M441 gets room up to temp, then quits

[gearsoup]

Picked up a Monitor 441 off of Craigslist last year. Been working decent until recently. Last week it would not run. It would fire up, go through it's routine, and then shut down to blinking status lights. So, I poked around the interwebs and decided that perhaps it might just need a good cleaning. Took the small filter out of the side, it was very dirty. Cleaned it out with compressed air, put it back in. The gaskets on my burn window and flame sensor were beyond shot. When I took the cover off, they were nothing but dust. Replaced those with flame-proof gasket material from my local plumbing store. I also cleaned off the sensor rod with some scotchbrite. Ran awesome all week.

Now, this morning.......

It starts up, goes through it's cycle and then runs. Gets the garage up to temp (74 or so). Kicks off on idle. When the temp drops in the garage and it's time to kick back on, it will for a very short few seconds, then it goes into alarm state, status lights blinking. Shut the unit off, turn it back on, then it will run. Any ideas?

Oh, this unit is in my garage/workshop/machine shop

Cold in Maine

[hawkins111]

many questions

A used Monitor heater should always be suspect. There are lots of questions before we can do anything but guess. How much fuel, how high is the tank, is there a tank vent, is the flue pipe clear of any obstructions, what about the tank filter, is the circulating fan spotlessly clean?

Tom

[gearsoup]

Well, tank is exactly half full. Last week, when it started acting up, I panicked and ordered 100 gallons. Got it running before I got the oil, so I ruled out that as the cause the last time. Bottom of tank is about 6" from the top of the unit. Flue pipe is clear of debris. Circulating fan "could" use a cleaning.

Now, here is something interesting. All night, it held 50 degrees in the garage, no issues. This morning, I turned it up to 60, and it held all morning. I just turned it up to 74, lets see what it does

[HayZee518]

heater

the thermistor is the temperature sensing device for the heater. if its allowed to get a blast of cold air, it will turn the heater on high until the going temperature stablizes around it, then it shifts into low until the setpoint is reached and it overshoots the set point by four degrees. this overshoot is normal.

[gearsoup]

Hayzee,

I'm not concerned about it over, or undershooting the mark by 4 degrees or so. I'm concerned by it getting to temp, then kicking back on to maintain temp, only to shut off to blinking lights.

Well, had it set to Auto today while I was at work. Was supposed to start up at 3:30, go to 74 degrees, and hold it there. Was quite happy to get home at 5 and see a nice warm garage. Still running. I hate intermittent problems......

[hawkins111]

M441 needs overhaul

The intermittent part is the fact that the combustion chamber needs to be overhauled. A M441 off Crag’s List may never have been serviced. It could be 20 years old. When you do get around to doing the service I would use an original flame sensor gasket to be sure the spacing is correct. You can use any of the other discussed material for the other gaskets. Bottom line is; you need to do an overhaul of the combustion chamber.

Tom

[gearsoup]

Well, it worked for a few days without issues. Back to doing it. Warm up, idle, then quit. Rinse repeat.

So, you say that the burn chamber needs an overhaul. Are these symptoms definitely indicative of a bad burn chamber? For the cost of a rebuild kit ($250 and up) I would hate to see this problem still present after it's rebuilt.

A local HVAC company wants $230 to come over, clean it, new gaskets, then evaluate it. I can see this getting expensive.

What is it in the burn chamber that could produce these symptoms? Is there anything I can check, electrically? I do have a multimeter........


EDIT

Just wanted to note: I am not opposed to spending the money on getting it fixed. I just hate throwing money at a problem, only to see it is still present.

[HayZee518]

combustion pot

all that's inside is a flame rod port, a fuel port and extension sleeve, the burner mat, the burner head, several baffles, an exit port with external gaskets and finally the top cover with gasket.
surrounding the internal burn pot are numerous small holes both midway and bottom of the pot where the vaporized kerosene flows. it is here that people see the blue flames. at the very bottom is another gasket and a round hole that connects to a rubber elbow. it is through this hole that the combustion air flows.

[FordMan59]

When my 422 started doing the same thing you're describing it was because the flame ring was distorted and was shorting out on the flame rod. Here's a complete chamber rebuild kit for $230. Monitor Heater 441 41 40 2400 Burn Chamber Rebuild Kit | eBay There's a good chance your burn pot would still be good (mine was after 16 years of service) and all you'd need would be a new burn mat, gaskets and flame ring. You could probably do the chamber rebuild yourself. If you only wanted to buy the parts I've listed, you can contact this seller by phone, just do a web search for Hickory Home and Garden, they have a toll free number listed on their web site. I'd never worked on a Monitor heater until last winter when I rebuilt mine. I started tearing it apart mid afternoon one afternoon last February and had it cleaned, rebuilt, back together and running late that night. HHG shipped my parts by USPS priority mail and I had them in KY in about 2-3 days.

[ticki2]

In your first post you mentioned cleaning the filter and it was very dirty . Did you clean the rest of the fuel chamber ? There is another thread on cleaning the fuel chamber . Did you change the filter at the fuel tank ?

It's cold in NH too

[Bryand]

Before you go buying expensive parts and labor. Try a few things. See if the flame sensor rod has carbon or sut on it again. Ensure it is equally divided between the burner wall and the burner ring. If your burner ring is warped a little it could be touching the flame sensor when the stove heats up. If all that is good make sure the line going into the burner is clear. Use a 1/8" drill bit about 6 inches long to drill it out. Should go close to 5 inches before it hits metal in the burner pot. Change your filter outside. If all that fails then you can look for more help on here or get someone to come out and look at it.

[Cardynal Syn]

My 441 was doing exactly the same thing two years ago. The problem in my case turned out to be sludge in the 50-year-old oil drum partially blocking the flow of kerosene, as well as a filter that hadn't been changed in a few years. I was able to stir the sludge with a stick (temporary solution at best, I know) and replaced the filter, and it ran the rest of the year with no issues.

[HayZee518]

tank sludge

It may behoove you to pump out all that crap on the bottom of your fuel tank.
The bung hole plugs, inlet pipe and level indicator screws into 2 inch threaded bungs.
Remove these with a two foot pipe wrench. Shouldn't be that tight!
Now use a 3/4 inch piece of pvc that reaches the bottom of the tank through one or more of the bung holes.
connect the other end to an air operated diaphragm type sludge pump. A small JABASCO rotary pump might work. Pump the crap into a clear plastic tank and allow to sit a while so that the kero and water crap seperates and floats one on top of the other.
Pour off the kero and throw out the sludge. Never, ever use a water scavenger like denatured alcohol or hot shot used for diesel engines.

[HayZee518]

fuel tank

manufacturers of home heating plants suggest you put the tank in the same area as the furnace. the gear pump in the burner will suck the fuel into the burner.
A monitor heater is strictly gravity feed. its fuel tank is almost always mounted outside so its at the mercy of the elements. kerosene starts to gel at minus 22 degrees. water freezes at 32 degrees. a blanket tank heater will help in most cases.
when you replace your fuel tank, have the supplier weld on a gate valve at the end opposite where you take your fuel flow from and mount the tank pitched slightly back from horizontal. this way condensate and crap will settle at the back side of the tank and not go into your fuel line. Also, where the fuel outlet is, there is usually a bronze threaded elbow, one half inch O.D. Braze a three eighths od brass nipple, two inches long into this elbow. when its screwed into the tank the fuel outlet will be two inches give or take above the bottom of the tank and will always receive clean fuel NOT water.

[gearsoup]

Well, I bought the rebuild kit from Hickory Homes. Spent the better part of yesterday afternoon putting everything back together. Runs well, no major burner issues yet.
I bought the deluxe kit thinking I was going to replace the combustion chamber bearings. Ran out of time last night, so I skipped on that part. Fan is making no noise, so I'll just store the bearings for later use.

I was disappointed to see that the "deluxe" kit does NOT include EVERY gasket needed for a rebuild. The 2 that are missing are: The one on the very bottom of the burn chamber, and the one between the radiator and the burn chamber. The former was still in usable condition, so no worries. The latter was in sad shape. But, I did have hi-temp gasket material on hand and was able to fabricate something that would work.

Now, onto the one issue I have....

When the room gets to temp, the burner does not shut off. The flame persists, keeping the burner ring glowing. Is this normal? Reason I ask is because before my rebuild, it would shut off completely, and then turn back on when the temp would drop 4 degrees or so. I've got it set to 70, and it's holding it, but it won't sit idle at all. It's showing one or 2 burner status lights, so I know it's on low heat. The air coming off of the unit indicates as well. Just wondering if it is supposed to go into cooldown state at any point. (this is in auto mode, fwiw)

When I turn the t-stat down, it does shut off, however.


EDIT: for more info

If I grasp the end of the t-stat wire (mounted on the wall) in my hands and trick the heater into thinking my garage is 88 degrees, it kicks off and goes into a cooldown cycle. Eventually is shuts down. Release the wire and it gradually reduces temp, until the unit kicks back on

Thanks