Boiler Circulation Pump Control Issue

Discussion in 'Boiler Forum' started by Reicherb, Feb 9, 2016.

  1. Reicherb

    Reicherb Member

    Joined:
    Nov 7, 2013
    Location:
    Linden, MI
    I have a Well-McLain Series 3 P-D--7 boiler that I believe to be original to the house which was building in 1968. 2 of the zone valves were replaced in 2008. The last was replaced by me a few months ago. I've discovered that the circulation pump is often running when no zone valves are open and the boiler isn't running. This explains the previously explainable high electrical use.

    The control/relay unit is VERY old. It's got magnetic contacts that seem to stick together when energized (B in the picture below). I've sanded them repeatedly and it's made no difference.

    I assume my next step is to replace the controls. Can you please help me select the correct part for this application?

    Here is a pictures of what I have now.
    [​IMG]
    Thanks,

    Brad
     
  2. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    There are any number of possible replacement parts out there that MIGHT work, but it's useful to have a schematic of the controls to work with. I suppose it's too much to ask that you might have a manual for the boiler kicking around? I couldn't find an online manual with that model number. A picture of the name-plate with it's BTU input/output numbers and a picture of the whole boiler might make it easier to figure out.

    Is there a part number on the (missing in the picture) cover? Does it have a thermocouple wire to the temperature sensor to the well on the boiler, or is it integral to the box?

    The spring on the contactor/relay is probably weak- you might be able to scavenge an appropriate spring somewhere if you can't find a direct replacement.

    You might have an easier time just leaving the contacts stuck but replacing the pump with the appropriate Taco Viridian and setting it up for constant pressure. When both zone valves are closed it won't use more than a watt or three of power, and when they're open it'll still use well under half the power that the old pump used. It's not cheap at $175-275 (depending on which flavor and where you buy it). A cast iron boiler that's more than a decade past being old enough to run for president is well beyond it's freshness date stamp (as are some of those actually running for office :) ), and isn't worth a whole lot of repairs, even if it's not leaking (yet). But a smart pump for the radiation can still be used with whatever replaces it when the time comes.

    Most boilers that age are 3-5x bigger than they need to be to heat the house, since most people have tightened up and insulated the house since 1968, maybe even replaced the windows, and the thing was probably 2x oversized on day-1. Replacing it with a right-sized boiler would be a big step up in both comfort and as-used efficiency. When you get to the point where you think it's time to retire it, check back on how to right-size it. The last thing you should do is just replace an old boiler with another of comparable name-plate output. With a fuel use history and a ZIP code determining a realistic upper bound on what the actual heat load is can be pretty simple.
     
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  4. Reicherb

    Reicherb Member

    Joined:
    Nov 7, 2013
    Location:
    Linden, MI
    We've only lived here a couple of years so no luck on the manual. Below are some images that might be helpful.
    IMG_20160209_191630234.jpg IMG_20160209_191727954.jpg IMG_20160209_191721035.jpg IMG_20160209_191648123.jpg

    I know we need to replace the boiler but can't afford it right now. I'd prefer to replace the controls as that seems less complicated than the pump but if we can't find a replacement control then, I'll do what I have to do.

    I did have the boiler inspected when we moved in and other than it being way to big (yup new windows and more insulation) and now the control issue, it's working fine)

    Thanks,

    Brad
     
  5. Reicherb

    Reicherb Member

    Joined:
    Nov 7, 2013
    Location:
    Linden, MI
    Does that info help?

    Thanks,

    Brad
     
  6. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    There's a good chance that a Honeywell L8124E would drop right in without any serious tweaks to the wiring. The "E" would be important (don't get the "A") since the wiring diagram indicates a 24V gas burner control. See figure 4 in the manual. It's on the order of $200-250 from online vendors. Setup on it is a bit different than the old W-R, since there's more than one temperature to tweak:

    [​IMG]

    I'm sure the boiler is working just fine, but at 65-70% thermal efficiency, maybe only 55-60% if there is isn't an automatic flue damper retrofitted onto it, since it's spends most of it's time idling sending much of the residual boiler heat straight up the flue. A boiler half that size is probably still overkill, and would have much lower idling losses.

    The bright red B & G NRF-22 looks less than 10 years old and probably just fine, and also probably more pump than is actually needed even with the oversized boiler. At 92 watts you'd probably be able to drop back to 25 watts or less with an ECM drive smart pump. At full-speed the BumbleBee has a comparable curve at less than half the operating power, but you'd have the option to dial it back to optimize system performance. The Viridian VR1816 would also work, and has other operating mode options, such as constant-pressure, which would use effectively no power when neither zone valve is open even when fully powered up. You can get either for under $200.

    [​IMG] [​IMG]

    [​IMG]
    ^^^VR1816 curves at constant pressure^^^
     
  7. Reicherb

    Reicherb Member

    Joined:
    Nov 7, 2013
    Location:
    Linden, MI
    Is there an online dealer you believe it a reputable dealer that I could get the L8124E from?

    Is this something a guy without any real boiler knowledge could install?

    Where did you find the boiler manual? I assume I'll need that to determine the temperature ranges to set the controls at.

    Thanks,

    Brad
     
  8. Leon82

    Leon82 Member

    Joined:
    Mar 13, 2014
    Location:
    Connecticut
  9. Reicherb

    Reicherb Member

    Joined:
    Nov 7, 2013
    Location:
    Linden, MI
    Can an amateur like me handle the install?

    Brad
     
  10. Leon82

    Leon82 Member

    Joined:
    Mar 13, 2014
    Location:
    Connecticut
    I would download the instructions and go through them.

    Your going to have to turn off the power and gas, then restart the pilot when your done.
     
  11. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    It's not rocket science, but it helps if you have electrician & mechanical skills. It's hard to tell in your picture whether the W-R aquastat is screwed directly onto the temperature sensing well on the boiler (which is how the L8124s are configured) or if it's on the end of a thermocouple wire. As I understand it Honeywell may longer ship thermally conductive compound boxed up with the aquastats for installing the sensor in the well, but if they don't you can buy it online for about a sawbuck (plus shipping.) Without the thermal goop the sensor reading can be pretty far off, so don't install it "dry".

    You might find some instructional videos on swapping out aquastats useful.
     
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