Pilot Generator Voltage


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Old 06-29-08, 04:42 AM
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Pilot Generator Voltage

I live is SW PA. I am having trouble with my Natural Gas swimming pool heater. The heater is a Pentair (PUREX) 150M CH MiniMax. This heater uses a millivolt control system with Honeywell components. The pilot burns steady but the burners won't fire. Following the schematic, I have tested the various limt and pressure switches (safeties) and they all read OK. The burners will fire up using a jumper across the TH and TH-PP terminals of the gas valve. I have also used a jumper to fire the burners in a way that includes the safeties.
The pilot generator terminals read 470 mV.
I read on another forum that a minimum of 500 mV is needed to open the gas valve. I changed the pilot generator. The new one reads about the same. I used a C battery to booster the voltage up to 1.5 mV and the burners fired. I used a propane torch to heat the old pilot generator and I was able to get 740 mV. I am stumped. Does anyone have a suggestion on how to proceed?
 
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Old 06-29-08, 10:29 AM
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Pilot Generator

If the valve opens when you use jumpers, the generator is putting out enough to operate the valve. I suspect you are getting a voltage drop somewhere. This is quite possibly due to corrosion, a common problem with pool heaters. What is the Honeywell number on the pilot generator? Knowing that, I can find out the rating. The number off the gas valve would also be helpful.
 
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Old 06-29-08, 03:27 PM
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Pilot Generator Voltage

The pilot generator is a Q313A 1170. It is rated at 750 Mv. The Valve ia a VS820.
I just found some interesting specs for the control TS820A millivolt control system. You can check it out at
http://vancontrols.com/pdf/hw/TS8205.pdf

I'll report back after some more trouble shooting. I recently bought a very nice multimeter and I have been looking for a chance to give it a workout. I just hope the rain holds off.

BTW: Thanks for the reply.
gsharpe
 
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Old 06-29-08, 08:32 PM
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Problem solved

The problem turned out to be a corroded slip connector on the sensor lead. I cleaned them up and the unit is running just fine.
Thanks for the help.
 
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Old 06-29-08, 10:04 PM
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Thumbs up All Fixed

Good job. With outdoor equipment or pool heaters exposed to the pool environment, corrosion is a common problem.

Coating the connections with electrically conductive grease may help to prevent future problems. This grease is available from any auto supply store. I use it on all the electrical connections on my boat & it really helps.
 
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Old 06-30-08, 04:51 AM
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Connector coatings

Is this the same as the dielectric grease that is used on the connections in meter sockets and breaker panels?

I used CRC 226 contact cleaner. However I have noticed that it doesn't protect from future oxidation.

On another note:
I am trying to find a compact AC evaporator coil for a house I am refurbishing. The plenum is only 18.5 in. deep, 16.25 in. wide and 30 in. high. Any suggestions? I may be able to use a separate air handle, but it must be a downflow model with top or rear inlet and a right side outlet.

Thanks,
Greg
 
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Old 06-30-08, 03:04 PM
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Evap. Coil

I have purchased a couple of "M" style coils which are only about 12" high. Not sure if they can be used in a downflow application or not.
 
 

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