COLEMAN Series COAT - COAS Oil Gun Furnace

Questions about repairs and parts for Coleman furnaces, air conditioners and heat pumps for manufactured homes. Click here for Coleman parts.

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Posts: 31
Joined: Wed Dec 24, 2008 11:42 am
Location: Ohio

Wed Dec 24, 2008 12:22 pm

I’m fairly technically inclined, I have worked on gas furnaces, but never on oil furnace. I thought that perhaps at least the first time I should have a professional do a tuneup and that I could watch and learn. My furnace works but occasionally doesn’t light. I replaced the fuel filter, and figure it probably needs a clean nozzle and to have the electrodes cleaned. It seems to have more difficulty lighting when it’s cold ( that figures). :roll: :evil: I thought perhaps it might be water or related gelling restriction so I replaced the filter and bled out the line, added a watered dispersant and had the tank topped off. It really didn’t seem to help that much, it perhaps works a little better if any. I’ve already purchased and have in my possession a couple of spare nozzles that meets the manufacturer’s specifications.

I’ve been trying to find a professional furnace service company to tune up my furnace (Hopefully local with reasonable rates). So far I haven’t had any luck; I’ve called several companies and so far they’ve all told me they don’t work on motor homes/trailers/trailer parks.

I was hoping for two things.

1) Hopefully someone can tell me of a service company in (Northern) Cincinnati, Ohio that would service my furnace at reasonable rates.

2) Any advice on nozzle replacement if I can’t find someone in my area to reasonably service my oil furnace or if I choose to do it in the future.

Another reason I’m reluctant to do it myself is that I have a bad back. A hour or so worth of work is liable to take me several days and liable to put me in severe pain for many days. It might require strength and contortions that I’m not sure I can do. It looks like the pump, motor and burner comes out as an assembly; I suspect it’s about 40 pounds. I’m not sure I can handle it. It looks like there’s three or four main bolts holding the assembly in. If there is a fourth I’m not sure I can get to it.

I tried the service Company but they told me they didn’t work on mobile homes.
Thompson Heating & Cooling
Cincinnati, OH 45238
(513) 851-4411

The specifications of my furnace.

COLEMAN Series COAT - COAS Oil Gun Furnace

Model number
Serial number
BTU input
66,000 19.3
Oil fire burner part number
Oil burner model
Nozzle GPH US (Hollow core)


Wayne high speed flame oil burner
Firing range

1/7 horsepower
120V 5.5A 3450 RPM CWCPE

Diagram and parts list

User avatar
Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Fri Jan 02, 2009 4:13 am

Do you still need help ?

Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?

Posts: 31
Joined: Wed Dec 24, 2008 11:42 am
Location: Ohio

Fri Jan 02, 2009 11:44 am

Robert wrote:Do you still need help ?

Yes and no.

I replaced the nozzle and adjusted the electrodes (by dead reckoning), I tried to keep all the other adjustments identical for the most part. However I am still tempted to see if I can find a professional to tune and inspect the furnace as a precaution.
I never did find a service company in my area that would work on my furnace let alone at a reasonable price.

I even have a neighbor a couple doors down that is a heating and air conditioning service man by profession and he said he wouldn’t work on my furnace and didn’t know of anyone that would work on my furnace. He says he wouldn’t even work on his own oil furnace because he is unfamiliar with this type and he doesn’t normally work on oil furnaces; though the main reason is that he rents his trailer and his electric is included with the rent so he uses electrical space heaters for heat.

Since I’m an owner, that pays his own electricity; it is more cost-effective for me to heat with oil at this time.

I called about 1/3 -½ of the furnace maintenance/repair companies in my area and they all had some reason to exclude me. Either they did not service my location, or they did not work on oil furnaces, or they did not work on trailers/mobile homes. I left many messages and even sent a few e-mails not to get any responses. The people that I talk to on the phone did not know of anyone that worked on oil furnaces in my area in trailers.

So in my frustration I stopped trying to find a serviceman.

I had a couple of offers from handymen that claimed that they would give it a shot; but I declined their offers because I know them and have seen their plumbing and electrical work; from what I’ve seen their work wouldn’t pass code let alone my standards. I can be pretty forgiving when it comes to appearances; but when it comes to safety, function and integrity I’m not very forgiving.


In my frustration of not being able to find a professional service company to work on my old oil furnace on my trailer; I decided to try to do it myself.

I was initially intimidated because I’ve never done this type of work. Though I do have experience on automotive, trucking and aviation injection systems. I’ve heard stories that replacing the nozzles can be extremely dirty and potentially dangerous as far as a fire hazard.

When I initially looked at the exploded view of the furnace and oil burner I was under the impression that the oil pump, furnace blower, and motor entire assembly had to come out to get to the nozzle. This looked like quite a bit of work and look like it could be heavy for a person with a bad back like myself.

It was further complicated by my bad back because it limits my physical and mental abilities. Basically the more pain than I’m in: the stupider I get, the more angry and depressed I get. I don’t have any pain medication thanks to the Bible thumpers and bureaucrats and their witchhunts. So regrettably I’ve had to resort to alcohol to try to attempt this repair; alcohol does to some extent help the pain but it is very limited and has a very narrow window of the effectiveness. In other words it’s a delicate balance between controlling the pain to increase intelligence; but not to use alcohol to the point that intelligence decreases.

On New Year’s Eve I decided to consume alcohol and work on the furnace. I had prepped the area with an old rug and plastic in case oil and carbon became a mess. After consuming a few beers and literally shedding better light on the situation and studying it more closely; I realized that it looked like it was designed so I could remove the nozzle and the electrodes without having to R&R the entire pump, oil burner blower, and motor. Pleasantly to my surprise it was a lot quicker, easier, cleaner and lighter than I was afraid it might be. I thought it might be a nightmare, but it turned out to be a piece of cake.

I didn’t bother to bench check the spray pattern of the old and new nozzle. The old nozzle had so much carbon buildup on it that the spray pattern had to be lousy. The new nozzle met the factory specifications; and I assume the new nozzle was bench checked before shipment.

After I installed the nozzle I tried to start the furnace and it wouldn’t start which sent a scare down my spine. I had been suspicious that there was also an electronic ignition problem as on previous occasions when the furnace failed to start I didn’t hear the spark. But I wasn’t sure if the sound that was missing was spark or the spray pattern. I looked at the wiring schematic and it showed that the ignition unit fired whenever the furnace blower motor was running and also noted that it was 120 VAC. So for a test I removed the ignition coil and jumpered 120 VAC, I used an insulated screwdriver to see how big of a gap that the spark would jump. The spark would only jump equal or less of the distance that I could that I could dead reckon the electrodes were set. So I set the electrodes slightly closer and tried to start the furnace. The furnace promptly started.

I was quite worried about the start up because I was a novice at oil furnaces and have heard many warnings about amateurs working on old furnaces and the related fire hazards. I had taken the precaution of setting out phones so that I could call 911 if a retreat was necessary. I also strategically placed fire extinguishers and readied a garden hose so I could make a safe fighting retreat.

When I first started the furnace after the service (replacing the nozzle and adjusting the spark gap) the fire was unusually loud and ferocious. Before I started working on the furnace; the furnace completely failed to fire ( would not start). So there was several failed starts worth of fuel within the furnace firebox, I knew this and expected that it would be ferocious and possibly dangerous until the excess fuel burned off. I repeatedly stepped outside to make sure there wasn’t fire coming out of the smokestack. The furnace seem to be putting out more heat than usual and I was concerned that it might overheat the heat exchanger or some other component of the furnace so after a couple minutes I shut it down as a precaution and let it cool for about 30 minutes. While it might have been a good idea to shut it down to prevent components of the furnace from overheating it did allow the fuel and carbon to heat soak and become a vaporized/potentially explosive state; so when I started the furnace again there was somewhat of an explosive start. I was afraid it might happen and that it could potentially be a lot worse; it wasn’t that bad but in my concerned/paranoid state it was enough to constrict my sphincter valve (and make me feel like my heart skipped a few beats) to hear a fairly loud thump when the furnace started. After about another minute or two of rather ferocious burning the excess fuel and carbon had burned off.

Now the furnace seems to be running normally. It produces no smoke; the flame seems more stable than it was prior to replacing the nozzle; and moving the electrodes closer together has made the furnace start more reliably. So far it has started 100% of the time. It seems to put out the same; perhaps a little more heat than previous.

Sometimes when it starts (The blower pump motor) there is a slight roar or rattle for up to about 5 seconds. It could be normal; but perhaps in my heightened state of alertness/paranoia may be making me think it’s unusual. It could be normal startup noise; but it makes me concern if there is an out of balance or burner/flame issue/tuning.

So I think if I can find someone in my area to inspect and tune my furnace; that I might do it as a precaution and for peace of mind.

Though for the last 24 hours it seems completely normal. There seems to be in no unusual noises or vibrations from the furnace.

I suspect in the future I will probably have to buy a new ignition coil because of the apparent reduced ability to jump a gap. However I thought I might postpone such an expense, because if the price of oil goes up again as I suspect it will; it might be more cost-effective to heat with other means.

User avatar
Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Fri Jan 02, 2009 2:28 pm


You probably have about same amount of oil furnace experience as I do now. You'll find a lot of companies and techs who do not work on oil furnaces and especially in a MH, that would be normal.

A lot of companies have specially trained oil techs just for those calls or simply turn them calls down.

Alcohol and furnace repair would be dangerous at best for an experienced tech. For an unexperienced novice, it is extremely dangerous.

Doesn't take much alcohol or beer to start the process of unclear thinking in the brain cells.

May take a lot of searching for an hvac tech to work on it or a lot of study and research to become familiar with it yourself.

Take care and best wishes,
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?