Boiler Will Not Fire Unless............

Portgas

I have a 35 year old Utica PEG-187S steam boiler running on a millivolt system. The gas control consists of a Honeywell



VS820 with powerpile.



The boiler will not fire up unless I momentarily short the two wires going to the TH terminals on the gas control. Once the



boiler runs, it correctly shuts off on its own when the programmed thermostat temperature setting is reached.



The pilot light works. I all checked the wiring and the low water cutoff switch.



Can anyone suggest what may be causing this problem?

Steve Whitbeck

PP

Sounds like the power pile generator is getting weak. shorting the tt terminals bypasses the resistance in the boiler operating controls, BUT once you short the tt terminals this opens the valve - once open it doesn't take as much power to hold it open.

Tim McElwain

Poertgas do the following

Go up to the top and click on Resources, then go to Library and look for Tim McElwains Closet you will find "Procedure for Troubleshooting Powerpile Systems. I hope it helps.

unclejohn

Try just

Cleaning the powerpile. Also check all the connections for clean and tightness if thats a word. you have to remember its a millyvolt system and that means there is very little voltage to begine with.

Portgas

That makes sense

I rechecked and secured all connections and that seems to have solved this mystery. I concluded that when working with no more that 750 Millivolts tight connections are mandatory. I suspect it may be time to remove the powerpile and measure its output. After all it is 35 years old.



Thanks

Tim McElwain

Unclejohn, not sure what you mean by

cleaning the Powerpile? Are you talking about cleaning the pilot orifice? Cleaning the generator does nothing to improve millivolts and in fact using an abrasive could do more harm than good.



The only way to properly diagnose a powerpile system is to take a complete set of readings with a meter and then chart them out. Just tightening connections may get you by but I can pretty safely say you will have another no heat call soon.