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Let me know when you're at the unit and ready to troubleshoot
Back online this morning. Let me know when you're ready.
Right now I'm free to help you with this. That may not be the case if you don't get right back to me. But I'm online until ~7 pm EST. I do take breaks. But most likely if there is a delay it's because I'm helpng somebody else and I'll get back to you asap.
So what's the current snafu?
Do you have 24 vac at the gas valves PV & MVPV terminals? terminal designation could also be TR & THTR
Do you read 24 vac at the transformer?
Do you read 24 vac across terminal 1 (sould be connected to PV) and the multiple ground terminal?
Then you have a bad connection between the ignition control and the gas valve.
I don't know what you have for leads but based on what you're telling me you have 24 v at the control but not at the valve. The only thing it can be is a bad connection. If the leads look good I'd replace them. You could have an internal break that you can't see.
Honeywell terminal designation is usually (I've never seen different) PV, MV & MVPV. I can't tell you their relative positions. From the pic I have of your Fenwal PV, MV is indicated and MVPV would be GND/common. It might be easier to just spin the valve so you cn see the terminals.
If you don't have ~24v to the valve it won't work
As far as gas line size goes, 3/8 (OD copper?) is pretty small even for propane but it might be OK. It's certainly enough to light the pilot
I agree the problem is electrical. Electronic ignition valve terminal designation is PV, MV & MVPV
I'm here until ~ 7 pm EST other than breaks. I'll respond as soon as I can
Sounds like a flame rectification/sensing issue. Check the flame sensor, sensor lead
If the flame drops out that fast it's almost always the flame sensor
Is the pilot flame enveloping the flame sensor?
No work around. The flame sensor puts out a tiny amount of current measured in micro amps when it is sensing the flame. So any stray voltage can foul up that signal. You can get stray voltage if you don't have a good chasis ground connection to the ignition control. In this case the mounting screw holes are metal lined which is supposed to provide the chasis ground when it's mounted to the unit.
Does the pilot continue to arc once the pilot is lit?
Ok, if the igniter stops arcing then something other than flame sense is causing this to drop out. Next time fire it up but have your meter probing the 2 terminal and the common. If 24 v drops out you need to trace back along that lead and jump out each device one at a time until you find the one that's causing the problem
You need to track down where the voltage is dropping out. I only see a limit and draft pressure switch in that leg of the circuit. Maybe jump out your thermostat too.
Ok then the limit and the pressure switch
You said you had 24 v at the transformer. You have to track down where that's getting lost
Maybe a bad connection between. Put one probe on common the other at every connection point on that circuit all the way back to the transformer
I've never had occassion to take that reading before. I couldn't tell you if it's an anomaly for sure or not. Seems like you shouldn't read continuity but I don't know. I thought this was a new valve. If you remove the lead from MV does the voltage down stream recover?!
Assuming a 1/2" manifold.
Then the above linked valve is suitable. It has a 150k capacity and since your unit is 100k this will do the job.
This thread never goes away. You can always access it
I'd appreciate it. I'll answer related follow ups even after you rate me favorably
Heat anticipators don't fnction during start up only on shut down.
Wiring diagram shows draft pressure switch and the limit in series between the stat and the ignition control. Since you have the stat jumped out and you have 24v at the transformer and a new control then the only thing left is one of those 2 devices. So easiest option would be to jump them out 1 at a time and see what happens. Generally you can't jump out the draft switch until after the draft inducer fan starts.
The pressure switch proves that there is adequate draft present. So it's a primary safety device and can't be safely bypassed. If the switch isn't closing then either the switch is bad, draft is inadequate or the tubing connected to the switch is blocked. Since the only way to confirm adequate draft (check for obstructions in the fan blades or exhaust vent) is with a (pricey) manometer, once the other things are ruled out replacing the switch is a resonable approach.
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Note the associated dates. Switches usually have a pressure rating on them in inches WC. Usually a fraction of an inch. If your switch has such a spec then you can even use a generic switch. If you don't know the date of manufacture give me the serial number and I'll see if I can find it.
My source puts an AD date code at 1978. I doubt this is possible since unit heaters that old didn't have draft inducers. All that leaves you with is the info on the switch.
You can always contact a Reznor dealer for that part.
It will work but like I said before it is a primary safety device. You risk filling the space with exhaust should the inducer not work when the switch is jumped out