Insulation done! Shop heater questions. Electrical gurus.

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my5thmopar

my5thmopar

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I just finished insulating my 24x24x9 detached shop Monday. It was in the 18 F to about 35 F. I'm using a 1500 watt quartz space heater that has a small fan in it. It heated the shop to 48-50 F and didn't run all the time. The temperature was fine for what I was doing with a long sleeve shirt and occasional jacket. It does seem to have a few cold dead spots. I have propane available at the shop but, I’m just not comfortable having an open flame and the moisture they produce. Also, I'll be creating a lot of dust from grinding, cutting, sanding, painting etc. this winter. Yes, venting air while doing such.

If I stay with electric, watts are watts, whether I'm using 120 or 240 volt it isn't going to matter on the bill. I'm thinking about comfort and possible cost savings from run time or some other factor I haven't considered. I was wondering about the fan forced electric heaters sold at Northern Tool. Most have a higher BTU and wattage, so I'm thinking more air movement equates to quicker heat-up, more comfort. I do have a few shop fans I could run to get possible same effect. Thoughts please!

Am I thinking about this correctly?

Also, what about a heat-pump...I know a HVAC guy and can probably get a unit cheap from a disconnect or remodel.


Craig
 
That shop shouldn't need more than a couple of electric space heaters. Smallest heat pump is 1.5 ton, unless you wanna spend $$$ on a PTAC.
 
I use a 4500 watt electric forced air unit to heat the shop up pretty quickly, while I get the pellet stove going. The heater I use was purchased at Noland Company, it only runs on a thirty amp, two pole breaker and plugs into the same outlet style that I use for my mig welder. All I did different, was instead of using the base plate attachment for setting on the floor, I mounted it to the ceiling so as to be able to turn it towards where it's needed. The receptacle is mounted on the ceiling right beside the heater.
 
I agree about forced air electric. I like them much better than radiant, and they are safer, as they operate at lower temps.

So far as fueled heat, I doubt that with the heat you need in that shop.....and I'm assuming intermittent..........that installing a permanent such as a ceiling unit heater, etc, would ever justify in payoff savings over a or a couple of decent quality hardware store electric unit(s).

All electric and other "sources of combustion" in a garage should be 18" minimum? (code? not sure anymore) or 2 ft off the floor, the theory being floor based heavy vapors.

And you are right. ANY non vented combustion heater whether LP, oil, etc, produces a LOT of water vapor. Water is the MAIN product of hydrocarbon based combustion.

You could however use such as an LP portable heater for "quick" warmups on those really cold days, then shut down and "maintain" with the electric units.
 
I think you are onto something by thinking about working with your HVAC friend. I also have a friend who does HVAC for a living and I traded some computer work with him for my HVAC needs in my detached garage. I ran natural gas piping to my garage and he hooked up a natural gas furnace and ductwork to make my garage nice and toasty. I added insulation throughout the garage ceiling some time ago, as that's where the greatest heat loss occurs.

Check with your HVAC buddy and see what he recommends..
 
Putting a ceiling fan in to help move the warm air from the ceiling down towards the floor helps a lot also. Providing you have enough height of course.
 
Hi,
Before I got into computing I was in HVAC/R but that was a LNG time ago.
If my memory serves me correctly and the principals haven't changed I think you are on the right track.

As I understand it the electric bill is calculated against consumption of Watts. So if your heater consumes 1500 Watts an hour your bill could be a little lower using 240v over 110v. Typically 240v is more efficient than 110v because the amp draw is decreased which could result in lower line temperature which keeps the resistance value down essentially wasting less watts to resistance. Watts are calculate by multiplying amps and volts, keep in mind that amp values are influenced by resistance ,or Ohms.

Air movement is very important to maintain even cooling. Heat travels from a warmer to a cooler substance so it could take time to spread. You can improve travel by using air circulation to improve heat convection.

Regarding heat pumps. As I recall the principle is that they are air conditioners operating in reverse. That being said outside ambient air temp has a huge impact on the effectiveness of the heat pump. By me here in the NE we get down below 30 regularly and heat pumps struggle to scaveng heat from the air outside and are usually supplemented with electric heat strips.

As I said it been a while since I've been in the field and technology has advance so keep researching. I hope this info helps.

AlV
 
AlV said:
As I understand it the electric bill is calculated against consumption of Watts. So if your heater consumes 1500 Watts an hour your bill could be a little lower using 240v over 110v.
Click to expand...

!!NO!! Sorry, not true. If this WERE true, then it means your wiring is seriously undersized, and that you are headed for a house fire.

Wattage for electric heat (resistive) is a simple calculation of amps x voltage. If there were any significant loss due to wiring (otherwise know as " I squared R") then your wiring is in BIG trouble.
 
67Dart273 said:
!!NO!! Sorry, not true. If this WERE true, then it means your wiring is seriously undersized, and that you are headed for a house fire.

Wattage for electric heat (resistive) is a simple calculation of amps x voltage. If there were any significant loss due to wiring (otherwise know as " I squared R") then your wiring is in BIG trouble.
Click to expand...
Hmmm. I don't necessarily disagree with your statement although I think you might have taken it farther than I was representing.

I did point out the calculation for Watts "Watts are calculate by multiplying amps and volts," I also pointed out the relationship between Amp and Ohms " keep in mind that amp values are influenced by resistance ,or Ohms."

The point I was making is that heat does impact and change the resistance value. I did not put a number on the value because it could be negligible to severe. That even a subtle change in resistance could have an impact on the bill. Will it be noticeable?? eh. it's a technical position in principal.

I would hope that his wiring did not look like a light bulb filament during operation.
 
Any electric heater I've ever seen is dedicated to a voltage, 110 or 220, any space heater, unit heater, PTAC, Heat pump, or electric furnace. As long as the amp rating of the wire is not lower than the breaker, you'll be ok. The wire size is the key factor. By the way, I'm a HVACR contractor for 10 years, in the trade for 25.
 
A 1,500 watt electric heater which is designed to run on 120 volts is not as efficient as a 1,500 watt heater that runs on 240 volts. Yes, watts is watts, but the variable here is the voltage.

Of course proper wire sizing is required for whatever you are doing.
 
I'm not sure what size it is but my buddy just had this LP furnace installed on Monday. He is going to insulate the garage this weekend.

20131126_103533_zps728d0360.jpg


I'm curious about the comment concerning the moisture that burning LP produces? Can anyone enlighten me on that?!?
 
Like ProDart I put a pellet stove in my shop, mostly because it uses outside air for combustion. Had a coworker try to blow himself up with a propane heater. I leave the stove run 24/7, on the lowest setting, and monitor the pellet, to ash levels daily. Whenever I want, I turn the rascal up and make the place 70' or 80' type of warm. In the interim, there's just enough forced air off of the stove to keep everything dry and rust-free. Bare engine blocks have no rust and I'm in Southern Ohio, moisture in the air, always adds 1000ft, to our calc's, at Edgewater.
 
BrianT said:
I'm not sure what size it is but my buddy just had this LP furnace installed on Monday. He is going to insulate the garage this weekend.


I'm curious about the comment concerning the moisture that burning LP produces? Can anyone enlighten me on that?!?
Click to expand...

Moisture is not an issue with VENTED heaters . Moisture is only an issue with UNvented heaters of any kind, which essentially turn your shop into the chimney.

LP/ Natural gas produces primarily LOTS of water and CO2
 
bighammer said:
A 1,500 watt electric heater which is designed to run on 120 volts is not as efficient as a 1,500 watt heater that runs on 240 volts. Yes, watts is watts, but the variable here is the voltage.

Of course proper wire sizing is required for whatever you are doing.
Click to expand...
????????? Look at the yellow tag on any electric heater.
 
BrianT said:
I'm curious about the comment concerning the moisture that burning LP produces? Can anyone enlighten me on that?!?
Click to expand...

Vented heaters have a heat exchanger. So they use a flame to heat up air, that air is run across the exchanger to warm it up. That combustion air has tons of water vapor and other combustion gases in it (carbon dioxide and carbon monoxide, etc) and is run up a chimney. Typically, 80% of the fire's heat stays in the space, 20% goes up the chimney (this is referred to as a 80% efficient heater). Others, like my house furnace, can be up to 95% efficient or even a bit higher but at a greater cost and higher mainentance.

Now, that heat exchanger has air tubes in it. Air from the heated space is pulled through and blown back out into the space, heating it in the process and never mixing it with the combustion gases.

A non vented just lights an open flame and spews all that heat and combustion gas into the space. With it comes carbon monoxide, water vapor and all the rest.
 
bighammer said:
A 1,500 watt electric heater which is designed to run on 120 volts is not as efficient as a 1,500 watt heater that runs on 240 volts. Yes, watts is watts, but the variable here is the voltage.

Of course proper wire sizing is required for whatever you are doing.
Click to expand...

Not true. If we're talking about electric resistance heat, they all work the same and all are 100% efficient, meaning 100% of the heat goes into the space. 240v vs 120v doesn't make a difference at all, because WATTS is power and WATTS is V times A. The only thing making it more expensive than another fuel source is that typically, electricity is more expensive than other fuel sources.
 
I use a kerosene "torpedo" style heater in my garages. 55 000 to 100 000 BTU heats up my garages fine. ( a 1 1/2 car and an 8 car garage). Menards or any home improvement store carries them.
 
ht413 said:
Not true. If we're talking about electric resistance heat, they all work the same and all are 100% efficient, meaning 100% of the heat goes into the space. 240v vs 120v doesn't make a difference at all, because WATTS is power and WATTS is V times A. The only thing making it more expensive than another fuel source is that typically, electricity is more expensive than other fuel sources.
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I stand corrected then, thanks for the clarification. I was told differently some time ago and have always thought that was the case.... Guess ill be more careful about giving wrong info!
 
Send me sketch with the size of building,window and door sizes with locations and insulation values in wall and ceiling and where you are located town & state I will give you an exact BTU per hr you need to heat it and cool . ( I do Heat loss and duct design calculation for a living )

George [email protected]
 
A 220 heater will heat quicker while drawing less amps, this is why anything using heating is 220; such as electric dryer or stove

plug a 1500W 110 heater in and watch your meter and then do the same with a 220 1500W heater
 
66plyValiant said:
A 220 heater will heat quicker while drawing less amps, this is why anything using heating is 220; such as electric dryer or stove

plug a 1500W 110 heater in and watch your meter and then do the same with a 220 1500W heater
Click to expand...

True that the lower voltage heater draws more amps. But remember, you dont't buy power in amps, you buy power in watts (kilowatt-hrs really, which is just the watts x the amount of time you draw it).

Remember that WATTS = VOLTS x AMPS
So a 1500W, 100v heater (using 100 for simplicity) draws 15 amps.
But a 1500W, 200v heater draws 7.5 amps.

They still use 1500w to create the same amount of heat. The reason you'd want the 240V vs the 120V is because your electrical service can only handle so many amps, so you raise the volts of the heater and it draws fewer amps, thus saving more capacity for the rest of you shop/house.

A reason you might want the lower voltage heater could be for safety (110v is less dangerous than 220). But this becomes more important when talking about 600v industrial systems vs a 110v residential.
 
bighammer said:
I stand corrected then, thanks for the clarification. I was told differently some time ago and have always thought that was the case.... Guess ill be more careful about giving wrong info!
Click to expand...

No worries. This is what I'm good at, but the car stuff is where I need the help lol.
 
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