Pilot on Powerpile

MIKE6

Milli volts are tricky,you need a nice blue flame hitting the generator and it should be cherry red,watch the pilot when the main burner comes on if it pulls away from the generator clean it.If it is lazy clean it.Next it could be a weak generator,or a weak magnet in gas valve,or poor pressure to unit

JM_2

The Pilot

on my Burnhan steam unit (1974) has gone out three times this season. after the second time, I cleaned the pigtail on the low pressure pressurtroll.(the one set to .5psi). The safety pressuretroll which is set to 6psi i did not touch. Any ideas what might be causing this. There is a second unit in the basement which is fine so I dont think the wind is causing it. each time i relight it it runs for a week or so.
Thanks.
JohnM

ken D

what is the millivolt reading on it? It creates DC current through the heated tip to keep solenoid open. Maybe current isn't enough? Pile tip not aligned in the pilot flame properly? Maybe it's bad?

Joe_45

powerpile

The output reading from a new, properly adjusted powerpile should be around 750 mv. If the output is less than 500mv., you have either a poor pilot or a bad generator.

ed wallace

powerpile

check the wiring diagram i believe the safety pressuretrol is wired to the thermopile if thats the case then i would think its due to primary pressuretrol not operating

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

larry_9

Thremopile

I find that a new thermopile runs at 240mv maybe 230mv but anything over 200mv will operate the gas valve. I have read as low as 76mv that will opperate the pilot only. That is with a fluke 16 meter reading dc volts on millivolts other setting give to much of a fluctuation with my reading I have also used a uei same setting with the same results.

larry

JM_2

560 milivolts

is the reading. The thermopile isnt as cherry red as the other unit in the building.

Unknown

If 560 millivolts

is your open circuit reading it is low (minimum allowed is 540). The tip of the generator should not be "cherry red" it should be "dull red". If it is "cherry red" the pilot is adjusted too sharp and needs to be softened up,too sharp a flame will weld the tip and shorten the life of the generator.

A typical set of readings with a steam system using a TS86 Honeywell Thermostat with 30 feet of 18 gauge wire,a low water cutoff and pressuretrol and any self generating gas valve are as follows:

Open Circuit 750 millivolts taken with generator disconnected from the gas valve.

Closed circuit 360 millivolts taken with leads connected back at "PP" terminals on the valve and the meter connected to those leads.

Closed circuit (Jumped out) 270 millivolts taken at "PP" terminals with a jumper across "TH" terminals.

Now move the meter to the "TH" terminals after removing the jumper a typical reading is around 175 millivolts or less.

Now test across each switch:

Pressuretrol 0 to 10 ideally "0"

Low water cutoff 0 to 10

Thermostat (assuming a TS86 110 to 135 millivolts)

30 feet of 18 guage wire 60 Millivolts this can be determined by adding up all the readings across the controls and then subtracting that reading from the TH reading. If it is high you need to look for bad splices and loose connections or replace the wire (make sure it is 18 gauge and not 20, 22 or 24 guage)

Now reconnect your meter to the PP terminals and blow out the pilot the valve should drop out "audible click" at 95 or less.

After the pilot drops out relight the pilot and turn the valve to on position the valve should pullin at between 179 to 320 millivolts, (burner should come on) any more than that replace the valve.

John I need to know what controls you have in order to give you the next info you need.

Gas Valve make and number? This will help to give diagnosis if pilot keeps going out.

Remember pilot outage can also be caused by a combustion problem. Do you have a combustion analyzer?

Unknown

The pressuretroll

connected into the pilot generator line should be set to shut off at 14 lbs pressure cut back in at 9 lbs pressure (set cut in to 9 and differential to 5). It is wired in to function as a limit. If it is set too low it can cause premature shut down of the pilot.