Monitor 441 Heater

[edindex]

Back in service

In a previous life -- some 35 years ago -- I repaired home appliances for a living, so I expected high prices for parts. But I was still surprised at the prices I had to pay: burner pot $136, combustion ring assy $67, assorted gaskets, etc. $98.

I also learned that MPI specs call for tank outlet to be 16" above #41 inlet for sufficient line pressure for gravity-fed system. Local law prevents fuel delivery to tank with legs any longer than 12". In our case, that means I can't let the tank go below about one-third full.

I *will* change to a propane system, which is virtually maintenance-free, before I spend this kind of money again!

Thanks, again, for all your help. I'll print this thread out & keep it for reference.

Regards,
Rob Rudnick

[edindex]

Thanks, again. I can't tell you how pleased I am to have such articulate advice! -Rob

[HayZee518]

In answer to your original posting - lights flash when the pump is starving of fuel. check the screen below the float chamber. shut off the fuel outside and make a channel out of aluminum foil and remove the large screw. drain the bowl's contents into a shallow cup. remove the two screws and the filter should come out. use clean kero and clean the screen. I noticed a bunch of crap inside the float chamber. take it out of the heater and thoroughly clean it with Q tips and rags. Re-assemble it and put it back together in the heater. you can use permatex on the old gasket when you put back the filter screen inside. the spring goes onto the element and inside the far end of the filter chamber. the plastic "tit" fits the small depression on the filter cover.
lack of fuel, no ignition will cause the unit to lock out.

[HayZee518]

ok, the way you take the thing apart is; on the grill there are three screws near the top of it. the bottom has two tangs that are in slots. remove the screws and lift the grill out. the top is secured by three screws one on each side and one in the back. the top lifts off. there is a sheet metal shield with two klixon overloads on it. remove the phillips head screws I think there's four and rotate the cover out of the way. now you can get at the pot. one screw sideways that holds the pot to the side support and about nine that holds the top on the pot. careful of the insulation. it may shred when you take off the top. the burner head rotates counter clockwise about 40 degrees and lifts out. in the base you'll see a U shaped piece of metal. the igniter goes in here. in the base is the burner mat. you can get this from an MPI supplier -or- use a fireproof insulation like I got from mc master carr. use 500 degree rtv or stove cement to hold it in place on the bottom of the pot. the inspection window is a quartz glass - if you break it get a piece of boro silicate glass from mc master carr. use a new gasket to hold it in place. you'll find that the combustion blower motor will cost around $136. The solenoid pump is around $65. thank the Lord I haven't needed to replace the computer YET!

[edindex]

Thanks for all your help -- and the warning. I'll leave that adjustment just where it is. -Rob

[HayZee518]

monitor 41 (441)

look at the attached diagram of the fuel chamber.

[HayZee518]

that screw is for emptying out the float chamber when you do servicing. my attached drawing will show the insides of the float chamber. there is a black very fine threaded screw in the tang of the float. by adjusting this screw in or out, you are adjusting how high or low the float needs to travel to open or shut the needlevalve.counter clockwise opens the valve - clockwise closes it more. unless you intend to spend some time with the heater don't touch the screw. I found out the hard way.

[edindex]

Fuel filter & adjust

Hay,

Thanks for the speedy response. Since there's no ignition, I'm pretty sure it's a fuel problem. My supplier hasn't arrived to fill the tank, which shows just under half full (or is it just over half empty?). I asked the dispatcher to make sure the driver was prepared to check & clean/replace the outside filter because I suspect that as the level in the tank drops, there's insufficient pressure to push fuel.

May I safely assume that the attached image shows the fuel rate adjustment screw in the upper left, & that I must remove the other 2 screws to get at the filter? Is there anything I need to watch out for as I go in there?

Thanks again,
Rob

[HayZee518]

the flame rod goes in the side of the burner pot and is positioned downward. it's supposed to detect ionized air when there is a flame. basically there is an a.c. voltage on the rod. when a flame hits it, it changes into a d.c. signal to the electronics and through relays and solid state stuff on the computer board, keeps the solenoid pump on depending on need. the solenoid pump can be heard and felt running if you put your finger on the small copper tube. it will be pulsating if it's running right. you can hear a pa-pa-pa-pa when it's pumping. what you'll sometimes find is a lot of crap inside the fuel inlet chamber. the line comes in at the bottom left where there's a little hole. inside the chamber is a stainless steel and plastic filter with a spring on one end. then there's a hole that goes up to the needle valve assembly. there is a very small hole in the bottom of the needle assembly. this is what determines your flow rate of kero to the heater. the kero is gravity feed. with the float fully up the flow shuts off. as it drops kero feeds into the chamber. if there's a slug of kero that comes right in, there's a linkage which flops and shuts off the fuel so it doesn't overflow the chamber. when you press that button on the side you reset the lockout on the solenoid chamber and needle. I'll add you to my yahoo IM.

[edindex]

Interested in Monitor 441 PDF

My name is Rob & I'm pleased to have found this forum, and you in particular. I, too, have a model 41 which came with the house I bought 10 yrs. ago, and I'm having trouble with it for the first time. It's doing what was described elsewhere in this thread -- behaving as it did when I ran too low on fuel last hear. However, I seem to have enough kerosene & it flows OK when I disconnect the line from the heater.

Would you mind e-mailing that file to me? I'm on yahoo dot com with the same ID as my login here.

Thanks,
Rob

Arne - I have a monitor 41 which is one series BELOW the 441. I do all my servicing on the heater. I have a pdf file for the 441 which I could email to you. as far as a repair manual, you'll never get one. NO ONE on this green earth will EVER sell you one. I tried to get one through MPI but since I'm not an authorized dealer, no way. Some replacement gaskets I was able to get from mc master- carr industrial supply and a piece of boro-silicate glass for the view port.

[HayZee518]

soot IS carbon in its purest form. the black sh*** inside a battery is sawdust and carbon dust with an electrolyte. soot is very conductive. glad it worked out. I got a heat proof gasket material from mc master-carr. got a piece about 4' X 3' and only paid like 9 bucks for it. I made my burner mat out of it - still working and hasn't disintegrated.

[arne97]

Monitor 441

A-OK now !

I opened up the combustion chamber and cleaned it out. What I found was a 1" square piece of soot/carbon leaning against that sensor rod.

I know carbon can be a conductor but did not realize soot could do that so well.

Vacuumed everything and heater now works normally.

I appreciate your help and feel lucky that it was (apparently) something so trivial.

Yes, I checked out Al Luce's site. It took about 3 pages until I got to the part about not working on Monitors. !!

I haven't used Yahoo messenger in years.

Stay warm.

[HayZee518]

monitor 441

You'll find a site on the web by Al Luce. Stay away from this guy - he's all hype and no action. He advertises parts for all monitors, but when you go looking for parts you're re-directed to another page on his site with no parts to be found.
A typical cycle for a monitor is an air purge, then fuel and ignition. with a flame detected the solenoid pump goes into high and so does the flame. After a delay a klixon detects the plenum heat and turns on the fan - lo or hi speed. The flame rod must sense ionized air in the burner pot and complete its circuit or the unit goes into a lockout condition, then resets.

[HayZee518]

I been in my house since 2000 and my monitor came with the house. when I moved in I had no idea what to do with it other than tinker around with it getting it to light and stay lit. My fuel tank is the original one that was here. I removed the fuel filter at the tank. It was just another place for water to build up and freeze. I replaced the fuel line with a piece of 3/8" truck air line and suitable air line fittings. These have a brass ferrule that embed themselves as you tighten the gland nut. The only copper piece I have is the flared end that goes on my heater inlet. The copper goes through the house directly to the heater. So when I have to service it I need to shut off the fuel at the tank. I'm gonna change it out this year with an angle fitting and a valve inside the house. OK. when the unit starts up, it goes through a purge cycle of three minutes, then the fuel solenoid pump turns on low and admits fuel to the burner mat. within 30 seconds the igniter turns on and starts the flame. if the flame isn't detected inside of 1 minute the solenoid stops and the lights flash indicating no fuel. you got yahoo messenger? would make this so much easier than back and forth thru the forum. my handle in yahoo IM is buffalo12980@yahoo dot com.

[arne97]

Monitor 441

Thanks Hay,

St.Regis Falls? How's the weather- snicker, snicker - ? I was born in Newcomb, grew up in the snow belt and moved to Virginia 3 years ago. Left my snowblower near Syracuse

Anywho , I needed a cartridge for the external filter and the guy at my local "has everything" hardware told me what is probably wrong with my heater.

He said the burner gets distorted and touches a rod and the fuel switches off. Actually,his pencil diagram makes more sense than my explanation.

So tomorrow's project is to take apart that area and see what is what. It is also an opportunity to get rid of any soot/carbon build-up.

I'll report back if/if not successful.