Re: GBlist: re:masonry heater + radiant flooring

[Norbert Senf <mheat@mha-net.org>]

At 06:31 PM 2000-01-31 -0500, Robert W. Tom wrote:

>Well MeatHook, I would say that if the office (and the rest of
>the house) were made more efficient to begin with, that in our
>climate (~8500 HDD/yr, ~48 deg NL) one wouldn't need to fire-up
>the wood-burning appliance in the mornings during the coldest
>months of the year (Dec.-Feb.)
>
>I would say that the house would usually still be plenty warm (70
>degF-plus) from the fire of the night before and that the
>appliance would not need to be fired-up again till later in the
>evening, way after sundown. (Unless there has been a long period
>of overcast days)

Hi Rob:

In practice, this tends to depend mostly on the inhabitant's work shedules 
-- if people are away during the day, firing the heater in the evening (and 
watching a fire then) is preferable. This way, the house is warm in the 
morning, and is cooling during the day when it is unoccupied. If you need 
any backup heat, you could kick on a bit about an hour before the occupants 
return.

If one or more occupants is at home during the day, firing in the morning 
also makes sense. The house is warm during the day, and if it is a bit cool 
the next morning, well, you light the fire!


>In fact, I would say that if the appliance were fired-up early in
>the morning, the house would probably be over-heated by late morning
>if it is a sunny day.

We get this concern a lot (particularly, it seems, from engineers, who have 
a harder time understanding an appliance with no controllers on it ;-)

If the house is set up to handle passive solar, then it will need adequate 
mass for that, anyway. If the house can't handle the 3 kW from the heater, 
it is borderline in the storage department, IMHO.  Obviously, if the house 
is warm enough, you don't light the heater. In the fall, for example, we 
might light ours only every second or third day during chilly weather.

I'm still looking for a simulator that can demo this. I know from 
experience that it works in most situations, but it would be nice to have a 
software demo. for different house types and climates.

We put the first masonry heater into an R-2000 house in 1985 on an 
Allen-Drerup-White project. They got some CMHC funding for monitoring, and 
I've got a copy of the temperature profiles somewhere. Very even. There 
were some other unusual things going on, however, such as an air-to-water 
heat pump that takes excess heat and puts it into the domestic hot water 
tank. The backup heat is a 5 kW electric sauna heater upstairs with a duct 
(through the heater) into a pressurized crawl space for distribution, 
through an electrostatic air cleaner, to perimeter vents. Voila: radiant 
floors.

As a more down-to-earth example, we've got a heater in a 2800 sq.ft. R-2000 
house in your neck of the woods, Dunrobin. It carries the house up to about 
0F or so, at which point a small amount of backup kicks in at night, since 
it is usually sunny in the daytime around here during cold spells. This is 
on a single 60 lb charge of wood per day. Interestingly, it is a fairly 
conventional floorplan, and there is no heat distribution system, except 
for the HRV. The heater is centrally located, near an open stairway.

If you had a conventional woodstove in a house as efficient as this one, 
you'd could easily have a creosote nightmare, because the stove would be 
idling (smoldering) all the time.

>I would also say that the insulated slab floor of the efficient
>house would remain barefoot comfortable  without any embedded
>radiant heating (hydronic or otherwise) during most of that
>period of time (again, assuming sunny periods, which is reasonable
>in our climate because the coldest days are also the
>sunniest).

Total agreement on this point. I walk around in bare feet all the time on 
our masonry floors. I have nothing against radiant floors - I only question 
the need for two radiant heating systems when one will do - in an R-2000 
type house, anyway.

Best ........... Norbert
----------------------------------------
Norbert Senf---------- mheat@mha-net.org-nospam
Masonry Stove Builders	
RR 5, Shawville------- www.heatkit.com		
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092
			
		
				


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