Gas Supply Fluctuations at Certain Times of Day

[rmcderm313]

Hi All, I have a Heat & Glo 'Escape' gas insert. I'm generally happy with it. On certain days, for periods of the day, the pilot light will go off, but not long enough for the electric ignition to need to click and start it again. It goes off, and then with a little 'poof' it goes back on again. Again, there is never a click of the ignitor. It goes off for less than a second.

I have not been able to determine any pattern. Sometimes it happens on a perfectly calm day with no wind and on some days where the wind is howling it stays lit constantly. Yesterday it was going out every 2-3 minutes. Today it has been lit constantly for hours.

I can't be sure if this is related but I'll mention it. When we have had storms and lost power, we have noticed that the gas flow (and resulting flame when lit) is substantially less than when we have power. When the winds are bad enough, which is usually when we lose power, we sometimes have trouble keeping the insert lit. Not just the pilot, the fire itself. This has been a bit of a disappointment. We love the fireplace for heating, but one of the main purposes was as a backup for losing power. Last time we lost power the flame never got higher than an inch and it was wispy and blue. As soon as the power came back on, the flame was back to normal.

It seems to me that the incoming gas supply is varying. Is it possible that the gas company is doing that? When electricity in an area is out, do gas companies throttle back gas delivery pressure to an area for some safety reason?

Where this happens only on certain days/times, it seems less likely to me that this is related to my equipment, although certainly possible. We are in Massachusetts if that matters from a gas delivery standpoint.

Any thoughts? Thanks,
Rob

 

[gthomas785]

I'm also in MA and my gas supply has always been super consistent over the past 2 years that I've had my house. I've never had any interruptions or had to relight any of my standing pilots.

With that said, I cannot explain the poofing issue. As for the pressure being low during a power outage, more likely your neighbor has a NG backup generator that is sucking down the supply pressure when the power goes out. That is not supposed to happen and the gas company needs to address it.

 

[brenndatomu]

Sounds like there may be water in your line somewhere...that can cause fluctuating like that...

 

[ABMax24]

Sounds like an issue with the regulator. Have a look at it and make sure the vent screen is clear and doesn't have cobwebs or other junk blocking it. Otherwise the regulator could be sticky, or faulty which is a problem for the utility to fix.

I find it hard to believe that gas pressure is that low in your area to make the flame go out, in my area we get gas delivered to the house at about 100psi which is stepped down to 0.25psi for use in the house, it would take an immense amount of usage in my area to pull gas pressure down in the main to anywhere close to 0.25psi.

 

[rmcderm313]

I'm also in MA and my gas supply has always been super consistent over the past 2 years that I've had my house. I've never had any interruptions or had to relight any of my standing pilots.

With that said, I cannot explain the poofing issue. As for the pressure being low during a power outage, more likely your neighbor has a NG backup generator that is sucking down the supply pressure when the power goes out. That is not supposed to happen and the gas company needs to address it.

Thanks for the response. Glad to hear your pressure is good. I've never had any other symptoms of low pressure in any other gas appliances or our boiler. Can't figure this one out.

Interesting point about the NG generators. We've had a boom of them installed in the last 10 years. On Monday mornings if you walk around the neighborhood you can hear them all firing up for testing. I don't know of any immediate neighbors that have them, but maybe just having enough in the neighborhood could do it.

Thanks again!
Rob

 

[rmcderm313]

Sounds like an issue with the regulator. Have a look at it and make sure the vent screen is clear and doesn't have cobwebs or other junk blocking it. Otherwise the regulator could be sticky, or faulty which is a problem for the utility to fix.

I find it hard to believe that gas pressure is that low in your area to make the flame go out, in my area we get gas delivered to the house at about 100psi which is stepped down to 0.25psi for use in the house, it would take an immense amount of usage in my area to pull gas pressure down in the main to anywhere close to 0.25psi.

Thanks for the reply. Where would my regulator be? Is this outside the house coming off the meter?

How does the pressure get stepped down? Is it the regulator that @gthomas785 mentions above?

As I type this I'm watching my pilot go off for a half second every 2-3 minutes and 'poof' back on

Thanks again!
Rob

 

[rmcderm313]

Sounds like there may be water in your line somewhere...that can cause fluctuating like that...

Thanks for the reply. That seems like a good candidate. Is there any way to check for that? Or is that a job for a plumber? I'm pretty handy but probably wouldn't screw with a gas line.

Thanks again!
Rob

 

[rmcderm313]

Poof!

Here is a short video of the pilot going out twice in a little over a minute. It's very frequent this morning. If you listen close you can here a faint clicking sound as it starts up again. This isn't the pilot igniter, as you can probably tell by the lack of spark in the video. It sounds to me like the gas pipe 'rattling', like when there is air in a water pipe.

This might be another clue for the 'water in the gas line' thought.

Thanks for all the reply's so far.
Rob

 

[rmcderm313]

and Hmmmmmm. Now watching the video I think I do see a spark on the igniter when it goes out. Normally when the fireplace is lighting I hear a pretty loud clicking sound which is not present during these times. But I do think a spark is present.

Puzzled....

 

[DAKSY]

Might be debris in the gas line. If a small piece of debris reaches the pilot tube & consequently, the pilot orifice,
it'll stop the flow. When the gas pressure stops due to the safety feature in the gas valve, the debris can fall back
& the gas flow will resume.

 

[brenndatomu]

Thanks for the reply. That seems like a good candidate. Is there any way to check for that? Or is that a job for a plumber? I'm pretty handy but probably wouldn't screw with a gas line.

Thanks again!
Rob

You can shut off the gas valve coming in and then take the cap off of any drip legs you can see...that's the short pipe hanging down below the tee near where your appliances connect...see if any dirt or water comes out. You will need to use some thread tape or pipe dope on the threads before reassmebly, so if that is not something you are comfortable dealing with, then yes, you will need to call a plumber or HVAC tech.

 

[gthomas785]

Thanks for the response. Glad to hear your pressure is good. I've never had any other symptoms of low pressure in any other gas appliances or our boiler. Can't figure this one out.

If the issue is isolated to this appliance then that rules a few things out, like the house regulator.
It could be a clogged line going to the fireplace, and it could be a bad or dirty gas valve.

Seems like the blipping pilot and the pressure drop during power outages are two separate problems.

 

[gthomas785]

One other thing... Check the wire and connections from the thermocouple/thermopile to the gas valve. If that connection is intermittent it would cause this behavior.

 

[rmcderm313]

Thanks for all of the replies! I will start to take a look at all of these suggestions. The fact that it is intermittent, not just minute to minute but day to day, makes this an interesting issue to troubleshoot. Of course I've been fooled by intermittent issues leading me away from the cause before. I will try and post updates as I address some of the suggestions.
-Rob

 

[peakbagger]

Street gas pressure in Mass is very local and its a big problem in some areas. There is big ramp up in natural gas combined heat and power facilities being built in places where there was just residential use. They really can drag down the local gas pressure. I have been involved with several of these CHPprojects and the utility frequently has to upgrade their piping in the area to scrape up enough pressure. If your regulator is not working right some nearby new gas user could be bringing down you street pressure to level lower than previously and you are seeing the side effects. Mass is on the end of the pipelines and any attempt at putting in new transmission lines gets shuts down by landowners who do not want them on their property or environmental groups that want to limit additional gas generation.

The other aspect is the utilities really do not make much money on residential gas and they have under invested in the underground piping for decades, they have a lot of leaks on these old networks and do not address them that well. I drive by an area in Shirley Mass where homeowners have signs in their front yards demanding that the utility fix their leaks. The Merrimack valley gas explosions in 2019 ultimately were tied to weak old pipes being overpressurized. They do make good money off of CHP plants and my guess is those piping systems get the priority with homeowners on the bottom of the barrel.

 

[gthomas785]

I find it hard to believe that gas pressure is that low in your area to make the flame go out, in my area we get gas delivered to the house at about 100psi which is stepped down to 0.25psi for use in the house, it would take an immense amount of usage in my area to pull gas pressure down in the main to anywhere close to 0.25psi.

Sadly that's not now most regulators work in real life. If you have a regulator that's designed for 100 psi supply pressure, then there's probably a range of input pressure from like 50-250 psi where it can reliably output 1/4 psi. Outside of that range and the behavior becomes erratic. I know this because I work a lot with industrial/scientific gas regulators and there is usually a certain minimum delta P between inlet and outlet for it to work properly. There are, of course, different regulators with different characteristics depending on the application.

In the Merrimack valley incident that peakbagger described above, the gas supply lines were grossly overpressurized due to a broken feedback loop - some dumbass closed off a valve to a pressure sensor while the system was still using the sensor to regulate the system pressure. The first question people asked was, "what about the service regulators? shouldn't they limit the pressure getting into people's houses?" And the answer is yes, up to a point. But you can always blow past a regulator by supplying more pressure than it was meant to handle, and that's what happened. Just in the same way, you can get a drop in outlet pressure even when there's still some inlet pressure, if it's not enough to operate the regulator properly.

 

[coaly]

The gas pressure delivered to a regulating station is determined by a high pressure sensing line. This is a very small line tapped into the regulator inlet at the destination regulator. It goes back to the supply station to let the supply know what pressure is available at the destination station. Higher flow rate reduces main pressure, so this sense line raises the delivery pressure in main line. If this small sense line is obstructed or partially closed off to reduce the sense pressure, the supply station raises the pressure to the destination. That’s how the main can over pressurize. Someone inadvertently closing the sense line raises the pressure to the next regulating station.

The more regulators in line, the more accurate the pressure. This is called stages. For example, a 200 plus psi regulated down to 1/2 psi is what a single stage bbq regulator is on a gas grille. From 275 in a full cylinder down to a few pounds pressure it can vary since inlet pressure at 200 may put out 1/2 psi, but inlet pressure at 20 pounds or less will put out less pressure. So second stage regulation is used with a first state regulator from tank pressure down to 10 psi. The second stage is then a 10 pound to 1/2 pound. The first stage is capable of the high inlet pressure down to 10 psi in a wider range. So even if it releases only 5or 8 pounds at low inlet pressure, the 10 to 1/2 psi second stage can still supply the 1/2 pound needed at the lower input it gets. So you can see how multiple stages make it more accurate down to lower pressures. That is an example for 1/2 psi for LP. Natural gas appliances use half that pressure, about 1/4 psi.

Make sure you have a drip leg before the gas valve on appliance. Most Natural Gas appliances also have a appliance regulator at the inlet that is the final regulation. As mentioned, debris or fluid from condensation in a line varies pressure. You will see liquid on a gauge by a fluctuating needle as the moving vapor gurgles through the fluid.

Some gas logs and inserts have gas valve very close to the hearth floor, so the line goes directly into gas valve. There is a sediment trap available that works like a drip leg designed to be used in any position. It is a straight pipe configuration like a muffler with an inner pipe inside a larger outer shell to allow fluid or debris to be trapped before entering appliance. They have a pressure tap as well for pressure testing at the appliance. Stainless screen inside, I carried one with me in case a appliance had no room for a drip leg at the installation.

 

[peakbagger]

We are having a tough time getting the local gas supplier to guarantee 10 PSIG at the street for a current project in central mass. Boston reportedly has lower street gas pressure in an area we are looking at. On another project, the utility had to upgrade a few thousand feet of pipe in the street some distance away from the plant to be able to get a reliable 15 psig in winter. Amesbury Mass used to have a municipal gas liquification system, they would run it when it got cold to make LNG to store and then re-gasify it when the gas pressure got to low. Nashua NH was injecting propane into the natural gas supply when pressure got too low. Unfortunately the system used to inject the gas malfunctioned and they had home appliances bursting in flames.

Lots of aging infrastructure.

 

[Lennox65]

Poof!

Here is a short video of the pilot going out twice in a little over a minute. It's very frequent this morning. If you listen close you can here a faint clicking sound as it starts up again. This isn't the pilot igniter, as you can probably tell by the lack of spark in the video. It sounds to me like the gas pipe 'rattling', like when there is air in a water pipe.

This might be another clue for the 'water in the gas line' thought.

Thanks for all the reply's so far.
Rob

Your problem is not gas pressure. In the video you can see a perfectly full pilot flame that suddenly goes out immediately. When it goes out you can see the ignitor start sparking as it relights the pilot, and continues to spark after the pilot is lit. Your problem is electrical, either in the power supply or the flame sensor. I would start by cleaning the ignitor and flame sensor rods and checking for cracked wires on the white and orange wires that go from the pilot assembly to the module.