Today I had a service call on a Trane ReliaTel gas pack. M#YSD150F3RHA04000/ S#15021058D When I tested unit in heat it started up went through its step and when the gas valve was energized it started chattering really loud. I had 24 volts going to the valve. So I thought I had a bad valve, but before putting on the new one. I hooked it up to make sure it didn't do the same thing. It worked fine not installed. But as soon as I installed it and tested unit the new valve did the same thing. So confused. Any ideas what may be causing this problem? Make note would not chatter right out of the box.
11austinlee
Does gas supply come into the bldg at higher pressures than 7" w.c.? If so, the "step down" or secondary regulator on gas supply could be failing. Should be easy to id with suitable range pressure gauge. I have had gas valves completely shut down (as some are designed to do) from high inlet pressure..
I like the concentric tube type. I fill with coffee rather than water (no sugar or cream, please) as it is always at my side and the warm brown gives a beautiful contrast for reading the pressure with an old pair of eyes...
I like the concentric tube type. I fill with coffee rather than water (no sugar or cream, please) as it is always at my side and the warm brown gives a beautiful contrast for reading the pressure with an old pair of eyes...
Do you have a drip leg in the gas line?
We had a unit that suffered from such a problem without one.
Sincerely,
William McCormick
We had a unit that suffered from such a problem without one.
Sincerely,
William McCormick
Post offices are notorious for having open interior doors, and running a lot of gas all day long. You can get a lot of liquid in a very cold line moving a lot of gas all day long. A diminishing diameter gas main is important as well.
Sincerely,
William McCormick
Sincerely,
William McCormick
If you go over what you wrote you might also uncover the variable that you found and mentioned, that will lead you to another possible problem, after the valve.
Sincerely,
William McCormick
Sincerely,
William McCormick
We went out on a call to a very large commercial industrial building that was turned into smaller commercial spaces, most unoccupied. It had a huge gas main, ten inches in and then eight inches in diameter and perhaps 150' long. But now with much smaller heating units and hot water heaters. Some requiring only a 1/2" feed.
We found that some of the units were failing on a regular basis. The pilots were going out during the night, and the place was ready to start freezing pipes at night. Some of this information came from people that either lived there or worked there.
So we changed a unit that was totally gone, the gas valve was damaged, which made me suspect air in the main. My experience is 99.9 percent of the time it is not the gas valve.
From what people had said about the large flames upon ignition that took a long time to ignite, and would sometimes create flames outside of the unit. I figured it was air in the main. Or someone hooked up a propane tank outside and did not say anything, haha. That really happens. They had people working on it almost everyday. Plumbers, HVAC guys, landscapers, friends, family anyone they could get.
The amount of gas you have to purge is unnerving to say the least. Having purged such mains successfully at a post office I knew exactly how long it takes. And how unnerving it is. You have to keep it flowing or you create a large volume of faulty non-spec gas. Scary has heck though.
An attempt to light the unit prematurely singed my coworkers hair and created quite a pop, as it took out the new gas valve haha. I was instructed not to say a word or else haha. The valve was banging quite a bit, as it would light and go out with a pop, and then finally a boom haha. That does not sound like your problem, however it is something to think about.
The bottom line the building needed to be properly repiped for the new application. Every unit needed a new service valve.
Leaks needed to be fixed before the branch service valves so each technician came in and vented and allowed air into the main pipe.
Sincerely,
William McCormick
We found that some of the units were failing on a regular basis. The pilots were going out during the night, and the place was ready to start freezing pipes at night. Some of this information came from people that either lived there or worked there.
So we changed a unit that was totally gone, the gas valve was damaged, which made me suspect air in the main. My experience is 99.9 percent of the time it is not the gas valve.
From what people had said about the large flames upon ignition that took a long time to ignite, and would sometimes create flames outside of the unit. I figured it was air in the main. Or someone hooked up a propane tank outside and did not say anything, haha. That really happens. They had people working on it almost everyday. Plumbers, HVAC guys, landscapers, friends, family anyone they could get.
The amount of gas you have to purge is unnerving to say the least. Having purged such mains successfully at a post office I knew exactly how long it takes. And how unnerving it is. You have to keep it flowing or you create a large volume of faulty non-spec gas. Scary has heck though.
An attempt to light the unit prematurely singed my coworkers hair and created quite a pop, as it took out the new gas valve haha. I was instructed not to say a word or else haha. The valve was banging quite a bit, as it would light and go out with a pop, and then finally a boom haha. That does not sound like your problem, however it is something to think about.
The bottom line the building needed to be properly repiped for the new application. Every unit needed a new service valve.
Leaks needed to be fixed before the branch service valves so each technician came in and vented and allowed air into the main pipe.
Sincerely,
William McCormick
Usually a chattering gas valve, relay, contactor, or any similar component is caused by a voltage drop. This can be caused by a ton of different scenarios with the low voltage and sometimes with the high voltage side, so do not focus solely on gas supply issues.
14" w.c. incoming is the maximum the valve is designed for. with that said, please keep in mind that when a valve shuts off, the incoming gas pressure can rise several inches of w.c. also, some gas regulators are not "positive shut off"...they allow a little gas past the valve...this is ok if you have a pilot light but not if you have a hot surface or direct spark ignitor. proper tools are most important. gathering more information than necessary is also a good idea.
You can very rarely come across a jet that is partially clogged with what looks like tar. I suspect it is oil that dried and then baked on the inside of the jet. This can cause the jet to flutter and create pressure behind the jet.
It has to do with the velocity of the gas in the small orifice, it allows oxygen intermittently back into the small orifice where it ignites a small quantity of gas behind the jet, creating pressure enough to shut down the flow of gas. It was for a friend and I could not find info on the jet, it was very old, so I cleaned it. It worked well. I do not recommend cleaning jets though.
I have heard this can happen with a rotted burner as well but i have not come across it.
Sincerely,
William McCormick
It has to do with the velocity of the gas in the small orifice, it allows oxygen intermittently back into the small orifice where it ignites a small quantity of gas behind the jet, creating pressure enough to shut down the flow of gas. It was for a friend and I could not find info on the jet, it was very old, so I cleaned it. It worked well. I do not recommend cleaning jets though.
I have heard this can happen with a rotted burner as well but i have not come across it.
Sincerely,
William McCormick
Without the almighty manometer, the OP and all of us are doing nothing but playing basketball in a pitch dark gymnasium.
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