I have a small cottage (construction in progress) where living during
the weekends; there is one room, 16' x 24' with a cathedral ceiling,
16' high at the top.
Inside this, is an open (no walls) mezzanine (as bedroom) 16' x 12'.
For heating I have installed a wood stove and a ceiling fan for air
As a second option for heating (mainly during the night or when not
in), I did install baseboards for heating this room with a total power
of 4000 watts.
The sizing formula for baseboards, I found from web, is:
"Required power (in watts) for baseboards is calculated by multiplying
the number of square feet in a given room by 10."
Thus a 16 x 24 ft. room (380 sq. ft) will require 3,840 watts of power
(380 x 10).
I am using one programmable thermostat which supports 4000 watts.
I am wondering if this is enough, considering there is a cathedral
ceiling and living in areas where in winter is cold (Canada).
If I have to add more heating elements, is it better to add portable
heaters or another thermostat with new baseboards?
How many watts should I add for heating elements?
Thank you, Chris
The cathedral cieling is a killer, I would of gone with radiant floor
heat, puts heat where you are.
in cathedral cieling ALL heat goes to peak. cieling fan helps but
creatyes cool draft.
4000 watts totally undersized, might be lucky to keep building barely
above freezing in zero weather.
so how thick are the walls? what sort of insulation? closed cell foam
R6 PER INCH elminates drafts too.
Question - Did you mean electric radiant floor heat, like we often
seen under tile? Since it is a cabin, I am guessing that the OP might
not always have the heat on, so any hydronic system would freeze.
I frankly don't know anything about HVAC, but I have some experiences that
might help you. I am assuming you will not be heating it when you are not
there. If you are rich enough to do that, then you can just put in all the
heaters you want and not worry about it.
Two weeks ago we went away for the weekend and I turned the heat down to 55.
It was about 25 out.
It took 8 hours to get back to 72. Unless your heating is way oversized,
you won't have it warm until you are ready to leave.
My cottage is about the same size as yours, but the ceiling peaks at 12'.
The insulation is not good, so maybe they are about equal. I can get it
about 25 degrees over outside temperature with my wood stove. With better
windows and insulation I am sure I could do better, but getting it actually
warm on a cold day would be a challenge for a wood stove.
And finally, my cottage takes about 3 hours to winterize for subfreezing
weather, and maybe an hour to bring back. That could be improved with
better design, but there is still alot to do. Make sure you know what you
No actual experience with anything unusual, but I"m surprised to hear
there would be a limit on the wattage suppported by a thermostat.
After all, all it does it turn on power to a relay. If the relay drew
too much power (which seems unlikey) one could use an acceptable
intermediate relay to provide power to all the other relays/
ISTM, it seems to me, that two thermostats can be aproblem if they
aren't set to the same or almost the same temperaturee. At least it
would be a problem if you want to use both systems. If you by accident
set one to a higher temp, it will go on first and might keep the temp
at the other thermostat from ever getting cold enough to turn on.
That might be fully acceptable, but might not be if the first source
of heat costs more than the other, or other reason.
OTOH, if one thermostat is higher and so gets warmer air, it might run
all the time and keep the lower heat source from running, even if set
to the same temperature.
I don't know what is recoemmended.
240 volts up on the wall, or near my shoes, where I might touch it? I
guess I won't be taking apart any electric heat thermostats from now
OK. Didn't know that. One could still use that line voltaghe to
power two other relays. Or to power 3995 watts worth of heat and a
relay to turn on the rest of the heat.
There are two kinds of thermostats.
"Low Voltage", the most common type that typically run on 24vac and use a
relay to control the actual heater.
"Line Voltage", these connect between the electrical source (120V or 240V)
and the heater.
We have line voltage digital thermostats in our house, and the contacts are
limited to 22 amps.
I used 12/2 wire which can support 20 amps, but it has to be "derated" with
electrical heat. So, I kept my total load on each thermostat under 3840
watts (16 amps).
I could have used 10/2 wire to control more wattage with the thermostat,
but I prefer not to max out the circuit or thermostat, and I didn't need to
anyway. We have individual heaters in each room with separate thermostats,
on their own circuits. Most are 2250 watts or less, except for our
kitchen/dining area where I have 3750 watts.
Thanks for answers.
I think I will add more insulation only on the peak region, making the
part of the ceil as horizontal in that area. I hope this will help
The walls are insulated with R28 fiber glass. The floor with R31.
I will keep the 4000 watts baseboard with one programmable thermostat,
as long as they are the second source of heating. The main one is the
wood stove and I was able to increase the temperature from -5 C to 15
C in one hour.
The baseboard will be used for keeping the temperature during the
night and when not in (to a minimum +5 C).
I will use portable heaters (aerotherme) if need more and fast heat. I
already have 2 of them.
What do you think?
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