SW 60k BTU Multifuel Heater, Not Working, Won't Light

[cranetruck]

Kerosene is harder to start.

 

[74M35A2]

So I have new updates. The heater will not light off, and I have fuel flowing out of the regulator block, but it is not flowing out of the exhaust, even after several attempts of 2 minute start attempts each. I need to pull the copper injection tube and the glow plug assembly.

So after reading the manual, I find that the heater will shut off on "hi" if inlet air is over 60F. We'll, this means it was working just fine when I received it, because that is what it was doing. So in summary, it was ok, I sent it to SW, and now it is hosed, but getting closer to working each time I dig into it.

So anybody with these things, it will auto-shut down on hi if you are bench testing it in 60F or higher ambient air. At least the 60k unit is rated to raise the air temp by 250F, and the over temp fuse cuts at 320F or so. On hi it is rated to heat 110F, so it will run on lo at any ambient temp.

Yes, I learned this by reading the manual, and now I'm prepared for paddles from the "Read the Manual" crew. Thank you sir, may I have another....

 

[74M35A2]

I pulled the glow plug. It looks like new. I need to confirm it works, but it ohmed out ok. The wick looks new, but was bone dry. I'm going to pour some fuel down the glow plug hole as a prime to saturate the wick, and try it again. 5F outside right now, let's see what happens... I have this image of coming in the house with no eyebrows.

 

[gimpyrobb]

I have this image of coming in the house with no eyebrows.

Hmm

 

[cranetruck]

So I have new updates. The heater will not light off, and I have fuel flowing out of the regulator block, but it is not flowing out of the exhaust, even after several attempts of 2 minute start attempts each. I need to pull the copper injection tube and the glow plug assembly....

A 2-minute start attempt is not long enough! Try 3 to 5 minutes, just don't quit.

Keep in mind that all the while, fuel is dripping into the combustion chamber and accumulating. After several aborted starts, you will have a fire hazard with fuel sloshing around in the heater.

In the beginning (5 or 6 years ago), I would siphon out the fuel after failed starts. In military service, you'd return the heater to maintenance for this procedure.

The "HI" is locked out during the start sequence, so don't worry about the hi and lo switch at this time.

The fuel flow, or drip, from the fuel control valve is critical during the start period and the valve must be calibrated exactly as specified in the TM. A soaked wick may not help.

The igniter is designed for about 6 volts and is connected via a large resistor (to last longer), in case you decide to test it.

The fuel is also important, #1 diesel (Winter diesel) probably best, but I have never tried gasoline. Don't even think about using waste motor oil or biodiesel/veggie oils.

To make sure my fuel supply is not a concern, I have a dedicated jerry can with good fuel on my truck and my heater seems very happy.

 

[74M35A2]

A 2-minute start attempt is not long enough! Try 3 to 5 minutes, just don't quit.

Keep in mind that all the while, fuel is dripping into the combustion chamber and accumulating. After several aborted starts, you will have a fire hazard with fuel sloshing around in the heater.

In the beginning (5 or 6 years ago), I would siphon out the fuel after failed starts. In military service, you'd return the heater to maintenance for this procedure.

The "HI" is locked out during the start sequence, so don't worry about the hi and lo switch at this time.

The fuel flow, or drip, from the fuel control valve is critical during the start period and the valve must be calibrated exactly as specified in the TM. A soaked wick may not help.

The igniter is designed for about 6 volts and is connected via a large resistor (to last longer), in case you decide to test it.

The fuel is also important, #1 diesel (Winter diesel) probably best, but I have never tried gasoline. Don't even think about using waste motor oil or biodiesel/veggie oils.

To make sure my fuel supply is not a concern, I have a dedicated jerry can with good fuel on my truck and my heater seems very happy.

View attachment 537113

Thanks everybody for sticking with me. Not that it matters, but I don't think "Hi" is locked out during a start. The fuel solenoid clicks twice as fast on Hi as it does "Lo", even during a start attempt. I am keying into this because maybe it is an indicator that something else is still wrong? Also looks like my igniter is getting about 12V during usage.

My my next step is to measure the fuel inlet pressure and outlet flow, and compare it to spec. If OK, then I will move down into the unit and look for fuel flow obstructions at the end of the injection line and check to see how it is arranged.

Also electrically, the indicator lamp does not illuminate when the heater does start (only starts if I prime the wick). The blower does go into high speed though. The bulb checked ok when measured and tested on a 24V battery. The push-to-test feature does not work, feels like the bulb collar is seized in place and will not depress. This is the least of my worries, but I am trying to use it as an indicator if something else is not configured correctly.

Back to to the manual...

 

[cranetruck]

The blower runs at a lower speed during start (lower than in "LO").
Which control box do you have? The push to test light is supposed to confirm that you have 24vdc to the unit and turns on after the unit start up.
Is it one of these?


After the unit has shut down (switched to "OFF"), there is a purge time, that could last 1 to 2 minutes as remaining fuel burns up after fuel pump is shut off...

 

[Wildchild467]

Kerosene is harder to start.

Good to know. I used kerosene with the unit in the back of my M109 and Iwondering if that is part of the reason that does not want to start. I noticed diesel works better for the manifold flame heater on my deuce. I have a separate tank for my manifold flame heater since I use WMO for engine fuel. Thank you for the confirmation, it helps. I guess I should switch fuels. I know they were designed for diesel but I was thinking kerosene was more pure/better for the wicks. I had wick issues so thats why i went with kerosene. Good to know.

Since we are on the topic of wicks.... is fiberglass the correct wick material for these heaters?

 

[cranetruck]

Yes, fiberglass is the wick of choice, cotton will not last.

 

[Wildchild467]

The blower runs at a lower speed during start (lower than in "LO").
Which control box do you have? The push to test light is supposed to confirm that you have 24vdc to the unit and turns on after the unit start up.
Is it one of these?
View attachment 537126

After the unit has shut down (switched to "OFF"), there is a purge time, that could last 1 to 2 minutes as remaining fuel burns up after fuel pump is shut off...

74M35A2 has the heater switch box on the right.

I think his light assembly is corroded some or something.... it does not want to push in when it says on the front, "push to test". We tested the bulb and it tests good and worked for him in the past. Everything else in the control box looks healthy and no signs of corrosion.

 

[cranetruck]

74M35A2 has the heater switch box on the right.

I think his light assembly is corroded some or something.... it does not want to push in when it says on the front, "push to test". We tested the bulb and it tests good and worked for him in the past. Everything else in the control box looks healthy and no signs of corrosion.

Okay, then the wiring diagram is as shown here, with and without correction by yours truly.

 

[74M35A2]

Thanks. 10-4 on the blower running at a reduced rate, and also the purge run after flame is out. Both of those are working correctly, and yesterday I adjusted the flame switch to insure it, prior to testing (1/2 turn CW after click when cold).

So is the error a mistake in just the TM, or are control heads wired incorrectly? I have the control head on the right of your picture.

Pretty sure I am just down to a fuel volume delivery issue. Everything else seems in check (besides the push-to-test light, but I think I just read the box requires grounding for that to work, and now confirmed that via your schematic).

 

[cranetruck]

Thanks. 10-4 on the blower running at a reduced rate, and also the purge run after flame is out. Both of those are working correctly, and yesterday I adjusted the flame switch to insure it, prior to testing (1/2 turn CW after click when cold).

So is the error a mistake in just the TM, or are control heads wired incorrectly? I have the control head on the right of your picture.

Pretty sure I am just down to a fuel volume delivery issue. Everything else seems in check (besides the push-to-test light, but I think I just read the box requires grounding for that to work, and now confirmed that via your schematic).

The flame switch adjustment is important and if the heater shuts down after, say 10 to 20 seconds, then you may want to turn the screw an additional 1/4 turn or so, which will require the temperature to be slightly higher before the "switch-over".
About the error, the diagram is wrong IMHO, since it probably wasn't used as a guide when the control boxes were assembled.

Do you have fuel pressure at the fuel control valve?
Is there a fuel filter in the fuel line? There is also a strainer right at the input of the fuel control valve, that you may want to clean (at least on the old dual solenoid types).

Do you have any pictures of your install?

 

[74M35A2]

Flame switch tested good, and its adjustment seems good. I have fuel pressure into the regulator block, and fuel appeared when I loosen the copper tube on the outlet side of the regulator block when the solenoid is clicking. It is all there and working, I think it is just not enough fuel flow.

I just finished reading the entire manual, yummy. But now I am at least armed with the fuel flow rate, and I have something to measure and compare. That is the next step.

Also, TM says these heaters should start in 75 seconds or less. So, for those who have to hold theirs 2-5 minutes, you may need a tune up!

Install is N/A until it works correctly. I have been working on it at the kitchen table, with a door mat and the towel under it. Here it is in all the glory. Note TM open in iPad also:

 

[cranetruck]

Thanks, the starting time varies a lot from TM to TM, you may have some smoke after 75 seconds, but I have yet to see one that actually switches over and runs on its own in less than 2 minutes. If fuel flow is correct and the igniter working, there isn't much one can do in terms of a "tune up". It also depends on the type of fuel. Like I mentioned earlier, don't quit too soon, you'll end up with a heater full of fuel.

 

[cranetruck]

These are actual Stewart Warner test results. Note the variation in start and "FD switch" times.
"F.D. Switch" is the time it takes for the flame detector to switch and the unit running on its own and it is not a constant by any means. Fuel used is #2 diesel.

 

[74M35A2]

....and, we have IGNITION! Thanks to all that input here. I did not really want to become an expert on these, but it is what it is, there is not a piece I have not went through at this point. I disassembled the burner, and found the tip to be clogged with chunks of carbon. Cleaned them all out, then flushed everything with carb cleaner. Did the same to the fuel regulating block. Put it all back together, and away we go. Everything works correctly. Start, low, high, cool down, hot restart, igniter, control panel indicator, fuel pump, flame switch, all work correctly. Here is a pic of this 60k BTU blowing on high, at 39F ambient temp:

 

[74M35A2]

...and a pic of the carbon encrusted fuel tube which I believe was the issue:

 

[gimpyrobb]

Frigging sweet!


Now I know who to send mine to, to get working!

 

[74M35A2]

Absolutely. Free for you bud. Cost anybody else a 12 of Corona's and 3 limes.