thermopile

jerryb46

Could some  one refresh my memory the millivolts a good one should put out? Thank You

RJ_4

millivolts

The newer pilot generators should produce 750 millivolts (volt reading needs to be done while generator is connected to gas valve and thermostat.  Some of the old general controls pilot gen. came in 750 and 250 millivolts.  If your having a no heat problem check the following

(1) Is your pilot flame strong enough, could have a dirty pilot or low gas press.

(2) check all your wire connections, if  possible restrip wire and make new connections

(3) make sure your t-stat is designed for millivolts  ( can't have a heat anticipator ).

furnacefigher15

It depends

There are 250 MV and 750 MV models



They can also be wired in series to provide more MV



If they either can't produce voltage, or drop significantly under load, try replacing them first.



Also make sure what ever controls are in the MV circuit are not restrictive.

Tim McElwain

The only generators

still around are 750 Millivolt.





The newer pilot generators should produce 750 millivolts (volt reading needs to be done while generator is connected to gas valve and thermostat. 





Actually the generator needs to be disconnected from the gas valve in order to get a correct open circuit 750 millivolt reading. The procedure is to be found here at RESOURCES above then LIBRARY and look for TIMS CLOSET.



(3) make sure your t-stat is designed for millivolts  ( can't have a heat anticipator







The TS86 thermostats (no longer avaialble) had a fixed anticipator which caused a millivolt drop across the thermostata of around 110 to 115 millivolts. You can set the anticiapator on a 24 volt thermostate to around .3 and it will work fine with a millivolt system.

Tim McElwain

A couple of questions?

There are 250 MV and 750 MV models



Where are you getting the 250 millivolt generators? There also used to be 500 millivolt generators. The 750 millivolt can replace any of those safely



They can also be wired in series to provide more MV



How do you wire them in series, what are you using for a pilot to heat the generators?







If they either can't produce voltage, or drop significantly under load, try replacing them first.



Also make sure what ever controls are in the MV circuit are not restrictive



Check the procedure here for testing powerpile/thermopile systems at RESOURCES/LIBRARY/TIMS CLOSET

furnacefigher15

Tim

Some older systems I've run across have multiple power piles built into the design. Multiple pilots for long burner racks. If memory serves me I think it may have been a Ackomatic, or maybe a Bryant boiler that comes to mind.



Regardless there were two pilots. Both pilots has a powerpile. The powerpiles were ran in series with one another, and in series with all the thermostats and the limits. There were 2 gas valves in this case, and they were wired in parallel I believe. The valves may also have been in series, I honestly don't recall. But I do remember the powerpiles being in series.

Tim McElwain

That is interesting

I have seen  systems with multiple pilots but never powerpile systems. The ones I saw were either gas actuated systems with differential pilots or those that were converted from gas actuated to powerpile one pilot for the generator the other was a standard thermocouple with a pilot safety switch wired into the millivolt system.