GBlist: non-toxic antifreeze for infloor heating

[Stephen Thwaites <stephen@thermotechwindows.com>]

A sad story:

While not exactly infloor heating, our new (to us anyways) shop is heated
w/ a boiler that distributes warm fluid to a series of thermostat
controlled ceiling mounted fan coils.

We moved in during our quiet season - January.  In the middle of the move
the system froze solid ( and i mean SOLID - coffee pot, urinals, toilets,
boiler the works) over a weekend of record low temps (insert Canadian cold
weather legend here).  When it comes to water based heating systems,
especially for offices and warehouses, in cold climates I now believe: 

1. that a low temperature alarm on a monitored security system is a good idea.
2. that anti freeze in the boiler fluid loop is a good idea.

we now employ both of these insurance policies  what's the expression? once
frozen - twice shy ?


For those who care to know, automotive anit-freeze is usually ethylene
glycol (toxic).  Anti-freeze protected solar collectors and some ice cream
makers use proylene glycol (more expensive than ethlyene glycol).  I heard
a rumour that a Canadian retailer (Canadian Tire) was selling an
environmentally friendly windshield washer fluid based on propylene gylcol
rather than ethylene glycol  -  but i never noticed it in stores i visited.



At 09:57 AM 5/26/00 -0700, Richard Kadulski wrote:
>I may have missed something, but why the concern for anti-freeze in a
>radiant heating system? Presumably it is heating indoor space, and not
>outdoor walkways (In which case anti-freeze is an issue).
>
>A well insulated building, including a slab on grade floor, will be
>insulated.  Even with modest solar gains the house temperatures should
>not fall below freezing even if the heating system is shut off. Don't
>forget the coldest temperatures coincide with sunny weather, so there is
>
>daily solar gain potential. Temperatures may fall close to freezing, but
>
>there will be enough thermal mass to keep temperatures above the
>critical freeze-up.
>
>If the heating system is regularly shut off in winter during prolonged
>absences, and temperatures are allowed to drop too far, you could be
>setting up potential health hazards because of the condensation and mold
>
>growth that will take place.
>
>Now, if the house is well shaded and never sees the sun, is poorly
>insulated, with lots of crappy windows all facing north, then the
>thermal dynamics will be more severe and heat losses so great, freezing
>inside could happen. But you will also have other problems too.
>
>
>
>--
>Richard Kadulski Architect
>204 - 1037 West Broadway
>Vancouver, BC V6H 1E3
>
>Tel/fax 604-689-1841
>
>Climate adapted, energy sensitive, sustainable and healthy design
>Editor Solplan Review: the independent journal of energy conservation,
>building science &
>construction practice
>
>
>______________________________________________________________________
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> 
Stephen Thwaites
Thermotech Windows Ltd
Ottawa  Canada
(613) 225-1101
______________________________________________________________________
This greenbuilding dialogue is sponsored by CREST <www.crest.org>
BuildingGreen <www.buildinggreen.com> and Oikos <www.oikos.com>
For  instructions send  e-mail to  greenbuilding-request@crest.org.
______________________________________________________________________