Furnace cycling on 2009 - 3665re - Montana Owners Club

et2 · 09-29-2009, 04:30 PM

We have a 2009 3665RE. We used the furnace for the first time last week. The outside temp was about 52 degree's. The furnace would heat to 68 degree's where we set the thermostat.What got my attention is it would shut off once reaching set temp,and then come back on after only 2-3 minutes.It kept cycling like this.

Any thoughts?

boje · 09-29-2009, 04:45 PM

Mine does the same thing. I have also purchased the insulation fittings that fit inside the vent cut-outs. I question the thermostat, but have not followed up.

et2 · 09-29-2009, 04:51 PM

Quote:

quote:Originally posted by boje

Mine does the same thing. I have also purchased the insulation fittings that fit inside the vent cut-outs. I question the thermostat, but have not followed up.

The thermostat was my thought as well. The only other thing I can think of is the where they put the thermostat. It is right next to the rear slideout. There seems to be a very slight draft where the edge of the slide is. The slide looks sealed against the wall though.

My thought is to run the ceiling fan next time and see if that pushes the heat back down from the ceiling.Maybe that will help.

Countryfolks · 09-29-2009, 04:51 PM

Ours is doing almost the same thing. I wonder if it's because a register vent about 3-4 feet away from the livingroom thermostat [the one by the corner of the counter] is blowing too much heat that way?

hookman · 09-29-2009, 05:02 PM

We use the ceiling fan and once the unit is warm the furnace doesn't come on as much and you don't seem to get cold spots. We also use the Electric fire place to off set the furnace.

jackel1959 · 09-29-2009, 05:15 PM

We have experienced the same thing in our 3455SA. Our thermostat is a Duo-Therm by Dometic "Comfort Control" and I assume you have the same. With these thermostats the "Differential" (the temperature difference between the "ON/OFF" cycle of the thermostat in the furnace mode) is preset on the circuit board and cannot be adjusted like on most digital thermostats. The kitchen island in ours is the same as in the 3665RE and our thermostat is located on the wall next to the "Entertainment" slideout. On ours too, there is a heat register close to where the thermostat is (probably just like the 3665RE). I replaced that register with one that can be adjusted. This past weekend while over at the coast I closed that register completely and it did seem to help reduce the amount of cycling. The temps were down to the low 50's at night. When it starts to get colder around here I will be interested to see how this new register works out.
Jack

richfaa · 09-30-2009, 03:16 AM

Welcome to the arctic package These campers are not exactly air tight.In fact they leak like a chunk of swiss cheese. Wait till it really gets chilly. Our 3400 did not come with the "warm and toasty" package as others seem to have. It is all part of the joy of Rv'ing.

Bob & Lee · 09-30-2009, 04:08 AM

We have the 3400 the thermostat was on the wall between the floor vent and the fireplace, we had the reverse it would hardly come on when the fireplace was on. The living room would be a little warm and the remainder would be cold.. I moved the thermostst thru the wall to the kitchen side and it appears to be better.

Bob

grampachet · 09-30-2009, 06:21 AM

What an interesting thread. As I was sitting in the recliner from 4:30 am until after 7 am (I couldn't sleep on account of a coughing fit I had) I was thinking about the same issue, Our stat was set at 67 and I had a small electric heater on low heat (700 watts) running constantly. The furnace fan would come on for about one half minute, then the burner kicked in for one to two minutes and the fan would continue to run for another two minutes. It would shut off again for five minutes and continue this until 7 am when I finally turned it up to 69 which changed the cycle. As has been mentioned this seems to be a common occurrence in a "camper." On my other SOB I changed the state settings but never had any good results either. We have the 3000RK with the stat near the stairs that lead up to the bedroom area.

et2 · 09-30-2009, 09:19 AM

We have one more camping trip in two weeks.I'm going to try throwing a rug over that vent near the thermostat and run the ceiling fan.We will see what happens.Thanks for all the replies.

swanny · 09-30-2009, 01:04 PM

As grampachet said, " the cycling of the fan". This is what gets me. The fan turns on and blows cool to cold air for about a minute then the furnace turns on and take another minute or so to blow warm air. Then at the end of the heating cycle the furnace shuts down and the fan then blow cool air for another 2 minutes. I can kind of understand it at the start of the cycle, but why does it need to run soooo long at the end? I just warmed the place up and then blow cool air around. I must say our thermostate seems to be pretty accurate.

richfaa · 09-30-2009, 01:32 PM

Our furnace does not seem to be that bad in the 06 3400. It does hold the temperature and it does not seem to cycle on and off as often as most of you describe. In fact when it is cold (Florida cold)it runs nearly all the time and sucks up propane at a rapid rate. We keep the bedroom register closed off as it gets so hot up there it will burn your feet when you jump out of bed. My only complaint is that there is so many ways for cold air to get into the camper..the walls and floor are cold . It does a good job of keeping us warm as long as we wear socks or slippers, sweaters or long sleeved shirts, do not get too near or touch the walls. We are never toasty...

Countryfolks · 09-30-2009, 02:47 PM

I blocked the vent by the counter early this AM, it didn't change anything. The same with the overhead fan off/on. I'm going to try covering the thermostat with a box of some kind next.

EagleRunner · 09-30-2009, 02:55 PM

My 2005 2955rl did the same thing. After replacing the remote thermostat with CCC digital thermostat I noticed our furnace would run almost continuous. After some investigation into the problem I found a cold draft coming down inside the wall the thermostat was installed on. Also, the heat register below it was not helping matters any. I found a magnetic cover to cover the register and also placed some insulation material between the thermostat and the wall it was mounted on. Keystone makes some big holes to pull the wires through and that is probably what is causing the thermostat to cycle frequently. By doing both of these steps I was able to reduce the frequency of the furnace cycling. I used a foam shipping envelope and cut out the form of the CCC thermostat to form the insulation behind the thermostat. I have been extremely happy with that resolve.

richfaa · 09-30-2009, 04:18 PM

These things work the same as the stick house. Furnace comes on and heats up the ductwork. fan comes on and brings the house up to temp..furnace shuts off and fan runs till it hits the low limit. The thing is these things are so drafty that the furnace has to run almost continuous to maintain the set temp..

akf15e · 10-01-2009, 08:18 AM

Glad to see this post. I thought one more thing was going wrong with mine. Seems like it is a design issue, not faulty equipment. I noticed it last Spring, but it hasn't been cool enough to need the furnace yet this fall.

Looks like we'll use the fireplace and space heaters a lot to minimize the cycling.

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