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  1. #1
    Join Date
    Sep 2007

    honeywell RM7800 control

    I'm just wondering if anybody has come across this problem. I recently had to service an old carlin burner with a "fire-eye" primary control. Up-graded the control to a "honeywell" RM7800 series control. This burner also had a weak ignition transformer so it was replaced with an "Allanson" electronic ignitor.After the items were replaced, I was having intermitent lock-outs on the primary control.The lock-outs were "internal lock-out 109" according to honeywell this was a grounding issue. I had spent many hours trying to rectify this problem, checked everything on the grounding of the burner also looked into the phasing side. I did notice that this lock-out would occur during intial burner ignition. I went as far as wiring an isolating relay ocross the main valve output no luck moved the isolation relay to the lo-fire solenoid, no luck, moved the relay to the ignition output, this seams to have solved the #109 lock-outs. Just wondering if this electronic ignitor is creating excessive interference causing the controller to lock-out.

  2. #2
    Join Date
    Mar 2003
    unfortunately with retrofits, not every one is the same. it could be many things casuing this, butthe end result is you got your set up to work safely and reliably. we did a retrofit on a 1963 cleaver brooks and had similiar issues. we ended up rewiring the whole damn thing eventually. they never go perfect. good control though, especially if you got the display module to work with.

  3. #3
    We have been installing the new Hydrotherm KN Series boilers with the rm7800 controller and we had problems with the spark ignition "Electric noise" causing control to give all kinds of weird codes including 109. Even caused main flame to energize with no pilot or flame signal. Rememdy was to add noise filter on ignition wire or isolation relay like you did. We added relays until manufacture sent filters.

  4. #4
    We also have experienced intermittant lock outs on the RM7800. In the last year we have had two seperate installations with the controller on two different boiler makes.
    In the first case last year we had 5 Weil-McLains in two different schools having the lock out codes #47 and #111. After many hours of rewiring, adding relays, com filters, T-filters and replaceing units (RM7800's) we replaced the Honeywell ignition transformer with a Dongon. That seemed to stop the nuisance lockouts.
    On another installation just last month with 2 new Bryan boilers the code that was appearing was #52. We tried the T-filters we had left over from the previous job and that seemed to put an end to the lock outs.
    I went to the Honeywell's Flame Safeguard represenative with this and he claimed they have not had any reports similar to ours.
    I have been dealing with this control for over 20 years and it has been very reliable. I agree that some of the earlier issues was in the proper grounding of the device and we to this day drive a rod to earth ground for that purpose.
    Hope this helps.

  5. #5
    Join Date
    Sep 2007

    RM 7800 issues

    Thank's guys for the responses, i'm glad to hear that I'm not alone with these problems. Durring my issue, I had installed temporary grounds to a near-by cold water line and also drove a grounding rod next to the boiler, none of these attempts fixed the problem, I also had an electrian run a new 120V power feed to the burner from another power panel. Nothing on the grounding side was resolving this issue. If the boiler room had smoke detectors I would have set them off from the smoke coming out of my ears. At this point, grounding was not the issue. I now had to focus on electrical noise. I installed a control transformer 240v 1ph.X 120v to eliminate any noise being generated on the buildings neutral leg, no help. At this point I started to isolate burner components and finally found the problem with the ignitor. I suppose if I had used an iron-core ignition transformer I probably would not of run into this problem. I was told by our supplier that the "old" iron core transformers are a thing of the past (outlawed) due to their PCB's.This being the case, these problems will happen more often. The manufactures need to improve their products to prevent these issues.
    I also contacted the area "Honeywell" combustion controls rep. and got little help.

  6. #6
    Join Date
    Nov 2000
    Hoggtown! Toronto, ON
    Run another ground wire from the G terminal to a good ground on the unit chassis.
    "...refresh my memory. When did I start caring about this stuff...?"

  7. #7

    lockout problem

    Hey guys I actually just posted this in the general hvac section. I continue to have random lockout 52 on my 7840L-1075 wich is pilotvalve 2 was off when it should be on, i dont even use termial 21 or pilot valve 2. We use lp gas and i also called honeywell and they told me it could be the low psi guage tripping for a split sec but not actually causing the mechanical part to trip hummm. Anyway he also said I could buy a new 7840-1018 that does not have valve proving.

  8. #8
    Join Date
    Jan 2006
    ill bet you ,,yes use a 12,000 volt standard carlin transformer,you know the big heavy black kind,and ground it ,youll be fine

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