Heil 9MPT flame won't stay on


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Old 01-05-12, 01:18 PM
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Heil 9MPT flame won't stay on

Last Thursday problem occurred for the first time. Unit is only 3 years old.

Calls for heat, inducer motor goes on, flame goes on for less than a second then goes out. This happens 4 times.

I first get 6 flashes - "failure to ignite or flame sense lose while running" during the 4 attempts; then 6+1 flashes - "soft lockout - max. of 4 trials for ignition reached (3hr delay)".

Up until a few hours ago, turning off the power to the unit at the cutoff switch and turning it back on fixed the problem for a couple days but now, that doesn't do anything so something that was able to be reset before has degraded to where I am now - competely without heat.

The last time resetting worked, a few hours ago, it never reached temperature so I assume the flame went out while running for some reason and never came back.

Intake/Exhaust vents are not blocked, I cleaned the sensor - no soot at all on it but still could be the problem but I don't think so because it doesn't even have time to sense heat before the flame goes out - less that a sec.

Any way to test the sensor? Electrical Multitester - test for continuity and stick in the flame of a match? Will that work?

Another thought. Could this be air in the gas line to the heater? How is that checked? Wondering if the flame goes out because there's no gas to burn.

Any thoughts would be appreciated before having to call the serviceman.
 

Last edited by JustWannaKnow; 01-05-12 at 01:55 PM.
  #2  
Old 01-05-12, 06:47 PM
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Most furnaces have a small rod with porcelain part the way up which sticks into the flame. Remove & clean the exposed metal rod with scotch brite or very fine sandpaper.
This one is straight, others are bent. http://www.hogslat.biz/images/produc...e/G20-5045.jpg
 
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Old 01-06-12, 12:28 AM
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Thanks, Grady.

As I mentioned in my write-up, I did clean the sensor and there was no soot on it at all. Also I didn't think the sensor was the problem because the flame goes out so quickly, like immediately after the flame is lit, it goes out.

The heat has been on (and off when reaching temperature) for the past 10 hours before going into this lockout mode again just a few minutes ago. Resetting (master switch on and off) worked again.

What I am now noticing is that each time this happens, the pilot on a gas fireplace also goes out (a pilot that has been on for 4 years) so I'm now wondering about that air in the line idea.

Any way to test this theory and would one-time bleeding the gas line fix the problem or would air keep being introduced? Is this a gas company problem?
 
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Old 01-06-12, 05:27 AM
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It's very unlikely that you are getting air in a natural gas line without the gas being shut off and the gas line physically opened.

Possibly you could be losing gas pressure to your home as an explanation for your symptoms, although that's unlike too.

Do you have other gas appliances other than the furnace and fireplace? If so, what are they?

If this was the explanation for the problem, you would notice that the size of the flame on the gas fireplace was greatly reduced in size when the pilot on the furnace wasn't lighting. So turn on the fireplace when that symptom with the furnace is happening and report what you observe.
 
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Old 01-06-12, 07:58 AM
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Thanks Seattle Pioneer,

Very informative. I wasn't sure how air would get in the line but I now see that it's unlikely.

To answer your question, I have 2 gas heaters, one in the basement for the 1st floor and one in the attic for the 2nd floor, a gas fireplace, a gas water heater, and a 4-burner gas cooktop. Only the gas fireplace has a pilot, everything else has a spark igniter.

I'm observing the fireplace and will report.
 
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Old 01-06-12, 08:08 AM
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The water heater doesn't have a pilot light?

You can turn on a range burner and get an idea of whether you have a low or no gas pressure problem.

That probability is low, but it can happen. It is more likely to happen during very cold weather conditions that might strain your gas utility's distribution system --- so what kind of weather have you had lately?

Also, do you have a gas regulator just before your gas meter on the pipe coming out of the ground?
 
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Old 01-06-12, 11:14 AM
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[HR][/HR]Water heater definitely has an ignitor.

Everything started on the first coldest day of the year (I remember because the attic was freezing). Today is mild (48 degrees) and I'm not experiencing problems today. May or may not be related to outdoor temperature.

I do have a gas regulator. Everything's in the basement. I'm attaching a pic.

Why did you ask about the regulator. Just this morning I was wondering if that could go bad.

 

Last edited by JustWannaKnow; 01-06-12 at 11:46 AM.
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Old 01-06-12, 01:21 PM
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If the gas utility was having a low pressure problem in your area, it would likely happen during exceptionally cold weather such as you had. Very likely, your neighbors would have had similar problems --- you might want to ask them.


With a regulator, your utility is typically providing gas at 30-50 PSI in a high quality system. It still could be inadequately sized for high demand, cold weather situations and cause a low pressure problem. Unlikely but possible.

Without a regulator, it would have been in a low pressure system, probably very old and a lot more prone to problems.
 
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Old 01-06-12, 02:25 PM
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2 last questions:

do gas heaters require a certain pressure level and do they provide that pressure level in the specs of the furnace?

and

could I have a plumber install some kind of pressure valve just before the furnace to make sure it has the right pressure. The flex yellow gas tubing runs up 3 stories (and some sections where it's horizontal); maybe that makes marginal pressure in cold weather low pressure in my house because of the long run to the attic. thoughts?
 
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Old 01-06-12, 04:09 PM
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The sizing on the yellow flex tubing is far more critical than that for steel pipe. Because of all the ridges there is more friction loss. If the line is small for the length of the run, especially if the gas pressure is marginal, the flex tubing could be the source of the problem. What seems strange to me is this just started happening. Have there been any additional appliances added in the past year?

SeattlePioneer is the gas expert around here. I'm just throwing things out as they pop into my head.
 
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Old 01-06-12, 05:09 PM
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You should find the gas pressure desired by the manufacturer specified on the rating plate in the burner compartment of the furnace. This is typically pressure measured in inches of water column (WC) with 24" being about 1 PSI.

I suppose you could get a pressure gauge installed at the furnace, but I wouldn't bother. It's unlikely that you have a pressure problem, but if you do it would be caused by the gas utility, and they would be responsible for fixing it.

Don't get too involved in fixing a problem that hasn't been diagnosed yet and probably isn't the problem. So far it's just guess work, which isn't a diagnosis.
 
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Old 01-07-12, 03:27 PM
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Here's another interesting piece of information.

Today the water heater went into lockout mode and one of the reasons for the error code shown was no gas or low gas pressure. So as unlikely as it is, I'm now leaning toward a utility problem. Neighbors are not having any problems. I have to wait until Monday to get the gas company out here.
 
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Old 01-07-12, 03:39 PM
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Please let us know what they have to say.
 
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Old 01-07-12, 05:06 PM
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I used to be the guy who responded to calls for service from gas utility customers. They ought to do a good job for you.


Strictly from a probability point of view, a utility gas pressure problem is a low probability. But that doesn't mean low probability problems don't happen, and three appliances arguably with a pressure problem certainly merit investigation.

I'd still be turning on your range burners from time to time to see if their is any indication that the flames are unusually low --- that would be another easy check on this possible problem.

One way the utility could test this problem would be to put a recording gas pressure gauge on the gas line. This uses a sheet to record the pressure for hours and days at a time, so an infrequent loss of pressure would be noted. It's unlikely the utility guy would have that kind of thing with him, but it's something he should be able to get from somewhere in the company.

You can probably impress the heck out of the repairman by asking about that!

Another test he can do is to put a pressure gauge on your fuel line and measure the gas supply pressure while ALL the appliances are turned up and maximizing demand on the gas supply. That would some weaknesses in the gas supply, but other might only happen at periods of peak demand for the whole neighborhood or area, although I'd expect other people to be having complaints if that were the problem.
 
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Old 01-07-12, 09:01 PM
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But as Grady said,

What seems strange to me is this just started happening. Have there been any additional appliances added in the past year?
These same appliances have been working together perfectly for the past 4 years with no problem up until Thursday before last when the attic furnace starting acting up, so something happened. Neighbors aren't having problems. So it's just me. Today we had a high of 65! There was no overall high demand for gas yet my water heater had no or low gas supply (and the furnace too although it wasn't on much of the day). I guess I'll know Monday or hopefully shortly after but I'm really wondering what this could be.
 
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Old 01-07-12, 09:04 PM
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Frankly, I'd call your utility company again and report the collection of symptoms you are experiencing. They ought to send someone out right away because your service is impaired, and arguably because of a defect in the service they provide.

In addition, they should want to observe the problem when the symptoms are clear, rather than delaying when an intermittent problem might go away.
 
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Old 01-07-12, 09:52 PM
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I'm just playing detective here. I'm sure this will be solved soon.

So I go to the basement to gather some information on the sequence of events with the water heater since that just happened today for the first time.

In the basement are the 1st floor heater, the water heater, and the gas meter.

I get to the basement and the water heater is in lockout for the 2nd time today. I reset it. It's an A. O. Smith Powershot with an inducer motor and an ignitor.

The inducer goes on, I hear the spark ignitor, and I hear a whoosh (not sure if it was the flame going on or off) and immediately after the inducer goes off. The system cycles 2 more times trying to light, then back to lockout.

BUT, I noticed 2 things since I was in the same area as the gas meter. Normally when the gas is on, I hear this high-pitched flow of gas sound coming from the regulator BEFORE the water heater or the furnace go on. This time I only heard a brief flow (1 second) AFTER each cycle - that's after the inducer motor went OFF each time to recycle. No flow of gas when the water heater was trying to light.

So I decide to check the 29 year old 1st floor furnace. I set the thermostat high. Furnace came on with no trouble and I did hear the gas flow in the regulator normally. While the furnace was on, just 2 minutes after the water heater had locked out, I reset the water heater again and this time it went on and stayed on with no problem. I turned the furnace thermostat down, the furnace went off and the water heater stayed on.

Also during all of this, the burners in the kitchen ALWAYS go on just fine showing no signs of pressure fluctuation, and after being on continuously through 4 summers and winters, the pilot on the gas fireplace hasn't stayed lit for more than a few hours since all of this began.
 

Last edited by JustWannaKnow; 01-07-12 at 10:20 PM.
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Old 01-07-12, 11:19 PM
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Sorry, the additional information doesn't give me additional ideas.
 
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Old 01-08-12, 06:35 AM
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At least I now know how to consistently and reliably turn on the upstairs furnace; just reset from lockout when the 1st floor heater is on and it will light.

So what I've been looking at as inconsistent behavior for the 2nd floor heater really has been consistent; if the 1st floor furnace happened to be on, it would light and if the 1st floor heater wasn't on, the 2nd floor heater wouldn't light.

Same is true for the water heater since yesterday.

It's a bit scary that the last post didn't cause an "aha moment" for you SeattlePioneer. I wonder what the utility guys will make of it tomorrow. (I get a recording when I try to call today, only emergencies and she hung up on me, not considering this an emergency.) I was hoping to impress them by telling them exactly what the problem was.

I'm going to read up on regulators. I know they rarely fail but this one is 29 years old. I find it odd that yesterday the water heater needed gas, didn't get any, but apparently just enough was released after the fact into the line for the next lighting attempt to get enough gas for a brief flame and then go out, and this happens again and again until lockout. And this is probably the same thing happening for the 2nd floor heater. I had ruled out NO gas to the appliance before because of those 2nd and 3rd attempts having a brief flame but now I see that the gas in the line was being replenished.

So the lockout was being caused by no gas rather than low gas pressure. For both newer appliances the lockout code says no gas or low gas pressure and I had been assuming low gas pressure but it has been no gas.

The older appliances don't know about lockout and just work, the gas fireplace (after relighting the pilot) will always work. The cooktop burners sometimes make this sound like a fan is blowing on them but always work, and the 1st floor furnace in the basement probably just opens the valve, gets gas and lights. The 2 newer appliances, water heater and 2nd floor furnace are the ones that fail.
 
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Old 01-12-12, 11:52 AM
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Update:

First my apologies to Heil for suggesting a problem with their (my) furnace.

Monday all problems stopped - worked perfectly for 3-4 days - no lockouts, all appliances worked perfectly and the pilot on the gas fireplace stayed on for 4 days. Then this morning, no gas at all.

The gas guy came out and reset the regulator. He unscrewed a cap, pulled back a plunger to reset it and left (he did put the cap back on). He said if it happens again, they'll replace the regulator.

I was reading that this was the Overpressure Shut-off that he reset. I was wondering what this means. Is this overpressure a symtom of a larger problem, overpressure one day, low pressure another? Or is the regulator just bad? Time will tell.
 

Last edited by JustWannaKnow; 01-12-12 at 12:32 PM.
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Old 01-12-12, 01:38 PM
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An OPSO is a safety system to shut off the gas should it the pressure become excessive for any reason.

It's a sensitive device. It might have shut off on a fluke, so resetting it is reasonable. So would doing further check if you have a repeat problem.

I think the utility guy acted reasonably.

Few home meter sets are protected by OPSOs. Most meter sets have a regulator that reduces the gas pressure and also has a vent that will bleed off gas should the gas supply pressure be excessive without shutting off the gas supply.
 
 

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