Monitor 441 Noise/Vibration on Cool down?

[NH Forester]

Hi all from NH, I have two Monitor 441's. One needed a new combustion chamber last year when the fuel line was clogged with carbon. I tried to remove it and the fitting that is brazed/soldered onto the can twisted off during disassembly. The guy I brought it to at that point also had another 441 that he had "rebuilt". I needed a second one to use in my shop so I bought the rebuilt unit and installed it in place of my original unit so we could use our other unit in the shop whenever it was ready (the shop still needs drywall, etc.). Right away the rebuilt unit had issues. The unit was resetting and then shutting down, always when we needed it most. We have a wood fired hot air furnace and in the wee hours when it burns down the 441 takes over. The window was getting soot covered (is, soot covered still) and the unit would shut off to the dreaded blinking zeros (or whatever character flashes, I can't recall). The unit also had a very strong fuel smell on startup. He came over and installed a new solenoid and left. That night, same thing. He came back and discovered that he had neglected to plug in the solenoid after installation... OK, so now it seems fine but I am still getting (since we got it from him) what he calls a "sympathetic vibration" when the unit is cooling down. He claims it is no problem but at 4:30am when I can hear the damn thing grinding away, I am ready to give him a logger's version of a "sympathetic vibration"... It sounds to me like it is coming from the fan area but before I got into it I wanted to ask the folks here as when I search the most useful info, and sometimes the only info, comes from this forum. I am reluctant to call this guy again as he has been here several times now, he is always nice but I don't really need the social visit... I have not even hooked the original unit back up as we are still working on the shop. The units don't get used full time except in the Spring and Fall when we aren't burning as much wood. The one in the house takes over when the wood furnace or Jotul burn down in the wee hours. Because of this it's harder to diagnose and easier to try and forget about it... It is a major thorn in my side when it wakes me up though. I really don't want to listen to anymore excuses from this guy. Is this a bearing issue? He claimed the fan bearing was replaced. Thank you in advance for any help or info you guys can share.

[HayZee518]

441

both blowers use ball bearings so there should be no vibration either on start up or shutdown.
the circulation fan operates off the plenum switch, the combustion blower is the first to come on and the last to shut off.
the original motor halves are riveted together. those rivets need to be drilled out to take the end bells off the motor to get to the armature.
bearings are the ".001" interference fit [7mm bore] regular inline skate bearings will work but I'd go with SKF or NDH bearings.
the combustion blower connections are through two rubber elbows, so any vibration should be absorbed by the elbows.
you mentioned a solenoid. are you talking about the solenoid fuel pump or the damper solenoid?
you also mentioned a sooted up viewing window. This indicates to me several things. One, naturally is the combustion blower motor speed and the volume of air entering the combustion pot. Secondly, the burner mat may be deteriorated or lifting up off the bottom. Along with that symptom, the burner ring may be warped to the point of touching the flamerod which will shut down and lockout your unit and give you an error code.
a smell of kero means the O ring in the "Z" pipe is missing or just not sealing. There is another gasket between the heat exchanger and the pot.
Another larger gasket is between the combustion pot and the unit base, where the air elbow hitches up to the combustion pot.
An air restriction could exist in the double piped inlet/outlet tube, maybe wasps or spiders.

[NH Forester]

both blowers use ball bearings so there should be no vibration either on start up or shutdown.
the circulation fan operates off the plenum switch, the combustion blower is the first to come on and the last to shut off.
the original motor halves are riveted together. those rivets need to be drilled out to take the end bells off the motor to get to the armature.
bearings are the ".001" interference fit [7mm bore] regular inline skate bearings will work but I'd go with SKF or NDH bearings.
the combustion blower connections are through two rubber elbows, so any vibration should be absorbed by the elbows.
you mentioned a solenoid. are you talking about the solenoid fuel pump or the damper solenoid?
you also mentioned a sooted up viewing window. This indicates to me several things. One, naturally is the combustion blower motor speed and the volume of air entering the combustion pot. Secondly, the burner mat may be deteriorated or lifting up off the bottom. Along with that symptom, the burner ring may be warped to the point of touching the flamerod which will shut down and lockout your unit and give you an error code.
a smell of kero means the O ring in the "Z" pipe is missing or just not sealing. There is another gasket between the heat exchanger and the pot.
Another larger gasket is between the combustion pot and the unit base, where the air elbow hitches up to the combustion pot.
An air restriction could exist in the double piped inlet/outlet tube, maybe wasps or spiders.

I apologize for not being more clear. Both units are rebuilt by the dealer. Combustion rings, mats, gaskets, etc. are all new. Sooty glass came from when the solenoid was bad but has not burned off yet as the dealer claimed it eventually would. I don't remember which solenoid but it was described as.controlling the air allowed into the combustion chamber. When he forgot to plus it in it created an overly rich condition and sooted the glass.

[Bryand]

I apologize for not being more clear. Both units are rebuilt by the dealer. Combustion rings, mats, gaskets, etc. are all new. Sooty glass came from when the solenoid was bad but has not burned off yet as the dealer claimed it eventually would. I don't remember which solenoid but it was described as.controlling the air allowed into the combustion chamber. When he forgot to plus it in it created an overly rich condition and sooted the glass.

It honestly sounds like the baffle inside the burner is loose and making a noise. It is located in the top right hand corner of the burner inside the burner. It is spot welded in about 5 different places and also has a slot to hang in. If the welds break loose it will vibrate and rattle till it drives you crazy. The 40's and 41's would just fall down into the burner as they did not have a slot to hang in when the welds broke.

[NH Forester]

It honestly sounds like the baffle inside the burner is loose and making a noise. It is located in the top right hand corner of the burner inside the burner. It is spot welded in about 5 different places and also has a slot to hang in. If the welds break loose it will vibrate and rattle till it drives you crazy. The 40's and 41's would just fall down into the burner as they did not have a slot to hang in when the welds broke.

Boy, I hope not. What would be the best way to check? It really sound like it's coming from the fan area. I tried isolating it and putting a little pressure on the wire shroud but I am having a hard time isolating the exact area where the noise is coming from. I really appreciate all of the suggestions. It really only ever does it during cool down when the fan is winding down shortly before it shuts off when the room has come up to temp.

[Bryand]

Boy, I hope not. What would be the best way to check? It really sound like it's coming from the fan area. I tried isolating it and putting a little pressure on the wire shroud but I am having a hard time isolating the exact area where the noise is coming from. I really appreciate all of the suggestions. It really only ever does it during cool down when the fan is winding down shortly before it shuts off when the room has come up to temp.

Before getting too deep take the top and the front off the heater. Then take the heat shield off over top the burner there is two screes in the back of the case and 6 screws that holds the heat shield. Ensure that all the screws are in there and tight. Once you remove the heat shield there should be on screw in the top left of the burner holding the burner to the case of the heater. It is possible they left that screw out and the case is vibrating against the burner. Ensure that they put the screw in that holds the heat exchanger to the base of the case as well. It will be in the middle of the heater it is hard to see if the heater is dirty at all.
If this fails take the door off the burner chamber carefully, try not to mess the gasket up. Once the door is removed take your left hand and reach up inside the burner towards the top right of it. You will feel the baffle or deflector move it with your hands to see if it is loose. If it is you can move it and it will break loose there is one little flange that holds it in place besides the spot welds you may have to apply some downward pressure to get it loose. You can throw this piece away. You will not notice any difference in the way the heater preforms. Where we live there is probably 10,000 heaters and probably on a 1000 still have the baffle in them. It was a design flaw on these heaters from the start.

[NH Forester]

Before getting too deep take the top and the front off the heater. Then take the heat shield off over top the burner there is two screes in the back of the case and 6 screws that holds the heat shield. Ensure that all the screws are in there and tight. Once you remove the heat shield there should be on screw in the top left of the burner holding the burner to the case of the heater. It is possible they left that screw out and the case is vibrating against the burner. Ensure that they put the screw in that holds the heat exchanger to the base of the case as well. It will be in the middle of the heater it is hard to see if the heater is dirty at all.
If this fails take the door off the burner chamber carefully, try not to mess the gasket up. Once the door is removed take your left hand and reach up inside the burner towards the top right of it. You will feel the baffle or deflector move it with your hands to see if it is loose. If it is you can move it and it will break loose there is one little flange that holds it in place besides the spot welds you may have to apply some downward pressure to get it loose. You can throw this piece away. You will not notice any difference in the way the heater preforms. Where we live there is probably 10,000 heaters and probably on a 1000 still have the baffle in them. It was a design flaw on these heaters from the start.

I really appreciate the info, thank you. I didn't get a chance to look at it or crack my laptop until today as I was finishing up some skidder/tree projects around the house all weekend. Before I tear it apart I wanted to share a small video clip I shot this morning that captures the noise pretty well but I don't have 15 posts yet. You can search for Monitor 441 "Sympathetic Vibration" on youtbe. Notice it doesn't seem to bother the Boston Terrier at all, he keeps alternating between the Jotul and the Monitor. Thanks again for all of the help guys. This is driving us crazy, waking up the kids, etc.