Suburban furnace valve?

[Mrcrowley]

Hey folks been a while but it is good to be back fixing up the trailer. I have a question and a problem. I pulled the Furnace from my airstream and clean it all out air blew the fire chamber and cleans off the electrodes. well I wanted to see if it still worked (which I didn’t think it would even though it was in good shape) So I hooked up a Propane tank to main gas line on the furnace and hooked up the wires to my battery charger at 10 amps (remember just to see if it would run) well I turn the gas on and plug it in and it fired up right off. Then it shut right down with only blower fan running. Ok before I go any further left explain setup.

Old forty gallon LP tank full
Direct gas line to furnace (no valve)
Battery charger for power at 10 amps
Blue and red wire twisted together
Yellow wire to ground
(Second blue wire from the red wire not hooked up)

Sequence: plugged in battery charger ran to LP tank turned it like 1/4 turn and nothing. Waited fifteen seconds still nothing.
Trouble shooting: unhooked line from gas line to fire chamber and UN power the LP gas valve used charger to do direct line to solenoid valve switch and heard it click, Turn gas on no click turned gas off heard click, Left power on while the valve clicked and turn on gas and it worked. Turned off gas hooked up lines and turned on gas and nothing no click or sound of gas. First question really is.

Am I getting enough power from the charger to make valve work ?

Where Do I get parts for the suburban nt30M furnace?

[HowieE]

Your power source is enough. As long as you have 12 volts that is enough. Most heater have a builtin time delay before starting the fan. Once the fan is started it should run for about 15 seconds to purge the fire box before opening the gas valve, the click you hear. There is no need to keep turning the gas on and off, once it is hooked up to the heater.

If the fan runs for longer than 60 seconds without the lighting. Suburban suggest turning off the gas and let the fan run for 5 min. then do a normal startup. Not sure what that does but it has worked for me.

[Mrcrowley]

Originally Posted by HowieE

Your power source is enough. As long as you have 12 volts that is enough. Most heater have a builtin time delay before starting the fan. Once the fan is started it should run for about 15 seconds to purge the fire box before opening the gas valve, the click you hear. There is no need to keep turning the gas on and off, once it is hooked up to the heater.

If the fan runs for longer than 60 seconds without the lighting. Suburban suggest turning off the gas and let the fan run for 5 min. then do a normal startup. Not sure what that does but it has worked for me.

Ok so the valve should open in about 15 seconds after power is on ? . Also do you need a lp regulator before I hook up to funace?. I bypassed the valve to see if the furnace would fire which it did . So when the power goes on the circuit board should turn the gas on and fire the ignitors ?

[thecatsandi]

You may not be getting enough amps fro mthe charger and the changer may not be putting out enough stable power. Put a 12V battery in the circuit and see how it behaves.

[Excella CM]

Here is some info from the 1978 manual. Notice that using a battery charager is not recommended. Also, w/o a regulator in the line you may overpressure the valve and burner.

[HowieE]

Originally Posted by Excella CM

Notice that using a battery charager is not recommended. Also, w/o a regulator in the line you may overpressure the valve and burner.

It's not a case of MAY OVER PRESSURE it's a case of you might have a bomb on your hands. Yes you must have a regulated gas source. Depending on the temperature you could have more than 10 times normal operating pressure on the line without regulation.

If you were operating without a regulator and the heater lite the pressure probably blew out the flame and the lack of heat on the flame sensor shut down the gas valve.

A battery in the circuit will filter your source voltage and provide a true DC source. Depending on the tolerence of the components on the control board this may be necessary, but in any case it is a good idea.

[lewster]

Mrcrowly,

Your furnace, as with any LP appliance in an RV, is meant to use REGULATED LOW PRESSURE LP, meaning that the pressure should be NO MORE than 11" water column, or approx. 1/2 PSI. Any RV regulator will give you this.

A furnace of your vintage has a little device called a 'time delay relay' or TDR. This is what allows the blower motor to start and purge the chamber initially before ignition, and after the thermostat has been satisfied and the burner is extinguished when the gas valve closes, allows the blower to keep running to again purge the hot air from the chamber to prevent overheating before complete shut-down.

In reading your wiring scheme, I think that may be the problem. Unless things have change at Suburban, the yellow wire is for your ground, the red is for positive 12VDC, and the two blue wires are for the thermostat. Use the blue wires as the thermostat by-pass and connect them together for the 'on' function, and separate them for 'off'. Remember about the TDR and allow the unit some time to cycle thru the purge functions.

The battery charger is NOT the problem, as I have used them on several ocassions to bench test furnaces, but as the manual says, a battery is a better source for 12 VDC.

[Mrcrowley]

Would I be able to use a gas grill regulator to test furnace?
I can get those at home depot . I need to replace the main regulator for trailer later. I want to get a automatic switchover regulator and also need new tanks and hoses.

I bet the pressure of the lp was keeping the valve shut which is a good thing as some of you were saying (a bomb and all or a flame thrower) next time I think Ill come here for suggestions before I attemp things of this nature.

Now I blew out the fire chamber with compess air,cleaned the ignition electroids off . Is there anything else I should check to clean ?

My plan of attack is to remove clean and run all the equitment out side the trailer I believe there is a main line gas leak in the trailer which I will have to replace the gas line . Only thing I see a main problem is the hot water tank what would be a good way to clean and do maintence on that ?

One more thing how far apart should the ignition electroids be right now there 1/4 inch apart from the center rod?

[lewster]

Originally Posted by Mrcrowley

Would I be able to use a gas grill regulator to test furnace?
I can get those at home depot . I need to replace the main regulator for trailer later. I want to get a automatic switchover regulator and also need new tanks and hoses.

I bet the pressure of the lp was keeping the valve shut which is a good thing as some of you were saying (a bomb and all or a flame thrower) next time I think Ill come here for suggestions before I attemp things of this nature.

Now I blew out the fire chamber with compess air,cleaned the ignition electroids off . Is there anything else I should check to clean ?

My plan of attack is to remove clean and run all the equitment out side the trailer I believe there is a main line gas leak in the trailer which I will have to replace the gas line . Only thing I see a main problem is the hot water tank what would be a good way to clean and do maintence on that ?

One more thing how far apart should the ignition electroids be right now there 1/4 inch apart from the center rod?

IIRC, the spec calls for 1/8" gap between the electrode and ground. The gas grill regulator is usually too high pressure, being a single stage reg while RV appliances take a 2-stage version.

For the water heater tank, remove the drain plug and T & P valve and run a garden hose thru it with the drain pointing at a steep down angle. You won't believe the stuff that comes out!

Too bad you didn't post this last week. I was in Manchester coming and going to the UNH graduation last weekend.

[Mrcrowley]

I did as some of you suggested and ran a battery and a grill regulator and it did all the cycles it was supposted to .

1) Turned gas on and hooked up to battery and within 8 seconds it fired up

2) Ran for about five minutes put out good heat

3) Unhooked blue wire fan kept running for about 2 minutes and the whole thing shut off .

So this is a good thing now just need to clean out all the venting had mouse infestation dont want to heated smell of mouse dung blowing through the trailer . I have question about that to .

Would it behieve me to put a in line fan from mid cabin to the rear to move air towards the back of better?

OH lewster that would been cool if we had crossed paths oh well oce I gt the sovereign back together hope see a bunch of you people out there.

[Excella CM]

Get the mouse turds out or you'll possibly have a Hanta virus germ warfare disseminator!

Inline fan's a good idea.

[Mrcrowley]

Originally Posted by Excella CM

Get the mouse turds out or you'll possibly have a Hanta virus germ warfare disseminator!

Inline fan's a good idea.

Ooohhh I agree 100% I am going to remove all the venting spray it down with simple green and pressure wash it ...There will be no turd left in those vents ...

[Mrcrowley]

Any suggestions on who makes a good square vent inline fan?

[Mrcrowley]

I was thinking about removing square venting and putting in round like out of the furnace and using a boat engine vent fan which is 12 volts and draw low voltage. and I belive same size as the furnace vents...

[Mrcrowley]

I had left the tarp over the trailer because one of the vents is leaking. Well today I was looking on roof of trailer and I noticed some branches had fallen on the roof,upon doing a walk around I notice that a two good size branchs on the ground about 6 inches round five feet long one in the front one in the rear . SO I pulled the tarp off to inspect and to my horror I find THIS:










I need help who can I get to fix this I think home owners will pay but who can fix airstream bodys in New Hampshire .

[Excella CM]

Not what we normally think of as a wind fall! Sorry to see that! When you get back to it, you can use square computer type cooling fans in square ducts.

[Mrcrowley]

I have some 120 mill 3cu fans from some computer build I have done bet they would work great. But need to know how I am going to handle the damage to trailer first...

[Inland RV Center, In]

Originally Posted by Mrcrowley

[COLOR=blue]

Now I blew out the fire chamber with compess air,cleaned the ignition electroids off . Is there anything else I should check to clean ?

You cannot blow air through the combustion chamber to clean it out, with any degree of success.

You "MUST" remove the furnace, take out the burner log, tap on the combustion chamber with a small hammer, then tilt the chamber back and forth until you empty all the dirt and rust.

Secondly, blowing air into the combustion chamber, has been known to "rupture" the chamber, rendering it useless.

Andy

[wkerfoot]

Mrcrowley,

Don't know about New Hampshire, but Colin Hyde of GSM Vehicles is in Plattsburg, NY.

Bill

Originally Posted by Mrcrowley

I had left the tarp over the trailer because one of the vents is leaking. Well today I was looking on roof of trailer and I noticed some branches had fallen on the roof,upon doing a walk around I notice that a two good size branchs on the ground about 6 inches round five feet long one in the front one in the rear . SO I pulled the tarp off to inspect and to my horror I find THIS:










I need help who can I get to fix this I think home owners will pay but who can fix airstream bodys in New Hampshire .

[Mrcrowley]

Originally Posted by Inland RV Center, In

You cannot blow air through the combustion chamber to clean it out, with any degree of success.

You "MUST" remove the furnace, take out the burner log, tap on the combustion chamber with a small hammer, then tilt the chamber back and forth until you empty all the dirt and rust.

Secondly, blowing air into the combustion chamber, has been known to "rupture" the chamber, rendering it useless.

Andy

Well luckly I did not rupture it it works fine my problem now is skin damage..