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| Author |
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keesan
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Electric heat
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Nov 25 23:40 UTC 2000 |
We will be installing electric heat, probably baseboard since it is cheapest
and will not be on much, and welcome opinions on the pros and cons of: oil-
or water-filled, heavy cast aluminum, heavy steel (all said to be quieter and
to produce less temperature swings) versus aluminum fins (also found on the
oil-filled). How noisy are the noisiest model and how much does the
temperature actually swing. Then do we really need wall thermostats or will
the cheaper type do, that is installed in the heater. Line- or low-voltage?
(We already have to put in 24-volt relays to qualify for Detroit Edison's 1/2
price electric heating rate). Please share your experience with baseboard
heaters. Also, for bathroom heat is it better to have convection, or wall-or
ceiling-mounted radiant (glowing element), or fan-forced heat? Or cables in
the floor (warm feet) or ceiling (dry ceiling)?
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| 61 responses total. |
scott
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response 1 of 61:
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Nov 26 00:05 UTC 2000 |
For the bathroom I'd suggest a heated floor. That's what they use in Norway,
and it's quite nice. The room you're most likely to have bare feet in...
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keesan
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response 2 of 61:
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Nov 26 04:00 UTC 2000 |
Except that the floor will heat up slowly and the idea is to be able to heat
the room up quickly before taking a shower. How long does it take for the
floor itself to start feeling warm, and how long for the air temperature to go
up 5 degrees after turning on floor heat (Klaus?). I already have experience
with a bathroom that takes 2 hours to heat (from 45 to 55, in the basement).
Perhaps a combination of a little floor heat, and a ceiling-mouted fan forced
heater? (No wall space available in one bathroom.)
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i
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response 3 of 61:
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Nov 26 04:15 UTC 2000 |
If you're looking for quickie-heat in the bathroom and have no wall space
down low, i'd say go for the ceiling-mounted radient element. It'll give
a near-instant perception that the room is hotter (if only a little), and
(IF efficient, well-placed, etc.) will put most of it's heat down near the
floor (where the coldest air lurks looking for bare toes to nip).
I use one of those cheap little cube-shaped-heating-elements-in-front-of-
a-fan portable electric heaters in the bathroom. It big virtues are that
it sucks in cold air off the floor and can be aimed as i please.
Ceiling-mounted hot air blowers will be the best at heating air that's too
far above your head for your to care and worst at heating cool air near
the floor.
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n8nxf
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response 4 of 61:
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Nov 26 18:08 UTC 2000 |
24 volt heat for a house? 1000 watts of heat would require 40 amps of
current. That would be mighty big wire running to your heater! More likely
you have relays (and a separate meter outside the house) so that your utility
supplier can shut off your power whenever they want. That also gets you a
lower rate. How fast something heats up has to do with how much power you
dump into it and the thermal mass that needs to be heated. A radiant floor
with low thermal mass and a lot of power input would warm you fast. Being
electrical, the temperature that it turns on it could be very close to the
temperature that it shuts off at. With solid state switching, it could turn
on and off several times a second without any trouble.
I personally don't like fans blowing hot air in a bathroom. Even nice warm
air moving past you when you are wet feels quite cold due to evaporative
cooling. If you want to heat a room up fast for only a short period of time,
low thermal mass and a sizeable heater would be my recommendation. I'd steer
clear of heaters fill with oil and such since the oil is thermal mass and
these heaters are designed for uniform, even heat over a long period of time.
I like i's recommendation of using IR heaters. You will feel the IR heat
instantly even when wet, no air blowing around to cool you and the thermal
mass is almost zero. Electric heaters with long, glowing elements sounds
like the ticket for a bathroom. Thermal mass and low wattage heaters for the
rooms where you want to maintain a constant temperature. I like radiant floor
since it is a more efficient way to heat a dwelling. Heat rises so it makes
sense to introduce it as low as possible. Even heating contractors reduce
the required BTU input, to heat a dwelling, by 15% if you go with in-floor
heating.
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keesan
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response 5 of 61:
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Nov 26 20:17 UTC 2000 |
Jim says he has done real-live tests in his bathroom and finds that, at least
in a cold room (55-60 degrees with colder walls) radiant heat only heats one
side of you, but the hot air stream wraps around you. It also dries you
faster. Perhaps the situation is different in a room which already has 60
degree or warmer walls. In my bathroom, which is in the basement and has a
50 degree or colder floor and walls, even after I heat it to 60, radiant heat
works fine for standing in front of, but blowing air might work better. I
should try the experiment here.
The problem with floor heat is that, if you include all the thermostats and
other wiring needed, it would cost about $5000 to install. Baseboard heaters
run about $40 each, plus a $20 thermostat, and we have eight rooms. Also our
floors are high-mass (1.5" concrete) and rather than keep constant temps in
the whole house the idea was to heat the whole house to some minimum and then
turn up heat in the room that you are in. (I cannot be everywhere at once).
How much longer does it take for an 'oil-filled' (or other high-mass, such
as heavy steel or aluminum) heater to heat up than a lightweight one? I
suppose we ought to run experiments on how long it takes to heat up a room
2 degrees with each type. We won't have a lot of temperature swings in any
case because the house itself will be high mass and absorb the swings. And
lose heat very slowly.
We forgot to turn off one experiment yesterday (a 1500 watt heater set on
maximum temp) and after about 24 hours the top floor was up to 65 degrees.
Ten hours later it had cooled to 62 degrees. 40 out now, 30s at night. The
house had been tending towards 45-50 without heat but higher with teh sun
shining. Friday the upper porch, with leaky plastic on it, was 90 degrees
at 2 pm, and it heated the house to 70 after I opened the doors to it. The
heat gained is draining to ground now because we have no insulation beneath
the floors. One subzero night last year we forgot to close the door to the
porch and the next morning it was about 10 out and 38 in.
At 40 degrees north latitude (somewhat south of here) December vertical
surfaces gain 1646 btu/ft2. We have 200 ft2. 1000 watts/3400 btu.
Under ideal conditions, south of here, the porches could produce 97 KW in 24
hours. 4 KW/hour, same as four 1000 watt space heaters. For 48 degrees it
is 1304 not 1646 or 3 space heaters, averaged over the day. I calculated that
at zero out you need 2200 watts to maintain 70 degrees, so two sunny days
would in theory produce enough heat to keep the house warm for three days,
under ideal conditions. This is a reason for a high-mass house. ON cloudy
days we will bake bread.
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n8nxf
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response 6 of 61:
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Nov 27 13:53 UTC 2000 |
Yes, radiant heaters will only warm the side of you facing the heater. You
would want such heaters in all four corners of the bathroom to toast you
evenly. IR is, after all, just light. It does not go around corners and
other things in the room can shade you from it.
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keesan
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response 7 of 61:
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Nov 27 16:55 UTC 2000 |
That is one problem with ceiling heat while it is running - hot head, cold
feet, especially under a table or desk. The primary advantage of ceiling over
or floor heat over other sorts is that they take up no space. They are also
quiet, as no metal expands and contracts, but my portable 'oil-filled' is also
pretty quiet. The aluminum-finned non-portable types make small clicking
noises after they go off, as the fins contract. The various makers advertise
their products in glowing terms, making them seem like magic.
'Gentle heat keeps radiating even after the thermostat turns off because of
the hydronic element's retention qualities' (Translate this as: it takes
a while for the thing to warm up so it keeps heating after you turn it off.)
'Designed for quiet operation. No popping and pinging normally associated
with baseboard heaters'. (None of ours pinged, and the pops were miniscule
- maybe they are all comparing themselves with models from the fifties?).
Carrying Handle on All Models. Lets you carry your heater from room-to-room.
On/Off Light on All Models. Lets you know heater is operating. When you turn
the heater on the light goes on. Turn the heater off and the light goes off.
Wattage Indicator Lights on Model XXXXX... (fill this one in yourself)
Automatic Thermostat - Automatic thermostat lets you maintain desired comfort
level. Merely dial up or down to the level of comfort you prefer. (Translate
- there are no numbers on the thermostat since we did not calibrate it). The
thermostat will automatically control the heater to maintain that level.
Heater design produces gentle, radiant heater even after the thermostat's been
satisfied. (More free heat for the foolish).
The above is from a well-known manufacturer. The off-brands are more
creative.
One little diagram of how ceiling heat is better than baseboard heat shows
a 95 degree ceiling and 70 degree air and floor for the ceiling heat, but for
baseboard heat 150 degree air above it and a 60 degree floor. Almost makes
me want to climb a ladder and measure. Perhaps they took their measurements
over an unheated garage with no insulation in the ceiling of it?
Humidification is unnecessary with a radiant system......The air isn't dried
out by combustion. (Does combustion burn water to air?)
Because there's no need for fans or blowers, healthful humidity levels are
maintained by radiant heat. (I think they are trying to say that moving warm
air dries out your lungs).
Radiant Glassheat is ecologically balanced heat like the sun. .... Only
radiant heat is truly natural heat.... ....the closest thing science offers
to match natur'e own way of heating. .... no drafts, no cold spots or hot
spots (how about under the table?). Radiant heat does not dry out the air.
No artificial humidification is required. (Perhaps they are saying that there
is less infiltration than with an old-fashioned furnace which draws dry
outside air in through cracks around the windows?) No fuel is burned,
therefore no dust or dirt is generated or carried about to streak walls and
soil furniture. (Baseboard heaters supposedly streak walls without burning
fuel, they burn dust that lands on them, and furnaces are not supposed to be
putting the combustion products into the house - perhaps they are comparing
their radiant heat with an open fireplace?)
Then there is the Thermaray company, which is predicting that electricity will
be much cheaper than gas or oil in the near future, and then lists today's
heating costs for a 1200 square foot house. At 10 cents/kwh $988 for
baseboard, $741 for their radiant product (turn your thermostat down 6-8
degrees....), $1134 for the highest-cost gas ($13/50/mcf) and $843 for il
($1.70). Electric resistance cheaper than gas?
This is one of many companies that says if the walls are warmer the air can
be cooler for the same 'comfort level'. So you can turn the thermostat lower.
They neglect to point out that it takes more energy to get the walls warmer,
so that, even if the thermostat may be set lower (it measures air temperature)
the heat may run just as long to get the thermostat to that lower temperature
as it did with an air-heating system for a higher air temperature, since the
heat goes into the walls, not the air. For warmer walls, add insulation!
I have been finding 60 degree air with 9" wall insulation too hot at night.
Solar hot air 'makes air, fan or expansion noises.' Our porches do not.
Compare ceiling heat with baseboard electric heat:
They claim a 15 degree temperature difference floor to ceiling. We managed
to obtain only a ten degree difference when heating the upstairs and not the
downstairs, and it did not maintain itself for long when the heat went off.
Economical 95 degrees for ceiling heat. Inefficient 150 degrees for baseboard
heat. (The ceiling cannot be made warmer or it will deterioriate. The higher
temperatures actual transfer heat much more efficiently - faster).
Ceiling radiates heat long after thermostat is off. (Of course it does not
radiate much heat for the first hour or so after the thermostat goes on).
Baseboard heaters: low humidity, hot air temperature reduces relative
humidity. (Yes it does, for the 150 degree air coming off the heater, but
this mixes with the rest of the room air, which ends up the same temperature
no matter which system you use, unless you only breathe the air coming right
off the heater you will not notice a difference).
Gypsum will not rust. (Can't argue that one.) Metal will rust - look at any
two year old bathroom heater. (I looked at our 25 year old heater and there
was no rust. Bathrooms should not be kept in a state of constant high
humidity or the chrome plating will also deterioriate).
It works like a magnet: just as iron is attracted to the magnet, cold objects
attract heat energy. Both are electro-magnetic forces, operating under
similar principles. (Heat is magnetic?)
Enerjoy radiant heatmodules (ceiling panels): A single 2x4' Peopleheater is
all that is required to provide primary heat for your bathroom..... with 60%
less wattage than a space heater. (Are they saying that you need two of these
to give as much heat as a space heater, or is it possible that one of these
gadgets can convert 610 watts of electricity into 1500 watts of heat?)
Companies with the least ridiculous advertising are RaySol (RayChem), which
sent us out some very useful information on how to calculate and install
heating cable in floors, and Markel (The Choice of Professionals Since 1921,
sold by Madison Electric). Exclusive high mass all steel element - heats and
cools more slowly reducing room temperature fluctuations, expands and
contracts half as much as aluminum reducing the opportunity of disturbing
noises. We have a Markel aluminum-fin type heater with floating element
suspension to eliminate expansion noises.
Designed for clean wall operation - the air comes out the front, not the top,
in all the heaters that we have, eliminating scorch marks.
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scg
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response 8 of 61:
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Nov 28 00:48 UTC 2000 |
I've been pretty happy with the radiator heating in two of the three
apartments I've had that had it. The third apartment had a leak somewhere
letting air into the system, such that it would stop working and need to be
fixed every few weeks, but that was a maintenance problem.
The forced air heat I grew up with in my parents' house seems to work pretty
well for heating. I was reminded this weekend just how dry it gets there,
and why I tended to prefer radiant heating when I lived in Michigan. I'm
still undecided about my current forced air heat. It blows air through very
fast. That means it heats very effectively and never has to run very long
(it probably helps that it hasnt' gotten really cold here since I moved in),
but it also means that the air rushing through the vents sounds extremely
noisy. The furnace is also apparrently anchored to the bottom of the dining
room floor, which means that the furnace fan can use the floor as a sounding
board. Being in my dining room when the furnace comes on sounds somewhat like
a jet engine taking off. Again, though, I think that's an implementation
issue.
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n8nxf
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response 9 of 61:
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Nov 28 15:47 UTC 2000 |
The humidity level has more to do with how air-tight your house is. Yes,
combustion of most fuels produces water but the water is not wrung out of the
air in the house. It's simply a product of combustion. Most fuels contain
hydrocarbons. The hydrogen combines with oxygen to produce the water. The
humidity in our house has never been below 52% with the air-to-air heat
exchanger running and climbs to 60% with it off. This doesn't really prove
anything because or house is heated by the floor and the sun, when it
shines...
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keesan
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response 10 of 61:
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Nov 28 22:10 UTC 2000 |
Houses with furnaces that are not designed to draw in air directly to the
furnace, even if they are as air-tight as a house with radiant heat (hot
water, steam, electric of any sort) are more likely to be drafty and pull cold
low-humidity air in through cracks, which is why the air is drier in them.
Fireplaces also provide a lot of ventilation and dry the house house that way.
The water produced by burning fuels does not usually go into the house (only
in the case of unvented heaters, which are not healthy, and include kitchen
gas stoves). It goes up the chimney. Much of the heat is transferred from
the air containing the combustion products, to the air that circulates around
the house, through a metal plate (or stovepipe). Baseboard heat should feel
about the same whether produced by circulating hot water or circulating
electrons. I don't like the forced-air type either, but a forced-air
(fan-type) electric space heater lets you get a lot more heat into a smaller
heater without overheating it, because it blows the heat away into the room.
That would be the advantage of using one to quickly heat up a bathroom where
there is not 6' of free wall space for a baseboard model, only wall or ceiling
space.
We will be getting a special interruptible HVAC rate for our electric heat
in combination with the water heater, and have to figure out how to install
a relay and 24 volt wiring to each heater so that they can shut it off, along
with the water heater, during peak (May-September) days of super hot weather.
Normally people have two different rates and meters for heat and hot water,
but we are not using enough to justify two meters so they allowed a
combination. Tomorrow someone is supposed to call to hopefully give us
permission to omit the relays on the space heaters, which they are unlikely
to be turning off by radio signal in July, and only use them on the water
heater and central dehumidifier. The cost of the extra relays would about
equal what we would save in ten years of this special rate. The water heater
relay (about $40 plus $20 for a 24 volt transformer) might pay for itself in
four or five years. The other option is a large gadget called a contactor
that disconnects all 10 circuit breakers and is itself the size of a breaker
panel and costs about $1000. The relays just interrupt current to the
individual heaters. To use low-voltage thermostats you also need relays, or
you can use line-voltage thermostats in the heaters themselves, supposedly
less accurate but an awful lot easier to install, or electronic line-voltage
thermostats on the wall, which require more 220-volt wires to them and a
positive disconnect (?terminology).
The baseboard heaters themselves are $25 and up, the line-voltage thermostats
start at about $20, meaning the relays and transformer would more than double
the cost of the heating system.
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keesan
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response 11 of 61:
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Nov 29 20:18 UTC 2000 |
Forget relays and interruptible rates. We do not have permission any more
to put the heat on the special 5 cent/kwh rate used for Air Conditioning and
Heat Pumps or Water Meters. They suggested the Whole House Rate of 6.9
cents/kwh, but neglected to tell me that the rate was actually 8.71 cents
until (unless) you went over 20 kwh/day. Even with heat and hot water we
would not be using that much electricity. The other suggestion was
time-of-day rate, over 13 cents/kwh summer 10 am to 7 pm, otherwise much
cheaper. Under 3 cents/kwh off peak winter, and only 6.7 cents onn-peak.
We will put the water heater on a timer not to run 10 am to 7 pm, and leave
the heat on at night.
Nonviable options I just investigated included: electric storage
heaters, they put the heat into insulated bricks at night and blow it back
out in the daytime. Cheapest model (850 watts in, 6000 watts out and then
dropping off) is $704 suggested list price. Line-voltage setback thermostat
- $86.40. Nonsetback line-voltage thermostat (which can be installed in the
heater or on the wall) $17.50. FOr 8 thermostats setback is an extra $560,
or more than ten years' cost for heat. Low-voltage setback (programmable)
thermostats can be found used, but they require a $60 relay/transformer for
each heater. Baseboard heaters, 500 watts, are up from $99 to $128 for
hydronic (oil-filled) models, and down from $29 to $27 for plain types, which
we already have a few of.
Rather than turn the heat off at night and on in the morning, we will
leave it on all night (which is supposed to be better for the house anyway)
and maybe also boost it 5 degrees before 10 am (we have lots of those plug-in
type times and portable heaters that could be set to run 7 am to 10 am). We
can install some time-of-day outlets as well, and just be sure not to use them
during summer peak hours. (Orange outlets for time of day?) Jim was talking
about rigging up a timer for one 20 amp circuit, to turn it off summers from
10 am to 7 pm.
Off-peak rates are 2.76 cents winter, 3.71 cents summer, on-peak 6.7
cents winter, 13.35 cents summer (air conditioning times). If we heated only
off-peak, it would cost us about $60/year for heat, electrically. If the heat
were on at random times, the rate averages 4 cents, or $80/year. During peak
hours we will have solar heat (on sunny days) and warmer outdoor temperatures.
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n8nxf
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response 12 of 61:
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Nov 30 03:59 UTC 2000 |
I love this country. Use more electricity and it gets cheaper per kwh...
Meanwhile, Engler is inviting private power producers into Michigan because
we have only a 5% surplus during peak power consumption periods. You're
better off heating with the fuel instead of burning the fuel to make
electricity to run your heater. That process is about 35% efficient while
burning it in a furnace or hot water heater is 80% efficient or more. i.e.
fewer greenhouse gases for the same BTU's heating your home / whatever.
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rcurl
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response 13 of 61:
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Nov 30 06:43 UTC 2000 |
I've been puzzling on why anyone that believes in economical and
resource-saving construction and infrastructure would choose electrical
heat. As Klaus says, it is less than 1/2 as efficient as a fuel and
hence costs more than double and produces double the waste gases to
"help" heat our planet.
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gelinas
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response 14 of 61:
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Nov 30 17:56 UTC 2000 |
If you are going to use electricity, it may be worthwhile to explore on-site
generation. With small enough demand, solar panels can probably meet the
need. Storage may be a problem, of course.
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rcurl
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response 15 of 61:
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Nov 30 18:38 UTC 2000 |
Wind turbines may be even better. Why would storage be a problem? The weight
of batteries is not a problem in a house, as it is in cars.
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keesan
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response 16 of 61:
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Nov 30 22:21 UTC 2000 |
We will be generating most of our heat with the sunporches, on sunny days.
Gas is much more expensive than electricity in our case because the gas
company charges $8/month plus tax on that to just read the meter. So if the
gas cost $100 we would pay $180 for it. Also the combustion products would
go into the air in town right next to the house. And it would not be as easy
to install, the equipment itself would require a lot more energy to produce
and need maintenance. It would be harder to zone. Natural gas is a more
scarce resource than the coal used to generate electricity, plus we are hoping
more electricity will be generated via solar by the power company. Save the
gas for motor vehicles. $500 or so will install a baseboard heating system
(less if we can use our used heaters, which are free and do not take any
energy to produce). What did the floor heating system cost in materials,
Klaus. (Not even counting time, maintenance, the need to replace movingp arts
eventually).
We may do the whole house on time-of-day if Jim can figure out how to
wire both panels on one meter (if that is possible) and do our canning and
freezing on weekends or late evenings. Only 45 hours/week is peak and we will
not be air conditioning.
Madison Electric sells the storage heaters for half suggested list
price, about $350 not $700. We are better off just heating the house up 5
degrees warmer than normal between 7 and 10 am on days when we don't expect
it to be sunny. The heavy floor and walls will store the heat and release
it for the next 9 hours and I don't mind a large swing (55-75).
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rcurl
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response 17 of 61:
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Dec 1 19:11 UTC 2000 |
Coal is an extremely dirty technology, less efficient than gas, spews
quantities of toxic sulfur compunds and mercury and vanadium into the
atmosphere, and produces ash that leaches toxics into groundwater. You are
being rained on now by the effluvium from coal generating plants to our
west. Gas is cleaner and more efficient, and may not be "scarce" if the
gas hydrate development works out in an environmentally friendly manner.
But I agree that your lifestyle may save more resources than those
wasted by the inefficiency of using electricity, with a net social
benefit.
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keesan
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response 18 of 61:
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Dec 1 19:33 UTC 2000 |
A typical American household is apparently expected to use 20 KWh/day of
electricity for things other than heat and hot water, as that is the amount
you pay for at full price before they give you the electric heat rate. We
can heat for a year with what a typical household uses in three months of
electricity usage. A typical American car travels 10,000 miles a year. At
20 mpg this is 500 gallons of fuel, which is way more than the energy which
would be used to heat our house, and I suspect 500 gallons of gasoline as
burned by a car produces a lot more pollution than it would take to make the
same thermal value of coal into heat for our house. This is why I suggest
that people heat with electricity and save the natural gas for mobile use.
What is a gas hydrate development?
I could heat my little room up from 45 to 60 in about an hour with 750 watts.
Two walls and a ceiling are insulated, the others are leaky drywall next to
a 45 degree space. It should be no problem to heat the house up from 55 to
65 between 7 and 10 am. The only problem I foresee is that it will be hard
to keep the bedroom cooler than the rest of the house, and it will not even
cool off much at night with the heat turned off everywhere. 60 is too warm
to sleep in, with warm walls.
At 11 am the sunporch and the house were both 45, with very pale sun. Outside
was 28. It does not take much sun to be usable for heating. In theory you
could heat the sunporch to 35 and still get heat out of it with a heat pump,
but again, the energy required to make the equipment and maintain it is
probably more than the energy that could be obtained with it.
How much sulfur etc. actually get through the scrubbing process of a modern
coal-burning plant? I thought most of it was captured and converted to
gypsum, useful in drywall, except in the older plants that do not have good
scrubbing systems. In the case of cars, the pollution goes right into the
city air, as they cannot carry around heavy scrubbing equipment.
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n8nxf
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response 19 of 61:
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Dec 1 19:44 UTC 2000 |
Our in-floor system was quite expensive. The tubing alone was around $1 /
foot. New technologies are expensive not because the materials are expensive
but because the quantities are low and the 'local' knowledge base is low.
Any hick can install a furnace, while one would have a much harder time
finding someone who can install a radiant floor system. Converting it to run
off electricity, solar energy, coal, wood, natural gas, etc. would not be
difficult. There is also little to go wrong with plastic buried in concrete.
Heating elements fail, so if you go that route be sure they are easy to
replace and that there will be a source for parts when they do fail.
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keesan
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response 20 of 61:
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Dec 1 23:57 UTC 2000 |
We have not found any 'central' type heating system that puts oout 2200
W/hour. How much does your hydronic system produce?
In-floor electric heating would have cost about $5000 for materials, and a
lot of time laying it out, but no maintenance after that. It would work as
off-peak heating since the floor stores a lot of heat.
Madison Electric told me that their oil-filled heaters are five times the cost
of the plain heaters probably because fewer are sold, not because they cost
more in materials.
As a rough guess, Klaus's system probably puts out at least four times as much
heat as we would need, because his house has twice the heated space and about
half the insulation.
2200 x 4 x 3.4 BTU/Watt hour = 30,000 BTU to maintain a steady temperature,
and more than this to be able to heat the place up quicker. Am I close?
What size does the smallest furnace come in?
How much would the house cool off at night with the heat off?
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rcurl
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response 21 of 61:
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Dec 2 07:35 UTC 2000 |
"W/hour" is meaningless. Watts are power, or energy-per-unit-time
(joules/sec). I think you mean "2200 W".
A BTU is *energy*, not power (a "British Thermal Unit"). There are
1054 joules/BTU, so 1054 watts = 1 BTU/sec, or 1 watt = 3.414... BTU/hour.
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n8nxf
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response 22 of 61:
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Dec 2 10:14 UTC 2000 |
Our house needs more heat because we have a LOT of glass. Most of it on the
south side. Our ceiling is R-40 or more and the walls are R-20 static and
and average of R-35 dynamic. (They are a pi section thermal filter: Thermal
resistance-thermal mass-thermal resistance.)
An oil filled heater will cost more than a plain heater. Oil filled heaters
have to have oil-tight seals for the electrical connections to the submersed
heating elements and the oil tank has to remain sealed despite thermal
cycling. Plain heaters are just coils of nichrome wire suspended in air.
The problem with plain heaters is that the if the coils shift you can get a
hot spot that will burn out faster due to the greater thermal stress. The
thermal resistance of air being a lot higher than that of oil also means that
more resistance wire has to be used to to minimize this stress. Oil, on the
other hand, has much lower thermal resistance than air. It is also a fluid
that conforms to the container that holds it. The heating element in oil
heaters can dump lots more watts per inch, without getting too hot,
because the oil carries the heat away faster and it can distribute it to
to the much larger surface area of the container. The oil can be thought
of as a thermal impedance matching device between the heating element and
the air.
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keesan
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response 23 of 61:
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Dec 2 20:57 UTC 2000 |
We are thinking of using our portable oil-filled heaters (four of them) if
the city will allow us to wire in just 3000 watts of heater (in the bathroom
and laundry room). The one I am using gurgles softly once in a while and has
a faint click when the thermostat goes off but is otherwise silent. Plug-in
lets us run them through a timer rather than buying a $70 setback thermostat
which consists of a thermostat and the same sort of timer, together.
Does anyone know how to wire two breaker panels to the same meter. Jim thinks
he should run two wires from the meter to the two panels (after pulling the
meter so as not to electrocute himself, and getting Edison's permission to
do this).
The oil filled heaters are 2" shorter than the plain ones, same wattage. Both
have identical looking aluminum fins.
We separated our large areas of south-facing glass from the house, as a sun
porch, so as to eliminate the problem of heat loss from the house when the
sun was not shining. Klaus, did you need to add heat today? At 11 am my
leaky sunporch was already 65, with half-sun. Are there sunny days when you
still have to run the floor heat?
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n8nxf
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response 24 of 61:
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Dec 4 12:11 UTC 2000 |
When the sun shines, no extra heat is needed. I got up to 70 in here both
Sat and Sun from just solar heating.
I don't think either Edison or the electrical inspector will allow you to wire
your utility controlled meter to lighting circuits. You can use that only
for heating or hot water. If you do do it, one usually goes out of a breaker
in the supplied panel to the sub panel. In the sub panel you get the power
to the power buss by back-feeding another breaker. If the panels are right
next to each other, you might be able to get away with not having the
back-feed breaker. The code requires there be a local disconnect at the panel
(So it can be worked on with no power applied to it and so that the person
working on the panel is within easy sight of the disconnect. The though being
that you don't want a second person turning the power on while you're working
on it.)
Oh, no, I have yet to see the floor system run when the sun is out.
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