Hello all.
This is an old weil mclain e.g. 75. Pilot is on, but the unit will not start. Changed the thermocoupler and nothing happen. Jumped the 2 wire mercury thermostat and still nothing. A week ago I had electric power problems in the house like short drops lights will dim a bit and came back to full power, computer was shot down and so on. Con Ed came and fix it outside at the pole. Is this problem may have something to do with the boiler? Maybe something went wrong with the control transformer (24 Volts) .
This is the first attempt to start the boiler after the summer and the pilot light was on all this time (for nothing - last time I'll do that! )
Any help?
Thanks in advance, shartov.

Check for 120 volt power to the boiler
Then check for 24 volts out of the transformer
If both of those check out OK then you will have to use your electric meter to back track the circuits till you find the one holding off the boiler.

Hi... thanks for the reply... the transformer and boiler has power... no power at the thermostat.

You are at this point now.

If both of those check out OK then you will have to use your electric meter to back track the circuits till you find the one holding off the boiler

Thanks for the advise... I found the problem at the rollout fuse... boiler is working now. :)

Good deal and it did not hurt to bad. PS I hope you replaced that very necessary safety device and also located the reason for its failure.

Hello there and thanks for the concern... yes, I did replace the ceramic rollout fuse the reason to the problem I found too... last year when I replaced the thermocoupler the supply tube to the pilot broke and local store got me similar but larger tube which with the time leaked gas to the botom... I notice fire on top and botom of the pilot... I guess this extra heat fail the system by breaking the rollout fuse. I change the gas line tube now to the correct size. Wow... thanks again

I hope your problems are solved.