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Backup low water cutoff.

Ed2 Member Posts: 17
I'm a customer trying to understand a bid for replacing a gas fired steam boiler in a home, roughly 125,000 BTU.

The bid includes both a low water cut off and a back-up low water cutof "for extra boiler protection." The contractor said the back-up low water cutoff is not required in residential installations but is for other installations in our state. So, it's just an option.

I'm trying to understand if having both a low water cutoff and a back-up cutoff is overkill or a good idea. It adds about $500 to the job.

This seems like a good, knowledgable company. I'm just trying to understand my options.


  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
    Ed in Mass it is required for boilers over

    a certain size. It is a good idea but not often done. The question I have is what type of pipe are they proposing to use and how did they size the boiler. I have seen many of my competitors as of late pushing extra controls and pushing finance options but piping the boilers in copper and sizing the boiler by looking at the rating of the old boiler not sizing it to the load of the system.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Ed2
    Ed2 Member Posts: 17
    they measured

    I didn't see the details of the calculation, but he did note that the loop in the basement is insulated and measured all the radiators in the house, so that was reassuring. Another guy just proposed matching what was installed. I thanked him and sent him on his way.

    We didn't discuss how it would be piped other than that he did not like how the header was piped (colliding steam?) and he'd do it differently. If there are questions to ask, things to look for, I'd be glad to ask. What did they use copper for?
    RDSTEAM Member Posts: 134
    what type of lwco's

    is he planning on installing. one is probably the probe type that comes on most, and my guess for the other one is probabyl a #67. Is he planning on installing a auto feed? Is he planning on installing a king valve as well as a return valve? Is he planning on checking all the vents in the house and making sure the SYSTEM works? ask these questions and you will find out if this guy knows what he is doing.
  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    I'm right with Charles

    on this one -- for a boiler that size, I would very much want a second, backup LWCO, and I would want it to be a manual reset type.  Whether it is required by your local code or not, it's just a darn good idea.

    It is most encouraging that your contractor is at least thinking about the way the steam piping is going to be done -- and that he has the wit to see that what you have now may not be correct.  And also that he had the wit to actually measure the radiation.  Very promising!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ed2
    Ed2 Member Posts: 17
    very helpful

    Thanks for the helpful answers and suggestions. Sounds like I should say use to the 2nd LWCO.

    RDSTEAM- There will be an auto-feed. They offered to change out all the vents, including main, which disturbed me since he did not look at them. I refused because I changed them all out myself for vari-vents to balance the house and also changed out the main vents. So, I was just going to reuse all those. The system heats at low pressure- half pound? I'd have to check. Too bad the boiler leaks.

    Can you tell me what a king valve is so I understand what I'm asking?

    Thanks for your patience with the questions.

    By the way, if I asked for a guarantee that all visible steam piping in the basement will be correctly pitched after the job, would that be crazy? Do I understand correctly that above the boiler is the high point for both legs of the loop? One person said the outbound leg of the loop should pitch back towards the header and the return leg should pitch forward to the return. I thought it was all supposed to pitch toward the return, no steam/condensate counter-flow anywhere.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    new boiler installation

    perhaps a requirement of the new boiler "to be installed following the manufacturer's instructions to the letter in threaded iron pipe".

    it would be a good idea to get a vaporstat, and low pressure gauge [0-3 psi] and have them installed at the same time. will your auto-fill record the water usage [very handy].

    what sort of main vents are on the system now? if you had to balance the steam arrival, with your radiator vents, then it is likely that you need more main venting, and slower radiator vents [hoffman 40's].

    the header should pitch to the equalizer, but the rest of the main should slope towards the dry return.--nbc
    RDSTEAM Member Posts: 134
    king valve is

    king valves are valves that will isolate your boiler from your system (on your supply side). king valves need to be installed along with a return valve. this will allow you to completely isolate your boiler, fire to about 10psi steam and flush out mud once a year.
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