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New Honeywell R7284U to replace R7184B wiring question

KimberlyOrdKimberlyOrd Member Posts: 14
I just picked up the new R7284U control and when I went to wire it, there is no wire in my furnace for the LIMIT. The display just reads STANDBY. I've been reading here and just want some clarification as how to handle this as I don't want to mess up my furnace. The old control R7184B had no spade for the LIMIT and no wire to hook up to it. This is a mobile home (Nordyne/Miller) hot air oil furnace. All wiring is neat and wired without any wire nuts and the old control uses the same type of spade connections. The old control had no spade for the LIMIT. Blower fan limit has it own wired connection and did not hook up to old control. Thus, I have seen, in my web research, that the new control needs 120v power going to the LIMIT to work. Is that correct? If so, can I use one of the wires that came with the new control and hook the bare wire end into the spade connection of L1 and the connect the other end to the LIMIT spade to give it power? Like a jumper. I have wired up the other lines as they should be, meaning Igniter to igniter, burner to burner, valve to valve, L1 to L1, cad's to cad's, all 4 L2's to all 4 L2's. The LIMIT is the only one not connected. I don't want to cut and splice wires if I can get away with it, since the wiring is so neat. Is this what I need to do to get this new primary control to work?


  • newagedawnnewagedawn Member Posts: 406
    a pic would help, sometimes you need the wire sometimes not depends on application
  • newagedawnnewagedawn Member Posts: 406
    most times splice the black and red together and connect to L1 or connect red to limit and black to L1
  • STEVEusaPASTEVEusaPA Member Posts: 1,904
    A competent professional would know how to wire it properly.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Well, if I could afford a competent professional right now, I would not be posting here. Last time, I had a competent professional come in, they did not clean the air intake when they "cleaned" and serviced the furnace, or I would not have found 2 inches thick of dead stinkbugs and wasps in the air intake hose and shroud two days ago. But that is another story in and of itself. Based on what that guy did, what another furnace repair company did in the past to my old furnace - messy situation, the fact I'm an older woman (and some guys around here like to take advantage of that) and I do have mechanical knowledge, I decided to tackle this one myself as I did change out the primary control on my last furnace. I took pics and will post them shortly.
    Next post is background.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    What happened this time was in late January 2018, a substation that services this area had a transformer catch fire and we lost power. I was at work and my roommate called to let me know. I told her to turn off the furnace so any spikes or such wouldn't harm it and not to turn it back on for at least an hour after the power came back on without any "hiccups". So that was done. About two days later, the furnace caused the control to trip and I pressed the reset button once and it fired up and ran okay. About a week later, I woke up to 62 degrees, control tripped again. Hit reset once and back to running. Two days later, it did it again. And on occasion after. I have a 5/2 day programmable thermostat and the pattern seemed to be when the thermostat would either bump up the temp or lower it, it would trip. So, I turned the thermostat programming off and set the temp to a straight 67 degrees. That was in early February 2018. Ran fine, no resets until two weeks ago, basically beginning of this month, give or take a day. It did the intermittent trip again, once every day or two, thermostat still at straight 67 degrees. Last week, the furnace wouldn't start on reset so it had to be fixed.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Replaced nozzle and electrodes (yes, proper measurements), cleaned cad (it was clean though), took it out of hard lockout, bled the line and it fired up and ran. After completing a full cycle, when call for heat was made, it tripped the control again. Reset and it ran a complete cycle and trip on next call for heat. And again .... So did research and since the last time a repairman was here, the oil pump went, I decided to check it as it does have the solenoid on it. Oil into pump, nothing coming out to the nozzle. So ordered a pump and shaft coupling for it and they came on Saturday the 10th, two days ago. Put them on, bled the line and the furnace ran 10 or so complete cycles without a problem and then tripped the control again. Hit reset once, it ran another complete cycle and tripped again. So I stood by the furnace and really payed attention to see what may be going on.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Okay, what I noticed was that the control's led would stay on after burner shut down and after fan shut down too. Then it would go out after a minute or so. When next call for heat came, the motor would start for just 3 seconds and then it would trip. When I pressed the reset button just once, the furnace would fire up and run a complete cycle with no problems again. At this time, I noticed the primary control seemed really warm to the touch (not hot or burning), even though the actual burner motor did not. The top of the transformer was only 1/4 the temp by my opinion. So thinking back, my old furnace did something similar and replacing the primary control took care of the problem, so went to home depot and got the new control, one with a diagnostic display so I could get info on it, if the control wan't the problem and know what had to be fixed afterwards. So now to the current, at hand issue, the wiring of the control to get it to work. Next post is old control pics
  • KimberlyOrdKimberlyOrd Member Posts: 14

    burner model

    old control

    old control, no blade for limit hookup
  • KimberlyOrdKimberlyOrd Member Posts: 14
    New control

    back of new control wired, wire for wire, exactly, as it came off the old control

    as you can see, there is no wire to hook up to the LIMIT blade.

    no extra wires in the box.

    The thermostat is hooked up to the T-T connections of the top, see the first pic in this post.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Now, with electricity on, the display will read STANDBY and it won't do anything else (excluding tech setup, check the cad resistance, go into history mode which is nothing at the moment). With research, I discovered on three different sites where it says for this control to work, 120v power must go to both the L1 connection and the LIMIT connection. Of course, none of those sites showed pictures of how to accomplish the task of powering the LIMIT connection, they only state to splice the L1 line or jumper between them. The new control came with color coded wires to hook up the unit, if the old control didn't have the proper quick connectors. The old control had them, so that made that part easy. Now what I want to know, is if I take and cut the connector off the L1 black line and use the red and black wires that came with the new control, wire nut them together and hook black to L1 and red to LIMIT, is that what I need to do?
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Pasted from another site, question about LIMIT:

    (i have the same problem as your previous person with a new honeywell r7284 universal replacement oil primary control. the screen reads standby when the thermostat calls for heat and also when i jumper the two t terminals. the previous r7184b-1032 did not have a limit terminal and so there was no wire to connect to the limit terminal. my incoming power feed wire was red but connected to the black terminal spade on the r7184b-1032. your previous answer to the previous person leads me to the conclusion that i must supply 120 volts ac not only to the black terminal on the the new r7284 but also to the red limit terminal spade. this could be done by splicing an additional wire and terminal into my current red power feed and attaching to the limit terminal. am i correct with this assumption?)

    Expert's response:

    (You are correct. The limit must get 120v also.
    You will need to provide a jumper from your red 120v to the limit terminal.)

    Now my L1 wire is black, not red as in the person's question.

    On another site about the same issue is this person's answer to powering the LIMIT:

    (You have to tie the Limit (red?) & L1 (black?) wires together & connect them to the incoming power. You should use blue for the ignition transformer & orange to the burner motor. Do you have an electric oil valve? If so connect it to the terminal marked valve (violet?).)

    Now to me, this means I need to use my black L1 wire for both the L1 and LIMIT connections. Am I correct?
  • SuperTechSuperTech Member Posts: 251
    That will work. But your primary control is doing it's job by shutting off the burner during unsafe operating conditions. Do yourself and anyone else in your house a favor and hire a professional, the cad cell relay is telling you that you need help.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Ok, I took the chance and using the red and black wires that came with the new controller, I connected them together and hooked them to the black L1 line and then connected them to the control. Furnace is running. I bled line good. Now to see if it runs on next call for heat after it stops this time. I'll post later, but enjoying the warm air now.
  • STEVEusaPASTEVEusaPA Member Posts: 1,904
    The reason why I told you hire a 'competent professional' (there are plenty out there), is because if your primary was bad, and I'm not convinced it was, it may not be your only problem. And the burner needs to be set up properly with instruments, and checked with a meter and an analyzer to see what is the true problem.
    With all the parts you purchased, some unneeded, combined with your lack of experience, it would've been cheaper to hire the pro.
    Wiring them together and you lose you post purge, important in general, more so for a mobile home.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    And hiring a pro doesn't give a person the experience to fix their own things. My first occupation was a car mechanic. I helped my dad restore old muscle cars even his prized '66 GTO convertible) from the ground up, they come out of junk yards! Before that I helped my dad fix the old Miller gun furnace in the mobile home I grew up in, literally helping from age 7 or so. Thus the reason I am not afraid of doing things on my own.

    I am the only person who worked on the last furnace we had here, it was new in 1985 and we got it in 1998 when we bought the mobile home. It did not have all the bells and whistles, so to speak. I replaced many parts on it, including the primary control (had a used one from a friend's old furnace) when mine kept tripping. The one on mine was a metal box type and was the original part. I even upgraded the thermostat from a simple one (mercury switch) to the 5/2 Honeywell programmable one. On a side note, I am the person who installed a new 240v dryer receptacle, wired up the new dryer pigtail and completely installed the new 240v electric water heater (electric and pipes). Yes, I had a helper and that was my late husband. He just wasn't knowledgeable to do the work, so I had to. Oh, and I even keep the gas lawn mower running and purring along. Weedeater too.

    I watched the guy replace the pump in 2016 and what he did to determine it was not working, I did the same thing and the pump was not putting out oil to the nozzle at all, hence replacing it. When he brought that pump from his truck, it was dirty and I honestly feel it was a used part. His hands weren't that dirty to make it that way. The other parts, except the primary were done for it's yearly tuneup. The electrodes have NEVER, EVER been replaced in this furnace and the furnace is about 9 to 10 years old. They were inspected, and yes I had furnace repairmen come do that about every 2 years. I measured the setting as it was on the setup and used a gauge to set it according to the specs. I know that the main breaker (in breaker box for the furnace) and switch in the furnace were NOT turned off by the roommate when we had that large power loss in January. As the tripping happened shortly after that, I believe the primary was damaged. All the roommate did was turn off the furnace at the thermostat.

    The idea of buying this particular primary was to get the diagnostic info from it that I could use if there is another problem. The furnace is running now and I have set the valve on delay and burner off delay and they do work. No fire in the chamber when on burner off delay mode. Now its time to pay attention and see if it trips and it will tell me what caused it.
  • SuperTechSuperTech Member Posts: 251
    edited March 12
    What is the cad cell resistance reading? What info has the new primary given you? That primary isn't going to troubleshoot the furnace for you. It only shows how long it takes to ignite and what the cad cell is reading.
    Pump pressure needs to be checked and combustion needs to be set. Where are you located? I'm concerned about the safety of your furnace. Please tell me that you have a carbon monoxide detector...
  • KimberlyOrdKimberlyOrd Member Posts: 14
    CAD is running at 150-160 ohms on average when burner is running, and when on standby is reading 7000 something according to the primary control. The pump comes factory set at 100 psi and my burner has the spec of 100 psi. (I know they may be off, but how many people take a new car and have their pressurized gas line checked before buying or test driving the new car??) As of right now, the furnace has gone through 20+ complete cycles without a hiccup or burp. The primary does provide errors if they happen and none so far, I checked.

    I do have carbon monoxide detector and my home is never, ever sealed tight. I have screened opening where my range vent louvers used to be (result of canning tomato products one time and caused the louvers to warp, knocking the actual fan blade off and busting the louvers. Screen was installed to keep bees from coming through) and both doors leak a little bit of air all the time. Also, lavatory vent lets air in and out. Only 2 of my 8 windows have their inner storm glass installed, 3 windows have ac units in year round (read, air leaks). I understand fully about carbon monoxide issues and allow some air leaks to prevent buildup.

    As for what this primary tells about the furnace operation, here is info directly from Honeywell:

    Detailed Diagnostic Information – The “quick-fix” digital display delivers clear data designed to lead you to any problem, fast. Patent-pending technology determines and displays why a lockout has occurred, including lack of spark at the electrode, partially-functioning flame sense, line voltage dips and more.

    Simple, Streamlined Set-up – Set-up is simpler than ever, requiring no external tools to access the set-up and diagnostic features, saving you additional costs. Everything is fully operational out of the package.

    Multi-Faceted Monitoring – From cad cell and flame check to the voltage and the spark of the igniter, you can quickly tell how everything is functioning and, in case of a failure, which component is faulty ensuring the right part is fixed the first time.

    As I had to clean out the air intake hose (downdraft along side flue) from all those dead bugs in it, it is most likely functioning better now. More fresh air getting into the combustion chamber now due to just that. I know for a fact that the guy who replaced the pump and "cleaned" the system for me in late 2016 did NOT clean that air intake tubing or shroud. I stood there and watched the guy 99% of the time. That is how our "professionals" around here work. And I also know the previous company I dealt with also did not clean that air tubing or shroud. 9 years of dead stinkbugs and wasps, filling up about 3 inches deep in a 4" air tube. That's the fresh air intake for the combustion chamber.
  • SuperTechSuperTech Member Posts: 251
    It sounds like you have done what you can do with the tools you have. Good luck with it. If you have any further problems let us know.
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Well, I'm off and going to deal with other matters now.
  • newagedawnnewagedawn Member Posts: 406
    there should have been a jumper for the limit/L1 connect it and why do you have a black wire on an L2????? that could be your problem
  • STEVEusaPASTEVEusaPA Member Posts: 1,904
    She replaced a "B" with a "U". I'm sure power is coming in from the limit (I hope it is), but without a separate constant source of power she needs another wire ran to the control.
    I've seen on units where all the wires for power come from the board, that they are of thicker insulation, and not necessarily just black and white (like oem blower motor wiring).
  • KimberlyOrdKimberlyOrd Member Posts: 14
    Just a follow up since I got new posts on this. The furnace is running fine now with the new "U" control on it. No errors or tripping. It's nice to be able to go to sleep and not wake up cold or getting up several times every night just to check the furnace.
    As for the black wire to L2, the main line to the control is a thick black wire just like any heavier 2 wire cord one would use to wire up any appliance. (Don't ask me why that is.) It is split just inside the junction box. One side was totally black and was on the L1 on the old control. One side has a white stripe and it ran to L2 on the old control. I just took one wire off and place it on the new control where it went and did so for each wire, one by one. There was no jumper to use, as the old control didn't have a LIMIT connection. Should the new control have come with one? The wiring has not been changed from when the furnace was manufactured.
  • STEVEusaPASTEVEusaPA Member Posts: 1,904
    I think your black wire has to come from the limit of your fan/limit switch, a pressure switch in series, or at least from the limit in the board-this is standard wiring.
    Otherwise it will never shut the burner down if the heat exchanger gets too hot. It really is a safety issue and you need to check that it is working properly.
    Is there a wiring diagram on the furnace you can post, or provide name/model no. of furnace.
  • SuperTechSuperTech Member Posts: 251
    I've seen plenty of those controls installed the same way. Just as long as the furnace shuts down the burner like it did with the original control and cycles the fan normally. It sounds like it tested out ok.
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