Furance Problem/Trick/ Need advice

[Econ]

We were unable to camp much this year. Decided we would camp in the SMNP the 10 days before Thanksgiving, come hell or high water. About a week before leaving, the heater, a 7916 Mark 2 was tested to make sure it worked.

There is a post on the first time camper subforum several months ago where someone asks how cold is cold? Well, It depends.

The long range weather before we left showed one night in the 20's. Short story, we had 3 in the lower 20's and at least 2 in the upper 20's before losing count, WITHOUT a working heater. After working on the heater all week here is the conclusion. My factory thermostat didnt like to work if the temperature was cold in the beginning of the heat cycle. I went thru the thermostat and heater multiple times. Every contact point was checked with 800 wet and dry for corrosion. Never could find the problem till the day we were moving to someones cabin so it didn't matter. You could set the thermo at 100*F and it wouldn't come on.But if you set it for 70*F and jump started the thermostat it would work perfectly. All you have to do is jump the thermo til the gas valves clacked the first time and its good for the rest of the morning.

Its been in the lower 20's several times since getting home so for humor I would go out there and turn the heat on to no avail, til I jump it.

In the starting sequence the ignitor fires just after the gas valves clack. When its 50 ish it works perfect.Its only when it gets below "35" ish of so that this happens.

Tenters are crazy<GG>. We arrived at dark thirty and set up. The next morning we were the only camper there. We looked out upon a sea on tents.

How did we survive? It wasnt bad. We had a summer weight sleeping bag shoved inside a winter weight bag with a blanket on top. It was rather toasty til nature called at 2 am. I thought 20* would be colder. At 21* it did get down to 31* inside.

DW doesn't like the bag in a bag method so what is a decent thermostat replacement???????

Thanks

 

[gladecreekwy]

We got it a simple digital on Amazon. There are many to chose from. 10 min job.
https://www.amazon.com/gp/aw/d/B071X9DGHY?psc=1&ref=ppx_pop_mob_b_asin_title

 

[Hilldweller]

I bring the Buddy heater as a back-up too.

 

[gladecreekwy]

Having spent many nights below freezing in a tent , a pup and a TT I’ve found without heat a tent is always warmer. Most have an inner and outer layer and the small space is heated by your body. Our pup is the coldest. We use a double wide winter sleeping bag because we don’t run the furnace while sleeping. It would cycle on every 10-15 min. Just right before bed and in the morning. It’s below freezing almost every morning from mid August till October where we camp. Last trip last year it was 8 when we woke up.

 

[generok]

My troubleshooting suggestion is to take the T-stat out of the loop. Pull it off and twist the two wires together. There, now you have a reliable, definitive call for heat to the furnace. If the furnace lights and runs at cold temps, let it run a bit and then untwist the wires. Flame should go out, fan will run a bit, then go off. Repeat. If the furnace responds well, then I'd say you have a T-stat problem. Pitch it and get one you like.

If the furnace does not respond as above, then you have a problem in the furnace circuits. Could be a few things there. But if you suspect a T-stat, get it out of the diagnostic loop and eliminate that uncertainty.

 

[Econ]

I bring the Buddy heater as a back-up too.

But if you suspect a T-stat

Hilldweller. You mean your DW does not enjoy sleeping in a 31 degree Aliner? It really wasnt bad till when nature called at 2 am and we live in an area where you call 80's "pleasant". I think first frost was mid November this year.

@generok
The thermo was off so many times that is was reattached with velcro.<GG> The key to success when I figured out how to jump the thermo without removing it from the cabinet. The thermo is mounted on a cabinet face frame "rail' just above a door. It has two shrt wires attched to the back of the thermo that you can pull down and play with to jump it. same principle as twisting the thermo wires togeter but you dont remove the tstat from the circuit.

By saying "jump the thermo it is the same as twisting the thermo wires together

 

[Sjm9911]

I look at it this way, the one you have dosen't work. Any new one that works would be a better option.

 

[davido]

I bring the Buddy heater as a back-up too.

^^ This.

One time having the sail switch fail on my popup's furnace was enough to convince me that having a backup plan for heat is a pretty good idea. I purchased a Mr Heater Buddy, a 12' propane hose, and a propane filter. Whenever I'm camping in temperatures where I know I would be uncomfortable in the evenings without heat, I bring the Mr Heater just in case. I've only needed it one time since getting it (one time, camping, that is). But it proved its worth.

Additionally, in the four years I've owned the Mr Heater Buddy, my home furnace has gone out twice. The Mr Heater Buddy is no match for a large home in a Utah winter, but it was at least enough to keep the main part of the house over 60f until the furnace technician was able to come fix it. In this application, it is about twice as effective as an electric space heater. Space heaters produce about 5100 BTU. Mr Heater Buddy is a little over 9000 BTU.

 

[tfischer]

By saying "jump the thermo it is the same as twisting the thermo wires together

It sounds like you "jumped" it and then once the gas kicked on, you went back to normal T-stat operation? What's being suggested is that you take the t-stat completely out of the equation. Disconnect the wires from the stat. Connect them together. This should call for heat and fire up the gas. Keep them twisted for a few minutes to verify operation. Then disconnect them. The gas should fairly quickly shut off, and within a minute or two, the fan should as well.

This will prove that it's the thermostat that is bad.

 

[Westcoast]

^^ This.

One time having the sail switch fail on my popup's furnace was enough to convince me that having a backup plan for heat is a pretty good idea. I purchased a Mr Heater Buddy, a 12' propane hose, and a propane filter. Whenever I'm camping in temperatures where I know I would be uncomfortable in the evenings without heat, I bring the Mr Heater just in case. I've only needed it one time since getting it (one time, camping, that is). But it proved its worth.

Additionally, in the four years I've owned the Mr Heater Buddy, my home furnace has gone out twice. The Mr Heater Buddy is no match for a large home in a Utah winter, but it was at least enough to keep the main part of the house over 60f until the furnace technician was able to come fix it. In this application, it is about twice as effective as an electric space heater. Space heaters produce about 5100 BTU. Mr Heater Buddy is a little over 9000 BTU.

You don't need 2 use it only when needed. Tosty is

 

[Westcoast]

Good

 

[Hilldweller]

Hilldweller. You mean your DW does not enjoy sleeping in a 31 degree Aliner? It really wasnt bad till when nature called at 2 am and we live in an area where you call 80's "pleasant". I think first frost was mid November this year.

...

Actually the heat is more for keeping the water in the tank in a liquid state for dishes and potty ---- we camped for over ten years in the teardrop with no heat, just a 12v electric throw blanket when boondocking and 110v mattress cover with Shore Power.

 

[kitphantom]

When we decided to switch out the original thermostat in the Coleman Cobalt, I found one that was rated for garage and basement use. In other words, it was OK with a lower cabin temp to start the furnace. It was a Lux, non-programmable. We put the same thermostat in our travel trailer, it decided to go a little strange on our last trip, so we've replaced it. We ended up with a different brand, but again the description and reviews all mentioned RV or garage use success.
We didn't have a fridge in the popup, but have one int he TT and have found that it works better if the cabin is at least in the mid 50s. If it's too cold, the freezer temps begin to rise because it doesn't kick on as often.

 

[Tait]

....it decided to go a little strange on our last trip, so we've replaced it...

Hopefully my wife doesn't read this and agree or I'll be getting replaced...

 

[Econ]

It sounds like you "jumped" it and then once the gas kicked on, you went back to normal T-stat operation?

Accurate. The reason for posting is most would take the wires off to jump it. How many people would jump with the tstat in circuit?

My speculation is there is some sort of corrosion that could never be found in the Tstat. All the contact areas I found were the on/off, the spring contacts and the attentuators <SP> aka the wire to adjust cycle length. The bottom line is the old analog Atwood Tstat is inaccurate and difficult to adjust so just move along to modern electronics.

The battery is a 130AH 1 year old and was generating over 10.5 volt at the heater. We'll never know for sure why as I'm moving along.

But if you are in the middle of the woods with a heater that wont start try this <GG>

 

[Econ]

Actually the heat is more for keeping the water in the tank in a liquid state for dishes and potty

If you use that method I would be unemployed. My job is to go to the potable water spicket and make sure all 4 jugs are filled every morning. Plus a plastic one for potty water. We use about 1.5 gall for bathing, 2 gall for coffee water, and a quart or so to flush.

 

[Hilldweller]

....

The battery is a 130AH 1 year old and was generating over 10.5 volt at the heater. We'll never know for sure why as I'm moving along.

...

Check for resistance in the wiring --- 10.5 is low. You might just have some sulfate creeping up the wires from the battery end.

 

[Econ]

Check for resistance in the wiring --- 10.5 is low. You might just have some sulfate creeping up the wires from the battery end.

Its a new day and the sky is blue and the sun trying to come up. The SEC championship decided.

The point being made is a 7916 mark 2 wont start if the voltage supplied is less than 10.5 DCV. That's why some people have problems when on battery only but they are "cured" when they go on "house voltage". Check your battery voltage first when a heater problem.

There was a symptom that I have heard before on these pages. The heater would try to start. It would try to run up for a quarter second then fade off quickly. These attempts might come frequently or minutes apart. That gve me the idea it was corrosion on the board so the board was cleaned

 

[tfischer]

Accurate. The reason for posting is most would take the wires off to jump it. How many people would jump with the tstat in circuit?

My speculation is there is some sort of corrosion that could never be found in the Tstat.

I think you are likely correct. But you can't completely rule out other things until you take the Tstat completely out of the picture.