Raypak propane heater issue. M266A

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
I wonder if you can turn the gas off, try firing heater and check the flame strength. It should be 0 but if sensing flame through the igniter when there isn’t a flame it could possibly a board issue.
I have done that and it shows zero, but that was after it had run. I'll check in the morning. Normally it shows 8 which is good. You did give me an idea though. I may shut the gas off, try to run it to purge the propane, and with a propane torch to the igniter, see if I hear a click (or 2 from the gas valve).
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
To rule out a slow leaking gas valve I suppose you can place a fan near the face of the heater to try and air it out for a while before firing on a cold fire.
Exactly, I was going to do that, but when I cleaned and vacuumed the unit out, I was pretty sure any residual would have been gone. Immediately after that I started it and boom. I have come out in the early morning removed the front and sniffed the floor. Not leak detected.... and I can smell the neighbor smoking at the next property over. lol.
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
I have had one of these units that did this and it was a bad ignitor but you say you replaced part of it but not the entire ignitor. Why not?
I thought the propane orifice might have been clogged. Unlike the natural gas unit, this one (propane) is very tiny and hard to clean. Those igniters are a couple weeks delivery from East Coast online suppliers, but I got one in 7 days from CA.

OK, so just a short while ago I received the new igniter. I put the propane orifice in it and swapped it out. It did not help. Still starts with boom (delayed ignition) when cold, but fires normally when warm. I have a pre-owned control board coming, all set up for propane. I'll swap it out next. Not really hopeful. When I get a chance, I may pull the burner tray out again and try inspecting the heat exchanger on the right side, I can see through from the top down (mostly through the center), but the view on the pilot side is not that visible. I have an endoscope camera, so I may try an inspection using it. If I pull the burner tray again, I'll probably just replace the gas valve since it is a bit of work to do either of those jobs. I might as well do the stage two regulator too. This is a very frustrating situation and with out any diagnostic error codes, I can only replace parts.
 

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hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
Tried to run the endoscope camera up through the bottom, past the burners, to look at the bottom of the fins on the heat exchanger. Camera is not really good enough to tell if there is a lot of blockage, but I put the picture here. What is the best way to clean those fins? I have access to compressed air and if I pull out the burner tray, I could probably hit it with the pressure washer (90 degree adapter). I don't want to cause any damage. Would just a fiber brush, compressed air, and a vacuum be adequate? I'm still trying to follow up on the suggestion of insufficient draft when cold, and improved draft when hot.
 

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hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
Burner removed this morning. Inspection of heat exchanger fins from below with light and mirror. No blockage and looks very clean and open. When viewing from top, the bottom can easily be seen when pushing aside those diffuser baffles. Pictures on a best effort basis.
 

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ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,128
FL
Burner removed this morning. Inspection of heat exchanger fins from below with light and mirror. No blockage and looks very clean and open. When viewing from top, the bottom can easily be seen when pushing aside those diffuser baffles. Pictures on a best effort basis.
Yes looks good and clean. Even if they were dirty that would not cause a delayed ignition issue. With so many responses to this thread I might have missed it but have you had the propane company out to look at their things like the regulator on the tank and the one by the heater just to confirm there isn't something in that area that isn't just right. BTW, I read back on you earlier comments and wanted to let you know that the ignitor never shuts down when the burners are lit. Also, you say you inspected the board. So you removed it and inspected both sides?
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
Yes looks good and clean. Even if they were dirty that would not cause a delayed ignition issue. With so many responses to this thread I might have missed it but have you had the propane company out to look at their things like the regulator on the tank and the one by the heater just to confirm there isn't something in that area that isn't just right. BTW, I read back on you earlier comments and wanted to let you know that the ignitor never shuts down when the burners are lit. Also, you say you inspected the board. So you removed it and inspected both sides?
I did perform pressure checks on the incoming line to be sure my stage 2 regulator was set right. Everything checks out on the gas supply line. 11 in WC into the gas valve and 10 in WC out. I believe that is the spec for propane. All measurements are with burner firing steady state. A replacement board will be in soon. Thanks.
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
Possible clue!! After removing the burner tray, inspecting the heat exchanger fins, putting it all back, and testing propane lines for leaks, etc...... I fired it up (started with a boom), but I let it run for about 20 minutes. All of a sudden I heard some buzzing from the propane valve, and then it got a bit louder, like a chatter. I verified that the furnace was still running and heating, and put my hand around the valve. I could feel some vibration. That doesn't seem right. The supply control voltage on the display shows about 28 volts, but I think I need to check it at the valve. I am going to order a new valve too.
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
Replacement (previously owned) board did not do anything different. Acts the same. On to a gas valve replacement. I suppose the transformer could be intermittently opening or shorting even though the screen always shows 28. Very frustrating.

I found out there are two tabs that can be broken out on the control board for propane. One allows 90 seconds for ignition and the other 15 seconds. Manual says to choose according to local code. Mine have the tab broke out for 90 seconds (original installation) and same with the previously owned board that I just put in.
 

hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
I know I have a bad gas valve now because I just proved it. I removed the purple black main valve wire from the valve (MV lead), just leaving the pilot PV and the common PV/MV wires connected. I turned the furnace on and the main valve opened and it lit and fired off. I was rather shocked, but now I know why it is starting with a boom. Has anyone ever heard of that? I double checked the wiring, the labeling on the valve, color code of wiring, and the manual. This seems like a serious safety breach. I'm going to get my security bits and take the plastic cover off. Maybe there is a pest or a nest bridging the contacts internally.
 

Poolbreh

In The Industry
Jul 31, 2021
300
San Diego
That is unique, it didn’t show when the wc was tested? Pv opens first flame rectification mv follows. I guess it wouldn’t be noticeable if only checking the vac at leads. Either way good job. Now let’s build you a second heater with all your spare parts. 👊🏻
 
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hoosierrun

Well-known member
Mar 28, 2012
196
Tampa Bay, Florida
That is unique, it didn’t show when the wc was tested? Pv opens first flame rectification mv follows. I guess it wouldn’t be noticeable if only checking the vac at leads. Either way good job. Now let’s build you a second heater with all your spare parts. 👊🏻
I found a small spider under the plastic cover, but no evidence of any contacts being bridged. I even took the circuit board for the valve out. Nothing unusual on the back. I just don't see how this can be happening. No way you can see the other side of the board without destroying it, so maybe I'm not seeing something. In summary... it appears when the pilot solenoid activates, the main solenoid also activates.... even with the MV wire disconnected from the main valve.
 
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