Gas regulator/ Meter problems.

Al_12

I am seeing alot of meter/regulator problems on my service calls. Mostly on large btu units (500,000 and greater) At standing pressure is normal About 6.5"wc to 8"wc inlet. On main flame we will drop about 2" wc to 4.8"wc to 5"wc. I have always gone By the half inch rule, Meaning the inlet pressure should not drop more than a half inch of water colum. The main problem is intermittent lock outs for no reason. I have put in for a meter/regulator check with the gas supplier which always comes back as "the regulator is fine, We have 8" of wc." The problem is they are not checking the supply pressure at my valve only at the meter which could be 50-150 feet away. The piping and friction losses are not an issue due to the fact that these units have been operating for many years. Any ideas, Oh and we are on long island.

Unknown

The rule is NO

pressure drop with full load. A pressure drop says something is wrong.

I assume your pressure drop is at the equipment itself. Try checking your load pressure both at the inlet to the gas valve and at the same time at the outlet of the meter. If your pressure is steady at the meter and not at the valve then your piping is undersized or partially plugged.
You state in your post that is not the case but I would do a pipe sizing calculation just to be sure. If the pressure drops at the meter then I would suspect the meter. Have new or different meters been installed recently?

You mention this only happens on 500,000 BTU equipment or higher. Do you have a low pressure control on that equipment?

Is the meter sized correctly? What does the utility say is the allowable drop across the meter?

What kind of regulator do you have on the equipment?

Rich W

PD

Sounds like a large meter set. If it has a bypass around the meter have the gasco test with it open. You may have a problem with the meter under high loads.You have to prod those guys sometimes.(I was one for 20 yrs.) Good luck.

Rich W

OOPS

Duh, I didn't read the first response. Dito what Tim said.

Al_12

Tim, in my area a 1/2" drop is the least that i can expect. Yes there are low pressure cut outs usually set at 3"wc and 10" high. Again these are old sytems which were never a problem before. Powerflames, 500 cfh and up with honeywell and fireeye controls with flame signal within the parameteres 3-5 vdc. Do you live on long island?

EBEBRATT-Ed

In the areas I work the pipe sizing is based on 1/2" wc/ 100 feet. I think this is typical. The other posts are correct you must check the pressure at the meter outlet. Subtracting the two will give you the piping pressure drop.

Is there a possibility of overfiring the unit?? If firing into a negative draft or induced draft boiler for instance and the unit calls for 3" of wc to get full capacity and say you have 1/2" neg. furnace pressure you would only set the gas pressure to + 2 1/2" to get capacity.

Also you could check for excessive fittings in the run.

Ed

EBEBRATT-Ed

What model Power Flame have you got?? Most likly a J or C Burner. I worked for a company that used to rep them. Chances are you could have pilot trouble is the most common thing with those.
ED

Al_12

Tim, As far as a pressure drop is concerned this is not only an issue of high hp systems, I see it on residential appliances as well. I wish i had the time to wait for the gas co to meet me on each job without crying wolf for a gas leak.

Al_12

Ed, Most of my work is on large municipalities I.E, nys,towns, I personally conduct a start-up when possiblle and replace worn flame sensors, ignitors, sight glasses flush l.w.c.o. ect. I spend no expense at doing the right job. You know whats fuuny? when you make a call from a certain muncicipalites the gas co shows up real quick.
Go figure???????????

Al_12

What happened? Is my gas going to be turned off?

Al_12

Oh Boy,Its getting cold in here, I think They shut off my gas, Thats it i am moving to florida.

EBEBRATT-Ed

My experence with Power Flame is when getting nusiance lockouts and can't find a reason it would usually turn out to be the pilot. They will work every time--till you walk out the door. We used to scrap the single pole 6,000 volt and put in a single pole 8500 volt. We used to find jobs with low voltage say 112 volts and with the 6ooo you won't get6000 out with only 112 input. We fixed a lot of jobs with the 8500 We had jobs where they shaved the gas (Berkshire Gas Pittsfield, MA.) and put propane in in the cold weather and they would not work dependably with the 6000

Maybe you have had the same problem.

Unknown

No I live in RI

why do you ask?

Bob Harper

Regulator lock up?

What was described sounds like a regulator locking up but not releasing immediately once the pressure reaches normal. When high BTU appliances suddenly shut off with a quick valve, the line pressure spikes. To keep from damaging equipment, many regulators have what's called a Full LockUp. This means the regulator closes quickly until the pressure bleeds off such as by a standing pilot. The lockup pressure should not exceed 130% of the regulator setting. A quick rise above this indicates the piping is undersized or the regulator has a worn seat. Continue monitoring the pressure with all appliances off for at least 5 minutes. If the pressure continues to rise slowly, this is called "creep" and indicates a dirty, damaged, or worn seat.Either way, the regulator should be serviced/replaced but it also may mean the piping is too small.
HTH, Bob

Tom Blackwell

Years ago I had this problem with a string of fast food restaurants near Carrollton,Ga. We continued to check out no heat calls-always got there after noon. Well, arranged for early visit and found gas pressure downstream of the meter at 1" with units trying to fire. Contacted gas co and was met by a knowledgeble individual that knew the answer. When gas services are tapped off of a high pressure main, the actual hole cut into the main is an orifice sized for the load so if there is a break the gas loss would not be so great. The main pressure was lower than normal due to system problems. They enlarged the tap and the problem went away. Finding a utility that will admit guilt is rare indeed.

Al_12

Thanks for all your input Guys, About a month ago had the same problem with a 5-ton rtu 125,000 btu, Back and forth, Back and forth, with the gas co. I say regulator, they say no. I say regulator, they say no. Anyway I refused to come back to the call intill the gas co replaces the regulator. Customer was not happy and got involed with the gas co. Gas co replaced the reg, No more lock-outs the Customers happy, I am happy, Life is good.

Boiler Guy

Gas Co

can do NO wrong. After all most of them went to utility school for 3 weeks. What the heck does a 25 year tech know about gas supplies anyway? Sound familiar?