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What questions to ask

Chris Bain
Chris Bain Member Posts: 28
As the VP of the local historical society in Port Washington (<a href=""></a>) I have been asked to look into getting bids for an AC system for our 18 room historic house.  The heating system is 2 pipe steam, and I don't know how old that boiler is.  The house isn't currently air conditioned, and the artifacts are subjected to more heat then they should be in the summer months.  Other than references (obviously) is there a list of questions that I should ask potential HVAC contractors?  None of us are fluent in this field, so central air conditioning a house of this size is daunting, both financially and procedurally.  Thanks for any directions that anyone might offer.

Chris Bain

Vice President

Cow Neck Peninsula Historical Society


  • Jamie Hall
    Jamie Hall Member Posts: 17,080
    I'll get back to you later

    I have a meeting right now.  I am the building superintendent/senior curator of an historic house and museum in southern New England, and I would be happy to help you based on my experience.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,510
    a/c for a museum

    i would suggest getting the steam perfect, then installing  mini-split air conditioners.


    a number of manufacturers make these units, so you can choose the make which is best supported in your area. another advantage would be that the installation could be staged so as not to break the bank.--nbc
  • Jamie Hall
    Jamie Hall Member Posts: 17,080
    Nicholas is right

    so far as general overall procedure is concerned.  Based on a good deal of experience in this area...

    First, get the steam system operating correctly.  This may involve (probably will) a new boiler, and may involve some repairs.  It is not that expensive to do this.  However, in terms of questions to ask, the most obvious is just how familiar is the contractor with steam heat.  A lot of contractors, and very good ones, know either nothing about steam, or just barely enough to be really dangerous.  There are some excellent men in this field, however, in your area; find a professional on this site may help. on this.

    Second, get the building envelope right.  I don't know (you don't say) whether this is a Register property or not.  Either way, though, you will want to keep the original windows, and supplement with exterior storm windows.  If it is a Register property, you pretty well have to; otherwise, it is just good practice.  Wall and roof insulation can be a real can of worms, and may be impossible to do without damage or potential damage.  If you decide to do insulation, you need to ask about vapour barrier location, potential for damage to plaster and structure, and so on.

    I cannot recommend central air for an historic structure, unless there is already ductwork in place, which I would imagine is not the case.  The mini splits mentioned by nbc work well if you really need them.  The only other alternative, if you feel air conditioning is really necessary (and I would think twice about that) is small diameter high velocity air ducts.  They do damage the fabric of the structure when installed, but not as much as conventional duct work.  So I would ask any contractors about what steps he might take or suggest to minimise damage to the fabric of the house.

    You will note that I say to think twice about air conditioning.  Port Washington is not that much hotter than my location, and we have not found air conditioning to be needed.  The enemy, in most cases (the exception is certain musical instruments and wax artifacts, and even those are OK up to around 100 Fahrenheit), is humidity, not heat.  Humidity must be controlled; the limits are narrower for musical instruments than for books and paintings, but if one keeps a range of 45 to 65 percent, you should be OK on it.  Air conditioning in summer, unless it is accompanied by aggresive dehumidification as well, raises the humidity to potentially damaging levels.  If you are considering air conditioning, ask your contractor how he proposes to control the humidity.

    Please feel free to contact me directly if you have further questions about these things.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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