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    Issues with & Replacement of Honeywell L8148E Aquastat (32 Posts)

  • pfarq pfarq @ 4:49 PM
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    Issues with & Replacement of Honeywell L8148E Aquastat

    We have a Honeywell L8148 that has started to act up and in
    lieu of spending $450 to have a technician replace it, I’m interested in
    swapping it out myself.
    This will be the third time within 6 years of ownership that
    the aquastat will have to be replaced.
    To give some background of the problem, the burner will
    sometimes fail to ignite. The “solution” to the problem is giving a slight
    jiggle to the plug and wire shown in the red box of the attached image. The
    burner ignites and heat is restored.
    Then the same problem will happen again, usually at 3 in the
    morning of if we’re away for the weekend only to return to a house with an
    internal temperature in the 50s.

    So, I assume it’s not possible to replace the suspect plug
    or circuit board and a total replacement is in order. It seems like a
    straightforward r&r, though I’m a bit uncertain about the physical
    connection of the aquastat to the boiler (see attached image).
    Do I need to drain the boiler prior to unscrewing this nut?
    Do I unscrew the aquastat off this stem?

    Any .02, thoughts and advice would be very welcome.
    Regards,
    PF
  • Tim McElwain Tim McElwain @ 7:11 PM
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    The plug you are

    "jiggling" is the place that a vent damper if one were used could be plugged in. If you are going to have your contractor replace the relay then install a Universal Replacement L8148J, the plug will be eliminated and that is not a problem as you do not have a vent damper anyway.
  • pfarq pfarq @ 9:09 PM
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    Hmm...

    Hi Tim,
    Thanks for your thoughts. Interesting tidbit about the damper in that last year, the technician that installed this current aquastat unplugged the damper for some reason; if I recall correctly, he said it wasn't working and that we were just wasting energy by keeping it in the open position, so he must have placed that plug in place of the damper plug. Interesting in that the tech that visited 2 years prior said it was no problem to leave it open. (Which train of thought is the right one? I'm still trying to get up to speed on boilers, relays and dampers.)

    Nevertheless, I plugged the damper back in and the boiler has now come back to life (it shut off again about half an hour ago, as you might notice in the pics, the temp had dropped down to 120.)
    Do you think this is the cause for the recent failures of the boiler to remain on and hold temperature or does the aquastat need to be replaced?
    This post was edited by an admin on January 20, 2012 9:12 PM.
  • Plumdog Plumdog @ 9:56 AM
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    damper danger

    Try this: get the damper to actuate one more time by turning the power off and back on. With the blade in the OPEN position (the flat shaft will be vertical, look up inside the draft hood with a flashlight to verify) find the little switch on the side of the vent damper motor and place it in Man. Hold Open position. The unit should work with the damper open all the time. Your damper jumper plug is probably loose.
  • furnacefigher15 furnacefigher15 @ 9:13 PM
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    Damper

    With the damper functional, you save about 2% on overall fuel consumption.

    But, those dampers are fairly expensive, so for some the payback is not there.
  • pfarq pfarq @ 4:21 PM
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    Update

    I removed the jumper plug and plugged the damper back in. The boiler has been performing perfectly ever since. Can't believe I had been dealing with the jiggling issue for nearly 3 months! Thank everyone for your help.

    PF
  • Eric Eric @ 6:47 AM
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    Keep an eye..

    It could be that the end switch in the damper has sporadic issues and will work sometimes and not another.
    I have done 50/50 on removal or replacement, but was up to the customer.
  • Tim Tim @ 12:11 PM
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    Replace your own... if yours starts giving trouble again

    http://www.beckettcorp.com/Product2/productdetail.asp?detailid=35

    When my Honeywell failed, (intermittent Bad solder connection,) I replaced it myself with this Aquasmart, reasonably priced, easy to program, it works great, has an option for built in LWCO, was easy to install, has smart control for fuel savings, & I was able to wire up my existing SlantFin specific 4 wire plug Damper Harness.

    PS, they are a site sponsor, look to the right on the main page


    Tim
    This post was edited by an admin on February 8, 2012 12:12 PM.
  • Gregpa Gregpa @ 11:33 AM
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    Have a Q

    A have exactly the same problem as pfarq had but my aquastat is L8148B. If I manually connect contacts B1 and B2 (Burner) I'm able to ignite the burner. What could be a problem here?
  • Tim McElwain Tim McElwain @ 6:43 PM
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    Your problem is not the same I

    would say. The relay you have the L814B has an isolated burner circuit typically used with powerpile systems.You probably have a powerpile (self generating) gas valve, is that correct? If so is the pilot lit? If it is then you need a professional to come in and take some millivolt readings on your system. It can sometimes be that the pilot needs cleaned and a new generator installed. I have a section here at Heating help called Tim's Closet, go to resources above and click then library and look for that section it outlines how to take readings on these systems.
  • Gregpa Gregpa @ 8:43 PM
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    Thank you Tim

    I'm reading your troubleshooting doc. Just want to let you know that the pilot stays lit all the time and  the burner sometimes ignites (can take hours calling for heat).
     
  • Tim McElwain Tim McElwain @ 7:25 PM
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    That is typical of

    powerpile systems. You have a very simple circuit just the hi-limit in the relay and the wire from B1 - B2 to the gas valve not a lot can go wrong there. In addition to the troubleshooting procedure the gas pressure needs to be checked before the gas valve and at the outlet when it is running.
  • rocky22 rocky22 @ 12:40 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
    Contact this user

    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
    Contact this user

    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:40 PM
    Contact this user

    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:41 PM
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    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • rocky22 rocky22 @ 12:41 PM
    Contact this user

    similar issues

    I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 
  • Tim Tim @ 1:40 PM
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    c-90?

    Rocky22,
    I Cant find any reference to the c-90, possibly a v-90???
    Anyway your description of the symptoms sounds remarkably similar to my problems with my slantFin SX-150. It used the same control (L8148E) and it drove me & my boiler man mad trying to find out why the boiler would intermittently not fire. It was suggested to replace the vent damper & gas control too, but I resisted until the failure was confirmed. Good call on my part, because it was a cold solder joint on the L8148E control relay. Its a DP relay, and the burner contacts were the problem, so the circulator would work ok. I chose to replace with the Becket Aquasmart (similar pricing, but features are included to save$$$) check it out,
    http://www.beckettcorp.com/Product2/productdetail.asp?detailid=35
    its a nice unit

    Tim
  • p00 p00 @ 12:13 PM
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    Similar problem

    I have L8148E, 2 zones with 1 Circulator.  I have 2 zones, which are downstair, upstair.   Downstair is working fine and Upstair is not.  Both zone valves are working properly and switches in the zone valve are also working properly (I heard the sound on/off, measured the voltage, 24V or 0 V).  But the Upstair's control could not fire the Burner.  I could not understand.  Any idea ?

    Thanks,
  • Tim McElwain Tim McElwain @ 10:16 AM
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    What make

    zone valves do you have?

    Try jumping out the end switch on the zone not working and see what happens?

    The relay is obviously okay as zone 1 brings every thing on.
  • p00 p00 @ 12:05 PM
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    Honeywell

    These are Honeywell  V8043 E 1042 Motorized Valve.

    Each of the out from the Valve has 24V or 0V depending on the Thermostat temperature setting.   Out from the valve are parallel and these go to TV and T in L8148E.

    If there is a heat demand from  Th1 (thermostat 1),  voltage between TV and T goes to 0V from 24V, then the furnace starts to burn.

    If there is a heat demand from  Th2 (thermostat 2),  voltage between TV
    and T goes to 0V from 24V,  the furnace does not start to burn. --- I do not understand.

    If making a jump between TV and T (short circuit), it would not fire either -- I do not understand.
  • honeowner honeowner @ 9:15 PM
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    more problems with Honeywell L8148E

    I have a similar problem to many here.  I have a Slant Fin S-120-DP with a Honeywell Aquastat relay L8148E.  It has a motorized damper vent control.
    I started to have the intermitent problem a year ago (once), but this year has become a regular occurance. stat signal is confrimed, zone controllers (I have 3 zones) open, pump starts, but no fire.  For a while I would shut off power and back on, and the vent woudl open, fuel control woudl make and it woudl fire.  I tried cleaning the contacts on the realy w/ emery cloth (man, it is hard to get in there) and thought that worked, but then it happened again.  I finally have figured that I need only "tap" the top of the L8148E box, and "click!"  But...WTF? Easy to do when I am home, but not when I am out of town on a -20F MN day.
    It SEEMS to me like there is not enough current (sometimes) to pull in the contact, but why would this work sometimes and not others?  No rhyme or reason.  I have jiggled for other loose connections but found none.  Any help woudl be appreciated.
    stumped in winter,
  • We Had About

    4 of these problems last season, my electrician solved the problem quickly by soldering the back of the board, behind where the vent damper plugs in, we haven't had one come back yet.

    Thanks, Bob Gagnon
  • BobC BobC @ 8:35 AM
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    cracked solder joints

    Molex board connectors are known for developing cracked solder joints, it's often because of a small solder pad that does not allow everything to heat up properly in the soldering process. If you look closely you might see a faint black ring around the joint, cleaning and resoldering the joint usually works.

    Manufacturers often use the cheap tin contacts in them and they are prone to corrosion and loosening up with vibration and thermal cycling. For a dime they could have used a decent bronze phosphor contact but the bean counters are adamantly against that.

    Bob

    Bob
    Smith G8-3 with EZ Gas @76,700 BTU, Single pipe steam


    Vaporstat with a 12oz cut-out and 4oz cut-in


    3PSI gauge
  • unclejohn unclejohn @ 8:50 AM
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    I didn't Read

    Every post but no you do not have to drain the boiler to replace the control. You may try using a plastic wire tie through the loop of the jumper wire on the plug to add some tension that will hold the plug down and that will usually work until you get a replacement control. I would also contact Honeywell customer service and let them know your issues with their controls.
  • Tim Tim @ 10:58 AM
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    Bad solder Joints on Honeywell control

    Ditto on the bad solder joints on the Honeywell control on my slant fin SX-150.
    Same symptoms, intermittent no heat, not a good thing on a vacation home on the Colo Mtns when you are not there to know....
    I replaced the control with a Beckett AquaSmart. There is some wiring needed to operate the vent damper, but otherwise a nice control.

    If you need more info, let me know

    Tim
  • soeasytobefake soeasytobefake @ 2:01 PM
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    Solder points

    Found the problem. Apparently its a common one. The solder points on the back side of the circuit board are junk. the amount of force required to install or remove the cable gives these solder points no chance to survive even with the two heavy screws holding the plug to the board. Im going to attempt to resolder these points. Wish me luck.
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