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Thomas W 03-04-2021 07:56 PM

Trillium Furnace Quit
 
Perhaps I'm the only one that still likes the original Duo Therm gravity furnace in their 1980 Trillium. I appreciate that its vented (yes I do use a a CO meter and venting), can be used boondocking, has a good thermostat, and really cranks out the heat when you need it.
The pilot still lights properly and stays lit, but the valve does not open to allow propane to the main burner. I apologize if its a repost but I'm looking to answer a few questions, response to any of these are appreciated:
-What is the consensus of the problem, gas valve that wont open, maybe thermostat?
-Is it fairly easy remove the whole furnace, some of it looks interlocked with other pieces and accessing the propane line does not seem real obvious.
-Are parts still available, or do people still work on these? They seem so simple but I really am not familiar with trying to repair one.
-Alternatively, are there other furnaces that would fit in the original space that are available?
Thanks so much, any other suggestions for a vented furnace are appreciated
Tom W

thrifty bill 03-04-2021 08:01 PM

One thing I like about my Trillium 1300 is the aisle way is wider than many other brands. This is accomplished by having shallower cabinets (there is no free lunch after all). The typical propane furnace will not fit, there are other options, none cheap. Keeping that gravity furnace is a good option, plenty of threads on people that have repaired them.

Too many of these furnaces get tossed, like the prior owner of my Trillium did. So when I dry camp, my "heat" is provided with a sleeping bag....

If I get really serious about heat, I might go the diesel heater route. But I have other things to work on.

Joe MacDonald 03-05-2021 09:12 AM

sounds like the control, (not sure if it is a thermocouple or a bourdon tube on yours)failed, picture would help, also google our site and the internet for manuals with your model number

Joe

David Tilston 03-05-2021 10:01 AM

Thomas, I don't consider myself an expert on anything, but I probably spend more time thinking about Trillium Duo-Therm furnaces then most people. In a recent thread:
https://www.fiberglassrv.com/forums/...ter-94819.html
I have posted links to a number of resources, including the currently available replacement gas valve for your furnace. It is expensive. Also since the various ports are in different places than the one you have, it is also difficult to install.
I think your best bet is to find another second hand furnace that uses the same valve and swap it out. The valve in question was fairly common at the time. Several other manufactures used it.

In the thread that I link to above there is also a link to a tear down of the valve that I did. The thermostat in this valve uses a bulb with a volatile fluid that expands when warmed. That expansion triggers the valve to close. If the bulb / capillary leaks the furnace would not turn off. The fact that your furnace doesn’t come on implies that the bulb is still intact. The problem could be in the snap action of the thermostat, or the diaphragm of the main valve. There are not many other failure points that I can think of that would explain your problem.

Chris from Comox 03-05-2021 02:37 PM

Thomas..
I had a similar experience with my 1975 Trillium furnace a couple of years ago.. Pilot would light but main flame would not ignite.. Thinking it was the thermocouple, I went to my local RV folks who had one that they found in the back corner and said it would work.. I got down on the floor and started disassembling stuff and having a thorough look at the parts.. For some reason I recall that I took a look at the nozzle and discovered that when holding it up to the light I could not see the proverbial “light at the end of the tunnel”.. So being the problem solving guy that I like to think I am, I searched my little shop for a small wire, found a piece and started gently poking at the hole at the end of the burner tube.. The wire wouldn’t slide in at first but after a few more pokes a little pellet of debris slid down the tube into my palm.. I got the compressor, gave the nozzle a blast, put all the pieces back together, fired the furnace up and it’s worked fine ever since.. (Now I have to go and knock on some wood now as I haven’t fired it up yet this year - Better yet, since it’s a nice sunny dry afternoon here on Vancouver Island, I am gonna go out and fire it up ;-)

AlanKilian 03-05-2021 03:10 PM

Quote:

Originally Posted by Thomas W (Post 807382)
-What is the consensus of the problem, gas valve that wont open, maybe thermostat?

If the pilot lights and stays lit, the thermocouple is working fine.
That's the only job of the thermocouple in fact. To turn off ALL the gas if it doesn't detect heat from the pilot.

When you turn the thermostat from cold to hot and back, you should hear a "Boink!" somewhere in the middle. That's the noise of the gas valve opening and closing the main gas passage. (It's more complicated, but this is the simple version)

Do you hear that boink?

I'm sure since you've used this before that you moved from "Pilot" to "Main" or "On" or whatever it says, right?

David Tilston 03-05-2021 04:05 PM

4 Attachment(s)
Yah, like Chris said, I would check the orifice first. This would require some disassembly of the furnace.

You will need some high temperature gasket goop. Currently on sale at Princess Auto: https://www.princessauto.com/en/ultr...t/PA0006400004
It's good to 371įC, (700įF)
Attachment 139751

The attached pictures are from this thread:
https://www.fiberglassrv.com/forums/...rly-44108.html

The gas valve has been replaced with a Robert Shaw version, with an external thermostat, but the orifice is in the same place yours would be.

Terry in Fowler 03-06-2021 01:24 AM

If you have not started disassembling the unit yet try whacking the body of the gas valve firmly several times with the base of a hammer or some other heavy item while the pilot is lit and the valve is set to on. It is not uncommon for an old diaphragm to stick shut from setting unused. Over 34 years working on residential units this work at least 25 times. In November it work on the furnace in my Scamp. If it does work cycle it several times. Furnaces like air conditioners last longer if run once a month every month.
It's likely to happen again at some time. I had one unit I went out on once a year for five years before it decided not to start again. I worked for a public agency so they wanted to put off replacing a $200.00 valve as long as possible.

Darwin Maring 03-06-2021 10:45 AM

a bad thermocouple will do that.

AlanKilian 03-06-2021 11:13 AM

Quote:

Originally Posted by Darwin Maring (Post 807499)
a bad thermocouple will do that.

Thomas said in his initial post "The pilot still lights properly and stays lit"

A bad thermocouple will not allow the pilot light to stay lit, so I think his thermocouple is fine.

Darwin Maring 03-06-2021 12:56 PM

Quote:

Originally Posted by AlanKilian (Post 807507)
Thomas said in his initial post "The pilot still lights properly and stays lit"

A bad thermocouple will not allow the pilot light to stay lit, so I think his thermocouple is fine.

I have had a pilot stay lit but not warm up the thermocouple enough to trip the main burner.

I also had water in the burn chamber (Not a gravity furnace) that prevented the burner from lighting.

Thomas W 03-06-2021 01:33 PM

Thanks all for the great pics and info. A couple questions:
-The whitish goop on the plate that joins to the burner is high temp sealant? I was concerned it might be an asbestos product.
-Once the orifice is out, as shown, it just unscrews from the burner assembly so you can see if it is clogged?
-I do see from another post that a DuoTherm thermocouple/valve is apparently still available for $250. Expensive but I'd get it if it fixed it. Is that the entire 'guts' of the furnace, meaning thats what turns the main gas flow?
-Re the thermostat comments I have to wait till it warms up here a bit to test it. Its about 30 deg out and the thermostat only goes down to 40 so its always on right now. But I believe I do recall the 'boink' it should make when it clicks on.

Thanks again

David Tilston 03-06-2021 11:55 PM

1 Attachment(s)
Quote:

Originally Posted by Thomas W (Post 807522)
Thanks all for the great pics and info. A couple questions:
-The whitish goop on the plate that joins to the burner is high temp sealant? I was concerned it might be an asbestos product.

Correct. That is asbestos. I recommend a mask is used when removing it. Then use the high temperature gasket goop to replace it.
Quote:

Originally Posted by Thomas W (Post 807522)
-Once the orifice is out, as shown, it just unscrews from the burner assembly so you can see if it is clogged?

It does unscrew, but unscrewing it is not so easy. I used an impact, and a six sided socket to minimize damage to the brass orifice. I still damaged it. I would try a stripped twist tie, or other very small wire, to poke at it.
Quote:

Originally Posted by Thomas W (Post 807522)
-I do see from another post that a DuoTherm thermocouple/valve is apparently still available for $250. Expensive but I'd get it if it fixed it. Is that the entire 'guts' of the furnace, meaning thats what turns the main gas flow?

Yes, the gas valve is the brains of the operation. The thermocouple and the gas valve are very different things. $250 would be a good price for the gas valve. The only, currently available, gas valve that would work, that I know about, is the Robertshaw 710-201. Grainger, in Canada, sells this valve for ~$400 Canadian Pesos. The ports are in different places then the orignal ITT valve. So practice your tube bending.
https://www.grainger.ca/en/product/G...nls=NLSAA_NA-2
The thermocouple should be commonly available.
https://www.amazon.com/Robertshaw-19.../dp/B001TXJ06M
Quote:

Originally Posted by Thomas W (Post 807522)
-Re the thermostat comments I have to wait till it warms up here a bit to test it. Its about 30 deg out and the thermostat only goes down to 40 so its always on right now. But I believe I do recall the 'boink' it should make when it clicks on.

I am not sure what you mean by "thermostat" The original gas valve looks like this:
Attachment 139769
https://www.fiberglassrv.com/forums/...a02-86546.html
The copper capillary that exits the bottom of the picture is attached to the bulb that I mentioned before. The heat control is the numbered dial from 1 to 5. If you have an actual thermostat, then you don't have an original valve. This opens up several other possible points of failure. Please post a picture of the valve that you have, and the thermostat.
Also, the temperature setting on a thermostat is for the interior temperature. It should shut off the furnace when the inside of the trailer reaches that temperature. I thought you said that the furnace does not come on. Am I missing something?

Thomas W 03-07-2021 08:49 AM

Thanks for your reply, Im going to start with the easiest options first, hoping to not have to dismantle it.
My model is a 65512-00 which does not have the adjustable heat control as your pic shows. It is more like the one shown on this link Duo-Therm Gas Control Valve, 710-501 (901343.000)

Darwin Maring 03-07-2021 11:46 AM

I dont know how far back these heaters go but when I was coming up our range at home had a pilot that remained lit. When you turned on the gas valve, the stove lit. This was B4 thermocouple tubes.

Thomas W 03-07-2021 01:40 PM

Well I got very close to getting the furnace to work. Its a 65512 in a 4500. I did confirm the thermostat works. I lit the pilot and tried adding some extra heat to it to see if it helped, it did not. Pilot flame appears ok. I then tried hitting the burner box, valve, and gas tube. After several shots the burner tube did light but with a very low blue flame. I tried again a couple times and the burner went out, so Im thinking its the orifice. I was hoping to not have to disassemble the whole unit as in your pics. If I remove the cover plate is it possible to remove the burner tube to expose the orifice? If not, once I disconnect the gas line can I remove the assembly as show in David's pics?
Thanks

Joe MacDonald 03-07-2021 03:57 PM

Don’t push something through the orifice that will definitely ruin it Cleaning with alcohol or brake cleaner may open it up, use that stuff only outside the trailer, well ventilated area.
Allow to dry at least a day before bringing a flame near it

Joe

mszabo 03-07-2021 04:10 PM

You need too pull the burner and clean it also. Spider tend too make there nest in the burner.

mszabo 03-07-2021 04:16 PM

You need too pull the burner and clean it also. Spiders tend too make there nest in the burner.

Darwin Maring 03-07-2021 04:45 PM

Quote:

Originally Posted by mszabo (Post 807627)
You need too pull the burner and clean it also. Spiders tend too make there nest in the burner.

Yes, I had that problem once. Some very small critter made a nest in the burner tube.

David Tilston 03-08-2021 09:50 AM

Quote:

Originally Posted by Joe MacDonald (Post 807621)
Donít push something through the orifice that will definitely ruin it Cleaning with alcohol or brake cleaner may open it up, use that stuff only outside the trailer, well ventilated area.
Allow to dry at least a day before bringing a flame near it

Joe

Joe, I have seen other people say that as well. I am not sure I understand. The orifice is brass, so softer than steel, but if a wire that is smaller than the orifice, (like a stripped twist tie) is pushed through, (gently) what problem does that cause?

Thomas W 03-08-2021 04:18 PM

Success! Decided to dismantle the furnace, came out quite easily. When it was pulled out far enough to clear the cabinet I rotated it 90 degrees and propped it up so I could remove the plate easier and not have to slide the exhaust all the way out, then worked on the assembly indoors. Dismantled the burner, full of rust dust. Tried briefly to remove the orifice but it was tight. Blasted it several times with an electronics cleaner, no residue and it evaporates quickly. Then inserted an unsheathed twist tie wire which was about 1/2 the diameter of the orifice, no resistance. Reassembled for a test and Voila! it worked!
Feeling much better about using it after I see how it has a separate intake, exhaust and sealed burner unit.
Also re discussion of thermostat, this is a 65512-00 Duo Therm and I am sure this was the first time it was disassembled and was original in my 1980 4500. My Duo Therm 'manual' references unit with and without a thermostat. I have pics but havent figured how to post yet

Thomas W 03-08-2021 04:24 PM

Trillium furnace
 
4 Attachment(s)
Attachment 139783

Attachment 139784

Attachment 139785

Attachment 139786

David Tilston 03-08-2021 05:09 PM

Good job!

There is a bit of rust, but I think your furnace is in excellent condition. Typically when I disassemble one of these furnaces, at least one of the studs gets sheared off due to corrosion. It looks like all of yours are clean.

The next test I would do is to ensure that the furnace turns off. I assume that you had to short out those two terminals on the gas valve to get it to go. I wonder how long it takes to go from on to off, and vice versa. I want to know the model number of your gas valve more than ever now.

When I rebuild reassemble a Duo-Therm furnace, I paint the burner, and the combustion air intake, on the back of the fire box, with high heat paint. Both of those are where I find the most rust. If you do paint the burner, cover up the slots that the flame comes out of. That is stainless steel, and won’t rust. You don’t want paint plugging up those vents.

You will need some high temperature gasket material to close it up. I am not sure how the exhaust / intake air vent extension is going to look like, but if it is still a sliding concentric affair, I suggest some high temp anti seize compound to prevent it fusing with rust.

Thomas W 03-08-2021 06:01 PM

Per my previous post: Also re discussion of thermostat, this is a 65512-00 Duo Therm and I am sure this was the first time it was disassembled and was original in my 1980 4500. My Duo Therm 'manual' references units with and without a thermostat.
The thermostat is on the wall by the bed and connects to the furnace at the two terminals below the red pilot valve (the little plate says 'therm' on it). To test it I just reconnected the thermostat wires to it and turned it up, it works like one of those 30 year old house thermostats. If you look back on these posts one of them mentions a 'boink' when the thermostat turns on. I dont know if that actually generates a little voltage or if it just closes the circuit but thats what turns on the main gas valve.
I was careful with the nuts, using penetrating oil, loosening, backing off, cleaning, repeat.
Perhaps its in better shape cause its been garaged for the last 9 years. I'll clean it up and reseal properly but I'm not painting, chimney was snug, better to let sleeping dogs lie.

David Tilston 03-08-2021 06:37 PM

I was asking about the gas valve, not the thermostat. I believe it is manufactured by ITT. The model number is printed on the side of the valve.

Also, it is my understanding that having an actual thermostat requires a thermopile vs a thermocouple, (more power). This may mean that you can’t use the part that I linked to. Could you please post some close up pictures of the gas valve, and the pilot light assembly?

canyon Rafter 03-09-2021 12:51 PM

A word of advice....Don't try to clean out the parts with compressed air. The compressed air can cause gadgets to leak or disintegrate, or simply blow out in places where you had no problem before. I made this mistake with my thermostat on the magic chef oven. I thought I could just go and buy a new thermostat but they are no longer manufactured, as a result I spent a couple days figuring out how to rebuild the thing. If you use compressed air use the small dust cleaning aerosol cans, they clean but don't have a lot of pressure.

Thomas W 03-09-2021 02:01 PM

Trillium furnace
 
3 Attachment(s)
I ended up pulling the whole unit out so I could clean everything and reseal the inspection plate and burner connection. The outer exhaust droops about 1/2 inch. Is there any trick to line it up with the inner exhaust without taking off the outer grill?
I did get some pics of the gas valve, unfortunately the markings are not very clear. The upper left number might be 76 14 8, the one on upper right looks like 136 with a circle around it, the others are not legible.

Sorry about the thermocouple pics, I reassembled before I saw your note. But if you go back to my previous pics it does show the pilot and thermocouple. Looks pretty similar to what I have seen in previous pics.

Attachment 139796

Attachment 139797

Chris from Comox 03-09-2021 03:38 PM

From personal experience, it’s easier to remove the outer grill, remove what I call the “chimney”, put the furnace in place then wiggle/slide the “chimney” into the furnace itself and reinstall the outer grill.. The reason being that the “chimney” is a lot easier to wiggle around , has less sharp edges and is lighter than furnace itself. And you are not “blind” to the whole process as you can sort of see how everything is lining up at the same time

Thomas W 03-09-2021 04:15 PM

Trillium furnace
 
3 Attachment(s)
I got it all back together and tested it, furnace comes on about 5 seconds after thermostat is tripped.
To prop up the chimney I used a plastic strip used to unclog drains (see pic) inserted in the air intake and then run vertically up to the chimney. Eyeballed where it looked straight and then taped the plastic strip down to hold it. Went right in first try.
Re the pilot/thermocouple David, it is identical to the picture of the 65512 you posted. Ooops the second pilot pic should be rotated 90 deg to right
Thanks again everyone for you help, I was really happy to save this furnace, and learned a lot about in the process.

David Tilston 03-09-2021 04:25 PM

2 Attachment(s)
Quote:

Originally Posted by Thomas W (Post 807811)
I ended up pulling the whole unit out so I could clean everything and reseal the inspection plate and burner connection. The outer exhaust droops about 1/2 inch. Is there any trick to line it up with the inner exhaust without taking off the outer grill?
I did get some pics of the gas valve, unfortunately the markings are not very clear. The upper left number might be 76 14 8, the one on upper right looks like 136 with a circle around it, the others are not legible.

Sorry about the thermocouple pics, I reassembled before I saw your note. But if you go back to my previous pics it does show the pilot and thermocouple. Looks pretty similar to what I have seen in previous pics.

Thanks. I guess the model number will remain a mystery.

The previous pictures were also from a thermostat version of the gas valve. Below is what the business end of a standard thermocouple looks like.
Attachment 139802
The picture is from this thread:
https://www.fiberglassrv.com/forums/...tml#post295738
The pilot light is the top protrusion. There is a piece on the end that deflects the flame downward to the thermocouple. Note how thin it is in comparison to yours.

I have been looking into where to get a replacement thermopile. From this thread:
https://www.fiberglassrv.com/forums/...tml#post616381
I found this picture:
Attachment 139803
Which lead me to the following links:
https://www.americanhvacparts.com/p-...e-rodgers.aspx
https://www.americanhvacparts.com/p-...cartridge.aspx
They are not cheep.
Cheaper on Amazon:
https://www.amazon.ca/s?k=thermopile&ref=nb_sb_noss_1

Thomas W 03-09-2021 06:37 PM

Trillium furnace
 
Ok, I think I get it now. That seems unusual that the pilot's flame is deflected downward to the thermocouple, and yes it is thinner than mine. Had not heard the term thermopile before but makes sense that its a grouping of smaller units. And yes, my pilot is below the thermopile.

Has your paint job on the burner held up over time? How did you clean it up prior to painting? While mine had a lot of surface rust it seemed quite solid. I may change my mind in the future about painting.

Yeah, unfortunate that there were no other markings or stampings on the gas valve. My friend has a 1300 and he tossed the furnace a few months after he got it because it quit and he wanted to go a different way. These should be salvaged as they go bad or trailers are abandoned.

David Tilston 03-09-2021 08:10 PM

1 Attachment(s)
I gave it a light sanding to knock off the larger chunks of rust, but otherwise I didnít do much prep work. I used black RUST-OLEUM high temperature paint. I figured it was meant for rusty surfaces.

The paint is inside the furnace. I don't get a good look at it much. Since I used black paint, I never noticed any problem with it. But I didn't worry about it much, since any burnt paint would just go out the exhaust. The combustion air intake on the back of the fire box is both below the fire, and constantly cooled by fresh air. No issues at all. I only painted the outside of the burner. I couldnít see any way to do the inside of the burner, without plugging up the holes. I used masking tape on the stainless piece that has the holes for the burner. I painted both the inside and the outside of the fresh air intake, but I taped off the mating surface that connects it to the housing. I didn't want to affect the fit of that joint.

There are many threads on this site that discuss how hard it is to get the two pieces of the vent apart. The inner tube rusts to the point that they fuse and no longer slide apart. Many of these furnaces have been destroyed in the process of removing them. I would also suggest using some high temperature anti seize compound where the two hot parts slide against each other. This will make is much easier to remove your furnace in the future.

If your friend had advertised the gas valve from his furnace here, I would have paid $100 plus shipping for it.

I am not so sure that your pilot is below the thermopile. The silver tube is for the pilot light. The flexible wire is the thermopile. The pictures that you posted seem to show the tube above the wire. The big tube is for the main burner, and is on the bottom.

canyon Rafter 03-10-2021 01:19 PM

Good job Thomas! Glad you got your heater working again! I stayed in my Fiber Stream trailer for an extended period of time and found that my furnace heater was way too loud during the night and ended up heating the trailer with an electric heater. I had hookup to electricity so that was an easy solution. My next heater will be a Mr. Heater MH9BX- or something similar. Safe vent less heater that can easily be plumed into the propane gas lines of the trailer. Easy safe heat.

Joe MacDonald 03-10-2021 01:47 PM

The reason to not push anything through the opening is that even if it is smaller than the opening, a steel wire is harder than the orifice plate and can potentially damage it, I suppose a nylon bristle might be ok, on our burners at work we replace the orifice plate on smaller heaters, on our big ones, we drill them with a drill sized to the holes in the cast iron burners or stainless burner plates
Joe

David Tilston 03-10-2021 02:06 PM

Quote:

Originally Posted by Joe MacDonald (Post 807883)
The reason to not push anything through the opening is that even if it is smaller than the opening, a steel wire is harder than the orifice plate and can potentially damage it, I suppose a nylon bristle might be ok, on our burners at work we replace the orifice plate on smaller heaters, on our big ones, we drill them with a drill sized to the holes in the cast iron burners or stainless burner plates
Joe

Yes, I see the potential for damage to the orifice. Why is brass the common metal for this application?

Since you are professionally involved with heaters, any idea where I would go looking for new orifices for the Duo-Therm furnaces? With a 3/4" hex head, (I think) they seem larger than I expected, but I am used to motorcycle orifices that have a 1/4" hex head.

I like spare parts, and I would like to locate a smaller orifice for use at higher altitudes.


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