Monitor cycle problems

[bhlbarto]

Hello thank you for the useful information in the previous posts. I have owned a 441 for 10 years now and seen it through all stages of repair. Now I am at a loss. At the end of a normal heating cycle the fuel pump will be called to come on and kerosene is pumped in, at this point when the next ignition cycle starts, there is a good poof and the room smells like kerosene smoke, the poof of smoke also happens on shut down about every other time. Just recently the economy plus stopped working in this manner, it would heat the room to 8 degrees over setpoint and when the heater was called to go into low mode, for the additional 4 degrees, the heater would shutdown and all panel lights will start blinking. Any insight to this problem would be much appreciated.
Thanks Brian

[HayZee518]

because the combustion cycle is essentially a closed circuit, I would examine the gaskets and the exhaust O ring seal. 8 degrees overshoot is awfully high. the cause for the blinking lights may be the unit tripping on plenum overheat. I have a 2400 and my heater does emit a poof sound when the kero ignites. there is no sound when the heater shuts down, the excess kero just burns up in the "pot." the economy plus is a function of the microprocessor but where it fits into the mix I don't know. you could check out the pdf file elsewhere in this forum.

[bhlbarto]

Thanks for the reply. I had planned on doing a rebuild with new gaskets and O rings, and you have helped confirm the expense.
Thanks again Brian.

[HayZee518]

elsewhere in this forum I have a mcmaster-carr stock number for the ceramic fiber gasket material that you would use for the gasketted areas on the heater. The material is one=half inch thick, but can be peeled off thinner for use. It comes as a sheet 3X4 feet for around $40.00. If you did an inquiry in an MPI site you'll see that a main widow-door gasket will be around 17 dollars for one gasket. RUTLAND puts out a product called Hi-Temp stove and gasket cement No 77 that I use for securing the burner mat material to the bottom of the combustion pot. It goes on easily holds tenaciously and does a final cure around 550 degrees. The ceramic fiber gasket material will withstand over 2000 degrees and not breakdown.

[adnadeau]

At the end of the normal cycle, is the fuel pump shutting off and then starting up again, or is it just not shutting off? How about on the beginning of the normal cycle; is it running during the pre-purge cycle? You can tell when its pumping by feeling the vibrations in the tubing going to the combustion chamber. There are a lot of controls in the 441 to prevent the pump from working when it's not supposed to. IC1, the microcomputer on the PWB, has two separate inputs to its circuit, the flame detector, the air pressure switch, and the overheat detectors are all in series in one way or another with the power going to the pump circuit.
When the normal cycle is in progress and the temperature reaches the set temp, the pump should stop completely, the solenoid damper opens with a clunk, and the burner status lights go out. The pump on my 441 starts back up about 3 min 40 sec after the start of the next normal cycle, which is what the manual spec is.

[bhlbarto]

Yes, at the end of a normal cycle when the burner lights are turned off and the purge cycle is in process the fuel pump will come on just before it shuts down. The length of time will very but usually it is enough to make for a smokey restart. I have not measured the air flow rate in the burn chamber with a manometer, but I do have the yellow flame telling me that there is not adeqate pressure. Brian

[HayZee518]

one way you could "test" the combustion air is to use a shop-vac on the inlet to the blower. just hold the small vac hose on the blower's inlet and see if the increase in pressure produces blue tipped flame. if it does then look into replacing the bearings on the blower's motor they are 608Z bearings with an 8mm bore. same kind of bearings used on inline skates and according to eBay are not expensive BUT I'll bet if you price them through MPI they'll cost way too much!

[adnadeau]

As far as the fuel pump turning on during the post-purge cycle, maybe the flame detector rod has crud on it, and as the combustion chamber cools down, acts as a diode long enough for the pump to be turned on. Either that, or something on the PWB has failed. Check the flame rod when you do the rebuild.

[HayZee518]

I did some research on the flamerod as opposed to a regular Cd cell and photo eye flame detector. The photo eye produces a dc voltage in the presence of a flame. The Cd cell changes resistance in the presence of a flame. The flamerod is unique in that it operates off ionized air. It is totally electronic in nature. With the flamerod not in a heated environment there is 120 volts across the gap [rod to ground] When there is heat, i.e. a flame, the air around the rod and ground is ionized, that is it conducts electricity and because of the flame the voltage changes to DC or direct current. The air heat combination makes the junction a semi conductor which is basically a diode and passes current in only one direction. If you downloaded the PDF file, there is a section where you actually use a diode and resistance to test the flamerod circuit.

[bhlbarto]

I will test the flamerod and main control board for proper operation has described above. I am planning the rebuild for April because I have a smaller 422 to keep the chill out at this time. HayZee I am having a hard time finding the fiberglass paper you describe in McMaster-Carr for making the gaskets this is all I can find. It would be a big help if you have come across the actual 2010 part# of the 1/2" thick material that you referenced, or maybe this is all they stock now I have not called to verify this. I included this to verfy that it will work and if I have to I can double it up to make the 1/4" thickness. As always thanks for your time and insight into this matter they have been a tremendous help for me.
Brian