millivolt system

[scrow]

I have an older gas heat only boiler with millivolt system.I installed a new thermocouple and new thermostat(2 wires red and white).Thermostat is battery powered.Everthing works fine,but 24 hours later the ciculator pump still comes on but the burner does not ignite.The same thing happens if I turn the switch off and turn it back on.If I remove the batteries and put them back in it works fine again until the next day.Seems like I losing the heat signal.
Thanks
Scott

[JCA1]

did the original thermostat have batteries? Milivolt systems normally use milivolt t-stats.

[scrow]

Yes the old one was battery powered.The new one states it's for millivolt systems.When I remove the thermostat and jump the wires the circulator pump comes on but the burner does not ignite.

Any ideas,thanks

Scott

[HayZee518]

does this system have a standing pilot? in order for the system to work you got to have a flame to generate the voltage to operate the main valve. I seem to recall a guy using a nine volt battery to operate his main valve on the burner. if I were you I'd check the high limit, and any other safety devices in series with the "stat" circuit.

[HayZee518]

i looked at a millivolt system on a web page - if the anticipator isn't set to the current on the main valve it will not work or short cycle until the contrl relay locks out.

[scrow]

The pilot works fine,new thermopile and new wire to thermostat.Everthing works fine,but 24 hours later the ciculator pump still comes on but the burner does not ignite.The same thing happens if I turn the switch off and turn it back on.If I remove the batteries and put them back in it works fine again until the next day.Sounds like it could be the short cycle problem.Where is the relay located,should I replace that next?

Scott

[HayZee518]

try this link looks pretty good.
http://www.toad.net/~jsmeenen/gasvalve.html