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Blowing Boil Controllers

BladdyK Member Posts: 2
In the past six months, I have blown two HydroStat 3150 boiler controllers.  I am guessing that the second one was probably faulty, but I have no doubt that power surges through the house are probably degrading the thing.  So the question is, do you just get a Brickwall surge protector for the boiler circuit, or do you do a UPS?


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Surge protector or UPS?

    I am a homeowner who did electronic engineering in one of my past lives. What I have is a whole house surge protector installed in my power service entry panel. Mine is one of these: https://encrypted.google.com/url?sa=t&rct=j&q=square%20d%20surge%20qo&source=web&cd=1&ved=0CAQQxAEwAA&url=http%3A%2F%2Fstatic.schneider-electric.us%2Fdocs%2FElectrical%2520Distribution%2FSurge%2520Protective%2520Devices%2FResidential%2520Whole%2520House%2F9990-0123A.pdf&ei=mfKyTt69BabZ0QHTstyMBA&usg=AFQjCNG322Usg2fQ_SvZaz6-eY06ycPvFA&sig2=LKkYCfYAng4lE9mIG5PumQ&cad=rja

    This would not be for you if you did not have the same Square D power panel series I have, but Square D has another one for one of their other panel lines. If your panel is not Square D, check with the manufacturer of your power panel. These greatly reduce the surges coming in from the outside power lines, but they do not provide absolute protection. My computers each have their own UPS that has surge protectors in them. My stereo equipment has a power strip with a surge protector in it.

    I would consider a UPS for my boiler, but my boiler is hard-wired into the house with BX cable, which would be a problem that could be gotten around, I suppose. The only place to put the UPS would be in the unheated garage where the boiler and power panel are. I do not believe it a good idea to let the UPS get too cold because it contains 4 lead-acid storage batteries in it and they do not work well when they get cold, and freezing them would probably be worse still. Also, I do not know how big a unit I would need. My biggest computer draws 400 watts has an APC Smart-UPS 2200 that will drive my computer for 72 minutes when the batteries are new, but they degrade over time, and usually need replacement about every 3 years. That unit costs around $800.

    My boiler has 4 Taco 007 circulators, and in the worst case, three could be running at the same time. The electronics of the controller, the variable speed blower for the sealed combustion, and the high voltage electrozapper to ignite the gas all require power too. I have not added that up, but I estimate it could be 400 watts. Sometimes the power here fails for a few seconds. It does this sometimes several times a week. Sometimes it fails for several hours. Once it failed for several days (but that was in the summer when the air conditioning loads blew out 2 of the 4 huge transformers at the local substation, taking out several towns.

    So could I affort a UPS big enough to run 4 days? I am pretty sure it is out of the question. How long would it take my copper tubes in my at grade radiant slab to freeze up? It has no anti freeze in it. It the slab was running, it would take at least 12 hours and probably more.

    I have had this boiler two full heating seasons and it runs all the time (not firing all the time) because my domestic hot water is heated by an indirect. So in about 1 2/2 years, my boiler has survived everything that came down the power line. This is not enough data from which you should draw conclusions, but it may help.

    My opinion is that I need both. Neither will do the whole job. And make sure your insurance is paid up because if you get a direct hit on the drop to your house, nothing will stop that.
  • BladdyK
    BladdyK Member Posts: 2
    Inside or Outside

    My issue with the whole house surge protector is that I don't know if the surges are coming from outside the house or inside the house.  I know that a surge from outside would be of greater magnitude, but I just don't know to what extent smaller surges from inside the house degrade its circuitry.  Do you have any thoughts on this?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Do you have any thoughts on this?

    I think any house with sensitive electronic equipment in it, and that probably means almost all of them, should have a whole house surge protector in the service entrance panel. Now they might provide some protection from surges generated inside the house too, though the  electrical geometry is not ideal for protecting from internally generated surges.

    As you say, the internally generated surges are likely to be smaller than the externally generated ones. Lightning, even less than a direct hit, is just enormous.

    So what surges are likely to be generated inside a house? By surges, I mean temporary increases of the voltage to a sufficient extent to damage things. Turning on a large electric heater will cause a dip if the wirnig is inadequate, but not a surge. About the only thing that would cause a surge (a spike most likely) would be to suddenly turn off a large motor. In my house, the largest motor is the compressor in my refrigerator, and I am pretty sure it is less than one horsepower. There may be a capacitor across the thermostat in there to protect the thermostat contacts. This would reduce any spike generated. I have run refrigerators for decades without any problems with surges generated by them.

    I am not even sure my computers are at risk from surges, even though the are plugged into UPSs that have surge protectors built into them. The computer power supplies rectify the incoming power to DC that inherently eliminates all the irregulariteis of the input power, and then converts that DC to the voltages actually required by the rest of the computer.

    I have looked at the electronics in my W-M Ultra 3 boiler and they seem to include a transformer that steps down the AC line voltage to low voltage for most of the control board. This low voltage is no doubt rectified and filtered before powering the board itself. This will surely be insufficient protection from lightning, but it should handle most of the small stuff. There is a small part of the control board that powers up to three circulators at line voltage. I do not know how that works, but it is probably an SCR type of switch and how much of a spike it takes to destroy one of those I do not know. That is the main reason I put in that whole house surge protector in my power panel.

    When I was studying surge protection, the consensus of what I read seems to indicate that one should use a whole house surge protector to protect against the big stuff, but to use additional surge protection at the input of sensitive devices. My senstiteve stuff (stereo, digital piano, etc.) are plugged into power strips with built-in surge protectors.
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