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Re: Radiant Heat in shop floor

Subject: Re: Radiant Heat in shop floor
From: Matt Wehland <>
Date: Mon, 30 Sep 1996 10:25:44 -0500
Well there was a very good thread on shop heating several months ago (Jan
96), and I thought that someone would have come up with some of it.  So far
I have seen nothing on it so here goes.   I just looked through my archives
and only found one message.  I must be getting sloppy as there were many
good ones.  It may be worthwile to search the Shop Talk archives for more info.
>From what I got out of the previous thread was that if I was building a
garage I would build in a radiant heat floor, possibly with a small forced
air system to bring up the ambient air temp.
Here is my condensed version of Pro/Con

   -the floor is nice and warm, this is a real plus for us as we are always
laying on it and nothing takes the life out of you like laying on a  cold
concrete floor.
   -low emissions into garage/shop area.  Little or no moisture from
propane, no smoke from kerosine, no wood ash etc.  This assumes a small
outside vented boiler.
   -garage is always warm, must leave heater on for the winter to work.
   -temperature stability, having such a large mass (the floor) up to temp
really keeps things warm even with opening a large garage door.

   -installation.  it is only feasable in initial construction, otherwise a
real pain.
   -possible maintanance problems.  If done right it sounds like they will
last forever, as even those done wrong lasted a long time.  When major
problems do occcur go to forced air (easiest solution?)

Anyone else have any more Pro/Con ideas for the list.  Let me know as I wish
to get is written up somewhat neatly and on my web site.

The following is the only message that I have saved.  Note the date (Jan 96)
if you want to search for more info.  The thread on garage heating was quite
good and covered most if not all possibilities.

Return-Path: <>
Date: Fri, 26 Jan 1996 21:17:45 -0700
To: shop-talk <>
From: Marcel Chichak <>
Subject: RE: Shop floors, was Re: Shop heaters
Reply-To: Marcel Chichak <>

At 01:52 PM 1/26/96 PST, Chris Meier wrote:
>Okay, back to heaters...
>This is another question I had about radiant heat in a garage.
>Now, this applies more to the garage part, than a separate
>workshop area. Does this type of heating result in a high
>amount of moisture in the air?  Does this cause more rust
>on tools, parts, etc.?  I would think this an advantage of
>heating with a forced air furnace.

YO! When I replaced my single car 50 year old rot box of a garage I knew I
was going to be staying here for a LONG time and that I would be spending a
LOT of time in my new dream garage, soooo...

I designed the 22x26' garage with a heated floor slab. 1.5" of SM and poly
vapour barrier underneath and 3" of SM around the perimeter. According to
ASHRAE the major heat loss is the perimeter, thus the double layer. Then
3/4" poly-B tubing was tied to the rebar on a 1' grid in 2 loops of 250'
each. 6" of concrete was poured in the centre with a 12" grade beam under
the walls. Structure consists of 2x6 walls with tiny 12" high windows along
the south eve line and standard gable roof. Two 7' insulated doors allow the
LBC's in and out. Insulation is R20 in the walls and R40 in the attic/crawl
space. More insulation than my house BTW! The actual 'boiler' (in an
insulated box in the attic) is nothing more than a 10 gallon water heater
with a 10,000 BTU 220 V heater element. A small 1/3 HP pump circulates a
very mild antifreeze solution around the system.

Through my calculations I figured I could store a lot of heat (~500,000 BTU
or something) in the 20 t of concrete. Unfortunately these systems are quite
'dead' in their responce to temperature changes. Mine was designed with a
lot of insulation so it kept the heat, so a very small heater is all that's
required. It can only heat at a rate of 1 degree C /hr, but the effect of
opening the big door is virtually nil since there's so much stored energy.
The system cannot be turned off from November to May because the heater is
so small it would take many days to get back to a decent temperature. It's
been running for 3 years with no maintenance, no major problems and no
noise. A change to a gas water heater is in the works though.

Working in a radient heated garage is most pleasent. The floor is dead
constant at about 15 C (60 F) no matter the temperature outside. It's quite
easy to forget how dreadful the last month has been.

As for moisture, forget it. With the outside air at -30 ish that same air
heated to 15 C means the relative humidity drops to the 20% range. When I
was doing the body work on my Morris Cooper I had it in bare metal for 2
years inside the shop. I mounted a hydrometer on the wall to monitor for the
potential of rust, which starts at 64% RH. It never got anywhere near except
in the summer on rainy days. I've trained my wife to knock the snow off her
car before she's allowed to park inside the shop.

Long winded huh? Hope this answers your questions!

*Marcel Chichak  Certified Mini Nut     |Go in deeper, come out   *
*voice (403)466-6004 FAX (403)469-5098  |harder and come from     *
*Edmonton, Alberta, Canada              |behind!, That's what it's*
*                  |like to race a Mini!     *
'69 Morris Cooper, "Hugo" ... sleeping ..... shhh!
'71 Leyland 1000, "Mr. Dressup" .... sleeping.....


       Matt Wehland, Networking & WEB Consultant        
       Naperville, IL  Chicago Suburb   (630) 355-1592  
  95 Mustang GT Crystal White 5spd
  Best 14.82, in street trim   

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