low gas pressure to heater

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E

e2015

0
Aug 10, 2015
18
Philadelphia, PA
The heater for our newly build IG pool stopped working after about 6 weeks. You can hear it fire up but then go out after 1-2 seconds. After a few cycles, the heater locks out and returns an IF (ignition failure) error code. Water pressure is fine, and orifices are clean. PB sent out their service company who reported that the heater appears fine but that the gas pressure was too low (0.09" instead of 2"). Sounds like there is a gas leak; PB says he is working with his plumber to get it fixed.

In the meanwhile, should we be concerned about this potential leak? Or is it safe as long as the heater is off? There is no discernable gas smell now although we used to smell some gas when the heater was running.

Thanks.
 
Is this natural gas or propane? Propane is some times harder to smell as it will pool lower towards the ground since it is a heavier gas. Do you have a shutoff valve for the gas supply? If so, and it doesn't prevent you from using other gas appliances, shut it off.
 
If you suspect a gas leak then you should absolutely contact your gas company. They have trained professionals with gas sniffing equipment that can locate the leak. Do this for your safety.

Is the gas line to the heater an single run or does it feed other equipment like BBQs or fire pits?


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e2015 said:
Gas line only runs to the pool heater. PB's plumber was supposedly contacting the gas company, but I will make sure somebody does. Thanks!
Click to expand...

Excellent. Glad it's a single run. My gas line splits between the pool heater and the BBQ/fire pit. I'm always fearful of the day when my yard will need to be excavated looking for a gas leak :(


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Follow-up with a little more information: gas company came by and reported that the gas pressure delivered to the heater is 7" of water column. Once the heater is turned on, that pressure drops to 2". No detectable leaks.

PB gas plumber claims that this must be a gas meter/pressure issue although he cannot be more specific. He points to the pressure drop and concludes that the heater is not being supplied with enough gas. He does admit that his theory cannot explain how the heater was working for the first 4-6 weeks after pool opening.

A technician from the pool equipment service company suggested that it might represent a defective diaphragm inside the heater. He says he will look into it further, but I fear that the PB is going to force a prolonged back-and-forth with the gas company before addressing this.

Does any of this make sense to the experts? Am I wrong to think that the problem must reside within the heater unit?

Thanks.
 
Gas meters themselves are fairly uncomplicated things and its rare for them to go bad (they're design to take a beating). For NG, it's all about volume and flow as the pressure in an NG line is only 1-2psi (for safety reasons). Therefore you have to be extraordinarily careful about how many NG appliances hang on a single run. If you have a flow rate hog like a BBQ or fire pit, which is like an open gas line, then it's easy to knock out things like heaters as they have very sensitive flow switches in them.

Since you only have one appliance on that line, I've got two thoughts -

1. The service meter that the gas company put on your main is too small for all if the gas appliances in your home ;

2. Defective diaphragm valve or gas switch inside the pool heater.

When we put the NG heater in for the pool, I also had a fire pit and BBQ on the same line. The gas company asked me for the total number of therms I had to supply to all water heaters, ovens, pool heaters, etc. When the gas company did the connection, I needed a new meter that was the next size up for a residential home. If I did not get that new meter, I was at risk of extinguishing my hot water heaters if I ran the BBQ or pool heater.

As for the pool heater, only a technician from manufacturer is going to be able to definitely diagnose a problem.


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The gas company guy went through our house and took all of our gas appliances into account; he concluded that our meter was just enough to supply everything. So although he said that we could consider upgrading our meter, it still does not explain why the pool heater is not working when nothing else in the house is on (oven, dryer, etc...). And even for the long term, I do not think we will ever be heating the house and the pool at the same time.

Thanks for the input. We will press them to follow-up on looking for a problem within the heater.
 
OK.

Can you isolate the house from the pool heater? What I'm getting at is if you can isolate the house and try to run the gas pool heater and it fails, then the PB can't argue that's it the gas company's fault. It has to be something internal to the pool heater.


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Hayward's are extremely picky on gas pressure. It surely can NOT survive on what you are saying. In fact, take the front of the heater off and you will see a label telling you what you need coming in to the heater and what is needed on the manifold side, after the gas valve. If you are not very close to the numbers, no go on the heater. It might have worked before but maybe for some reason you have something else gas related that is running at the same time as the heater. I do not see a bad diaphragm in the heaters gas valve. I've never experienced that. Here is a exert from the heaters manual. I would say you should have the maximum coming to the heater, 10.5" WC and then see how the unit works. Did they measure it on the provider side and on the manifold side?

Gas.jpg
 
Maybe a dumb or redundant question - what size gas line was used to feed the heater? If the diameter of the gas line is small and the run length is long, the pressure drop can be significant.

I have over 150' of gas line but the PB's plumber ran 2" line all the way from the service meter to the equipment pad.


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JoyfulNoise said:
OK.
Can you isolate the house from the pool heater? What I'm getting at is if you can isolate the house and try to run the gas pool heater and it fails, then the PB can't argue that's it the gas company's fault. It has to be something internal to the pool heater.
Click to expand...

That is a good idea, but I am hesitant to turn off gas to the whole house as I have never re-lit pilot lights before. I can approximate your experiment by ensuring that all gas appliances in the house are off.

ps0303 said:
Hayward's are extremely picky on gas pressure. It surely can NOT survive on what you are saying. In fact, take the front of the heater off and you will see a label telling you what you need coming in to the heater and what is needed on the manifold side, after the gas valve. If you are not very close to the numbers, no go on the heater. It might have worked before but maybe for some reason you have something else gas related that is running at the same time as the heater. I do not see a bad diaphragm in the heaters gas valve. I've never experienced that. Here is a exert from the heaters manual. I would say you should have the maximum coming to the heater, 10.5" WC and then see how the unit works. Did they measure it on the provider side and on the manifold side?

View attachment 42943
Click to expand...

We did see that the inlet pressure range was 4.5-10.5". The gas company measured 7" of water column both at the gas meter (at the side of the house) and at the pipe just outside the heater. He said that since we are getting 7" (with the heater off), then the heater should be getting what it needs. Are you suggesting that the drop to 2" after starting the heater is normal and that I should have the pressure increased so that it stays above 4.5" even after the heater is turned on (i.e. raise it to 10")?

JoyfulNoise said:
Maybe a dumb or redundant question - what size gas line was used to feed the heater? If the diameter of the gas line is small and the run length is long, the pressure drop can be significant.

I have over 150' of gas line but the PB's plumber ran 2" line all the way from the service meter to the equipment pad.
Click to expand...

Interesting question as the gas company guy mentioned that as well. The pipe leaving the gas meter towards the pool heater appears to be 1.25" but when it re-appears next to the heater, it looks like it is only 1". The gas plumber dismissed this and said that the pipe diameter was large enough for the length of the run (about 15 feet).

Thanks for all of your thoughts on this. Last we heard, the gas plumber is returning tomorrow to meet a foreman from the gas company at our house to review the situation.
 
I just saw your new post...I would start with the basics. How far is the run from the meter to the appliance? What size line was used? How many BTU's is your heater? Many times, the appliance will run on pressure that is too low, but it won't for very long (6 weeks in this case). You may need to upgrade your meter to high pressure and put regulators on the house and appliance side to drop it back down to 2". This will supply enough gas to both and you shouldn't have to mess with the in-ground plumbing...
 
Are you sure that the table (15) provided above, doesn't have a note attached to it stating that those readings MUST be taken while the heater is RUNNING? And that the difference between idle WC and running WC can only vary by 4 inches WC? I'm looking at a Sta-Rite manual for their Max-e-Therm, and the table they list has that note attached to it. I realize that these are two different manufacturers, but the numbers are very close (max inlet= 14 WC and minimum inlet= 4 WC). I think the easiest thing to try first would be to have the gas company come out and give you a "pool upgrade" meter. This would be a meter that is capable of delivering in excess of 400K btu.

This could very well be a free service from the gas co. Since it would mean an opportunity for them to supply MORE GA$ to you.
 
Pool Clown said:
Are you sure that the table (15) provided above, doesn't have a note attached to it stating that those readings MUST be taken while the heater is RUNNING? And that the difference between idle WC and running WC can only vary by 4 inches WC? I'm looking at a Sta-Rite manual for their Max-e-Therm, and the table they list has that note attached to it. I realize that these are two different manufacturers, but the numbers are very close (max inlet= 14 WC and minimum inlet= 4 WC). I think the easiest thing to try first would be to have the gas company come out and give you a "pool upgrade" meter. This would be a meter that is capable of delivering in excess of 400K btu.

This could very well be a free service from the gas co. Since it would mean an opportunity for them to supply MORE GA$ to you.
Click to expand...

You are correct. After checking the manual, the 4.5-10.5" inlet pressure range is for pressure readings with the heater running. So I think we are clearly back to blaming the gas supply.

Looking deeper into the manual reveals that the heater placed 0-50 ft from the gas meter requires 1.25" piping. I will double-check, but I think the pipe coming out of the ground near the heater is only 1". As far as I understand, this may explain the large pressure drop when the heater is turned on, but it would be far simpler to fix this by just increasing the inlet pressure. Am I correct in assuming that this will not cost me more when using the house appliances as they each have their own regulator and will only take in what they need?
 
e2015 said:
You are correct. After checking the manual, the 4.5-10.5" inlet pressure range is for pressure readings with the heater running. So I think we are clearly back to blaming the gas supply.

Looking deeper into the manual reveals that the heater placed 0-50 ft from the gas meter requires 1.25" piping. I will double-check, but I think the pipe coming out of the ground near the heater is only 1". As far as I understand, this may explain the large pressure drop when the heater is turned on, but it would be far simpler to fix this by just increasing the inlet pressure. Am I correct in assuming that this will not cost me more when using the house appliances as they each have their own regulator and will only take in what they need?
Click to expand...

A short stub of pipe (3/4" to 1" diameter) is not at all unusual for connecting to equipment. What matters is the diameter of the buried pipe. As I said, I have 2" diameter gas line that is ~150' run length. When in emerges above ground either at the service meter or the heater, it is stubbed down to 3/4" to fit the equipment.

But yes, I think you don't have enough pipe volume to handle the intake rate of the heater. Remember, NG is all about volume. The system is intentionally designed to be low pressure to reduce the hazard of an accidental leak unlike propane tanks which are higher pressure. So, in order to make up for the lower pressure, you typically need larger volumes to avoid pressure drops. The gas company may be able to fit you out with a new meter and boost the pressure a bit.
 
Boosting pressure is not the correct fix. Like you said, it's all about volume. You can only get so much through that gas line so that is what needs to be larger. If you decide to compensate for that short coming by increasing the pressure, you can and will damage the gas valve (diaphragm) that is only designed for lower pressures, rather inches of water column.
 
Just to bring this thread to a conclusion...

Gas company came out again and upgraded our meter. I was not home at the time so have no idea how much pressure we are getting, but the pool heater now works!!!

Even though the pipe coming out of the ground near the heater is only 1" and is then stubbed down to 3/4" to connect to the heater, the PB plumber assures me that the underground pipe is 1.25" (which is what the heater manufacturer requires). Not sure if that is true or if the increased pressure was enough to compensate for the smaller piping.

Thanks for all of your ideas and guidance.
 

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