The Mystery nobody can figure out

JEMM55

Intermittent Pilot Ignition

I still have this problem and it seems nobody can figure it out..

Ultimately I will be changing to a new powerflame burner due to this MYSTERY!!!



Loss of pressure across pilot solenoid



I have a Weil McClain model 580 with a Midco burner.

I am having a problem with the pilot.... it lights only intermittently when the boiler calls for heat or hot water.



Everything is freshly tuned...ignition, flame rod, all electronics ignition check out and there is excellent spark

The main gas pressure is over 6in col water. The pressure before the solenoid is also 6 after a 30 inch run past the regulator. The burner calls for 3.5 in column after the solenoid. BUT....No matter what I do the pressure drops to 1.8 max.

New solenoid, proper electric feed, everything clean but can't get higher pressure so the pilot is lighting only intermittently.



This is the mystery nobody can figure out...Any ideas are welcome........help?

JStar

Pilot

What model burner?



Have you checked if the pilot tap on the gas cock is blocked?

JEMM55

MIDCO ECONOMITE

Everything is clean...pilot lights outside of the boiler when tested.

Gas pressure is the problem





We thought of underpowered solenoid, blocked line...still no dependable pilot.

Always lights after several attempts....once enough gas gats into the system....



STILL A MYSTERY

billtwocase

possible

that the boiler is blocked?. Just a thought

JStar

Pilot

I would check for proper amp draw through the solenoid. You may be getting the right voltage, but not enough amperage to fully open the valve.

icesailor

I would also:

Try jumping out the solenoid with an alternate power source to see if you still get the low gas pressure when the solenoid opens. You say that the pressure is sub-specs when the control opens it. How about when YOU tell it to open? Like someone just said, maybe the power from control isn't correct.

Just a random thought.

Steamhead

Is there

a pressure regulator or other adjustment in the pilot gas line?

icesailor

Again I ask,

I was confused with another posting.

The below does not apply to this situation.

Again I ask, was the burner converted from Nat Gas to Propane? If it has the proper LP pilot orifice, and the gas valve is running under Nat Gas pressure, the pilot orifice is too small for the pressure and the pressure would drop like described.

If it's LP. shouldn't the gas pressure to the valve and the pilot orifice be 10" WC+? Do I remember that it was 3.0+ WC and it drops?

Whatever is wrong is stupid. Something is being over thought

Back to basics.

JEMM55

Natural gas...no conversion....

Still a mystery...the pilot orifice is not the problem!

unclejohn

Electrod problem

Are you measuring gas pressure after the valve on the burner side? I doubt you need 3.5 to the pilot. You may be arcing your spark to the inside of the boiler some where other then the electrod. You say it lights fine outside the boiler correct?

JEMM55

The electrode is at spec...spoke to Midco who says 3.5c.w. is correct.

The electrode on the end of the gun is in front of the orifice for the pilot and without the correct pressure it wont light

JEMM55

And there is no way to change the orifice as it is directly part of the gun

Therefore you cannot change the pilot orifice. Just not enough pressure.

JEMM55

And there is no way to change the orifice as it is directly part of the gun

Therefore you cannot change the pilot orifice. Just not enough pressure.

Zman

tunnel vision

Please map out your system for us. What controls the pressure to the pilot? How have you determined the pilot is correct and is not leaking? All mystery problems have one thing in common. The true cause was prematurely eliminated.

Carl

icesailor

Yup:

And one problem I have seen is leaking compression fittings on aluminum tube. I always lube the stuff with something as a lubricant/ Like Rectorseal #5.

I made up a "Rig" with a LPG outside regulator that drops the pressure to 11" WC and I can connect to my air compressor and connect it into a gas line going to a burner or whatever and not ruin the gas valve. A clever person could figure out a way to jump out controls and make a gas appliance run and instead of gas to the burner, you have low pressure air. You can then look for leaks. Without blowing yourself up.

No testing with live gas for this chicken. A couple of Presto-Taps and a refrigeration hose is a wonderful thing.

JEMM55

Pulling it apart tomorrow

Maybe this is being overthought.

Something has to be up with that run from the solenoid to the pilot.

unclejohn

Thi is a clue

MIDCO ECONOMITE

Everything is clean...pilot lights outside of the boiler when tested.

Gas pressure is the problem



How can it for sure be gas pressure if it lites fine outside the boiler?

nicholas bonham-carter

mystery

is there a reverse draft in the chimney, blowing out the pilot?--nbc

Mad Dog_2

Timmie Mc Elewain will

solve that.  Mad Dog

JEMM55

Not the draft

Pilot does not blow out.

Requires multiple starts to get enough gas to light the first time.



Not enough gas

RJ_4

pipe size

check your gas main to boiler is it the proper size, per burner manufact. is any thing else on that line like domestic hw or hvac equip. ?  If your burner is 580 mbh than you most likely need around a inch and a quarter to inch and a half line depending on how far from gas reg.  also check gas reg make sure orfice is the right size. I would also check the burner plate for cracks or to see if it is warped.