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Subject: Heating


From: Marc A. Williams <artcons>
Date: Wednesday, November 15, 2000
Peter Krantz <bkfndrs [at] ozemail__com__au> writes

>... It is intended that the method of heating be
>electrical elements embedded within the concrete slab, controlled by
>precise thermostat controls.
>Can anyone suggest why we might *not* use such heating?

We have built and occupied a conservation laboratory that utilizes
radiant heating in the slab for the past 8 years.  The primary
difference is that our system uses hot water running through
polyethylene tubes in the slab rather than electrical elements.  In
New Hampshire, USA, the cost of electricity to heat the slab would
be significantly higher than using fuel oil or natural gas in a
boiler.  However, the principles should be the same.  The advantages
and disadvantages of the system are as follows.

    1.  The slab is heated only to about 80-90 degrees Fahrenheit
        (and this is only directly over the tubing), so it does not
        become hot to the touch.  Initially, I was concerned that
        objects on the floor (we treat wooden objects, some of which
        are quite large) would be heated.  This has not been a
        problem.  In general, temperatures in the studio can be kept
        10 degrees Fahrenheit colder than in areas heated with
        conventional heating systems and feel the same warmth.  The
        floor is heated and not the air.  This has amounted to
        significant savings in heating costs.  In fact, I could not
        perceive a difference in heating costs after the studio was
        added to the system (system has three other heating zones
        with conventional radiators).

    2.  Even at 10 degrees colder, human warmth/comfort is greater
        than in a conventionally heated space.

    3.  Since the temperature is colder, less moisture has to be
        added to the air to hold a 50% +/- RH level.  Yes, as with
        any heating system, it will be necessary to add moisture to
        the air when the heat is on (unless you live in the tropics
        where heat is used only occasionally).  But with radiant
        heat, it is much easier to hold a desired RH level.

    4.  The system is very quiet and is virtually unobtrusive.  It
        does not require cleaning and does not smell, as radiator
        systems can.

    5.  Due to the large thermal mass of the concrete, the system
        can not quickly heat a space.  However, normally in
        conservation studios, it is not desirable to quickly change
        the temperature.

    6.  The estimated life of the tubing is approximately 100 years.
        While, granted, the cost of repairing the concrete portion of
        the system at some time in the future could be quite high,
        it is likely that savings in utility costs will more than
        compensate for this.  Personally, I don't expect to be in
        this space 25 years from now, but if someone desired, they
        could completely bypass the slab and install conventional
        baseboard radiators at relatively little cost if the tubing
        were to fail.  I would anticipate that the projected
        lifespan of electrical elements that are designed for this
        purpose would be at least as great as the tubing.

In summary, I have been completely satisfied with radiant heat and
have recommended it to many others.  If I were building another
studio, I would definitely utilize radiant heat again.

Marc Williams
President, American Conservation Consortium, Ltd.

                  Conservation DistList Instance 14:29
                 Distributed: Monday, November 20, 2000
                       Message Id: cdl-14-29-012
Received on Wednesday, 15 November, 2000

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