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CO Testing & Heat Loss Calculations

How can a contractor who bids on jobs perform accurate detailed heat loss calculations every time and not be wasting his time? Unless you close every job isn't the rule of thumb the way to go? Just seems like people request quotes from several companies and best presentation, price and value wins. Not a sheet full of numbers only you can understand. Let's face it a 2000 sq/ft modular is a 2000 sq/ft modular.

Also, on every single call and or install do you perform a CO test? I just get the feeling this will be a quiet but important post.

A Concerned Citizen


  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    Of course a contractor BEGINS with a "rule of thumb" to give a reasonable estimate for comparison to other estimates. Why would any reasonable person spend enough time for a detailed estimate unless this is a large competitive bid when nearly all specifications are a given via the architect/engineer?

    Guess what? The cost difference between sizes of boiler models in any line is generally insignificant compared to the overall cost of the system--or even in the case of replacement the cost of quality installation.

    It's your job as a concerned citizen (consumer) to give good information to those who are providing bids. Search out everything you can find but have serious ideas about what you want when you ask for an estimate.

    There is ALWAYS a balance between budget and desires--just make sure you communicate both to those providing bids. It's their job as a pro to know how to balance the two...
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

  • Mitch_5
    Mitch_5 Member Posts: 102
    Your suspicions are correct.

    Most companies just look at the plate on the existing boiler and maybe a square room rule of thump.

    I measure existing load and compair that to the existing boiler and a btu per square foot. That gets me close and in the case of steam attached load is what you need. Then I send the home owner the "ESTIMATE" with brochures and technical advice including the statement that "NO FORMAL HEAT LOSS HAS BEEN DONE BUT CAN BE PERFORMED AT AN ADDITONAL COST EITHER BY THIS COMPANY OR AN INDIPENDENT ENGINEER" Never had a taker on the heat loos at additional cost except high end homes with existing problems on fairly new installations.

    Guess how many times I have been told. You really know what you are talking about but the other guy is cheaper. I have even been called back to sites I did not get the boiler job to do other work. When we ask what about the cheaper guy that did your boiler the reply was "he was cheaper but we like working with you".

    As to co testing, in my area it is not required by law with the exception that we must install gas equipment by the manufactures instructions so in that case if it is written you should do it or be liable. But no one ever checks unless there is an incident.

    I inform my customers that I have co testing equipment (most don and only a few that do have training). Unless it is a new boiler set up I have them sign a consent form accepting or rejecting a test. On the form it states the peramitors I am looking for and that the equipment will be shut down and fuel source capped if it dose not pass.

    Most people do not want to replace something they feel has been running fine for years and refuse the test.

    I have had a couple of incidents when a waver was read, signed and I asked you fully understand. They say yes, I test then lock out the boiler and they get pissed off. I have on occasion tested found a problem and have gotten the gas company to come out and recheck. In most cases they haveing authority lock out the system but they have also put equipment I locked out back in operation, again they are the authority not me.

    Mitch S.

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  • Unknown
    Same thing here Mitch,

    "Most companies just look at the plate on the existing boiler and maybe a square room rule of thump."
    It`s done all over this town anyway! Sell yourself, discuss the options, calculate all the #s, then they go for the cheaper price! Even had HOs ask me for my #s to hand over to my competitor, then when I say "no let them do their own", they think I`m the bad guy! But HO`s are getting smarter & more informed now.

  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    Your concerns are well founded

    I'm not aware of any contractors in my area (Northern Lower Michigan) who do a heat loss for replacements or even new construction. I base that statement on conversations with other contractors and on the fact that I have never had a homeowner tell me that someone else has done a calc. 9 times out of 10 it's more like a blank stare indicating they don't have a clue what I'm talking about.
    Maybe I'm crazy but I run the numbers on nearly everything escpecially when I'm propsing the replacement of a 120,000 btu furnace with a 60,000. People give me some weird looks when I ask to measure their house........Like, what are you some kind of perverted snoop? Sad but true.

    AFA use of a combustion analyzer goes, I'm not aware of any other contractors in the whole county here that even own one let alone use one. Example: A lady called this week and said the family was ill all the time and she suspected the furnace. During the course of our detective work she said she had had another contractor check for CO. I asked what he used to test with and she described a store bought CO detector that he simply waved through the air. We found over 20 PPM coming from the registers. She's getting a new furnace Monday.

    BTW, you wouldn't believe the difference I find in the heat loss of two seemingly identical houses. There are a lot more factors than just the sq ft of the home. A given sq footage seldom equates to a given size furnace or boiler.
  • Darrell
    Darrell Member Posts: 303

    I don't do installs, but when I did I did the numbers.

    Regarding CO testing, I am a serviceman, and I carry a hand held co detector on my belt all day, everyday, and in every home. It is set to alarm at 10ppm and it alarms regularly. That measures ambient co. I then determine where the source is...it is usually cooking or the attached garage, and then I get a chance to educate the owner. Sometimes the source is in fact the heating equipment and we discuss the options available to the owner. If I do an annual servce check I pull a full electronc digital combustion check which includes co in the flue stream...it is a good gauge of how the combustion process is working. If I make any changes to a system that would affect the combustion I pull a full check.

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