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Furnace cycling on and off every 2 minutes


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Has anyone else had this issue, our furnace cycles on and off approximately every 1 1/2 to 2 minutes.  It got to the point that we turned it off completely on our drive back to Massachusetts after picking up our new Ollie at the beginning of October.  So far we have no answers other than to try to reinitialize and set the temperature degree spacing.  That has not worked and we are waiting for further info from service, there does not seem to be any blockages, fan is coming on and the heat does work when it is running.  It seems to cycle on and off more when the temperature drops below 40 degrees.

Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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That’s strange. Our furnace will run for 10-20 minutes or more if it is really cold.  Is it on for 2 minutes and off for 2 minutes constantly?  Does it ever warm up the living space?  I’ll be interested in what Oliver service says.  My first guess is a faulty thermostat.  Mike

Texas Hill Country | Elite II #135 | Ram 2500 6.7L

ALAZARCACOFLGAIDILKSKYLAMDMSMOMTNENVNMNYNCNDOHOKSCSDTNTXUTVAWVWYsm.jpgALAZARCACOCTDEFLGAIDILINIAKSKYLAMEMDMAMS

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Mike and Carol:

Bill and Nancy have a 2022 Elite II, hull  #1265. I clicked on their Icon and that information is on their profile.

2018 Oliver Elite II, Twin Bed, Hull #354 

2018 RAM 1500 Rebel 4 x 4, 5.7 Hemi, 3.92 gear ratio

Maine

 

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1 hour ago, dewdev said:

Bill and Nancy have a 2022 Elite II, hull  #1265. I clicked on their Icon and that information is on their profile.

Thanks, I did the same and saw that it was a newer trailer and so was hesitant to provide too much comment on what might be a different furnace than I have.  It’s just a good practice to remind folks to put their trailer info in their signature so we don’t have to bounce back and forth between posts and profile pages!  Mike

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Texas Hill Country | Elite II #135 | Ram 2500 6.7L

ALAZARCACOFLGAIDILKSKYLAMDMSMOMTNENVNMNYNCNDOHOKSCSDTNTXUTVAWVWYsm.jpgALAZARCACOCTDEFLGAIDILINIAKSKYLAMEMDMAMS

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If it operates normally up to the time it starts short cycling, it is most certainly a control problem. Does it do the same thing when cooling? I guess you will have to wait until June to try that….. 😳

An RV tech should be able to diagnose it very easily by installing a temporary test thermostat. This would be covered by your warranty, so don’t worry too much.

Old mechanical thermostats have an adjustable “dead zone”. I think that the digital types do have some sort of selectable value for this, to reduce short cycling under certain situations..

EDIT, your Dometic manual shows the default settings, it may be that something was not programmed right. That would be very easy to check. “Furnace Differential” refers to the dead band, in other words, the temp has to drop 2 degrees before the stat will send an “On” request to the furnace. If it were set to 1 or 0 (if that is even possible) it would short cycle. If it is set to 2 degrees, try changing it to a higher number.

 

B973F244-DCC2-4422-8081-584C27A22F24.thumb.jpeg.2f0b0d7e94215d7bfe5a21d4edef3bcb.jpeg

 

John Davies

Spokane WA

 

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"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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We have done all of the above already.

As of this morning this is where we are at:

We did the following to check on the heater:  Checked vent connections and visual inspection around the furnace.  The Dometic thermostat has been re initialized and the degree off set is set to 2 degrees

-Tested this morning  with 2 additional digital thermometers mounted on the wall next to the thermostat. The Dometic thermostat was set to 55 degrees with the fan setting on Auto. The outside are temp was 35 degrees.

Furnace came on and raised the temperature to 56 degrees according to the Dometic thermostat and furnace shut off. The other 2 thermometers read 53/52 degree

1 minute after furnace shut off there was a double clicking sound that came from the air conditioning unit mounted on the ceiling

1 minute later a 2nd double clicking sound came from the ac unit

10 seconds later a 3rd double click sound came from the ac unit

10 seconds later a 4th double click sound came from the ac unit

30 seconds later a 5th single click sound came from the ac unit and the furnace turned back on again

 The temperature read 55 degrees on the Dometic when the furnace restarted and ran for a few minutes and then shut off when the temperature on the domestic read 56 degrees.

This has been forwarded to service.

Sorry for not providing hull info, etc at the bottom, new at this...

2022 hull# 1265 with dometic ct thermostat/furnace

 

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Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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Try increasing the differential number. I don’t have that AC model, but I think the clicks are normal. The furnace gets its actual commands from the board inside the AC.

BTW you don’t really need to add any standard equipment details to your Hull description, though you can add options if you like, but please do add your Tow Vehicle. 

John Davies

Spokane WA

"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags, Safari snorkel.

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Differential is set at 2 which is the most it can go.  From what we've heard most people don't hear their furnace turning on and off and clicking every minute.  It's like a dripping faucet, the noise will drive you insane.  Thanks for the info on the ac driving the furnace

Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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You might try changing the fan speed setting on the thermostat from "Auto" to "High" (see instructions) and see if the problem(s) go away.  Assuming you have the suburban furnace, the furnace fan must always run at "high" speed anyway.  The "auto" fan speed setting is only relevant when using certain air conditioners/heat pumps.   

 

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Steve and Lornie

LE II Standard  Hull #657  2004 4Runner 4.7 L V8

Oregon

COIDKSMOORTNUTWYmed.jpg

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My furnace short cycled.  The furnace blinked out a trouble code that said something like 'blocked discharge vent'.  I popped all the grills off of the heat registers and ran the furnace again.  No more codes and no more short cycling.   I then put the grills back on while being very sure the adjustable dampeners were in the wide open position. Again no codes and no short cycling.  Mine doesn’t click from the air conditioner, so yours is probably something else.  It doesn’t cost anything to pull the heat register covers and give it a try though.  
 

BTW-The outside cover to my furnace is translucent white plastic.  If it’s dark out you can see the red LED on the control board blink out its trouble code through the white plastic without oven taking the outside cover off.  I caught the blinking codes by accident while walking around the camper in the dark. 
 

Good Luck.

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2013 Toyota Land Cruiser 200

2018 Twin Bed Elite II #351

 

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This is the latest information that was sent to Oliver Service,

When the heat turns on and off the temperature on the thermostat LCD displays remained the same. According to the manual there should be a 2 degree set back before the heat turns back on. This does not seem to be the case the heat cycles on and off at the same temperature according to the LCD display on the thermostat. After the heat shuts off, the temperature has not dropped the 2 degrees yet the furnace starts back up.  Also when the heat is off, approximately 1 -2 minutes before the heat kicks back on the air conditioner starts to click. It will click 3 to 5 times within this period before the furnace starts.
 
Here are some stats:
 
Outside temp 26 degrees set thermostat to 60 degrees. Heat came on and shut off when the temperature on the LCD display read 59 degrees. I have 2 other thermometers in the trailer one read 52 degrees and the other 53 degrees an 7 to 6 degree difference.  The heat shut off and the LCD display still read 59 degrees. The heat remained off for 4 minutes and 40 seconds then restarted. This continued until I decided to call it a night.
 
Off:       4:40      min/sec     
On:       9:36            "
Off:       2:59            "
On:       8:53            "
Off:       5:41            "
On:       7:42            "
Off:       5:34            "
On:        9:33            "
Off:       3:49            "
On:       7:55            "
Off:       3:17            "
On:       9:00            "
Off:       2:23            "
 
 
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Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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A long-shot but the stats above suggest to me that you may be experiencing a furnace air circulation problem in addition to any thermostat issues. I am guessing that you have the standard bed option and that you are testing your furnace with the bed made up.  If this is not the case, please disregard this post as it isn't relevant to you.  However, for others with the standard bed option, understanding my experience may be helpful.

Your furnace is running about 66% of the time and is off only about 34% of the time.  This seems like a lot of furnace on-time when it is 26 degrees outside. 

Off 4.04  
On   9.36
Off 2.59  
On   8.53
Off 5.41  
On   7.42
Off 5.34  
On   9.33
Off 3.49  
On   7.55
Off 3.17  
On   9
Off 2.23  
  26.27 51.19
  34% 66%

I experienced a similar problem with my LE II with the standard bed made up, although the outside temperature was up in the 40s.  The problem was the furnace was running hard and short cycling, having trouble raising the temperature at the thermostat to merely 60 degrees.  After getting out of bed, I realized that the temperature in the space under the bed was at least 85 degrees.  I diagnosed the problem was the location of the single return air vent in my LE II that is located in the rear curbside corner of the trailer way back under the bed.  It turns out, all of the hot air coming out of the two supply vents was being immediately sucked under the bed through the singe air return vent and back to the furnace and was not mixing with the remaining air in the cabin. Not only did this result in the rest of the trailer heating up very slowly, but the air from the furnace supply vents became very hot until the temperature over-limit switch in the furnace shut it down. 

Given the above stats, and assuming you have the standard floor plan and the bed is made up, it would be easy to test if you are experiencing this problem.  Just rerun the test above, but remove a cushion on the front dinette and open the hatch wide.  (also make sure your supply vents are angled forward so the warm air is not directed under the bed).  This test condition will result in most of the return air to the furnace traveling through the open hatch and not under the bed, allowing the warm air from the furnace to mix with the cabin air (and thermostat) before returning the the furnace.

If you experience a more balanced operation of the furnace on-off times resulting from this test, you have found at least part of your problem.  This could actually be causing the problem with your thermostat as well.  The Dometic thermostat anticipates when it needs to come on to maintain a temperature at no less than 2 degrees from the set-point.  It actually remembers how fast the trailer cooled off previously and adjusts furnace restart time accordingly.  If you have the air circulation problem I describe above, then the temperature around the thermostat is going to fall fast when the furnace turns off, even if the area under the bed is still a balmy 80 degrees.  The thermostat "learns" that it needs to run almost constantly to maintain temperature within two degrees of the set-point at the thermostat.

The clicking you hear may actually be coming from the furnace and not the air conditioner (mine was).  This can happen when the furnace shuts off originally due to overheating of the heat exchanger, and the furnace igniter tries to restart the furnace before the heat exchanger has cooled sufficiently that the safety cutoff switch opens to allow the furnace to actually ignite again.  This will generate a continuous, noisy clicking noise. 

 

 

 

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Steve and Lornie

LE II Standard  Hull #657  2004 4Runner 4.7 L V8

Oregon

COIDKSMOORTNUTWYmed.jpg

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I have not resolved the issue permanently but I have made enough adjustments that I am not too concerned about temperatures down to about 15 degrees.  My LE II is hull 657 and when I am running the furnace I open the round access hatch under the pantry ((for inverter access) and that makes a huge difference.  I am not sure your LE II has an access hatch under the pantry like mine.  I also modified the hot air supply vent under the sink/microwave by removing the movable baffle that formerly constricted airflow out of the vent.  This allows much more warm air to be blown forward in the cabin and mix with other cabin air before returning to the furnace through the vent under the bed.  It takes 15 seconds to remove the movable damper in the vent.  It made a huge difference.  I think OTT put the movable damper in to try to force more air to the bathroom but it doesn't really help in that respect and instead reduces the total supply vents in square inches to less than required by the furnace manufacturer.  A recipe for short cycling.  You can also open a drawer or two by an inch which will allow air to flow through the back of the drawer cabinet and down into the basement when it drops below freezing (there is a large cutout behind the drawers to allow access to the sink plumbing).

Again, your LE II may be different than mine.  The only permanent fix is to add return vents forward in the cabin and in the bathroom, and reduce the size of the return vent under the bed.

You should read the thread below that is currently active on the forum.  It has a lot of information relevant to your issue with good input and advice from many contributors to this forum.  Just click on the pic below.

Good luck.  You have an outstanding trailer.  I just wish OTT would acknowledge the issue and develop a recommended fix for customers based on input from a professional HVAC engineer.  Most of us are not comfortable winging it and cutting holes in our Oliver without guidance from the factory.

 

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Steve and Lornie

LE II Standard  Hull #657  2004 4Runner 4.7 L V8

Oregon

COIDKSMOORTNUTWYmed.jpg

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20 hours ago, Chukarhunter said:

I have not resolved the issue permanently but I have made enough adjustments that I am not too concerned about temperatures down to about 15 degrees.  My LE II is hull 657 and when I am running the furnace I open the round access hatch under the pantry ((for inverter access) and that makes a huge difference.  I am not sure your LE II has an access hatch under the pantry like mine.  I also modified the hot air supply vent under the sink/microwave by removing the movable baffle that formerly constricted airflow out of the vent.  This allows much more warm air to be blown forward in the cabin and mix with other cabin air before returning to the furnace through the vent under the bed.  It takes 15 seconds to remove the movable damper in the vent.  It made a huge difference.  I think OTT put the movable damper in to try to force more air to the bathroom but it doesn't really help in that respect and instead reduces the total supply vents in square inches to less than required by the furnace manufacturer.  A recipe for short cycling.  You can also open a drawer or two by an inch which will allow air to flow through the back of the drawer cabinet and down into the basement when it drops below freezing (there is a large cutout behind the drawers to allow access to the sink plumbing).

Again, your LE II may be different than mine.  The only permanent fix is to add return vents forward in the cabin and in the bathroom, and reduce the size of the return vent under the bed.

You should read the thread below that is currently active on the forum.  It has a lot of information relevant to your issue with good input and advice from many contributors to this forum.  Just click on the pic below.

Good luck.  You have an outstanding trailer.  I just wish OTT would acknowledge the issue and develop a recommended fix for customers based on input from a professional HVAC engineer.  Most of us are not comfortable winging it and cutting holes in our Oliver without guidance from the factory.

 

Thanks for all your input.  Bill has built fiberglass airplanes in the past, and if it takes cutting holes in things he is perfectly capable.

 

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Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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The previous owner of my Elite II (#354) has some type of problem with the heating system and Oliver suggested removing the dampers from each vent, as mentioned by Chukarhunter above. I have not had any problem with the furnace or short cycling of the furnace over the past 2 years I have owned my Ollie.

2018 Oliver Elite II, Twin Bed, Hull #354 

2018 RAM 1500 Rebel 4 x 4, 5.7 Hemi, 3.92 gear ratio

Maine

 

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12 hours ago, Bill and Nancy said:

Thanks for all your input.  Bill has built fiberglass airplanes in the past, and if it takes cutting holes in things he is perfectly capable.

 

Yikes!  Sheet metal airplanes are the only way to go 🤣

Actually, I've owned three composite airplanes in the past...

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Hi this is Bill again with an update. My wife Nancy and I have pretty much narrowed it down to the furnace and not the thermostat. Yesterday when we should have been eating turkey we spent most of the day out in the trailer. We got some smoke candles to see where the return air was coming from. The rear most air duct is situated only about 2 feet from the return air duct. With smoke candles we determined that a large amount of the heated air coming out of the duct would get sucked back into the return before it ever had a chance to warm the trailer. We theorized that this may be causing the furnace to over heat. So we decided to block the return air grill with duct tape and remove the front dinette seat to see what would happen. It greatly improved the air flow returning the air through the open front  seat. But the short cycle was not improved. After playing with different return air options I believe I will make a return vent on the face of the rear dinette seat under the table. This area is a better choice than the front seat because the return air has little to no obstructions going back to the furnace. I plan to install a return about 1/4 inch off the floor so it will pull the cold air directly from the floor not 6 inches above the floor as it is designed now. Next we removed the supply grills and inspected the flex pipe and left the grills off to see if they were producing to much back pressure, nothing changed. We then replace the propane tank with a new full tank, nothing changed. Then we removed the awning side bed to let as much air into the furnace as possible, nothing changed. But we did figure out that the flame is going out about 2 seconds after it ignite's then relights 10 seconds later then goes out again and re-lights again about 6 times in 5 minutes this continues until the thermostat shuts the furnace off when the desired temperature is reached. Next I removed the sail switch and cleaned some lint off, nothing changed. I contacted Oliver and they were of no help at all they said to contact Dometic directly as it is a warrantee issue with Dometic and not an installation issue that would be covered by Oliver. So I went to a local Dometic service center and they said that they can not do any warrantee work because they do not sell Olivers. Gee thats nice seeing how no one sells Olivers. But they did tell me that they believe its the control board as it is a common problem and it should be replaced under warrantee. The other possible cause could be either the sail switch or the flame sensor. So I have a phone call into Dometic and filled out a work ticket we will have to wait until Monday to see what they will do.  If Katanapilot  happens to see this post, I see in your picture you have a RV7A I built a Vari Eze a Long Ez and an RV7, Ive sold them all and bought a BMW 1200GS and an Oliver, go figure! Hence the email N227EZ@gmail.com

Bill

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Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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3 hours ago, Bill and Nancy said:

I contacted Oliver and they were of no help at all they said to contact Dometic directly as it is a warrantee issue with Dometic and not an installation issue that would be covered by Oliver. So I went to a local Dometic service center and they said that they can not do any warrantee work because they do not sell Olivers. Gee thats nice seeing how no one sells Olivers.

I would call Oliver back on Monday and ask them to lean on Dometic to find a service center that will repair your furnace under warranty.  I find it unacceptable that the Dometic service center declined to do warranty work on a Dometic furnace because it is installed in an Oliver.  All Dometic products are installed in trailers manufactured by somebody, i.e., Airstream, Oliver, Casita, etc.

 

Hull #1291

Central Idaho

2022 Elite II

Tow Vehicle:  2019 Tundra Double Cab 4x4, 5.7L with tow package

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6 minutes ago, Bill and Nancy said:

They basically said to contact Dometic it’s warrantee’d by Dometic not Oliver

If you don't get a resolution with Dometic, I would submit another service ticket to Oliver asking them to get you, through their supply channels, a replacement control board, and walk you through how to replace it.    I hope they will at least take those steps for a 2022 trailer still under warranty.

 

Hull #1291

Central Idaho

2022 Elite II

Tow Vehicle:  2019 Tundra Double Cab 4x4, 5.7L with tow package

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I imagine they would I haven’t pushed that hard it was only yesterday that we have determined that it is a problem with the furnace. At least it appears to be that and not an issue with Oliver. I will pick Dometics brain if they answer the phone on Monday and if they give me grief I will bring it up with Oliver. I’m sure we will figure it out it just takes some patience to narrow the problem down.

Bill & Nancy

2022 Elite II  Hull #1265
2022 GMC Diesel Canyon

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