Tested fuel burning heaters today

[cranetruck]

Both the coolant and the personnel heaters are now installed in the 757 and it was time to test them (the 4th of July is good in case of fire works).
The personnel heater worked well as expected since it was tested last year. I didn't pre check the coolant heater based on the fact that it came with a tag stating that it had been fully tested back in 1982, showing fuel rates and amp draw. Heck, that's just 26 years ago. Probably should have checked for possible obstructions.
The coolant heater started in about 45 seconds, but smoked like the dickens, I left the cab and grabbed a fire extinguisher. A 3-inch red flame was shooting out the exhaust below. I started the circulation pump and let it run for a minute before shutting it down. It shut down normally after about 2 minutes. It is normal to have a purge cycle without the fuel pump lasting 2 to 3 minutes.
The thing got real hot and that bothers me a bit.

There is one little item that needs to be investigated and that is the position...it was tested in a vertical position and I have it installed in a horizontal. The test tag has a note, "For use in any other position see instruction sheet PM 32333".

The rear engine hatch cover is not installed, so most of the smoke came from below, but it also smoked some from the top.
I'll have the camera handy for next test.....

 

[cranetruck]

Cranked up the coolant heater again this morning. Took a full 3 minutes, it showed signs of wanting to start, so I kept the switch in "start" position a little longer than recommended in the TM (2 minutes only). It finally caught and produced a lot of smoke again. The smoke in the cab is via the open engine hatch.
A coolant leak was found at the top connection.
Other than the smoke it appears to be okay.
In contrast, the personnel heater produces no smoke when running.

I realize that this is not a popular subject, so I 'm posting this "for the record" only.

 

[WillWagner]

Is it smoking due to fuel or is there a coolant leak into the heater area?

 

[ida34]

I enjoy hearing about it. I need the knowledge for when I try to start mine.

Chuck

 

[gimpyrobb]

Yeah, don't worry about the nay-sayers. We want details!

 

[jwaller]

the only instruction sheet I got with my kit we have talked about was the one with the heater unit. if you need it I can scan it for you. it has details abut mounting positions and testing and such.

 

[rosco]

Sometimes on start-up, the heater will accumulate fuel in the combustion chamber. When it startes, there will be an abnormal "rich" condition for a while, till it gets up to temperature, and cleans out. Another situation, that creates extra smoke, is less then adequate, combustable air, due to an obstruction, faulty blower/motor, or low voltage to the blower motor, resulting in less then adequate combustable air.

I once overnighted by the Sagavanirtuk River, North of the Brooks Range. It was -40f & I was counting on the engine coolant heater. Next morning, it would not start. After repeted tries, I was rather desperate & the batteries were getting low. I gave it a shot of starting fluid (ether), in the combustable air intake. Because it was so cold, the starting fluid came out in a rather thich squirt, rather then a spray.It started, but its hard to imagine, how much noise it made. But it didn't hurt anything, & it made me smile.

Lee in Alaska

 

[cranetruck]

the only instruction sheet I got with my kit we have talked about was the one with the heater unit. if you need it I can scan it for you. it has details abut mounting positions and testing and such.

Thanks, that would be great, the TM troubleshooting guide is not very detailed, "replace heater" is not an option...
BTW, you should be receiving your coolant heater tomorrow and like I said, it will be needing a going over.

Lee, I'll be checking the air flow next. The coolant heater doesen't have the same powerful blower as does the personnel heater, since it's not producing any hot air, it's only needed for combustion.

Will, the coolant leak on top is like a tiny cloud of steam, nothing like the white smoke from the exhaust.

 

[jwaller]

I'lll try and scan it today and post it up. I got the heater yesterday. thank you very much. now to try and find the oil pan box.

 

[cranetruck]

Checked the fuel rate setting on the coolant heater this afternoon, suspecting that the flame out the exhaust may be because of too much fuel.
Images below show the procedure. I found that the "LO" setting had a rate of about 20 cc/minute and the "HI" was about 35 cc/minute. That's way too much according to the TM, which specifies 6.5 to 10.5 for "LO" and 11 to 17 in "HI".
I turned down the fuel rate approximately to the specified, reinstalled the fuel valve and tried to start it. It didn't after 3 minutes, so I called it a day....

 

[cranetruck]

Jwaller, one thing that would be of interest would be any adjustment required for a different operating position, horizontal vs vertical, so if you find anything on it, please let us (me) know.
I think that the wicking action may be effected by gravity and a wick is used to bring fuel to the igniter.....

 

[DanMartin]

opcorn:

 

[cranetruck]

Tested the fuel control valve again yesterday after the unit failed to start and the results were not consistent with what I had the day before. It appears that the valve is sluggish and needs a cleaning. Would be nice to have new control valves available, I have several heaters with "sluggish" valves, some are taken apart and need new gaskets....

 

[cbvet]

Bjorn
I appreciate the info!
I still have two personnel & one coolant heater to hook up.
Eric
CBVET

 

[cranetruck]

I'lll try and scan it today and post it up. I got the heater yesterday. thank you very much. now to try and find the oil pan box.

Just bumping this...I'm interested in any info relating to the mounting position, please.

 

[Rattlehead]

I am very frustrated with trying to get mine to work. Even got ahold of a 2nd unit and it doesn't want to light off. My fuel volume was ok on the 2nd one, too.

 

[cranetruck]

Which model do you have? Keep us posted with the details of your trouble shooting, please.

I haven't worked on mine for a week or so, at least mine did fire up, just way too much fuel so I started to take it apart and checked the fuel delivery as explained above. Now it looks like the delivery valve is unpredictable. When I get on it next time I'll start with bleeding the fuel lines since it's possible that there may be air in the lines after me messing with it.
Some older models had provision for manual ignition, which may say something about the reliability of the wick and cigarette lighter method. Wicks have to be very clean to work well and are somewhat effected by gravity.
The personnel heater has been working well and starts within a minute every time...

 

[cranetruck]

Made some progress on the coolant heater.
Replaced the control valve with another that I was able to calibrate close to the specified flow rate.
Next, I went thru the starting procedure and could hear the flame catch after about 2 minutes. Good news it's running, however the flame detector doesn't sense the heat so the light on the control box never lights up and it can not run on it's own. After listening to the flame for a full minute I turned the unit back off. This is a false shut-down and extra fuel is now evaporating and turning into smoke. It clears up after a few minutes.

Suspecting that there is a problem with the flame detector, I remove it and test it with a propane torch. It doesn't switch. Sure enough it needed recalibration, which amounts to turning a screw and listening for a click from the microswitch. Did that according to the TM and re-installed the switch on the heater.

Started the heater one more time and could hear the flame rumble after 115 seconds. The flame detector worked this time and the light on the control box lit up along with an increase in fan speed. I flipped the start switch to "RUN" and the heater runs on it's own without smoke. It only runs for 30 seconds and shuts itself down. Okay, so there is still something else to check over, but I consider this a bit of progress....

 

[jwaller]

I posted the mounting position info in another thread. I'll try and find it and post it here as well.

 

[jwaller]

found it