H-120 ASH Fix-up Thread

[CallMeColt]

Well, I had a setback on this thing that keeps snowballing!

It started to leak fuel between the two solenoids. Of course, the way it is plumbed, it is at a super hard to get place and you need to disconnect almost everything to tighten it. Did all that, but in the process, the brass nipple coming off the fuel pump broke off in the pump!

I luckily managed to get that out. My plan was to mount the solenoids on the wall where the fuel fill area is so they're more accessible and use new 4AN stainless lines. Ordered a bunch of stuff.

As I was working along, while tightening, I broke the small fuel solenoid! Ordered one but turned out it was incorrect. All very frustrating!

I just want to get the unit back together and running properly again, then I will probably sell/trade it. It is to much for my needs. I need a smaller unit & they have them out there.

 

[CallMeColt]

Got to spend some more time with this.

Ordered two kits to make all new fuel lines;

https://amzn.to/3IjXrWt

https://amzn.to/3jUipBa

Also, ordered a few new fittings;

https://amzn.to/3CqAvAX

https://amzn.to/3VPNQtj

https://amzn.to/3GGFX5u

The fuel filer I ended up installing;

https://amzn.to/3Z8aFvo

I also got a second 3 solenoid. Got everything made and installed. When I started it up on vent, it started to heat! It took some real troubleshooting as I thought maybe I made a mistake with the plumbing of the fuel lines or wiring, but in the end I am at the conclusion that the solenoid did not function as the original did.

I wasn't able to really find much information at all on the part from the TM. But, looking at the drawing and reaching through the operation, I think it is a 3 way, multinational valve. The one I got is a single function.

So, I did find the original one at an astronomical cost & just got it because I can't find anything that can substitute it. and at this point, I have to much time & money involved to just abandon the unit as it needs only this to work.

Once that comes in, I will share some pictures of everything completed.

 

[CallMeColt]

Well, this project may officially be abandoned and be one of the biggest let downs I have had!

Got the new solenoid in. Installed. Same issue. Spend a few hours troubleshooting and trying things. Everything is 100% as it should be plumbing and electrical wise, but in vent, there is to much pressure.

I closed everything up to just run it on heat for a bit to see if maybe that would do anything. After about 20 seconds or so, it was making WAY to much smoke, so I shut it down. I could hear fuel dripping inside the burner, and noticed some had shot out the exhaust.

Can't for the life of me figure out why it did this and stopped working. It was fine, with exception of the fuel leak that snowballed into everything I have posted updated about. Now that way to much fuel has built up inside, I'm not sure if I damaged it at all. Obviously, something is wrong that I can't wrap my head around.

Something is not releasing pressure. I really want to just scrap it now, but it's going to be a hard loss to swallow with all the hours and parts into it. Sure, I can take some off, but what a loss!

 

[Guyfang]

So put it on a shelf, and wait until you are bored. If man made it. Man can fix it.

 

[DieselAddict]

Man, heartbreaking that its gone so sideways. I just picked up at H140 that needs some love. Crossing my fingers that it works once I have the visible issues corrected.

Did you end up selling the remote? I may build one for mine if I can't find one for a reasonable cost.

 

[CallMeColt]

Man, heartbreaking that its gone so sideways. I just picked up at H140 that needs some love. Crossing my fingers that it works once I have the visible issues corrected.

Did you end up selling the remote? I may build one for mine if I can't find one for a reasonable cost.

Yes, I sold it on eBay.

It has me completely stumped as to why it is not working. Everything is exactly as it should be. Makes it even worse that it all snowballed from the nipple breaking trying ti just tighten up a leak...

 

[CallMeColt]

So put it on a shelf, and wait until you are bored. If man made it. Man can fix it.

I wish I had time to be bored.

It can be fixed I'm sure, but I'm just not sure I want to put anymore time & money into it. I will make a last post with my issues & hope down the road someone will have a solution before it gets taken apart or sold as-is.

 

[CallMeColt]

Here is the broken solenoid next to the new one. Fittings moved over.


New fuel filter setup. You can see some of the new fuel lines as well.



Not easy to get in there for picture, but here is the new spot I put the solenoids in, on the inside where the fuel selection valve is. That way they can be gotten as easier.



Again, not easy to get pictures, but looking at the fuel pump.



Some of the lines are pre-made stainless, others were from the kits I shared above.

Checked all the lines & fittings for obstructions.
Checked both solenoids to function, both on the bench & while installed/in operation.

I thought MAYBE the fuel filter being higher than it used to be by chance, was causing the issue. I bypassed it and sent the pickup line directly to the pump, and it made no difference.

Checked 8 times that the fuel line plumbing was 100% correct. Even tried doing it incorrectly a few different ways to see if that by chance made a difference.

SOMETHING is making the system hold pressure when it shouldn't, or the re-circulation is not happening when it should. What is making that happen is the mystery.

Any help, guesses, or ideas would be great! I put it all back together and put it out back for a while. i might give it one more afternoon before I just decide to take it apart or sell it as-is.

 

[DieselAddict]

I think the problem is the recirc isn't happening as it should. When I was starting mine up yesterday for the first time it took me a few minutes to figure out what it was doing.

I'm sure you know what it supposed to happen but sometimes talking through it can help you see something you might be overlooking.

Purge - gives a low resistance path back to the tank to remove air and make it easier for the pump to prime. The 3-way solenoid shunts fuel to the tank

Recirc - fuel flows back to the inlet of the pump. The 3-way solenoid shunts fuel back to the inlet of the 2-way solenoid and back to the inlet of the pump.

Heat - When the 2-way solenoid closes it blocks recirc and the 3-way blocks the purge line. That is what builds pressure against the burner injector.

Assuming my understanding is correct, if you are building pressure when you should be in recirc, there is something going wrong with the 2-way solenoid.

 

[CallMeColt]

I think the problem is the recirc isn't happening as it should. When I was starting mine up yesterday for the first time it took me a few minutes to figure out what it was doing.

I'm sure you know what it supposed to happen but sometimes talking through it can help you see something you might be overlooking.

Purge - gives a low resistance path back to the tank to remove air and make it easier for the pump to prime. The 3-way solenoid shunts fuel to the tank

Recirc - fuel flows back to the inlet of the pump. The 3-way solenoid shunts fuel back to the inlet of the 2-way solenoid and back to the inlet of the pump.

Heat - When the 2-way solenoid closes it blocks recirc and the 3-way blocks the purge line. That is what builds pressure against the burner injector.

Assuming my understanding is correct, if you are building pressure when you should be in recirc, there is something going wrong with the 2-way solenoid.

I thought so to, but there isn't. It is a Normaly Open solenoid and not getting power. It is clear. The way to test this is to disconnect it, then in theory it should never heat, only do low pressure. Even with the power disconnected, it is building pressure. I confirmed it was clear by removing it & with the fittings installed, I can very easily blow through it.

The 3 way solenoid is doing what it should as well. I confirmed when purging, it lets fuel into the tank by removing the line to the tank.

The plumbing and electrical information I got from the TM diagrams and drawings.

The one thing that was not clear, but I kinda figured out, was that it seems the two top fittings on the pump are suction, and the lower are discharge.

Only thing I though of that I did not try was to swap the inlet from the fuel filter and the 3 way (L2) solenoid. If for some reason that second side of the suction is not sucking or is obstructed, the pump will have no choice but to discharge out the injector into the burner.

Here is a picture of the fuel system from the TM;



Here is a picture I happen to find of the original configuration of the two solenoids;



The T on the top of the picture was coming out of the discharge of the pump. As well as the bottom of the second T on top of the second solenoid. Then, the brass loop went to the other suction side of the pump. The last fitting at the bottom of the picture went to the tank, as the purge line.

Mine is plumbed exactly like this, though not as compact.

Side note to add to the burn of all this, that picture was from a listing as a tested good take out for everything, cheaper than I just paid for the one good 3 way solenoid. This project hates me!

 

[DieselAddict]

If you disconnect the primary bypass line at L2 and run it to a container (and plug the COM on L2), what happens to the pressure?

 

[CallMeColt]

Thank you for the final suggestions. I ended up letting it sit for a while. A friend ended up being interested & I made a trade deal, so they have it now and are going to dig in. Going to share this thread with them so they can get the details on exactly what I did better than off the top of my memory.

Thank you everyone for the help along the way, as always!

 

[Dcdiego91]

Everyone,

Got myself a H-120 Army Space heater this morning from the auction yard. Got it for a real good price so figured I'd get it while I was there for other things.

Has less than 3 hours on it.

Tires were horrible, but I had some to swap on at the house. Will do something better if I get it working 100%. Has the long exhaust pipe with it, but not the elbow. Had a remote inside but it was for a H-140 after doing some reading. Guess that will go on the eBay store to recoup some money into getting this thing going. Got two of the ducts with it as well. One vent cover and screen is missing. Broke one bolt trying to remove it from the exhaust pipe cover. Not sure, but I think something is broken with the Thermostat breaker.

View attachment 880988 View attachment 880987 View attachment 880986 View attachment 880985 View attachment 880984 View attachment 880983 View attachment 880982

Put 3 gallons of fuel in and cut the Amphenol connector off of the 110v power connector. Made a temporary connection and moved the switch to vent and we have a blower! Power light does not come on.

Held the purge switch for a while. Hard to tell if it was working. The gauge never moved... it could be bad, or no fuel is moving?

Got the Flame Out light. Kept resetting and purging, no luck. Nothing seemed to be going on in the sight glass. From the directions, there should be an ark or spark if there's no flame?

Confirmed fuel is pumping by checking the fuel filter. Found it had been removed. Need to figure out that part number as the one in the TM comes up with nothing.

My guess from looking at the diagram, was that the transformer for the ignition is bad. I also need to order some of the bulbs for the power light as I'd guess it's bad. May swap with the Fire Out to see quick. Want to see this thing make some heat before I go to wild with it. Though, I'm sure it will get going.

Any help in finding downloadable TM's would be great. I will then share them in the uploads section.

I NEED HELP IM LOOKING FOR WHEEL, SOLID RUBBER TIRE NSN FOR A HEATER H120, HEATER 120000 BTU PORT I CANT FIND IT ON THE TM I HAVE OR ONLINE

 

[Dcdiego91]

Here is the overview video I said I was going to make;

I NEED HELP IM LOOKING FOR WHEEL, SOLID RUBBER TIRE NSN FOR A HEATER H120, HEATER 120000 BTU PORT I CANT FIND IT ON THE TM I HAVE OR ONLINE

 

[Guyfang]

What TM do you have?
Please do not write all in Caps.
You need to start a parts Thread.