Cohousing-L Mailing List: Re: Re: electric heat in Tasmania

[Roger Diggle (diggle]

I tried sending this several days ago, but it never appeared on cohousing-l,
at least not in my mailbox.  My internet service provider was trashing a lot
of mail for a while, so that was the probable cause.  Here's a second try:

Depending on construction details, it can be reasonable to install radiant
heat beneath a wood floor.  If it's possible, it's likely to be more
comfortable than ceiling radiant heat.

That said, radiant heat from the ceiling can be a decent system in many
circumstances, especially industrial.  But there are reasonable residential
applications as well, particularly in bathrooms.  It is not to be confused
with systems such as fan-forced electric heaters that would directly heat the
air at ceiling level.  The radiant panels deliver most of the heat directly
to the occupants and surfaces without directly heating the air.  The floor
and other surfaces that are irradiated and warmed by the heat panels in turn
re-radiate and heat air by convection.  Its main drawback is that, as with
the sun, objects in the path of the radiation  cast "shadows".  For instance,
people sitting at a table in a room with radiant overhead heat will get good
coverage on their upper bodies, but their legs and feet, along with the floor
under the table, are in the "shadow" cast by the table top.  With radiant
heat from above, if the floor is cold enough, it's possible to have
uncomfortably cold legs and feet while hands and heads are very comfortable. 
It will be very important to minimize cold air movement across the floor. 
That's why radiant heat from the floor is the first choice where possible.

You might consider doing a system like this by installing tubing above a
standard ceiling, or beneath a floor, but on the occupied side of the
insulation.  This would allow for the use of solar panels, and electric
backup could be used on the crappy non-solar days.  A standard (well
insulated) electric domestic hot water heater could serve as the backup heat
source, or you might even be able to use hot water from your existing hot
water heater.

I'm a long-time refrigeration mechanic & HVAC service guy, now working as
building engineer for a company that owns several large commercial office
buildings, if anyone has questions along these lines I can help with.

Roger Diggle, Porch Light CoHousing, Madison WI      diggle [at] macline.com

- sent via an evaluation copy of BulkRate (unregistered).

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