Choctaw H140 heater cycles a lot.....normal?

[njjeeper]

I started using my H140 and I have noticed that it cycles often. It fires right up and then stays lit for about 3 mins, then shuts down for 1 min. Rinse and repeat. Ducts on or off makes no difference. It's not a flame out, no red light. It just shuts off fuel. My guess is the max outlet temp is being reached which is causing it to shut down. It restarts all by itself every time. Does anyone else have this issue? My H82 just stays lit all the time so it seems wrong to me. It's 30 degrees here so not too warm....thoughts?

 

[dangier]

Restricted airflow?

 

[njjeeper]

Nope, does the same thing without tubes hooked up....its odd for sure.

Restricted airflow?

 

[212sparky]

My H140 does the same thing, It seems like it heats up then turns off the flame then reaches its cool down point and restarts. I have been running mine 12 hours a week for the last month and i don't see any issues with it.

 

[njjeeper]

Perfect, thanks so much for responding. Hearing someone else has one doing the same thing makes me feel like its just the design.

My H140 does the same thing, It seems like it heats up then turns off the flame then reaches its cool down point and restarts. I have been running mine 12 hours a week for the last month and i don't see any issues with it.

 

[Neophyte]

Same here. It'll run hot, then cycle off.....a big puff of smoke, and she's hot again. I run into flameouts when using the remote box....seems to have something to do with the thermostat, not sure.

 

[dangier]

I attended the Army 52C Utilities training in the early 80's and worked on the predecessor to yours. So, I don't know for sure on yours, but in my experience the flame cycling does not sound normal. Have you verified that the burner control is cycling the flame or a safety? If operating on the high limit safety, I would guess there is too much fuel or not enough air movement. Is the fan setting on high? Some of the older units had a variable speed fan and the low speed was not enough and the burner would overpower the airflow and go off on high temp safety. I don't believe I would operate the unit on a safety full time. If the switch should stick, you are looking at major overheating and ruining the combustion chamber.
FWIW
David

 

[212sparky]

Same here. It'll run hot, then cycle off.....a big puff of smoke, and she's hot again. I run into flameouts when using the remote box....seems to have something to do with the thermostat, not sure.

View attachment 464541

What kind of duct are you using? How is your setup routed on the window. Right now I lower our receiving site on top and put cars board sheets on the gaps. I like you're design.

 

[rickf]

I agree with Dangier, If it is constantly shutting off on safety then you are playing with fire, Literally. I would verify that it is shutting off on the thermostat and if it is not then find the reason before you damage the unit beyond economical repair, or worse.

 

[212sparky]

I will read the tm tonight but it seems like it is running how it is designed.

 

[Neophyte]

Gents,

Ran into an issue this past week , my ceiling mounted Reznor heater crapped out (1 1/2 year old unit, PC board issue) in our pole barn. I hooked the Choctaw 140 back up, and seem to be getting a flame out about every 10 minutes. The heater will run through two cycles (heat/cool).....then it flames out and purges itself (as if it's cool down mode). I did notice a "popping" sound when it tries to start back up (see a cloud come from exhaust stack)... but nothing after that. The manual shows it could be a pressure switch issue (as fuel, air and electrodes all work fine). Any similar problems?

Thanks

 

[njjeeper]

Did this unit work normally before or is the first time you are using it?

 

[Neophyte]

Did this unit work normally before or is the first time you are using it?

It did....this happened after about 20 hours of use.

 

[njjeeper]

What kind of fuel is in it? Mine hates anything but clean diesel. Also, whats the fuel pressure when its running?

 

[Neophyte]

I'm using off road diesel, about 115-120 psi ......I've checked the filter multiple times, clean as a whistle. I considered maybe a viscocity issue, but off road diesel is for the most part regular diesel with dye in it (diesel without taxes). I've looked for potential issues (as these heaters are loaded with safety features).....and considered running the intake into the pole barn as well (prevent back pressure)....but after opening a door in the barn, did little to help. The pole barn is very well sealed.....so much it blew the vent off the heater after building up pressure (I leave the door cracked a bit to offset).

I've read through a good portion of the manual, and the trouble shooting menu leads to "seek unit maintenance" for anything beyond the basics. I intend to take it apart this coming summer (something I neglected last year when this problem arose) and resolve the issue.

 

[njjeeper]

Mine came with an issue from GL that I had to fix but if yours was working fine before I don't think it applies unless you dropped or hit the unit hard. In my case the heater would start and run but then once warm it would cycle off normally but then wouldn't restart. Sometimes I got the flame out light, other times I didn't. I solved my problem by taking it all apart and aligning the ignitors that sit in front of the fuel jet. The TM shows the proper measurements and orientation. My heater had 1 hour on it so I assumed it was dropped or mishandled and the impact shifted the alignment. They were quite far out of spec. After that, its been great!

 

[Lance Watkins]

My H-140 had 3.3 hrs but sat forever and the fuel or preservative turned to Tar in the fuel pump and sheared the shear coupler at start up. Cleaned the fuel pump and got a $204. coupler. started right up. Now it cycles every 3 minutes just like the original post. so my question is the same. Is this unit supposed to cycle or run constantly. What is the correct operation and if not what else did anyone do to correct the issue.

 

[njjeeper]

Its normal operation. There is a sensor in the front of the outlet that controls the on/off based on outlet air temp. Back when I was trying to figure this out I bypassed that sensor to see if it would just stay on like my older unit did. With the sensor disabled, it did indeed stay on and not cycle. All the way up until the sensor in the combustion chamber shut the whole thing down for being over temp. The way this unit keeps the heat exchanger from over heating is by cycling. My un-educated guess is that the heat exchanger is too powerful for the amount of air that flows across it to keep it cool. So, it cycles. I don't like it because when its real cold outside the air that it blows in is cold when its on an off cycle. I suppose if it was ducted into a plenum like the military did that would be less noticeable. YMMV...TJ

 

[jfelshaw6]

I work on these frequently. To verify its your temp sensor, unmount it from the output port and secure it outside the area of airflow. If the heater no longer cycles, you'll know it's the thermostat. How often it cycles depends on intake air temperature, and what mode you're running it in.

 

[blackrock]

So I have two of these heaters that I've been using for the past 4 years. Every year it always seems to be something. They will run really good but then all of a sudden be a mess. Both of mine have an issue a flame out they will not start the flame I don't know what's wrong with him. We have cleaned them reset the electrode replaced the Transformer and bypass the pressure switch still nothing I'm at a dead end with these things. Anyone have any idea? I have good pressure but no Flame and it doesn't seem like it's getting any Spark. Thanks Kyle