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Weil Mclain WM97 - Taco LWCO fail every few months

apanek01
apanek01 Member Posts: 10
The Taco electronic LWCO (model LTR0243T) fails every few months on my Weil Mclain WM97+ boiler. There is no low water condition in the boiler or air. Sometimes it fails with a red light, sometimes with an amber light. On occasion it blows the 3AMP fuse on the control panel. The only way I fix the issue is to replace the LWCO with a new one as it appears the LWCO electronics have been blown from something in the boiler itself.

Here is what has been done to try to determine root cause:

1) Replaced the transformer with new transformer
2) Replaced the front control panel with a brand new control panel
3) Installed a surge protector
4) Installed a RectorSeal VRM (Voltage Regulator Monitor) that cuts power to boiler in a surge or brown-out condition. I have set the low end of the cut-off to 115V and high end to 125V.

Has anyone experienced frequent failures on a Taco LWCO LTR0243T and determine root cause and how I might troubleshoot or override the Taco LWCO?

Thanks

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,900
    edited December 2021
    I don't know but I would certainly contact Taco. They hang out on this forum occasionally and may respond. @Steve Thompson (Taco) or @Joe Mattiello
  • EJN451
    EJN451 Member Posts: 3
    I have the same problem on the same(?) furnace (WM97+155). First fail was after 5 years of service, blew fuse. Second fail was 47months later, blew fuse. LTR0243 taco unit. Do not know is causing this, either. Both fails were during very cold weather, but no idea how this could be connected.
  • EJN451
    EJN451 Member Posts: 3
    Erratum re above: 2nd fail was 23 months later (last night), not 47 moths later.
  • Jamie Hall
    Jamie Hall Member Posts: 18,699
    It is a mistake to blame the boiler. It is an inanimate block of cast iron. You need to be looking either at the installation of the LWCO or in the other controls and power circuits.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,900
    Why not call Taco just replacing the controls with nothing found just invites another failure
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    edited January 30

    It is a mistake to blame the boiler. It is an inanimate block of cast iron. You need to be looking either at the installation of the LWCO or in the other controls and power circuits.

    Jamie, I believe the LWCO is a factory installed part on the WM97



    So .... Yea ... Blame the boiler ... all the wires, controls, tubes, and other parts (like the block) are all part of the boiler. There is something in there that is causing this failure, whether it be a bad connector, poor location design, or something exclusive to that particular boiler. Without locating that cause, than I agree with @EBEBRATT-Ed

    Edit: I like to think outside of the box. what if you extended the wire to a location outside of the boiler jacket. Can you install the LWCO on a fitting installed on the connecting near boiler piping? That would put the LWCO in a different temperature zone... Just a thought

    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • Jamie Hall
    Jamie Hall Member Posts: 18,699
    It may be a factory installed part, @EdTheHeaterMan , but it is not a Weil-McLain part -- any more than the Firestones on you new Ford Exploder are a Ford part. And blaming the Ford for the flat Firestone will not get you very far.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • JUGHNE
    JUGHNE Member Posts: 9,721
    But if the LWCO is married to a control board that powers it, there could be something bad in the marriage...so to speak. IMO

    For instance my Lochinvar factory LWCO plugs into the main control board so your read out will tell you of the reason for that particular shut down.
  • wmgeorge
    wmgeorge Member Posts: 222
    Speaking as an Electrician, find one that knows commercial - industrial not your typical house Romex runner. Tell them the issue and check the building ground to service panel and boiler ground connections. I have seen strange problems traced back to a corroded ground connection.
    Old retired Commercial HVAC/R guy in Iowa. Master electrician.
  • Lance
    Lance Member Posts: 209
    More fodder for your mill. I love a mystery as long as its not my heat system. Grounding is important. Verify all grounding of boiler is good. From The power supply to control boards. Follow Taco install instructions exactly. it says 2-3 wraps of tape dope, it means just that. Water chemistry is probably not an issue, but will it be a factor? The circuit must be measured. Is a heat anticipator involved at the stat and is it set properly? What is the voltage and amperage along the circuits between the control and the board? May require splicing in a test cord. Your clue is the 3 amp fuse blowing. This means the fuse did its job and you need to find the path and the condition that creates excess current. Divide and conquer. Isolate the thermostat loop. Measure the stat circuit disconnected and check for a voltage drop. Compare T T without the stat circuit and with the stat circuit in series. A possible partial short may be occurring due to poor insulation of wires or even a staple in a wire. Never jumper TT with the stat in the circuit to test the circuit. It can change the circuit from a series to a parallel loop. Hint: sometimes the tech for this job is an HVAC tech. He has the tools and understands control circuits. Good luck.
  • apanek01
    apanek01 Member Posts: 10
    @EdTheHeaterMan nice to meet you and finally great to hear someone with same issue -- although I don't wish this upon anyone!

    You are correct LWCO is factory installed and tied to the control board. I have used Weil McClain and Taco branded LWCO and they all fail the same in this boiler and same specs - just the Weil McClain branded LWCO is double the price so I switched to the Taco's. I have called Weil McClain and they offer no help with the Weil McClain LWCO installed - they say they have not seen this issue before. Taco says they have not seen this issue before either, but did confirm their LWCO is compatible with this boiler -- it is exactly the same as the Weil McClain branded LWCO.

    Taco said might be something with the blower motor or gas valve sending a surge as it on the same low voltage leg as the LWCO. Taco took 2 of my failed LWCO to send them out for diagnostic, but they never get back to me -- they just keep telling me they are out and haven't heard back from manufacture.

    You have the 155 model. There is an article about a MELTED BURNNER GASKET issue that only affects the WM97+ 155 regarding ground and the gas valve. Have you seen this or done the replacement?

    https://www.weil-mclain.com/download/file/fid/3021

    Are you using the integrated DHW tank that mounts to the bottom of the unit? If you are not, please be aware that the power leads sit on the bottom frame of the boiler in the left and right corner and they are not capped or protected! You will see them just sitting their when you take the front control panel off. I wrapped the DHW leads with electrical tape and zipped tied them off the frame in case they are shorting on the frame or getting wet as you get a little water when replacing the LWCO since it is in the boiler -- bad design!

    I am also planning to install this inline to hopefully protect the LWCO

    https://www.amazon.com/POP3-Lil-Popper-Fuse-Tester/dp/B07FWFZCSF/ref=sr_1_1?crid=1CFXKV8262ACU&keywords=3+amp+li'l+popper&qid=1643585811&sprefix=3+amp+li'l+popper,aps,68&sr=8-1





    Daveinscranton
  • Tim_D
    Tim_D Member Posts: 66
    If you are blowing the 24vac onboard fuse you have a short in one of the 24vac circuits which includes the LWCO. If replacing the LWCO corrects the issue for a period of time then that is the place to start looking. I have seen a few where the molex plug was 180 degrees out which causes a short.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    edited January 31

    It may be a factory installed part, @EdTheHeaterMan , but it is not a Weil-McLain part -- any more than the Firestones on you new Ford Exploder are a Ford part. And blaming the Ford for the flat Firestone will not get you very far.

    LTR0243T is a Weil Mclain Part number is 571-100-006

    So I believe it is a Weil Mclain Problem to resolve. But I see Your point. every part on a WM boiler is not manufactured at the foundry. But when your FORD fuel injector fails, you don't call Bosch or Detroit or the injector manufacturers... You go to the FORD dealer.

    And I believe you see my point. (you are one of the contributors that I look up to here) I contend this is a Weil Mclain Tech Support issue. But I am also of the opinion that WM probably won't be very helpful. It is past the part warranty coverage of 1 year.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    apanek01 said:

    @EdTheHeaterMan nice to meet you and finally great to hear someone with same issue -- although I don't wish this upon anyone!

    I'm not an owner of this boiler, I am a retired HVAC contractor that worked on many different WM boilers. I may have even installed one on a radiant heat job that I was assisting the plumber of record on the job. I think there was a separate DHW source on the job. I have mixed feelings on WM as a manufacturer. I became friendly with many of the WM employees at my local factory warehouse in Pennsauken, NJ in years past. But as a whole, they are not as customer friendly as some other manufacturers.

    I suggested that you relocate the LWCO outside of the Jacket. Put it on a pipe that is above the exterior of the boiler and just get a longer wire to connect it to the control board. You can put a plug in the hole (3/4" tapping) where the old LWCO is located. Just make sure the location you choose will not be subject to air lock of any kind. this means there mist be water at the location ALWAYS. This will remove the possibility that the area inside the jacket is overheating and causing the problem. Im not saying that is the problem, Im saying that this adjustment will rule out overheating or over-humidity that may be in that location.

    Just a thought. If you post a picture of your system from far enough away to see the near boiler piping above and below the boiler, I may be able to suggest a convenient location.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • wmgeorge
    wmgeorge Member Posts: 222
    If it was a product issue, would it not be failing for others? Looks to be a job specific issue. So no need to re-design the wheel.
    Old retired Commercial HVAC/R guy in Iowa. Master electrician.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    edited February 1
    wmgeorge said:

    If it was a product issue, would it not be failing for others? Looks to be a job specific issue. So no need to re-design the wheel.

    What is your suggestion? If the factory provided part and the identical aftermarket part are failing prematurely, do you try something different or just keep doing the same thing. Perhaps there is an electric amperage or voltage issue and that part is the weakest link in the entire house. It sounds like the OP has been trying to eliminate each item by the process of elimination. So far...

    1) Replaced the transformer with new transformer
    2) Replaced the front control panel with a brand new control panel
    3) Installed a surge protector
    4) Installed a RectorSeal VRM (Voltage Regulator Monitor) that cuts power to boiler in a surge or brown-out condition. I have set the low end of the cut-off to 115V and high end to 125V.

    I did not see move LWCO location on their list, so I made that suggestion... Here is another

    There are different manufacturers of the same device. GuardDog RB-24E uses the same basic footprint and same wire plug connector. Maybe that will resolve. There are so many ways to go here.

    I have been in the business for over 40 years. I have found that changing contractors is the worst way to resolve an issue.
    The new guy needs to start from scratch and possible try the same thing the original contractor did. by sticking with me, a customer gets my experience of all my customers and also the experience I have on their system. I already know what didn't work for the last 2 years, 3 years or more. When I stick with a problem like this, I'm determined to resolve it.

    OFF TOPIC but an example of thinking outside the box.
    There is a very interesting and unusual fix I was able to make for a customer that was having odor then after repairing the odor problem, there was a nuisance lockout issue that lasted for 3 years. Here is the post I made about that: https://forum.heatinghelp.com/discussion/comment/1651498#Comment_1651498

    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • Jamie Hall
    Jamie Hall Member Posts: 18,699
    True, you are talking about a Weil-McClain supplied part. As has been noted, an essentially identical part is sold under other trade names.

    However.

    The fundamental problem is that you have had identical problems several times with the same part. While it is tempting to continue to blame the part, almost always when a replacement part fails in the same way as a previous part -- it's not the part. It's something else. Keep looking.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • apanek01
    apanek01 Member Posts: 10
    edited February 1
    @EdTheHeaterMan I appreciate the suggestion, but if the LWCO had an issue located inside the boiler as root cause I would suspect to see more issues reported? My install is a condo / commercial building install so it also has a external LWCO installed by code. I was concerned at one point that amount of heat build up inside the boiler might be causing premature failure of the LWCO. But others with the WM97+ boilers are running fine as you are the first person I have stumbled upon that has a customer with same issue as I have.

    BTW I looked up the GuardDog RB-24E that you suggested to install outside the boiler. This has a lower ambient max temp rating of 120 degrees. The Hydrolevel SafeGuard 1100 has a 170 degree max rating and the Taco has a 150 degree ambient max rating if you are concerned about heat level.

    Maybe a different LWCO model would be able to survive the surge, but that would not be fixing the root cause and I have tried a few different models with same result.

    Here is what I think might be a better work-around until root cause can be isolated. Maybe try this with your customer for the WM97 155 with same issue. I am going to install a breaker inline of the LWCO to protect and isolate. I did not want to cut the existing wiring harness to do this and purchased a extension cable:

    StarTech.com Power Cable
    8in ATX12V 4 Pin P4 CPU Power Extension Cable
    Model: ATXP4EXT
    https://www.amazon.com/StarTech-com-ATX12V-Power-Extension-Cable/dp/B000O7WFHA/ref=sr_1_1?crid=295XW1ILW0IIR&keywords=ATXP4EXT&qid=1643711540&sprefix=atxp4ext,aps,73&sr=8-1

    and

    ESP Li'L Popper - 3 AMP Control Circuit Breaker
    https://www.amazon.com/Amp-Circuit-Breaker-Push-Button/dp/B0078S7N66/ref=sr_1_7?crid=NUCRADLFKXM5&keywords=lil+popper+3+and+5+amp&qid=1643711644&sprefix=lil+popper+,aps,70&sr=8-7



  • apanek01
    apanek01 Member Posts: 10
    edited February 1
    @Tim_D I have on order a new wiring harness (backordered until March 22). I have gone through all the molex connections and traced the wiring harness and don't see any visible issues -- but I purchased a new harness anyway to just rule it out. Reminds me of an issue with an old car misfiring and the mechanic and I spent months trying to figure it out - replaced ignition coils, spark plugs and wires. We finally isolated to the cars wiring harness. Replaced the main wiring hardness and the misfiring resolved!

    So Taco had suggested to look at the blower motor and gas valve as a possible root cause of sending a spike through the low voltage side as the LWCO shares the same leg. Any suggestions on how I might test these to see if it these are sending a surge back through the system? I think I would need some type of monitor and logger for this as this could go for months before the next issue occurs.
  • tim smith
    tim smith Member Posts: 2,459
    What's your total amp draw on the 24v circuit when running. Check with priority dhw running then with all heat zones running separately. Are you well under the 3 amp rated fuse? 2nd, make sure none of the control wiring in boiler is touching pipes, look close for slight wear/melting of insulation where they may have been touching. Good luck.

    apanek01
  • EJN451
    EJN451 Member Posts: 3
    I just want to point out that the taco unit all by itself presents a short-circuit across the 24VAC leads when it fails, hence the fuse blowing has nothing to do with other loads on the 3A buss. I have experience in semiconductor development and the failure mode does look like that due to a transient over-voltage into the unit, as some have suggested. I may de-pot the original (failed) unit to see exactly what failed, but it looks to me like it is the input diode bridge, as I can't imagine any down-stream (internal) component causing such a hard fail (effectively less than 1 Ohm load). I like the idea of the blower or valve causing transients. My original blower failed after 3years of service (tachometer failure), so maybe it too was a victim of transients, perhaps from the gas-valve solenoid? Thanks to all for the ideas and comments.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    edited February 13
    apanek01 said:

    @EdTheHeaterMan I appreciate the suggestion, but if the LWCO had an issue located inside the boiler as root cause I would suspect to see more issues reported? My install is a condo / commercial building install so it also has a external LWCO installed by code.

    If there is a LWCO located outside the boiler jacket, than I would just eliminate the internal LWCO and connect the wire to the exterior control. If the exterior LWCO controller does not use the same connector, then I would just jumper the interior control and rely on the exterior one. You certainly don't need 2 LWCO controls. Remember that all boilers are not equipped with internal LWCO controls. The code you refer to requires 1 LWCO and the inspector wants it outside the boiler where he can see it. A good Installer with a good rapport with the plumbing inspector could have made the case the the boiler has a LWCO and that one is better designed to protect the boiler based on the location. But that assumes the plumbing inspector has a half a brain.

    As far as other boilers like yours having your particular problem... I have found that "NO TWO SYSTEMS ARE IDENTICAL" You will need to find the problem that is unique to your system, or find a work around.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • Tim_D
    Tim_D Member Posts: 66
    I doubt that the gas valve or blower are sending a spike.
  • johnkingston386
    johnkingston386 Member Posts: 2
    I'm having the exact same problem with a WM97+ boiler every month I have to replace the LWCO, did anyone have a solution to the problem. The company WM said it was the cutout an to use a Hydrolevel LWCO instead but I don't think that is the issue.
  • apanek
    apanek Member Posts: 2
    @johnkingston386 I replaced my LWCO with the Hydrolevel 1100M in Feb as I had another failure. I switched from Taco to HydroLevel just because it was cheaper. It has not failed yet which seems a bit odd as I would have expected to fail in March or April based on previous history. But this has happen before were I install a new Taco and sometime seems to last longer than others. Now that I am out of the heating system and it is only heating hot water, I don't usually see LWCO failures in the non heating months. I would expect this one to fail in October or November when the heating season starts again.

    I will post back here if the Hydrolevel LWCO fails. Let me know how you make out as I am very interested in solving this very "expensive" mystery!

  • johnkingston386
    johnkingston386 Member Posts: 2
    Yes I will. I'm wondering if I should buy 6 LWCO for next season.
  • apanek
    apanek Member Posts: 2
    I keep at least 3 LWCO in my stock at all times.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,983
    edited May 19
    Just a thought. Place a LWCO on a different part of the system. Wire it to a different power source. Use only the dry contacts, isolated from the power source, to break the burner circuit using the auxiliary auto limit of the WM 97+ low voltage terminal board as shown

    The final step would be to take the connector to the factory LWCO and determine what wires need to be jumped to complete the burner circuit.

    I believe it is B4 and B12 on the plug but I can't be sure. Since many of you have these wires and these controls in your inventory, perhaps others can verify this. I do know that if you purchase the after market LWCO with the wiring harness, it is the two yellow wires on the aftermarket controls that need to be jumped. But that does not help on the Weil McLain control and wiring because the colors on the factory wiring are different. I believe that on the Molex plug, the wires marked 1 & 2 are 24V. power to the device, 3 & 4 are the switch dry contacts. Those numbers are very hard to find on the plug though.


    I'm not sure that this is correct so verify before you make the final connection
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org