Boiler overshoots setpoint

Discussion in 'Boiler Forum' started by Bleecker, Oct 13, 2012.

  1. Bleecker

    Bleecker New Member

    Messages:
    1
    Location:
    New Jersey
    I have a Burnham Alpine 105 w/ Sage 2.1 that won't begin throttling back until 5F or more above the setpoint (and takes its time once it does start, so the supply temp rises even further). This happens for DHW and central heat demand, regardless of the setpoint. The control board has been replaced but it hasn't changed this behavior.

    For now we've been tweaking the diff above/below and max modulation rate to try to reduce cycling, but any ideas or suggestions as to what may be causing this?
  2. mage182

    mage182 Member

    Messages:
    69
    Location:
    NY
    I have an Alpine 150 and it does the same thing. I was always under the impression that it was within acceptable limits of the unit. I have the high setpoint on my DHW set to 170 so if it goes to 175 it isn't a big deal. I don't think for a heat demand the unit did anything about 145 last winter so no danger there of overshooting a few degrees.

    But I am interested to know if this is in fact a problem?
  3. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
  4. georgemp

    georgemp New Member

    Messages:
    3
    Location:
    Massachusetts
    I have a similar issue. We have an Alpine 150 with an mcba board and I have set the setpoint temp down to 170. When you go to the information screen the setpoint still reads 190 and the boiler complete ignores the new setting and goes to 190+ thus shutting the boiler down sometimes. Do we need a new computer?
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,180
    Location:
    New England
    My boiler normally runs around 130-degrees, but when the priority zone (the WH) calls for heat, it jumps it up to 180-190. If yours has priority logic that is similar (I don't know if it does), that could be a reason why it is going to that high temp. Now, why it thinks it may be a priority zone call, if that's it, would take some further investigation, but that may give you something to check.
  6. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Read and understand the installation manual. You have to save any changes to factory defaults.
  7. georgemp

    georgemp New Member

    Messages:
    3
    Location:
    Massachusetts
    Thanks all. It turns out the DHW was set to 'on' which it shouldn't have been since we have an indirect water heater. This seemed to be overriding the setpoint temp I put in. There was also a loose wire going to the mcba control board that seems to mess with settings randomly. Here's my next question: Where do I get a new MCBA control board for an Alpine 150? I shouldn't even be asking this 3 year in. Burnham won't sell one to me. I can't find one anywhere on the web.... Or is it straightforward to upgrade to the Sage 2.1?
  8. mage182

    mage182 Member

    Messages:
    69
    Location:
    NY
    I'll assume you mean the control module for the unit when you say MCBA board? When mine blew from a power surge during sandy (I have a 105 model), I was told by a certified Burnham tech that it would take 6-8 weeks to get and would cost around $500 plus labor. I went to pexsupply.com and ordered a replacement model and it came in 3 weeks for under $300. I was told by Burnham that they would not be giving warranty support to any damage caused by Sandy.

    However, the 'repair' control unit is made to repair all sizes of Alpine but is locked into the smallest model (80) when shipped. You need a special passcode to change the model which I don't have and haven't been able to find anyone who will come over and make the adjustment. I spent some time adjusting my original configuration and it works better than it did before considering it's a newer version of Sage and despite the fact that the module thinks it's attached to an 80 model boiler.

    Burnham won't help you with anything. All they want to do is manufacture the hardware and sell it. After that they wipe their hands of it.
  9. georgemp

    georgemp New Member

    Messages:
    3
    Location:
    Massachusetts
    Yes the control module. I have an older version and not the Sage. I found that if I slid the control board drawer out it would work properly (you could hear a click and it would heat properly - sometimes it would click back and want to max out the temperature) Long story short, I found a supplier here in the Boston area I took a chance that the module was the culprit and not the wiring connections. Installed it in 5 minutes and everything has been great ever since thankfully. (after about 2 weeks of it shutting down randomly in the coldest weather)

    Here's something important I learned : make sure your plumber sets up you controller correctly - or at least get familiar with it and read the manual! Our plumber wired our boiler for both hot water and heat even though we were using on an indirect for hot water. The boiler was firing for hot water when the thermostats were calling for heat. So we received heat it was always maxing to 180+ and never paid attention to the outdoor sensor temp or the set point temp. Nice job. I became very familiar with the control board display when it was failing and corrected the issue and turned off dhw on the controller. It will be very interesting to see how much we start saving now. sheesh.




    Last edited: Feb 14, 2013
  10. mage182

    mage182 Member

    Messages:
    69
    Location:
    NY
    Did the place you bought the new module from sell them preprogramed for your specific model boiler? Or is it a repair unit like mine?
  11. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Burnham is an excellent company to work with; if you are a professional.

    We have parts sent next-day air from Burnham (through a local distributor) and nearly every other boiler manufacturer. Burnham has a responsibility and liability with every gas-fired product and that is; to make every effort to get their products installed and serviced by trained and qualified personnel. This is not an easy task, nor are they always successful. The one thing we know for sure, is that a boiler manufacturer can't support a retail-direct market. The layman can't be "trained" over the phone and almost always lacks the proper tools and requisite training to install, commission or service a condensing boiler.

    If the people you buy your condensing boiler from, can't help you with installation, parts and service; it is you, who has made the mistake.
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