Monitor 441 - burner won't stay lit...intake pressure switch?

[ashadowalker]

Hi all,

I'm new to the forum but I'm working on Linneus' machine. I'm trying to catch up on everything that's been fixed already so I can isolate the problem. The unit runs through it's start-up cycle, we get blue flame, the plate starts to glow a little, and then the flame shuts off. The unit cycles down and the lights flash red. Every time I try to start the heater, I get the same result.

The professional Lynneus consulted said there might be a pinhole in the airhose from the intake fan shroud to the pressure switch/over heat thermostat. I cut off a crispy end but couldn't find any actual pinholes. The flame wouldn't start with the pressure switch disconnected, so I know it's functioning. Any ideas?

[HayZee518]

Well, I'd like to know who Lynneus is.
The combustion blower is connected to outside air through the flex beige colored hose. Remove it at the blower and start the unit. It will suck in room air for combustion air. Remove the two wires off the air proving switch and connect them together - now start your unit again.
Write back and tell me what happens.
Look in my profile - I have yahoo messenger listed as a contact point. If you have yahoo messenger we can converse more freely than the forum.

[ashadowalker]

Thanks for the reply. Unfortunately, I don't have Yahoo messenger.

I jumped the pressure switch and the heater behaved exactly the same as when the pressure switch is in the circuit. So, now that's eliminated as a possible cause.

Linneus is my landlord. She posted on this forum in January of this year, titled "Monitor M441 - Fires up - goes out..." I'm the new tenant/farm-hand/handyman and maintaining the heater has become my responsability. You were advising her through March (according to the dates on her posts). She's replaced quite a few parts and you helped her straighten out the wiring as well. I already know I'm going to have to redo anything "Nimble fingers" Jack did so I'm starting with the simple obvious stuff and working my way through. The fuel pump works. The fuel lines are clear. The intake and exhaust pipes (not using the heat exchange pipe-within-a-pipe) are clear. Tomorrow I'll be checking the fuel filter but the flame is blue so I'm not expecting water. Maybe an obstruction?

Honestly, my hope is that the timing of the shutdown will prove diagnostic in nature. I have fuel. I have air. I have ignition. I have blue flame for about 30 seconds. Then, before the blower fan can turn on, the fuel pump stops and the heater goes through it's cooldown. Finally, the burner status lights start flashing, indicating ....burner failure? I think it means that the burn was terminated by one of the safety features. Some predetermined condition was met and the sequence was terminated. So I'm wondering what sensor is checked after 30 seconds of burn. Or what function is the computer trying to start at that point (that is instead failing) and sending the unit into shutdown.

hoping for a new direction
Raz

[HayZee518]

ok - umm - Jack. Now I remember!
your symptoms suggest two things. first is the fuel level in the sump tank. on the side of the unit you'll see a large phillips head screw and two smaller screws. shut the fuel off from the outside tank. make a trough out of aluminum foil and use a shallow pie pan. place the trough underneath the white metal part of the sump tank. remove the large screw. this will bleed out the fuel in the tank. next remove the two screws , the metal plate and the rubber gasket. pull out the filter screen and look at it. holding it up to a strong lamp you should see light through it. there may be some brown crap on it. clean this with gumout spray. shake it off or blow it dry and replace it. before you put it back in use a cloth and a screwdriver and clean out the filter chamber. put the filter back in re-apply the gasket, plate and two screws. replace the large screw. take the front grill off the heater. use a 9/16 inch open end wrench and unscrew the brass gland nut towards the rear of the tank. remove the two wires off the pump. remove the four screws that hold the tank to the heater. remove the tank. remove the two screws that hold the top to the sump. drain out any fuel left in the tank. look at the bottom of the tank. spray a liberal amount of gumout in the tank. use q-tips to scrub the bottom of the tank and flush with clean gumout. remove the float carefully and note where the "tangs" go on the needle valve. spray gumout into the housing the needle valve came out of. wipe the end of the needle valve seat. put everything back in place - DO NOT TOUCH THE ADJUSTMENT SCREW ON THE FLOAT! put everything back together and connect up your fuel line. leave the top off for now. watch as the fuel enters the chamber. the float should stop the oil at approx half full tank. there is a mark cast into the side wall of the tank. use a large hypo syringe and suck fuel out of the chamber. watch to see fuel enters the tank again and stops. now put the top with the pump back in and screw it down. replace the wires and try the heater.

[HayZee518]

The second item is the flamerod flame detector. In the right side about middle of the pot are two screws in a bracket. remove the two screws, bracket and the gasket. don't break the gasket - very brittle. remove the flamerod carefully. you may have to rotate it a bit before it comes out. use some gumout on a cloth and remove the black soot off the porcelain where the wire is. spray gumout into the space between the wire and porcelain. now shake the solvent out. use 600 griit sandpaper and clean off the wire. replace it into the pot. put the gasket on first, then the bracket. tighten the two screws first the top then the bottom a little bit at a time. look through the window. the wire should be about center between the side of the pot and the burner ring.

[ashadowalker]

OK,

The heater continues to behave the same. Everything inside the sump tank was clean as a whistle and behaving properly except the float. I had to loosen the adjustment screw to get the kerosine to the right level inside the sump tank. I sprayed everything with gumout just to be sure before I reassembled it. The flame rod is brand new, still clean, and positioned properly. All of the components inside the pot are new except for the igniter (which obviously still works). The inside of the pot has been cleaned of carbon.

What should I do next? Later tonight I'm going to bust out my VOM and test the draw of various components. Maybe the blower fan isn't kicking in when it's supposed to and so the burner is being shut down do to over heat? Doesn't seem likely with such a short burn. Isn't there an over heat thermostat under the top plate somewhere? It could have died of old age. Or maybe the intake fan is failing quietly and my flame is dying from lack of oxygen.

I'm off to other chores till this evening. Looking forward to the next installment of Heater Maintenance 101,
Raz

[HayZee518]

the only thing that could cause the heater to go out after a clean start is lack of fuel. have you or the other guy changed the solenoid pump? before you go ordering a pump, remove the copper cappillary tube from both ends. run a piece of wire through the tube all the way through it. there may be a partial obstruction in the end that goes into the pot. for this, use a 1/8" twist drill and clean out the orifice by hand, twisting the drill as you push it in. after you done this spray some gumout into the end and run the wire through it again. what might be happening is when the pump goes into high, the obstruction is preventing fuel from pumping in at a high rate. there's enough there for low speed [temp] and start but not for high heat. so it starves itself and the flamerod locks out the heater. did you know you need to unplug the heater to reset the computer?

[ashadowalker]

OK,

There are no air bubbles in the line or filter. The filter is a General Filters Inc. model # 1A-25A from Novi. Mich. It was replaced in Jan. 2011 with the other parts. I don't know how much higher the fuel tank is than the heater. I'm told that on installation (1996) the fuel flowed smoothly until the tank had 50 gallons left in it. Right now fuel flows smoothly and the tank has 70 gallons in it. I ran a wire and gumout through the thin copper fuel line between the solenoid pump and the fuel nozzle. I also inspected (probed) the fuel nozzle inside the combustion chamber. Both were clear of obstructions. The solenoid pump is the original, not a new part. I won't be able to test it's current draw until I put the combustion chamber back together, which is waiting on your input.

The combustion chamber is not new, nor is the igniter. However, the burner, combustion ring, and flame rod are new. I've included a picture of the inside of the combustion chamber. You can't really tell from the picture but the lower left corner of the square mat is curled up off the floor of the chamber. The 'glue' on that corner is about 1/4" above the metal floor of the chamber (the camera flash hid that detail). The floor and mat are also new and were installed at the same time as the rest (01/2011).

This is my understanding of the current issue's history. The new parts were installed in January of this year. Then, you helped Linneus straighten out the installation errors so that, in march, the unit was operating correctly. Except...occasionally, it would do what it is doing now. Resetting seemed to solve the issue each time but, it happened more frequently until now, when it won't proceed past start-up, at all.

Raz

[HayZee518]

the burner mat doesn't look good to me. the fuel nozzle is dumping fuel where there isn't any mat material. seeing this the fuel flares up and puts out the flame and the flamerod reacts accordingly and shuts down the burner. the last thing would be the computer.

[ashadowalker]

Thanks again for the input,

It's difficult to see it in the picture because of the soot but, there IS mat material under the end of the fuel nozzle. The igniter is sandwiched between two metal fins that stick up from the floor of the pot. There is a fine screen-like material under the igniter and a square of coarser screen-like material on the floor surrounding the fins. The fuel nozzle almost touches the right side fin. The coarse screen (which I have been assuming was the burner mat, is it?) stretches a little over an inch to the right of the fin. There aren't fins in the old burner. Regardless, this unit worked fine for months with this configuration. It seems to me if there were no mat material under the fuel nozzle the unit wouldn't have worked for months after the installation of the new parts. The problem has been developing over time and has recently come to a head.

Is it possible that the mat curling up off the floor has slowly reduced the amount of wick to the point that it now can't sustain the higher fuel flow? Any recommendations on what kind of adhesive to use when I reattach the mat? Any idea why there are fins in this version?

Tomorrow I'll get some adhesive and reattach the mat. Then I'll reassemble for a test run.

For the record, I agree that the computer is probably fine. However, the flame rod is not the only fail-safe capable of shutting the heater down. The air pressure switch and the over heat thermostat both shut the system down under the right circumstances. Honestly, the history of a gradually more frequently occurring issue is not what we would be seeing if one of these fail-safes had been triggered. Instead the heater would have suddenly stopped working and not worked again until the issue was addressed. Are there more such fail-safes in this heater and under what conditions do they activate? I don't know yet. Not knowing and having to act in ignorance really gets under my skin.

Is it the flashing 'burner status' lights that tell you it was a flame rod shut down?

Raz

[HayZee518]

from my own experience, flashing burner lights tell me- the flamerod circuitry was activated, because of no flame, the flamerod is touching either the burner ring or the side of the pot, lack of fuel causing no flame, so it goes into lockout. water in the line causing no flame. AND like you say a series of events prior to ignition or after ignition as in overheat. a sooting problem that caused the flamerod to shut down the heater.

[msearcher]

Hi all,

I'm new to the forum but I'm working on Linneus' machine. I'm trying to catch up on everything that's been fixed already so I can isolate the problem. The unit runs through it's start-up cycle, we get blue flame, the plate starts to glow a little, and then the flame shuts off. The unit cycles down and the lights flash red. Every time I try to start the heater, I get the same result.

The professional Lynneus consulted said there might be a pinhole in the airhose from the intake fan shroud to the pressure switch/over heat thermostat. I cut off a crispy end but couldn't find any actual pinholes. The flame wouldn't start with the pressure switch disconnected, so I know it's functioning. Any ideas?

I have seen this happen on a 441 that I was working on, turned out to be the damper. I adjusted it and works fine now. Seemed that most of the time it went to high the damper would be stuck and then shut down, once in a while it would run. Be sure the damper is working correctly.

[Linneus]

Hi Tom and all! I am the original person who wrote in the forum last spring.

The bottom of the 250 gal fuel tank is above the level of the floor the stove sits on by about a foot +. The fuel line leaves the tank in a straight line under the house (approximately 20 feet in length) until it comes up about a foot and into the monitor. The pressure of the fuel in the fuel line has always been fine for 15 years. There is 70+ gallons of fuel in the tank. I just don't think the pressure in the line is the problem.

Is there an adjustment on the damper? That is something that has not been checked. The damper does move open and shut but maybe it's not moving far enough open?

You guys have been a big help over the year and I thank you.

Another question: What kind of adhesive should we get to glue the mat down on one side? I know there are posts on the forum somewhere but I can't find it in a search.

[ashadowalker]

Hi guys,

Unfortunately, I'm back again. For a few days we seemed to have fixed the problem but, now it's back. We had the 275 gallon fuel tank filled and had a service tech take a look at the stove. The first thing he did was to set the target temp for 90 degrees. I had been allowing the default temperature (set at slide on right side when facing front of unit) to be the set point and chilling the thermostat with refrigerated container to reproduce the conditions needed to activate the unit. The unit fired up and worked beautifully for him, until the pump started pumping air.

The first time I opened the sump tank up, to take a look and clean everything inside, I ended up adjusting the float level screw to get the fuel to fill to the line marked on the outside. After the outside tank was filled the safety switch inside the sump tank kept activating (because the fuel level was too high) and shutting the needle valve. This would cause the pump to drain the sump tank and start pumping air. Then the unit would shut down. This was the condition of the unit when the service tech came. I've since re-adjusted the float screw to maintain the proper fuel level in the sump tank against the new fuel pressure from the outside tank.

After the tech's visit the stove worked again for a few days, then began shutting down during start-up again. So, we seemed to have made progress but what has really changed? We have eliminated fuel pressure as a contributing factor, maybe?

I currently have the combustion blower housing pulled apart to check the damper function (it's functioning perfectly). I'm working my way down the component resistance values and voltage readings included in our service manual. The combustion blower tests out correctly, runs, and sounds good. Isn't there a damper O-ring somewhere I'm supposed to replace? The only thing that stands out so far is the resistance value of the solenoid pump. The service manual says it should be 565 ohms but I'm getting a reading of 624 ohms. I've seen posts here on the forum that indicate the pump operates under AC but the service manual seems to indicate it's DC. Which should I be testing for? The pump still puts enough fuel in the pot to get flame for 30-40 seconds before the pump stops. I'm also going over the timing chart to see if I can get a better picture of whats supposed to be happening when the shut down occurs.

As always, any input is appreciated as we slog through the tedious process of elimination. Thanks in advance,

Raz


ps Does anyone know the replacement part for the Taisan solenoid pump originally installed?

[HayZee518]

TAISAN still makes pumps as per their site but I don't know if you'll get an exact replacement. You can try eBay. The pump is an AC oscillating pump - no DC. The newer 2400 vented heater has the pump controller integral with the motherboard. The pump is the same one used with the M41.