weil mclain gas boiler problem

Ben Maggio

I have a weil mclane hydronic gas boiler with intermittent ignition.Model CGM-25P1, 48k, btu. I'm having a problem with the boiler relighting after the temp on the T-stat is satisfied. I replaced the honeywell round stat. The room temp was around 60. I set the stat to 72. The boiler ignition lit the pilot and then the boiler lit. It brought the room temp up to 72. When I arrived back a few hours later the boiler was cold. When I go to the boiler and jump the tstat and boiler stat wires together the ignition work and the boiler lites. I don't have to keep the wires jumped continuously. Just the initial touching of the wires sets the boiler in ooperation. It then operates as the stat is calling for heat. But after the temp is satisfied it will not relite thru the stat alone unless I go to the boiler and trip it out. Can anyone give me any clues.
Thanks, Ben in the cold

Unknown

What is the module

make and number on this package? Some modules have a tendency to do this. It is the elecronics in the module which is at fault.If I get the number I will look up the internal wirng and give you some further info. If you have a module put it in and give it a try so they will have heat. I have had this happen several times and replacing the module solved the problem. Let me know how you make out.

Ben Maggio

what module are you referring to? Is this the pilot relite. If it is, it's a white rodgers type 5059-21

ta finnegan

Low voltage wiring

It sounds like the ignitor assembly, but look into the low voltage wiring as well.

There may be a problem with the stat switch closing on the panel to put the igniter into action.

The troubleshooting guide with the unit should take you throught the proper sequence to better define the problem. If there is no installation guide with the boiler, go on-line and you can download one from the manufacturer.

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Unknown

White Rodgers Cycle Pilot

Some step by step instructions

1. With thermostat calling go to 5059 module and at T1 and T2 you should have 24 volts. Make sure you have a good ground from T2 to an unpainted surface on the boiler, run a dedicated wire if you have to. You will notice on the T2 terminal a ground symbol it is very important that you have a good ground from that terminal.

2. If not check your transformer and limits and wiring. If the limits and transformer are good I would run a temporary wire from the thermostat to boiler and leave it for a few days if it works with out failure then replace the old wire.

3. You should have a spark and hear a click at gas valve (solenoid opening) The pilot flame should light, spark stop, and pilot flame now be heating the plug in mercury pilot, typically plugged into the gas valve. In 20 to 30 seconds you should hear another click which is the main valve solenoid opening. If not then there is a pressure switch inside the gas valve which makes at pressure of 1" WC or greater up to 3.5" WC. Check your gas pressures before gas valve (5" WC or greater) and after the gas valve. If pressure is okay and main valve does not come in then the pressure switch is faulty and gas valve must be replaced. There is a plug in resistor that White Rodgers recommends but I have had problems using that solution better to replace the valve.

4. Make sure the pilot is clean and that the tip of the mercury sensor is glowing "cherry red" the pilot flame needs to be a little sharper than normally set on other pilots (mercury boils at a higher temp that is the reason for sharper flame)


Hope this helps.