Author Topic: heat needed to sufficiently heat a room  (Read 1050 times)

Case

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heat needed to sufficiently heat a room
« on: January 22, 2019, 10:04:32 AM »
I have a 110 sqft room which is attached to my house but not connected to HVAC.  This morning it was ~40F (maybe somewhat remarkable considering the outside temp was 10F... it doesn't get too much colder than this where I live (e.g. I live in the mid Atlantic).

I'd like to heat this room in the winter in order to make it usable for a hobby of mine.  A nice target temperature is 60 F.

The room has a 110V, 15 A circuit attached to it (e.g. 1800 W).  I'm wondering, how many watts will a heater need to output to roughly reach this target temperature?  It seems like space heaters often go to 1500 W.  This would use the majority of the circuit load and wouldn't leave much spare room for lights and a laptop.  Online watt recommendations seem to be 1000-1200 Watt... I'm just not very well calibrated on this stuff.

Having an electrician install a line will cost me $300, and of course the electrician wants to install some fancy radiant heater, which at the end of the day will leave me with a $700-800 bill.  Therefore, if getting a simple space heater will work, that saves a lot of money.  The electrician recommends a radiant heater... I get that these are more efficient because they 'feel' warmer and have less heat loss from drafts, but for my hobby I need the ambient air temp to be raised.

Any thoughts?

J Boogie

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Re: heat needed to sufficiently heat a room
« Reply #1 on: January 22, 2019, 10:36:20 AM »
Sounds like you're going to be staying in the same place on a computer. Have you considered installing an overhead light (or replacing an existing fixture) using an infrared bulb with a fan like some bathrooms have?

That way you could directly heat your body, which doesn't require the same load as your whole room, and you wouldn't have a clunky plug in unit hanging around.

They're usually 250W per bulb and I think a two bulb unit might be enough. This is assuming you go full mustache and wear long underwear and wool socks of course :)

GuitarStv

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Re: heat needed to sufficiently heat a room
« Reply #2 on: January 22, 2019, 10:40:04 AM »
Is it possible to heat yourself rather than the room?  If you're sitting down, an electric blanket would make things much more comfortable.

Lulee

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Re: heat needed to sufficiently heat a room
« Reply #3 on: January 22, 2019, 10:44:10 AM »
I have some nice electric space heaters I spot heat with but they're 800W and don't seem to be available any more.  But it does mean there's lower drawing options out there like this 400W electric heater rated for a 200 sq ft room on Amazon --- https://www.amazon.com/Heaters-Mounted-Electric-Heater-Reflector/dp/B00865JZXO/ref=sr_1_8?hvadid=241911593732&hvdev=c&hvlocphy=9002371&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=15975504260239133838&hvtargid=kwd-299999895962&ie=UTF8&keywords=solar+electric+heater&qid=1548177885&sr=8-8&tag=googhydr-20.

For comparison, I'd check to see how much to connect the room to your HVAC system.  That would allow you to use all electricity for powering your other equipment.  If this is where the coffee roaster from your other post is going to reside, doesn't that require a lot of electricity too?

Case

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Re: heat needed to sufficiently heat a room
« Reply #4 on: January 22, 2019, 11:43:29 AM »
Sounds like you're going to be staying in the same place on a computer. Have you considered installing an overhead light (or replacing an existing fixture) using an infrared bulb with a fan like some bathrooms have?

That way you could directly heat your body, which doesn't require the same load as your whole room, and you wouldn't have a clunky plug in unit hanging around.

They're usually 250W per bulb and I think a two bulb unit might be enough. This is assuming you go full mustache and wear long underwear and wool socks of course :)

I'm totally down for full mustache wear, but the issue is that the hobby needs ambient air to be somewhat warm (for the process, not for me).  Now, what I could possibly do is aim an air heater right where I need it....

Case

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Re: heat needed to sufficiently heat a room
« Reply #5 on: January 22, 2019, 11:46:25 AM »
I have some nice electric space heaters I spot heat with but they're 800W and don't seem to be available any more.  But it does mean there's lower drawing options out there like this 400W electric heater rated for a 200 sq ft room on Amazon --- https://www.amazon.com/Heaters-Mounted-Electric-Heater-Reflector/dp/B00865JZXO/ref=sr_1_8?hvadid=241911593732&hvdev=c&hvlocphy=9002371&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=15975504260239133838&hvtargid=kwd-299999895962&ie=UTF8&keywords=solar+electric+heater&qid=1548177885&sr=8-8&tag=googhydr-20.

For comparison, I'd check to see how much to connect the room to your HVAC system.  That would allow you to use all electricity for powering your other equipment.  If this is where the coffee roaster from your other post is going to reside, doesn't that require a lot of electricity too?

Yes, it does.  I'm having a separate line installed for that.

I could connect the room to the HVAC system, but the room only needs to be heated for occasional period.  I suppose I could just shut off the vents when not needed... seems like a lot of work though for a simple heating process.

MDM

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Re: heat needed to sufficiently heat a room
« Reply #6 on: January 22, 2019, 12:12:22 PM »
There's always "plug in a space heater and see if it works well enough."

If you want a quick estimate, you'll need to know how well the room is insulated.  See Calculating Wall Heat Loss for the equation.  Once you get Btu/hr, multiply by 0.3 to get watts.

Jon Bon

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Re: heat needed to sufficiently heat a room
« Reply #7 on: January 22, 2019, 12:25:26 PM »
Electric space heater is probably fine. How often are you planning on using this room?

I kind of have the same situation but the room has baseboard heaters already installed. The issue is remembering to turn them on and off. Nothing like waking up in the morning with that room cooked and realizing you just spent money keeping it hot all night!

A few electric options
1: Space heater with thermostat or timer
2. Space heater on switch, so when you turn the lights on, the outlet powers on too.
3. Some sort of obvious heat, like an electric fireplace that you can tell by looking at it that it is on.
4. I kind of light the heat bulb idea as well, but that will take special fixtures I assume (250w is a bunch for a light)

Honestly connecting to your HVAC might be the cheapest option. Space heaters suck to run. It might be a PITA, but this is MMM after all! If there is a cheaper way to added conditioned space to your house I cant think of it.






Prairie Stash

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Re: heat needed to sufficiently heat a room
« Reply #8 on: January 23, 2019, 01:48:48 PM »
The CHEAPEST solution is to open the door from your house and allow the Heat from your house go into the room (didn't your parents ever yell a you to close a door, or was that just me?). Opening the door is the same as connecting it to the HVAC, if you want it to heat faster then you put a fan in and blow the heat into the room.

The original qustion is a trick question. To calulate how much heat is needed you need to measure heat loss; which is the heat lost over time and can't be determined with just a single measurement of outside vs. inside temperature. To properly do it I would measure it overnight so that you can exclude soar radiation effects, sounding fun so far? The reason it was 40 was the heat loss from your house warming it up, so that's a good sign that it can retain some heat, you just need ~40% more heat in the space.

You should consider adding insulation if there isn't much. Heat loss is a function of insulation, so a poorly insulated space will cost more and be harder to bring up to 70 (since its losing heat as fast as you put it in the room). I can guarantee that if you had enough insulation the room could be 70F from the houses heat loss.

For myself, electric heat costs 9 times more then natural gas heat for the equivalent amount of heating. 24 hours of space heaters costs the same as 9 days of HVAC. You say you won't use it much, but the 9:1 ratio is pretty huge.

Case

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Re: heat needed to sufficiently heat a room
« Reply #9 on: January 23, 2019, 07:30:04 PM »
Thanks for this clever advice.  I tried opening the door and the area warmed up from 7C to 10C within an hour.  Im going to try a space heater to supplement this... there are space heaters with multiple settings, and the ones that do 700/1150/1500 should fit the bill (flip down to 1150 watts if i need spare power.  I also have a nearby outlet on a seperate circuit that i can mooch off of.  Lastly, Iíll also try improving the insulation.  This likely means installing some cellular blinds on the windows in the room.  Beyond that, the insulation i think is already reasonably good and there isnt much i can do.

I just hve trouble justifying dumping more and more money into this room.  It would be one thing if we used it for more than just coffee roasting, or if my wife used the room.  But it will just be me, sitting there for a few hours per week.  And it looks like the air temp cna get within range of not being too frigid to effect the roasting.

The bigger challenge will likely be in the summer ... but what am i going to do, install a window AC unit??  At some point it gets crazy.  Iíll take off my shirt, get a box fan, and call it good.

MDM

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Re: heat needed to sufficiently heat a room
« Reply #10 on: January 23, 2019, 08:23:04 PM »
This likely means installing some cellular blinds on the windows in the room.
Or Window Insulation Film.

HipGnosis

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Re: heat needed to sufficiently heat a room
« Reply #11 on: January 24, 2019, 08:27:30 AM »
The CHEAPEST solution is to open the door from your house and allow the Heat from your house go into the room (didn't your parents ever yell a you to close a door, or was that just me?). Opening the door is the same as connecting it to the HVAC, if you want it to heat faster then you put a fan in and blow the heat into the room.

Actually, the thing to do is to blow the COLD air from the room into the house (which will cause warm house air to flow into the room, and the home heating will heat up the cold air).
It's easier to put a fan on the floor by the doorway than to hang a fan up in the warmer air.

Rocketman

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Re: heat needed to sufficiently heat a room
« Reply #12 on: January 24, 2019, 10:31:59 AM »
One other option - a Mr Heater buddy heater. This uses propane for the heat. The heater calls for the 16.4oz disposal tanks. You can refill those thanks with a 20lb tank. Or buy a hose and use a refillable tank on the heater.

We use this to supplement the heat in our condo. It has all electric heat. Get a CO alarm. Very efficient heat source.

Case

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Re: heat needed to sufficiently heat a room
« Reply #13 on: January 24, 2019, 03:09:01 PM »
The CHEAPEST solution is to open the door from your house and allow the Heat from your house go into the room (didn't your parents ever yell a you to close a door, or was that just me?). Opening the door is the same as connecting it to the HVAC, if you want it to heat faster then you put a fan in and blow the heat into the room.

Actually, the thing to do is to blow the COLD air from the room into the house (which will cause warm house air to flow into the room, and the home heating will heat up the cold air).
It's easier to put a fan on the floor by the doorway than to hang a fan up in the warmer air.

So, this room happens to be a staircase down to the basement that was converted into a boot room / 3 season room.  As a result, I have a door to the basement which I can open to let the cold air down.  In addition, I have a window to the main floor that I can open, and stick a box man in.  As a result, I actually have a means of circulating the main floor hot air in, and cold air out and into the basement.  <mind blown>