Just had my boiler cleaned last week. As part of the cleaning, the service technician checked the transformer by placing a screw driver across the 2 high voltage clips. He noted that since there was not a good spark arcing between the clips, the transformer was too weak; it would need to be replaced. Unfortunately, he did not test the actual voltage output of the transformer, and I did not think to ask him to do this. He also noted that the Franceformer I had was rated for 10,000 volts and should be replaced if the volts drops down to ~9,500 – to 9,600 volts, even though 9,200 volts would be sufficient for proper burner ignition. The Franceformer (according to the service technician a tar filled iron core transformer) was replaced by a Carlin Electronic Ignitor made for the Weil McLain QB 180 burner (Model 41000S0WM). Now I'm curious as to what the actual voltage output was for the Franceformer. 1. Is there a way to test the transformer voltage now that it is disconnected from the burner, and if so how? 2. What kind of a test device is needed and what is the device connected to – the 2 wires for power to the transformer, the 2 high voltage clips, or both? 3. If the transformer can be tested, then will the voltage shown under test be the same as the voltage generated for proper burner ignition if the transformer was still on the burner? Thanks for your input.

Hello, We have a Janitrol, GMT model 70-4, power-vented gas furnace. The furnace ran fine for about 10-yrs., then began "cycling" on cold mornings. A pressure switch was replaced by an earlier HVAC mechanic. The furnace tests fine during the warm day, but in the mornings the furnace begins the first cycle by: 1. Being called to heat by the wall thermostat. 2. The vent blower is energized. 3. "If", the safety circuitry is in the normal position, power is supplied to the ignition module.[B] ~ And there all progress stops. ~[/B] 4. The HSI does not light the burners. It will try about three times at intervals, (makes a dwoup, dwoup,. dwoup, sound, then shuts off for about 3-minutes.) Somewhere in the manual it says "that's a normal function if something's wrong". I called a HVAC trained mechanic. He tested everything. Pulled the pressure switches rubber tube off of it's base and blew into it. No restriction. He asked if the vertical vent was double-wall? Yes, it is. He seemed to feel that the vent line was too restricted in size diameter, by being double-walled, and wrote "exhaust problem" on the service call work order. They state that "this furnace uses a vent pressure switch that prevents the furnace from operating should any portion of the vent system become restricted, or a venter failure occur. To check this switch, place the furnace in operation and remove the hose from the switch. The gas burners will extinguish. Replacing the hose will allow the furnace to operate normally." [B]So, I've clean the "reusable, washable filter" and have not changed any of the vent pipe configuration since it's installation.[/B] [U]Venting.... seems to be my problem.[/U] After about [B]5 or 6 cycling attempts[/B], the [B]HSI ignites the burners[/B]. ....and all is well: 5. The flame sensor detects the presence of a flame and the main burners are allowed to remain ignited. 6. The circulatory air blower is started at a predetermined time. (approx. 30-seconds). ••••••••••••••••••••••••••• Any thoughts? I'll come back with photos and model btu specs. etc. THANX!