Atwood Furnace Problem '08 Excel 33TKE Ltd.

[Ken & Patti C.]

Hello Excel Forum:

Re: 2008 Excel 33TKE Ltd.
Atwood 8500-IV hydro flame 2-Stage Furnace
Model 2334

We have been in the South Fork, CO area for over two months enjoying the mild summer mountain temps. We do use the furnace during night and early morning with the thermostat set on 67 degrees. Just prior to rising for the day I'll get up and re-set the thermostat to 70 degrees start coffee, etc. 30 minutes, or so later, we'll rise for the day. This has been our regimen since we arrived. No problem with the furnace.

In the past couple of weeks I've noticed a, sparce at first, build-up of black soot around the chromed exhaust port, the access door and the fiberglass siding above the exhaust door. I cleaned it off easily with Fantastic and paper towels.

Yesterday morning we were awakened by the CO detector alarm. STARTLING to say the least. We normally crack the B/R windows and ceiling vent during the night. I wondered if the alarm needed a battery change. It seemed that, during the night, the furnace was on for a longer cycling time and didn't put out as much heat as previously. I mean this furnace has been wonderful as many of you know. After the sun came up we re-set the thermostat to 67 degrees and went about our day. I changed the batteries in the CO detector.

Same situation this morning. We did notice that during the night the furnace ran for longer cycling times and upon rising we noticed again the furnace just wasn't heating up, our Excel, as normal. The sun came up and we re-set the furnace again at 67 degrees as we have done all summer. The inside of our Excel warms up nicely during the day from sunshine.

We'll go to "Back-Up Plan 1" tonight and use a ceramic space heater instead of the furnace. The CO alarm causes us a lot of angst so we'll see how the ceramic heater works out.

My question is--has anyone experienced anything similar? Suggestions and ideas are most welcome--PLEASE.

Thanks in advance to anyone who responds.

We'll leave next week for home--Texas Hill Country and will check with our local service person upon return.

THANKS again,
Ken & Patti C.

[chief02]

Ken,
It seem like u have a incomplete cumbustion situation. Make sue nothing is blocking the furnace vents in the basement.The burner tube may have shifted giving poor air gas mixture. Alspo check the exhaust tube. Call Atwood they will walk you through an inspection.

[rockintom]

Ken and Patti.....Please DO NOT USE YOUR FURNACE....til you get it fixed. Your black soot indicates incomplete combustion (in this case a rich gas to air ratio). Your CO2 detector is telling you so. You have 2 indicators there is an issue. It may be something as simple as an insect nest in your orifice (your furnace gas valve, I mean!!!). A simple repair. Insects have a great affinity to propane and like setting up house right there. A clean out of the orifice and surrounding area is a simple fix. Use your ceramic heater until you get it fixed. Don't mess with your safety. For once I ain't jokin'!

Please let us know what you find. I would check it out if I were there!!! Hopefully it's a simple fix. Do you have an insect guard on the cover of your furnace? rockin'

[Still Working "NOT"]

Second what Tom says. A little electric heater cost less then $40.00 at the most. Cheap insurance. It will heat you rig easy. I have run two electric heaters in my Wild Cargo in 8* weather and my furnance only kicked on every 1/2 hour or so. If needed you can buy two heaters and run them on seperate circuts and keep your rig toasty in colder weather then your having now.

[Ken & Patti C.]

THANKS All for your replies and suggestions. We feel your care.

The ceramic heater is plugged in and is cycling on and off. It's 72 degrees according to the Atwood thermostat.

I have TURNED the thermostat off and furnace should be off now.

I'll reply in the morning how the night went. It was only in the low 60's here today and will be in the high--mid 30's tonight. We'll be OK with a GREAT B/R down comfort.

THANK YOU all for caring.

I'll not use the furnace any more 'till I get our home RV tech to diagnose what is happening. I look back and see the biggest clue of soot building up on the outside around and above the furnace exhaust and the furnace output just not heating like it did for the past two months plus. Previously the Atwood furnace is WONDERFUL--quiet with performance.

Oh yeah, one propane bottle is full plus about 1/2 on the other one--I didn't report that initially.

I've read many forums and posts for several years. This is the first instance, for me, of "incomplete combustion" I've ever read.

No, I don't have a screen over the furnace exhaust port. I do have two "flea-collar's" installed on the other outside openings (change yearly) to thwart wasps, dirt daubers, etc., but not on the furnace exhaust.

There are wasps around that we've seen all summer on our humming bird feeders so that may be a possible culprit.

Our home RV tech is a GREAT guy and when we return home I'll check with him.

YES, I'll report to the Excel forum what ever the outcome and diagnosis is.

THANK YOU all again for your response and for caring.

Excel 5'er RV's, owners, forum and factory are the BEST!

Sincerely,
Ken & Patti C.
Ingram, TX

[rockintom]

Thanks for your nice and detailed feedback. I will sleep better tonight just knowing that and about 4 glasses of "the fruit of the vine" will do the trick!!! rockin'

[Ken & Patti C.]

Hi All:

Does anyone know of a web site that has detailed instructions of performing a furnace inspection? So far my friend Google hasn't directed me to any. I'd at least like to have an idea of what is involved prior to talking to Atwood Customer Service as Chief 02 suggested. I could do this prior to returning home for service at our local RV dealership.

Last night was a comfortable night. The ceramic heater that I placed on the kitchen floor did a GREAT job. Inside temperature was 67 degrees when I wakened. I bumped the thermostat up a bit, turned on the coffee maker, returned to bed for another 20 minutes or so and it was 70 degrees when I dressed. The low last night was 36. Tonight's forecast is 31 degrees. We're safe, well and comfortable without the furnace which is switched to OFF.

THANKS again for everyone's suggestions,
Ken C.

[87_Fixr]

The following link will help you understand the components of your furnace and how they work.
Troubleshooting the RV Furnace
How's your battery?

[Workshop]

Here are two links that you might try. They are from Atwood and include troubleshooting and inspection information. The Atwood Service Manual is dated 2003 but provides good information that might help, knowing you have a newer unit/model. The other is just titled....Hydro Flame Furnaces.

They refer to it as 'yellow flame' when describing the sooting problem. They state several causes/problems....I haven't had a furnace problem with any of my units, so can't speak from experience with troubleshooting.... would agree that it does seems like it would be an air or burn issue.

I read your comment about the CO alarm going off....you also mentioned that you had a window and vent open that would allow outside air to enter the unit. As the 'burn and inside heat' chambers are separate and not having had a sooting problem inside the unit....that should still be good.

I would check the inlet air supply to the burner to ensure it is clear. Make sure the air return inside the unit is clear and tht nothing in the basement is setting to close to the inlet of the return air into the bottom of the case.

You might check the system using the other LP tank, as a low pressure is mentioned.

If you feel comfortable running the system for a short period...run it long enough to check the fan operation and air flow to ensure it is operating at a good speed and volume. If not could be a weak motor/fan or low voltage which should be checked.

As you haven't had a 'lockout' problem for not starting....you must be getting gas to the system, good spark and flame to keep the gas valve open. Flame just not burning clean and low enough to not trip the overtemp. I would think that the circuit board is good. Seems like it should be an air mixture problem?

Good luck.

[Loralie]

We had a problem with our Hydroflame furnace that standard troubleshooting did not fix. The furnace would start just fine but would start sooting when it went to the "low burn" stage. The techs checked for insects, low gas pressure, etc. and it ran fine after they worked it. However the techs were only running on one setting. It seems the board on the unit was bad, and would keep it running on one stage just fine, but when it changed stages (mostly high to low), the gas mixture stayed high and thus the soot. Replacing the board solved the problem.

[dschmidt]

I just had my furnace repaired it was doing the same thing .It turned out to be the gas valve.It was putting to much oxygen in and not enough propane.In Canada it was a 140.00 dollar part that our extended warranty paid for.