Modine Hot Dawg 45K won't light

[56servi]

Bought a used Hot Dawg heater last summer. Just installed this week. Won't light.
HD 45AH0134
s/n 30011023399
circuit board date code 1999

5.5" gas pressure into gas valve
0" gas pressure out of gas valve

Turn on & purge fan runs for about 20sec
spark igniter goes on (glows red)
gas valve solenoid clicks on
0 gas pressure out of valve
spark igniter goes off
fan turns on
LED on gas valve blinking on & off
repeats sequence 3 times then LED blinks 6 times

took bottom plate off gas valve & solenoid goes up & down easily
2 solenoids on gas valve. Checked both coils and they have continuity.

The hot dawg manuals on line are slightly different. Wiring diagrams & model # S/N codes different.

Everything points to bad gas valve but they are not cheap. Just want to make sure there is not something else that could be problem.

 

[Done That]

The pics are kind of small for me so I can't see for sure, but it looks like a Honeywell "SmartValve" system. Those valves have their own built-in circuit board on top under that brown plastic housing, then the ignitor and other system components plug into it. Kind of a distributed ignition system with that other little tan pcb working as the blower fan time delay. Anyway, those valves are notorious for bad solder joints and failures to the pcbs, as well as just loose connections.

I would try disconnecting all of those plug-ins on top of the valve and re-seating them first, but my guess is that you are going to be in for a new valve.

Post a part number on the valve, or more close up if you want better confirmation.

 

[Matti]

Whats the error for 6 blinking lights? On mine there is a list of the codes on a sticker inside the heater or you can get it from an online manual.

 

[HoosierBuddy]

Can you smell gas at the gas valve?

Is it possible the fuel line is full of air and has not been adequately purged?

Phil

 

[56servi]

The valve is a Honeywell SV9410M 2902 5H76382B
I did take the plastic cover off to check the circuit board. I saw no burn marks on the top & bottom of the board.
The 6 led flashes are "System lockout After 1 hour lockout reset delay, control will reset & initiate a new ignition sequence"
I went back to the garage and tried again. The flame would start burning for about 2 seconds for each of the 4 start attempts.

HoosierBuddy might have the right idea on air in line. Heater is in detached garage about 50 ft from house. I had the gas shut off in basement all summer. The input pressure I read may have been the air in line not gas. I will purge the line tomorrow. I also turned the pressure regulator screw in the gas valve yesterday to try & get it working. Not sure what position I left the screw.
Thanks for the ideas. I will let you know what happens tomorrow.

 

[acmikee]

purge the line and clean the flame sensor

 

[Matti]

I went through the troubleshooting manual when I had problems with mine.
I would expect some other code prior to the unit locking out after numerous unsuccessful starts. Hope it helps.

https://www.lpgandnh3.com/assets/hot-dawg-troubleshooting-guide.pdf

 

[56servi]

I found the problem. The input gas pressure drops to 0 when the heater gas valve opens. Now I have to find what is causing the drop in pressure between the basement and the heater. going to start in the garage where it comes in & work backwards to the basement.
Hope its not in one of the underground connections

 

[D45]

What size line did you run to supply the heater?

 

[HoosierBuddy]

What size line did you run to supply the heater?

With a 45,000 BTU heater, it's hard for me to imagine the line is so undersized that the pressure could drop to 0.

It's a blockage of some kind.

The most common cause of this I have seen is a leak on underground piping that is running at 7 inches w/c. If you have a leak on a low pressure line like that, it will eventually fill with ground water and block gas flow.

Disconnect the line from supply and your heater and blow out with high pressure air. Dollars to donuts it's full of water. If it is....then you have to find the leak. Let us know.

Phil

 

[Matti]

Our gas line pressure is only 0.25 psi so you would need a gauge with a low span/range to measure properly.

 

[56servi]

Got the heater working today Disconnected line in basement in front of shutoff valve & blew air from garage back into basement. Nothing came out of pipe and air flow sounded good so reconnected everything. Purged air from line in garage and heater started right up. Set pressure to 3.5 out of gas valve and now have heat.
Thanks to HoosierBuddy for tip on blowing out gas line
Gene