Trillium Furnace Quit

[Thomas W]

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]

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]

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]

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]

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]

Originally Posted by Thomas W

-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]

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 371°C, (700°F)


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]

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]

a bad thermocouple will do that.

[AlanKilian]

Originally Posted by Darwin Maring

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]

Originally Posted by AlanKilian

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]

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]

Originally Posted by Thomas W

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.

Originally Posted by Thomas W

-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.

Originally Posted by Thomas W

-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

Originally Posted by Thomas W

-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:

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]

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]

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]

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]

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]

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

[mszabo]

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

[Darwin Maring]

Originally Posted by mszabo

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.