Monitor 22 fan shutting down

[msearcher]

Burner lights up and starts heating . From there the burner staus climbs to half way, once it passes the halfway mark it shuts down and status light blinks. Sometimes the blower fan kicks on after the burner has kicked off, sometimes not. Pretty sure the first day the fan was coming on early as the burner status climbed. Guessing a heat safety switch is shutting it down due to the blower fan not turning on to cool it down.

Looking ideas

[hawkins111]

M22 needs overhaul

Your M22 has a burner ring that is warped and the mat has lifter or eroded away. The flame sensor is either touching the ring or is sooted and touching the pot. You need to overhaul the combustion chamber. While you're at it lube the combustion blower motor bearings.

Tom

[msearcher]

I have just put in a new burn ring and mat, the combustion motor was oiled and the sump cleaned out. I will check the flame rod
as that may be the issue.

Thank you
Tom

[hawkins111]

flame sensor

This may seem like radical surgery but the last 1/4 inch of the flame sensor is not necessary. I have cut off the last little angle of the flame sensor and had no problems. Since you just did a service are you sure all the wires are in the right place. If the pump is not coming on (thumping) the wires may be the issue.

Tom

[msearcher]

I am pretty sure the wires are on correctly, will check when the heater is returned. I did run the heater a number of times and it ran fine but the person that now has the heater has reported this. Will check
the flame rod first thing.

Normally I take the burn pot out and do not touch the flame rod but it maybe the issue.

Thanks again!
Tom

[FordMan59]

Getting fuel to the pot?

You might also want to check that fuel is getting to the pot. A few weeks ago my 422 started acting up in a similar way and the line going to the constant level valve had got partially blocked with trash and wasn't getting enough fuel to keep the heater running and causing a shut down. I blew through the line clearing the blockage and it's running fine now.

[HayZee518]

fuel flow

kerosene seems to have an affinity to attract water and upon doing so produces a jelly like brown sludge that gums up everything inside the sump.
if left unchecked in the sump IT WILL RUST LINKAGES!
The sump is white metal and isn't affected, but anything steel will rust.

[msearcher]

Thank you, I always clean the carb, filters and the copper 3/8" when I service any heater.

[msearcher]

I pulled the heater pot out to inspect - all ok, did check the flame rod to be sure it was not touching -ok. The carb had plenty of fuel - all is ok......

turns out I heard some clicking on the contacts so I replaced the air switch, better but also then switched out the pump controller as now all is good.

Ran the heater for a few hours and had it step down and stop and restart many times.

The heater did not put out much heat so thought the fuel controller might be the cause.
Thanks everyone

[HayZee518]

heater

the room circulator fan kicks in because of a plenum switch sending a signal to the motherboard. the motherboard then determines at what speed to run. [two speeds]
the pump controller admits fuel at whatever consumption rate is needed - at idle and high heat.
had you made up a test fixture for checking out the flame rod circuit?

you use a 1N4004 diode and a 100K resistor in series. two pieces of wire and two alligator clips. one clip goes to earth ground, the other to the flamerod terminal on the motherboard.
the diode bypasses the flamerod signal. it is polarity sensitive so if it don't work the first time switch it around.
two plenum switches prevent heat overload.
instead of buying another air switch, just use a jumper wire on the terminals to bypass the normally open contacts [closed when air is flowing]
if the thermister is open or disconnected, the heater will run in high all the time. the measured heat point will say 42 degrees.

[hawkins111]

M22 electrical parts

msearcher,

I'm glad you got the M22 going. Monitor has stopped supplying M22 main boards and fuel pump controllers some time ago. Where were you able to find one? The availability of electrical parts for the M22 and M41 is one of the reasons I don't service them any more. The fuel pump controller is the big one. If you can't get the pump to function at spec then you can't go much further with any repairs. Stay warm, Tom

[msearcher]

I do have a number of pump controllers, motherboards and misc parts. I just found out where the fuel regulator is located on the pump controller so now I can get the 40, 41 and the 21, 22 to run much better and not have the orange flame that is hard to get ride of on the older models.

[hawkins111]

adjusting fuel flow

msearcher,

Do you have the fuel flow spec for M22, M41? If not I can send them to you. You can get a calibrated cup for any Toyotomi dealer that measures up to 50 cc. Since the Monitor manual states gallon per hour you'll have to do a little math to get CC per min. Of course all this is done with a flame sensor by pass and no flame in the pot. I have found that you really need only have the spec set for High and Low. It is a real pain to try to set the Med because it messes up the High and Low and you have to go back over them to be sure they are correct. You may have found that it is very helpful to use the Economy Plus feature to be able to control the burn at either High or Low. If the fuel flow is set and you still have a yellow flame you will have to go after the solenoid damper. For that you'll need a Manometer. I've got those specs if you need them. Tom

[msearcher]

I would appreciate the spec's for the fuel, I do have a manometer and have the spec's that I was
able to get last year.

appreciate all your help, just worked on a laser 56 to help a lady at work, replaced the combustion motor bearings - give me a Monitor any day!!!!!

i can understand why they normally replace the combustion motor runit rather than replacing bearings

[msearcher]

Flame rod test

HayZee518

just finished up a full service on a 422 and used a flame rod bypass to determine it was the flame rod.

i did pull it out and put back in but still shut down so I replaced it and now it's working perfect.

thanks for the info on the bypass info. Can you tell me - can the flame rod just go bad as it's not broken and looks ok.

take care,
Tom