Insulation done! Shop heater questions. Electrical gurus.

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my5thmopar said:
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
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Regarding using a heat pump, depends on where in the world you live. Heat pumps are one of the most efficient forms of heat because they 'move heat' like a pump rather than 'create heat' like a fire. They are an A/C that acts in reverse. An a/c uses the freon to steal the heat from your home and move it outside. It doesn't eliminate the heat or create cold (both of which are impossible), it just moves it outside or pumps it, if you will. A heat pump works exactly opposite and in fact, you could technically just flip a window unit around and it will heat your home (just take care of the condensate, which will now drain in your room).

The only issue with a heat pump is they lose effectiveness below about 30 to 35 degrees F. There is just not enough heat in air that cold for it to steal and pump into your shop. So most have emergency electric heaters that kick in and then you're right back to electric resistance heat, which is far more expensive than propane in most areas. Generally, in the US, anything above the Carolinas or Tenn, don't bother installing one, as the cold days are just too damn cold. Anything below that and you might find some savings.

Dont forget that with a split system heat pump, ductwork, copper and a freon costs might kill the cost of that job, whereas a wall/window unit is self contained. So maybe a wall unit is something to consider. Also, the benefit of the heat pump is it should have a reversing valve in it so summertime it is also an a/c.

Or, use that propane and install a vented space heater and that will take care of the heat and eject the flue gases outside (including the condensation). Really depends on what region you are in. Probably best to run this advice past your local hvac buddy, as he would likely know what is best.
 
67Dart273 said:
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
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ht413 said:
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.
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Thank you both for explaining that. I was worried because he keeps several cars in this garage (mine included sometimes). Since it is vented, I will quit worrying.
 
Had a heat pump when I lived in the desert of AZ. In the 15 or so years I lived there I think I used it for heat maybe 10-11 nights. The one night we were in the mid 20's.....damn thing would go into its "defrost" cycle every 45 minutes or so. Made this extremely obnoxious noise...and sprayed a cloud of moisture into the air while doing so. A neighbor about 1000' down the road has one. When I go outside on cold nights I can hear the thing "defrosting"....have no idea how they sleep with that thing farting like it does right outside there bedroom....
 
"The way to go" with heat pumps is to install a ground heat exchanger. Higher output/ efficiency even up here, and no defrost. "If I were" rich and could afford to do that, I'd install TWO ground loops....one for a spare. Some folks drill a well for heat exchange as well.

Also, in the last 10-15 years, SEER ratings on heat pumps has gone up considerably. Defrost can be programmed on better units, and the unit MUST be installed / designed by someone who knows WTF they are doing. Duct sizing, system sizing, an install of OD unit above snow level and enough airflow to the OD unit are NOT options. They are necessities.

Usually when you see one going into excessive defrost, there's something wrong with it. Wet climates generally need more defrost. Wrong system design and even improper refrigerant charge can cause defrost problems

Friend of mine back in mid 90's bought a "good sense" prefab with Coleman heat pump. That thing was just awesome.
 
around my area fujitsu heat pumps are the way to go, there a split duct heat pump that can heat to -26C (-14F) before electric heat is needed
 
66plyValiant said:
around my area fujitsu heat pumps are the way to go, there a split duct heat pump that can heat to -26C (-14F) before electric heat is needed
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Yeah there have been a couple on the market for some time but are *really* expensive compared to other forms of heat, expecially with propane run into his shop. Unless the prices came way down, I haven't looked at that in a few years... still, it is a viable option for sure.
 
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!
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The difference in using 220 vs 120 is the wire size needed to feed the unit. For a 2kw heater using 120 volts in theory you can use a #12 feed. But it can't be a long run from the box. At 220 volts a #14 feed will do nicely. The cost of the wire is the main difference. If I was going to feed a 2KW/120 volt heater anymore then 20 feet I'd use #10 for the feed. Just a little overbuild!
 
ht413 said:
The only issue with a heat pump is they lose effectiveness below about 30 to 35 degrees F. There is just not enough heat in air that cold for it to steal and pump into your shop. So most have emergency electric heaters that kick in and then you're right back to electric resistance heat, which is far more expensive than propane in most areas. Generally, in the US, anything above the Carolinas or Tenn, don't bother installing one, as the cold days are just too damn cold. Anything below that and you might find some savings.
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Not so with the mini splits, my ductless heat pump operates at 100% efficiency at 5 degrees below zero. Even then, It starts to lose efficiency but still puts out considerable heat. I'm referring to a ductless heat pump, aka mini split. It doesn't even have 'resistance' or back up heat strips. I use it as my primary heat for the whole house (1,900 sq ft) and living in the northwest, on the coast, we rarely need AC, but its there when you want it! It is also the lowest cost heat I have found, other than maybe a wood stove.

The heat pumps referred to in the above quote are the traditional central systems which are ducted to various zones. They are no where near as efficient as the ductless ones. Additionally there is heat loss (or heat gain in summer) associated with the ducting, most ducts are only R8, lots are only R4, the ducts run thru the frigid or sweltering attic temperatures, reducing their effectiveness.

I'm In the heating business, primarily with hearth products (wood, gas, and pellet stoves, fireplaces and inserts) and I heat with a mini split, a gas fireplace in the living room, a pellet stove in the garage and a wood stove in my basement. I like to be warm in the winter!
 
bighammer said:
Not so with the mini splits, my ductless heat pump operates at 100% efficiency at 5 degrees below zero. Even then, It starts to lose efficiency but still puts out considerable heat.
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I don't know what you mean by "100% efficiency." ANY heat pump loses output as it's heat source (OD air) gets colder and dryer. Fujitsu even says on their website that "design temp" (for the unit I cherry picked) is 47F dry bulb. This would be the conditions under which the nametag BTU outputs are rated. This is derated as temp goes down, and power consumption goes UP for the amount of heat produced.

Some specs on a random Mitsubishi

[ame]http://www.mitsubishipro.com/media/214712/muz-fe09-18na_service_obh543a_9-10.pdf[/ame]

I was not impressed with what I found on Fujitsu's website so far as specs........I could not find deratings for lowered temperatures

So far as auxiliary heat..........

You may or may not be shooting yourself in the foot, there. "Not having" auxiliary heat might be great on paper to ring the last Green Drop of tree hugging, EPA friendly figures of efficiency out of the thing, but..........

not using it WILL cause a cooling effect during defrost, and........

if the damn thing decides to quit some dark and stormy night, and you don't have "something else" in mind, this could be somewhat unhandy.

(I read a BPA test of a unit, and they mentioned that "at no time" during defrost did supply temps reach below the return air temps, which were 70 degrees. I can assure you that a supply air at 70 degrees on a cold winter day is not very comfortable.)

That was always the "nice" thing about older, traditional heat pumps..........they were essentially two heating systems in one, so if the thing froze up bad, got badly drifted in with snow, or something went wrong, you could just flip a switch, WHAM you have an electric heater.
 
ht413 said:
Yeah there have been a couple on the market for some time but are *really* expensive compared to other forms of heat, expecially with propane run into his shop. Unless the prices came way down, I haven't looked at that in a few years... still, it is a viable option for sure.
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$4500 installed here, can't get a propane tank and the gear to burn it around here for that, then your all the time buying propane, here in canada thats expensive as old heck
 
Being an electrician by trade for 15 years and knowing a bit about heating and cooling and being in different shops of my buddy's that use an array of different heating types, I'll try and put my 2 cents in here as well.

First you should figure out how much realistically you are going to be out there working and what your goals are. If you are going to also want to cool it you have a couple of practical options that make the most sense.
Being that I live close to stl Mo, and you are in Tenn. I am hoping that I can assume that we are about the same climate in the winter and not like up north where it would actually matter more about how you are going to be heating your shop since winter lasts much longer and is much colder up there.

First option. If your wanting to be cheap, put a small wood stove in and cut your own wood, this being by far the cheapest. If you don't like the mess in the shop you could also put in a small outdoor wood stove. and to cool it in the summer put in a small window a/c unit. but this would
need a blower unit and add to your cost. There are also pellet stoves and other options that could spin off from this one.

Second option. You could tell your buddy that does the heating and cooling what you are wanting to do and then "wait", till he comes up with one for you that he has disconnected or that had a problem and get it fixed. for a medium/small shop an electric heater out of and apartment or townhouse would work great. Then for cooling you could have him get you an a/c unit and connect for central heating and cooling.

Third, and the one that I use for my oversize 3 car that's attached to the house. Get a 90 plus ventless wall hanging furnace/fireplace with a small blower, plum it to a 100 pound tank outside and "whala" heat. You can usually get one the size you need for around $125 give or take on your needs. A lot of people put these in there houses. They sell many different types/ sizes at lowes, I can send a pic of mine if you need. And to cool go with the window unit. If you have a larger shop go with something like the hanging lp heater in the picture someone had already posted.

In all reality we can sit here and argue the "best" way to heat and cool but your going to either have a big expense on the front end and take years to recoup the energy savings or a bit more monthly here or there with the other options. But really, it's a shop.. Your not going to be out there enough to notice a difference on a bill between electric or gas unless you keep it heated 24/7. Really you only see the difference when you have to have the propane filled and have an expense of lets just say $100. rather than have an extra $10 or whatever on the electric bill every month.

And for the salamander option. If you want to use a salamander to heat the garage which I would not! It's going to cost you $20 bucks a day for the fuel, it's going to sound like a jet engine the whole time it's running, and it's going to leave you with a headache from the fumes if you are working or standing around it much, Nuff said.

Hope this helps you out.
 
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