Monitor trips breaker then Blows the Igniter

[Polli]

Hi, I bought a refurbished Monitor 41 last fall and all went well thru the winter.
A few days ago it tripped the curcuit breaker. I thought maybe it was a fluke so I restarted it and it tripped again. on the third or fourth time the breaker didn't trip but the igniter must have blown because it kept running with the flame out until the flame indicators went out and a few minutes the flame indicators were flashing like out of fuel. I took out the igniter and it was blown,(no continuity)
I went to the guy I bought it from and he said he believe it was probably the ignitor gone bad, shorting out... So I bought a used igniter from him that had continuity for half price, unflooded the chamber, put everything back together and it did the same thing.it did start a flame, but shortly after tripped the breaker, three times and then blew the igniter. Can someone tell me what the problem and the fix is?

[hawkins111]

short circuit

Usually a Monitor heater will not trip a breaker. They have fuses that are meant to protect the circuitry. If you get too much voltage to the unit, most of the time the fuse on a M41 will blow. When you have high voltage you can blow the igniter in extreme cases. If the Monitor is really tripping the breaker then you have a short and that is very dangerous. I would plug something else into that socket and see if the breaker trips. Experimenting with the Monitor can get to be VERY EXPENSIVE. Your M41 is a very old unit and electrical parts are going to be very hard to find. If you can find a main board it will be $450. A new fuel pump will be all but impossible to find. I think your best money will be on a new Monitor 2400 or a Toyostove. Since Monitor no longer makes heaters, parts for older ones are hard to find.

Good luck,

Tom

[Polli]

Thank you for the info Tom.
It is not the outlet.We have tested that.
Next, I will check the wiring in the junction box on the back of the monitor.

Yes I would like a new one, but if I can figure this out, this one has a lot of new parts. Maybe I'll part it out.

I guess I'll also start pricing out the Toyostoves.

Thanks again,
Paul

[HayZee518]

everything on the monitor gets its power from the motherboard. the purge blower is the first thing to come on, next the pot igniter off the air proving switch. the blower comes on later in the cycle after the plenum is up to temperature. there are four fuses on the motherboard that protect its individual circuits. all the control relays operate off 24 volts to their coils - if anything could blow the circuit off the plug in cord IMO it would be the motherboard or a direct short in the combustion blower.

[Polli]

Thanks for that HZ,
I'm picking up a multi-meter on the way home tonight. Thank god it's not the dead of winter right now.

I don't know if my logic is correct, but if the power cord is is messed up inside
(A long shot, I know) Maybe the frame is getting energized and arcing to the igniter thru the K-1 to the pan.

all of the hook ups for the power cord are tight and neat no frayed wires or anything.

When I pulled the second blown Igniter out it had a tiny weldment on the end and didn't want to easily come out of the hole.

I'll be sure to post whatever I find out.

-P-

[HayZee518]

the igniter is a coil inside a ceramic tube. if the tube is cracked somewhere along its length, moisture may be a mitigating factor but I doubt it. if the igniter went through a lightning storm and the power supply into the heater got zapped, then I would suspect the motherboard is fried and several relays are welded shut.
Note to Hawkins: Fuses open or blow on high currents. If the fuse has a voltage rating of less than 250 volts, then it would create a hazard because of the breakdown level of the device. Look up bil rating of an overcurrent device.

[Polli]

Hi, I just ran a cycle with the multimeter in place of the Ignitor.
As soon as I set the temp to 4 deg above the room temp and pressed set
,I got 120 volts at the ignitor until the machine flashed the out of fuel flame lights (something like 5 minutes or so).
That means the ignitor would be on all the time it's running unless something turned it off. I was thinking the flame detector would shut it off , so I tried fooling it with a candle and a cigarette lighter to no avail, Ignitor still stays on thru the whole cycle till out of fuel lights come on.

wondering what your words of wisdom are for that.
If I can get past this, the next thing would be to get the cooling fan to kick on.

Could it be that I just screwed up and got the Ignitor soaked when installing the replacement? It was mentioned to me, but I would think it is possible that ignotors get soaked from time to time?
_p_

[Polli]

just a small amendment to my post.
Read in the service manual that the Ignitor stays on.
I thought it would shut off one a flame was going.
Wrong thinking on my part.

Is there an easy way to get the cooling fan to run mid cycle without any heat. Just to test it?

-P-

[Polli]

and, I'm new to this message board stuff, so please forgive and let me know if I'm not following protocall on anything.

[HayZee518]

there is no cooling fan in the heater. the blower behind the heat exchanger fins comes on when the plenum switch closes. the combustion blower is on any time the heater is on. you test the flamerod circuit by using a 100K 1/2 watt resistor in series with a 1 amp diode. there is no way to check the flamerod by any external source. it normally has 120 volts on it but in the presence of a flame, the voltage changes to DC. and conducts across the gap.

[Polli]

Sorry HZ, not cooling fan, Circulation fan.

I just got a call back from a furnace guy.
He asked me if all this happened when the circulating fan came on, but would not elaborate. He probably has an Idea of whats going on.

I think the circulating fan did try to come on when all this happened.

-P-

[hawkins111]

Igniter problems

Paul,

In your first post you presented two problems. One the igniter burned out. Two, the breaker tripped on the circuit. Two separate problems. The first igniter burned out and that is the reason for the flooding. Now we have the problem with the breaker. People burn the igniter all the time without tripping the breaker. As HayZee said the reason for the tripping of the breaker is current. You can not pump that much current through the igniter to trip the breaker without burning the main circuit board or one of the fuses. HayZee will have to give you the 101 on the reasons for tripping the breaker due to a short. I know what happens, but I am not the teacher.

Yes the igniter stays on for sometime. It is about 6 minutes for a M41. After that time you will either have aflame or the cycle will go into lock out. The igniter is timed by the circuit board. You want the igniter on through the whole start portion of the cycle. This will assure a light if there is any fuel pumped into the burner. You would be surprised how much they can take. I have seen people try ten or more times with no fuel and the igniter handles that.

One of the big causes for burning the igniter is water. If there is water in your fuel it will boil and spray up onto the igniter, which will crack or burn a hole in the surface. Another reason for burning the igniter is carbon in the pot that touches the igniter. You can have nothing touching the igniter. Incomplete combustion can make an awful lot of carbon in your pot.

If the breaker keeps tripping I think there is a problem with the cord, right at the plug. A session with your meter will prove the plug and wire.

Keep us posted.

Tom

[Polli]

Thanks a lot for this, both you and HZ for this help.
I am a machinist by trade and a half way decent home handyman (I think)
But my very big weak point is electronics.
I will check the plug/wire and for the carbon as you mentioned.

I understand now what you mean now that any thing that is on the other side the board would fry it in tripping the breaker.
HayZee said it, but I guess I didn't get until you said it again.

-P-

[Polli]

Hi Guys,
New Cord , Ignitor and gaskets going in tonight (and a good burn pot cleaning).
Wish me luck.
By the way Tom, the cord is sooty around the very edges where the prongs stick out and if I wiggle the cord near it, it makes clicking noises, I sign that something aint right and looks like it's been that way for some time. looks like that was good call, thanks.
It doesn't take much to trip an arc fault breaker, so hoping that is it.
I'll post hopefully some good news later.

Paul

[HayZee518]

You didn't say an arc fault breaker until now. that explains it. if there is a sparking issue within the molded plug and cord conductors, that is sufficient to trip the breaker. A standard breaker wouldn't do that! An afci is built to detect sparks, that's the reason they use it in a house. When they came out, they used it in bedrooms only. Say someone tried to nail up a picture in a wall and got a little too close to the stud face where the romex is stapled. Say they nailed or put in a screw right through the romex. You'd cause a hazard between the hot wire, bare ground and/or white neutral. The AFCI would trip. A standard breaker would not unless it detected a direct short.