Furnace problems

Hi all--
I'm presently camping in AZ. The furnace is not putting out heat. Not sure what I am doning wrong. Both propane bottles are on. Propane is flowing fine all three burners of the stove. Water heater is working off the propane and water is hot.
When I push the thermostat up the heater clicks on and I can see what appears to be a pilot light on behind the furnace vent in the trailer. It should click and the burner should light but the burner does not light. So I get essentially cold air forced through the vent, warmed only a tad by the pilot light.
Maybe I'm missing something because I have not used the furnace in a while, but, heck, it was chilly last night!

[Bill]

Originally Posted by Tonopah

When I push the thermostat up the heater clicks on and I can see what appears to be a pilot light on behind the furnace vent in the trailer. It should click and the burner should light but the burner does not light. So I get essentially cold air forced through the vent, warmed only a tad by the pilot light. Maybe I'm missing something ...

No, you're not missing anything. If you can see the pilot light, it proves that gas is getting to the furnace. I think it also proves that the thermostat is working. It also proves that the electronic ignition of the pilot light is working. I see two possibilities, or maybe three.

1. Is the blower running strongly? Are you on shore power? There is an airflow switch inside the furnace (appropriately called the "sail switch") that won't allow the gas to come on unless there is a good flow of air. The purpose, of course, is to make sure there is enough airflow to carry heat outside the furnace and into the living spaces. This, of course, prevents the furnace itself from overheating. If you are dry camping, your battery is low, and the blower running slowly, there may not be enough airflow to activate the sail switch.

2. The second possibility is the one which Leon suggested in his second post - the thermocouple is out of place. The thermocouple is a small metal cyclinder with a smaller metal tube coming out of one end. The body of the thermocouple must be bathed in the pilot flame. This proves to the system that the pilot flame is on, and that it is safe to turn on the main gas valve. If the thermocouple is off to the side so it doesn't heat up enough, the main valve won't turn on - and no heat! The thermocouple could also be faulty, of course.

3. Has your TM been in storage for a while? In some parts of the country, there is a tiny spider and otherwise-harmless that LOVES the smell of propane. They tend to get into the orifice area, and weave webs that clog up the jets. If you can get to the orifice area, this is easily cured by runing a Q-tip around the inside of the gas burner pipe.

By the way, I see that your TM is new. Has your furnace EVER worked (to your certain knowledge)? Or is this a first-time-I-tried-it problem? All in all, it probably requires at least semi-competent/experienced tech help to address any of these. Your dealer or any other RV dealer should be able to handle it - it is a common appliance, and it is under warranty. Good luck and let us know what happens.

By the way, Leon's first comment about the levers on the thermostat applied only to older models, such as the 2002 models he and I both owned. Newer TM's have a different thermostat.

Bill

Thanks for the comments.

The blower is running strongly and I am connected to shore power. I can see the pilot light so I agree that the thermostat is working ok.

The heater has worked just fine in the past. My TM has been in storage for about 2 months. It is stored in So Cal in an RV lot outside, covered by an Adco cover. Temps have been warm with no precipitation.

The heater did decide to work last night. I put the thermostat in the off position for a while and then snuck it up until it clicked and left it there. The blower went on, pilot went on, and then heat did kick in. I lowered the thermostat later and it did kick on with heat during the night. But it sure as heck did not work last night.

When I get back to So Cal I'll take the TM into Custom RV in Anaheim and ask Matt to check it out. Suspect the thermocouple might be a little off, as has been suggested here.

Hello,

My thermostat on our new-to-us 2005 2720SL works to turn the heater on. Even when it is really chilly, it heats the space up nicely. Too nicely. It never shuts off. When it gets to 80 degrees and it starts to feel stifling, we will turn it off. It doesn't matter what temperature we set. Is there an easy fix? Thanks.

Walter

Originally Posted by Texas_Camper

Seems to be a problem with the preheater. Click on http://www.trailmanorowners.com/foru...read.php?t=933. That may help.

Thanks for the information; I did not realize that there was a preheater inside the thermostat.

[Bill]

Right, Leon, except maybe backward. I was never completely sure, but I think the preheater works on the top end of the range. In other words, if the the room temp is 60 and the thermostat is set for 70, then the furnace comes on. And as the room temp comes up, the preheater works to warm the thermostat, hopefully at the same rate. If there is no preheat, then the thermostat won't get to 70 until the room is 80. If there is too much preheat, the thermostat will get to 70 while the room is still at 66. Finding the balance is the trick.

Incidentally, the thermostats come from the manufacturer with the preheat set to zero.

Bill

[Edit: the link disappeared when Leon pulled his posts. It is http://www.trailmanorowners.com/foru...read.php?t=933 ]