplying about 20 blocks with medium pressure after that.

icheat

A final followup:

The local gas company replaced the gas service to the house over a period of several days. They determined that the existing line was unusable and after several attempts at a replacement
they installed a new 2" line from the main on the other side of the street up to the sidewalk and then a 1" line the remaining 15 feet into the property. They installed a larger meter as well.

The upshot is that my two boilers are happy for the first time since I've owned the property. And the problem with the gas valves misbehaving has disappeared. Waiting to see what impact this all has on my gas bill, if any.

Thanks for all the advice.
AC

icesailor

Think replacing occluded (obstructed) galvanized potable water pipes in a house with low pressure. You turn on a faucet and the water pressure will blow a glass out of your hand. But takes 2 minutes to fill a 12 Oz. glass with water.