Propane Heater (Pool) Help

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Old 05-16-20, 08:27 AM
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Propane Heater (Pool) Help

Hey all,

Figured Id ask here because my issue isnt too far off from a propane water heater.
I'm opening the pool, and starting up the propane pool heater. This has a simple control valve as I've seen with propane water heaters. Anyway, I turn the control knob to pilot, push down and light the pilot. THe thermocouple gets warn and when I release the push button the pilot stys lit. I then turn to "On."

the heater wont fire when a heat call comes. There is a circuit with on/off switch, flow sensor (ensures water is flowing when the heater is on, and a overtemp sensor. I measure infinate resistance when the thermo is turned down (no heat call) or when I turn the on/off to off. When on, with thermo active, I measure about 75 ohms in the on/off circuit. This leads me to believe all protections devices (overtemp, and flow) are working??

So, I'm looking for some suggestions to troubleshoot the heater.

Any help is greatly appreciated.

Many Thanks,

Bryan
 
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Old 05-16-20, 09:00 AM
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Update: The valve is a HS820 V2099. The open circuit thermopile reads 75mV... I'm guessing the thermopile is shot? If so, where do I buy a replacement?

Thanks!
 
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Old 05-16-20, 10:49 AM
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Threaded moved to the pool forum.

Several problems.....
The control circuit needs to be as close to 0 ohms as possible. Since you're dealing with millivolts.... it doesn't take much to keep the circuit from working.

Yes.... 75mv open circuit.... is way too low.
It could be a defective weak thermopile or pilot flame not large enough.
The pilot flame needs to be fairly large and bushy to heat that thermopile.
A dirty pilot orifice is a very common problem on propane appliances.

Post the model number for the heater.
 
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Old 05-16-20, 03:12 PM
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Thanks for the redirect.

Its a Raypak P-R336A-MP-C with a VS820 H2099 Gas control valve,

Regarding the thermopile output voltage, should I try heating it up with a propane torch to see if I can get any more voltage out of it? I did wire brush the pilot and the thermopile to clean.

Should I check resistance of each safety (flow, thermostat and overheat) to see if one cultrip is giving rise to the 75 ohms?

If I short the switch and safety I hear a click (solenoid) and the pilot goes out. My thougt was shorthing would simulate a call for heat...

Any thoughts?
 
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Old 05-16-20, 08:17 PM
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Yes.... check the resistance of each device in the chain. A high resistance can be as simple as a slightly corroded connection.

Applying a dead short to the circuit would normally cause the burner to come on.
Since the pilot went out.... there's not enough voltage to hold the pilot valve open and main valve.

Page 44 discusses the voltages you should be getting.......
700mv open circuit -- 500mv with pilot valve -- 200mv with main and pilot valve open.

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Raypak manual (pdf)
 
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Old 05-17-20, 04:53 AM
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Thanks for the link to the manal and circuit.
I ordered a new pilot and thermopile assembly which I hope to have by Tuesday for installation.
In the interim I'l follow the circuit and get resistance measurements at all points to see where that 75 ohms is coming from.

I did notice that the pilot was hard to light, requiring some 3 min of holding down the control button before it would stay lit... It was also going out periodically yesterday once lit. My guess is still the thermopile but its a good time to open the cases a bit and clean things out to ekk a bit more efficiency out of this heater.

I"ll report back with findings.

Thanks again!
 
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Old 05-17-20, 08:51 AM
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Another update...
I traced all the resistances of the circuit and it seems the thermostat is acting up.
When I turn it up to a temp that calls for heat I go from infinate resistance to 0.3 ohms. Strangely, there is variable resistance in the middle of the temp range, and then back to 0.3 ohms when the therm is pegged. I'm guessing the momentary switch in the thermo is going.... Probably too much resistance to pass any current from the 75mV crappy pile.

So, I'm guessing I'll order a thermostat and replace that along with the pile and pilot. I'm guessing that should have me back up and running...

 
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Old 05-17-20, 10:22 AM
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I agree replacing the thermostat. It should always be down near .3 ohms when closed.
 
 

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