Replacement thermostat for Suburban furnace

SafeHarbor · 10-05-2005, 04:53 PM

Hi, folks,

I did a bit of maintenance and a test run on the NT-30 funace today as I could get it cool enough to run the furnace with all the windows open.

Then I discovered an irritant that I have forgotten from the short time earlier this year that I had used the heater - the thermostat makes a loud "boing" noise when it reaches the desired temperature. This wakes me up.

I would like to git rid of that thermostat.

Can anybody recommend a replacement, maybe 12V or battery operated, "smart" thermostat to use for the heater? I have searched the posts here on this subject and found them all to be two years or more old and mostly having to do with more modern trailers. This is for a 1979 Excella with separate A/C-heat strip and heater thermostats. (Yes, the Armstrong and its heat strips work fine.)

Also, it would be good if the "swing" could be adjusted. I don't mind a three degree difference between on and off if it means it won't run the heater continuously on and off, on and off in a sort of "hunting" mode, which is what I've heard some SOB owners complaining about during the winters.

Thanks,

Lamar

overlander63 · 10-05-2005, 06:13 PM

Or your favorite hardware store. You can get a battery powered thermostat and replace the thermostat you have. This was done on Vintage Thunder, it even runs the air conditioner as well. It is fully programmable, as far as time of day, temperature, when to change temperature from warm to cool, etc. Cost is reasonable, too.

Inland RV Center, In · 10-05-2005, 06:20 PM

Lamar.

Easy fix.

When the thermostat contacts are open, you will see a "stop" bar close to it.

Bend the stop bar, so that it places the contacts much closer together.

In doing so, you will stop the "boing" and the thermostat on-off temperature differencial will become much smaller, typically 2-3 degrees.

Andy

SafeHarbor · 10-05-2005, 06:21 PM

Hi, Terry,

I looked at some of them, and the ones I saw said they were for 24V systems. I take it something inside of them is powered by the small 24VDC circuit?

And thanks. There's an big Ace Hardware about ten miles from here, so I'll go see what they have.

Lamar

overlander63 · 10-05-2005, 06:27 PM

Quote:

Originally Posted by SafeHarbor

Hi, Terry,

I looked at some of them, and the ones I saw said they were for 24V systems. I take it something inside of them is powered by the small 24VDC circuit?

And thanks. There's an big Ace Hardware about ten miles from here, so I'll go see what they have.

Lamar

24 volts is what the transformer puts out in the air conditioner. It is probably AC (vs DC). Our thermostat in our house has three AA batteries powering it, and Vintage Thunder's is basically the same. If you want to save some money, try Andy's solution above first. If it doesn't work, you can then get one of the high-tech digital ones.

SafeHarbor · 10-05-2005, 06:27 PM

Hi, Andy,

Thanks. I'll take a look at that and try it. Here in south Georgia we're getting into the time where we'll have warm days and cool nights perfect for sleeping. After that, it'll be warm days and nights a little too cool with some heat required, and then it'll turn into blustery days and cold nights for about a month, and then it'll be spring again. (Or we'll be freezin' our butts off in March wondering where Spring went..)

Regards,

Lamar

**john hd** · 10-05-2005, 06:49 PM

lamar,

if andy's suggestion doesn't work, how about an old fashioned honeywell round thermostat?

low tech, no batteries, and no boingggg!

ace will have them as well.

john

Westfalia · 10-06-2005, 10:08 PM

Don't most of those round thermostats have mercury contacts? You'll have to be pretty level to get the right temperature, and forget about running the heater in the trailer when you are on the road (if that is what you do).

I hate the BOOINGGG, as it also wakes me up, but having the noisy heater cycle on and off more often would be majorly annoying as well. I'm going to find a small digital thermostat this weekend. Does anyone know of any thermostats that let you set your temp BELOW 50 degrees? I want the heat to come on enough to keep the pipes and tanks from freezing, but keep the heater off as much as possible!

SafeHarbor · 10-07-2005, 06:14 PM

Hmm... this is getting more complicated than I aniticpated. The air conditioner thermostat is working just fine, and that runs the heat strip OR the air conditioner.

I was hoping to set the heat strip at the temp I want to keep and then have the second thermostat turn on the furnace if the heat falls below a certain point with the heat strip already running.

Also, it would be nice if I could program it to come on and run (or not run, as the case may be) before I get up so the trailer would be nice and warm when I stumble out of bed.

I think the heat strip and a couple of space heaters will take 80-90% of the heating load this winter. The furnace will be used to augment the electric, and for when the power fails.

Lamar

SafeHarbor · 10-08-2005, 01:54 PM

Hi, folks,

Andy's fix, of course, worked just fine. It now has only a little-bitty boing, which is actually more like a "plunk."

However, I also noticed a bit of corrosion inside it, so I decided to replace it.

Since I wanted to keep the existing themostat for the A/C and heat strip, I went to Lowes and bought the least sophisticated digital thermostat that was not mechanical that I could find.

This was a $24.95 Hunter "Just Right," model #42999B. For use with the furnace only, it's only uses two wiring connections, it runs on its own batteries, and it's very easy to install. I put in the same place that the Suburban thermostat was, just under the Magic Chef thermostat for the Armstrong.

The two wires go to the "W" and "Rh" terminals. The Rh terminal is jumpered to the "Rc" terminal.

Now on to the next project. It seems that there's yet another thermostat in the trailer. This one is between the entrance door and the spice rack over the oven. It says "The Cat" on it, so I think it's supposed to control the Olympian catalytic heater. I have never indentified where the wires for this thermostat come out.

I did find two well-insulated wires coiled up in the back of the lawn chair storage area behind the stove. To my surprise, they carry 110VAC! What in the world could that have been for?

Well, another typical day off for me. Let's go see what I can get into now!

SafeHarbor · 10-08-2005, 02:05 PM

The mystery thermostat's wires were simply tucked underneath the inside rear door trim and they were cut at the base of the stove cabinet behind the fire extinguisher.

It looks like that particular thermostat has not been used in a long time.

Lamar

overlander63 · 10-08-2005, 06:37 PM

Quote:

Originally Posted by SafeHarbor

I did find two well-insulated wires coiled up in the back of the lawn chair storage area behind the stove. To my surprise, they carry 110VAC! What in the world could that have been for?

Those wires may be for an optional 110v light inside the oven, unless I misread your post about the cat heater.

SafeHarbor · 10-08-2005, 08:12 PM

Hi, Terry,

Good thought. I assembled this stove from one that I bought off eBay, very happy to find a NOS one in the box in almond to match my countertop, and parts of the old one, and neither the old stove or the new one has a light inside.

I would like to find a door that has a window in it for the stove, as I've already replaced the glass with a custom-cut tempered replacement. Fortunately, the old stove had the right handle on it, so at least the *look* of it is accurate.

I don't think the Olympian cat heater has a thermostat capability, but I did disassemble it and clean it today and do a test run. These things are so duck simple that I think one may last forever.

I removed the non-functional thermostat and pulled out the unused wiring. If I ever do get a cat heater that can use a thermostat, I can put it right back where they had it.

Thanks again for another spot-on answer.

Lamar

PS - I have 2 qts of strawberry-almond ice cream "ripening" in the fridge. I may be getting good at this...

SafeHarbor · 10-08-2005, 08:22 PM

Hi, Westfalia,

The instructions for the "Just Right" Hunter model I installed says that it can be set for 45 degrees low and 95 degrees high, and the on-off can be increased to three degrees to make the heater run less frequently but longer.

It really was easy to install, and at $25, I think I can recommend it. If it works well, it's just what I wanted.

Let us know what you come up with.

Lamar