Where is the model number for furnace?

[Dingo Girl]

Did you fire it up yet?

[2002sheds]

Hi Din,
I am sad to say that I have not. Life has interfered with my beautiful plans, including jury duty, car issues and various other inconveniences. The furnace sits on the bench, un-bench-tested...

I appreciate your post. Perhaps I can re-gain my pre-Life focus and test it today. No matter when it is, I will report the results -- good or bad.


Thanks,
David

[2002sheds]

Worked on the furnace bench test today. Had both gas and 12 volt hooked up, then realized that the gas connections that I had cobbled together for the bench test were leaking. Bummer.

Removed the gas, and hooked up the electrical. Runs perfectly. Tomorrow will be the real test though...



David

[2002sheds]

Hi Di, All,
After disassembly, a thorough cleaning and reassembly (including careful inspection and reinforcement by way of RTV sealant on the crossover tube), I bench-tested the furnace again today with the propane tank (using the regulator) as well as 12v.

This time, the fan spins perfectly, as before. The gas, on the other hand, is a no-show -- at least so far.

I read enough of the instructions to know that the fan shuts off after 3 minutes of no heat, and that is what happened. That entire time was spent with me trying to light the pilot and burner assembly by using a bbq grill top of igniter. No joy...

I will try to go back and find the path for the gas. I don't think gas even made it to the pilot assembly, but I will try again and sniff around after the fan shuts itself off.

If any of you would be so kind as to remind me of the "firing sequence", I'd be grateful. I left the cap on the end near the igniter "probe" because I read posts on here about flames shooting out of the sealed combustion area when it first lights. That is also why I am using a bbq igniter. If that is a bad idea, please let me know.


Thanks,
David

[Dremel]

Our 69 Ambassador is a NT30

[2002sheds]

Hi Dre,
I am not sure why you mentioned that your furnace is an NT-30. Ours is unlabeled. Are you suggesting that maybe it is also NT-30? It could be...I will try to get a better handle on it by reviewing the manual.

I found the manual for a bunch of models and realized that I had not followed the start up sequence at all. I will try again, this time getting the pilot light lit before any other phase (thermostat, etc.)...


Thanks,
David

[2002sheds]

Hi DGG, Dre, All,
I have started a different thread (but relating to the same topic) over in Interior Restoration/Furnaces et. al. I should've posted there to begin with, but I am clearly still learning how to use this fantastic site.
One last note here... I now have the electrical and gas hooked up and have gotten the pilot to light. Crossing the wires for the thermostat gets the fan going nice and fast, closing the sail switch. What does NOT happen yet relates to the solenoid. It will open if given 12v as a test, but it is not opening as part of the startup sequence. I will be investigating further with the multimeter, and also looking more closely at the wiring diagram. Maybe I re-assembled this thing with a wrong connection...

Thanks for all the help here -- hope to hear from you over in Interior Restoration/Furnaces !
David

[Dremel]

Sounds like you are on your way to figuring it out. I mentioned that the 69 Ambassador that we have had a NT-30 because I thought you were still trying to figure out what was in your 70 Ambassador. Figured that they might have used the same since it is the same body design and size.
Ours still had the metal label riveted onto it. tall label

[2002sheds]

Nearly Solved?
Hi Din, Dre, Lu, All,

I had started a thread in probably a more appropriate location over in Interior Restoration/Furnaces, etc., and now am 99% towards having the furnace purring like a kitten (and not a deadly, carbon monoxide-spewing kind). Here is my post from this a few hours ago. I put it over here as well to kind of close the loop....


I spent time with the furnace this morning. I mapped out the electrical path the best I could, and discovered a few fairly basics things that probably would come much more easily to those with more knowledge of electrical circuits.

First (and it is important to rookies like me), the brown wires are the path to ground, or return part of the circuit. While I still do not understand it completely, it has been explained to me that basically you need a place for the voltage to go. If the ground wires or connections are corroded or dirty, the electricity cannot energize the component (in this case, the gas valve). Once I removed the brown wire from the terminal of the gas valve and connected a lead to the negative cable from the battery, I had a clean path, so the gas valve would fire when the thermostat wires were joined (completing the circuit). For those that read this in the future, the brown wire connects to the relay at the same place that the yellow wire (the one connected to the negative side of the battery) connects -- terminal 1. That was my first hint about where the voltage returns to ground.

Second, all of the wiring diagrams I could find do not quite match up with what was in front of me, so a multimeter is your friend. I got mine free at Harbor Freight. The two settings that I used were continuity (ohms) and DC voltage. With the multimeter and the battery charger, I could determine how far the voltage got when it first got to the furnace using the DC volts setting, and then where it went from there. With the multi tester in the continuity setting, I could tell if switches were open or closed, further determining how the voltage moved from part to part.

The last thing I will say about this process is that I heard from several people on this forum that these furnaces are death traps waiting to happen. One person even wrote in to say that in the 1970s they witnessed people being pulled from their two year old Airstream -- incapacitated because of a furnace with a leak. I think it is important to be very wary of ANYTHING that has the potential to spew poisonous gas (especially this extremely dangerous stuff, which has no odor). It is also important to use logic and common sense. In the case of the people that were pulled from their AS in the 70's, the author of the post wrote that they would not trust such a furnace, but that would mean that THOUSANDS of people would have been in the same situation, and I am old enough to remember that not making the news -- as it surely would have. It also means that NO furnace over a certain age (2 years?) should be trusted -- again, not completely logical.

What is definitely correct (again) is to use an extremely skeptical and cautious approach when working on anything that has the potential to harm you. For example, there is a reason that (most, anyway) children are encouraged to not play with matches... The wall furnace in our house is from the 1950s. The main combustion chamber is super solid, but we have it checked often for any changes or damage. The only thing that has needed replacement is the pilot/thermocouple, which eventually wears out and needs replacement. That makes sense, because it is the old type of furnace that has a pilot light that is on all of the time (like your water heater) during the cold season. And we have a carbon monoxide detector to be extra sure.

During the entire disassembly and reassembly of this furnace I have looked for faults and weaknesses. This particular unit spent its life in Northern California. This meant that it was probably dry the vast majority of the time and used relatively few times in its existence (maybe 100?). I didn't just go on that, though -- I took this thing apart and found virtually no rust (maybe a teaspoon, and only surface rust) and everything but the gaskets (dried out) and wire insulation (also dried out -- if we keep this, I will replace the wires with similar color coded wires) to be in great condition. If the bearings were binding or if there was actual rust (I grew up in the Midwest, and would hesitate to ever trust one of these that is this age from back there), I would have immediately thrown this unit out. Since it passed those early tests, I kept going... if there was ANY point where this looked suspect, it would be abandoned in favor of a new unit.

In fact, I may still decide to purchase a more modern furnace, for the convenience of electronic ignition or other features (and, as has been mentioned by many, peace of mind). For now, we will go with the screeching carbon monoxide alarm with digital readout (so you can see exactly how many ppms, if any, are present). In my opinion, the carbon monoxide alarm and an LP alarm are a must for anyone with gas appliances in their coach. We will also first use it only during the day, to ensure that it operates correctly several times before trusting it while we are sleeping.

I have learned a tremendous amount from this site, and this thread is one more example of that. Thanks so much to all of you that wrote in! I tried to take into account all points of view when asking for your opinions and make an educated decision about how to proceed. Thanks to you, I feel that I was able to do that!


David