steam boiler with power venter

Del

Hi everyone-

     Was on a steam boiler no heat call today.  It was actually a simple fix, boiler was flooded and the 24V transformer for the LWCO and auto feeder controls was shorted out and the customer had fed the boiler with it still hot. Didn't want to take up the customers time figuring out the birds nest of wires, but it got me thinking about how the power venter was wired into the controls with the 2 transformers. Most of the steam boilers in my area are vented into chimneys.  Obviously it has a relay and pressure switch that closes and sends power to the other controls and gas valve. I'd assume something like this:  power from transformer---> thermostat---->power venter---->LWCO---->hi cut out/low cut in----gas valve.   What I'm also wondering about is if the second transformer was just for the call for water circuit (3 and 4) from the old float style LWCO with 4 terminals because the boiler fired even with that transformer out. (but the boiler still shut off on low water when I drained the system)



thanks!

Mike

Charlie from wmass

Lwco

maybe on the line voltage.

billtwocase

makes no difference

steam, hot water, or warm air, the power vent will and should be wired the same. Burner wired thru a fan proven switch, and a blower post purge of 3-5 mins. The power vent is called into action only when the burner is powered, and should have a seperate power source to complete the post purge cycle when high limit, pressure trol, or thermostat is satisfied. These are rarely wired properly. I know this by correcting them as I go.  peace