Furnace Fun (Suburban Model No. NT-20SE)

[westysplace]

Well Guys..........
I would guess there are two main reasons why there are a number of two and three year old travel trailers on the market. The first is that the choice of trailer was flawed. Design, layout, and or liveable area are inadequate. The second main reason is that the operation and maintenance become too much of a hassle, especially as we get into our 70s.
The above furnace model is supposed to have a shutoff switch and a gas valve shutoff (not clear on this one). I have managed to locate the shutoff switch, but I am relegated to getting down on my hands and knees and using a paint stirring stick to operate. The clearance between the rocker switch and the furnace chasis is about 1/2" and is set back a good 6" from the front opening. I swear that they must have set the furnace in first and then built the kitchen sink cabinet around the furnace unit without regard to access.
I am toying with the idea of boring a hand hole in the side of the kitchen cabinet. This switch should be accessible from the side through a grommeted access hole in the side of the chasis. I am somewhat fearful that I might cut through wiring or tubing, but I think this can be done relatively safely by drilling a few pilot holes. I can't think that I am the only one with this problem. I would like to save my knees for other things like tennis. Any comments would be appreciated. Thanks.

 

[TCP1971]

hmmm

Why are you looking for a cutoff switch? If you flip the furnace thermostat control to the lowest setting it cuts off power to the furnace. If you want more, pull the fuse. The kill switch on the side of the furnace isn't really an end user control.

As far as a gas shutoff, I've never had an RV that had a gas shutoff for the furnace. I just shut off the propane tank. If you really want a gas shutoff, find the 3/8th copper line running to the furnace and install a ball valve. I wouldn't cost a great deal for an RV tech to do it.

Here's a copy of the furnace manual:

http://www.scamptrailers.com/Portals/0/Suburban_Furnace_NT-16SE_NT-20SE.pdf

Just for the record, our 189fds came with an NT-16SE that i replaced with a ducted NT-20S before our first trip out mainly to quiet it down. We get some nice warm air to the front beds now.

 

[westysplace]

Furnace Fun (Suburban Model NT-20E)

I have had no problem understanding the operation of any of my TT appliances, with to some extent, the exception of the furnace. I most probably will not use it that often!
If the furnace has not been operated for sometime, or say the system is slightly fouled, the furnace may not light off the first couple of times. This shutoff rocker switch cuts the power supply to the combustion side of the furnace. This allows you to turn up the thermostat with an isolated gas supply and no ignition voltage. Turning up the thermostat will still operate the blower to allow purging out any LPG that did not light off! In fact they suggest that you operate this blower for a full five minutes before turning this switch to the "on" position for the next ignition cycle. This is the same procedure talked about in my walk through, but no one indicated where the switch was. I assumed it was accessible like all the others.
I am very respectful when it comes to LPG. It is not naturally bouyant like natural gas and will hug the botttom of the combustion chamber without being vented naturally. If there is too much LPG buildup in the chamber when ignition occurs there could be an explosion with, as a minimum, damage to furnace components. Every one of us grillers have experienced a flashback on the BBQ when lighting off a burner after a few false starts. Windy conditions help this situation.
I agree with you that a gas supply shutoff is probably not needed as long as the switch works. The tubing run at this low supply pressure doesn't contain much. What had me confused was under "TO TURN OFF GAS TO APPLIANCE", 3. Turn shut-off valve to "OFF". Do not force[/u]. How do you force a rocker switch? Why would they use this phrasing if they meant the LPG bottles?
Thanks for your reply.

 

[TCP1971]

more info

The only problem I've ever had with the furnace is if my propane lines are empty (after changing bottle or having bottle turned off and running stove until it dies or something) and I try to start it. It usually requires a cycle where it won't start until the propane gets to the burner and it lights on the second try. I worked inside the trailer through the winter (in Calgary) to get it set up for us and ran the furnace to keep warm. It always runs the fan for 15-20 seconds on startup to make sure the sail switch is correctly open. Considering the size of the combustions chamber, you'll never need more than that to clear any "excess" gas. The only way there would be any gas in there is if the solenoid leaked, but again, that should clear out with the fan on startup long before any spark is applied. I think if you took a poll here, you'd find almost nobody who regularly uses the switch on the side of the furnace. Most furnaces are mounted well out of reach of the user, especially ducted units.

 

[westysplace]

Furnace Fun

Well TCP,
I know that practical experience always seems to win out in people's minds. I can't for the life of me figure out why the manufacturer would install a shutoff switch with access through the chasis which seemingly has no use whatsoever! Without fan rating and system volumes, it is all guess work as to whether or not the fan at startup will sweep sufficient volume to clear the buildup of LPG after several ignition attempts.
All I really wanted to know is whether or not someone had a practical and possibly esthetic approach in gaining access to this switch. Right now I am thinking about going in up top inside the cupboard above the furnace.
I truly appreciate your thoughts though!

 

[westysplace]

Furnace Fun

To Those of You Who Have Interest,
After removing a drawer to obtain a good view of the furnace support and wiring, I decided to knock out an elongated decorative panel in the front of the cabinetry just below the face of the furnace. I reused this panel and fabricated an insert with pull handle just like the cabinet drawers. I still have to lay on my side on the floor to reach this switch, but it is a relatively easy reach. If you had "popeye" forearms, this could be a chore, as the slot is about 2-3/8" in width! When the knees and back go south, we'll have to light off the firepit or head for Mexico!!

 

[westysplace]

Since I initiated this post and had more RV time, I have found out the following:
* The three-wire thermostat "off" position does not prevent ignition. The "off" position only represents the lowest setting possible, which in my case is 54 F, as measured by inside thermometer.
* Although the operating instructions imply so, turning up the thermostat with the shutoff rocker switch in the "off" posiition does not initiate an air purge.
* With the rocker switch in the "on" position, operating the thermostat control setting initiates an air purge ahead of ignition and also when shutting down after reaching setting.

Eastern WA in October had some nights in the low 40Fs and one night got down to 38 F. To prevent the furnace from coming on early in the morning, I left the rocker switch in the "off" position until it was coffee brewing time. The furnace blower is rather noisy. We are now in the market for a small electrical space heater that we can tuck in somewhere just to take the chill off.

Conceivably, once camp is set up, I could just shut off the LPG at the propane bottles until cooking time. However, I like having access to the shutoff rocker switch as a valuable convenience.