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Heating/cooling a wood shop

12K views 24 replies 7 participants last post by  Garasaki 
#1 ·
Ladies and gentlemen -
I'm interested in purchasing a heat/ac unit for a small woodshop (approx. 450 sq ft with 10 ft ceilings and good insulation). I think I have a handle on the size of unit I would need but am unsure whether to buy a packaged terminal unit like - http://www.grainger.com/Grainger/items/1CFA5 or a propane unit like - http://www.grainger.com/Grainger/items/4LX41 and a separate window type unit. The electric unit seems pretty straight forward but I am curious about the propane. What kind of venting (gravity vs powered) and blower/fan should I be considering given the presence of wood dust and such. I assume these can be installed so that it is vented outside as well as pulling in outside air to heat? I'm sure I'm not asking all the questions I need so feel free to fill in where I might have missed
 
#2 ·
the unit heater with the propane seems to be more user friendly with it general application.the ductless HP is a little over kill even though you get the AC side with it,and the dust/wood shop factor might be more of a headache.the heater will still burn some dust with the space heater air running over it,but blowing it out weekly will keep that at a minimum..the ductless will fine filter and with a wet AC coil during the summer become a bigger problem....might consider window unit in the wall remove to wash out seasonaly and during the winter to store.
 
#3 · (Edited)
Do you need it to be vented outside? You might be best off with a very cheap, NON vented gas heater. If that is the case look at PRo Com from Northern Tool. You will spend more like $100 than $700+. If you spend long periods of time in there, or are concerned about carbon monoxide or moisture, you might think about a Rinnai. It vents right outside the wall where it sits, pulls outside air for combustion so you know that the burner is sealed to the inside. Much more efficient, as well, than the 2nd item you linked above. A little bit more money, but well worth it I think. This is what a Rinnai looks like:

http://xj.cdevco.net/heat/rinnai.jpg

Heres the pro com

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200332735_200332735

where are you located? how cold does it get? how warm?
 
#5 ·
woodshop

I would say that venting outside and the ability to draw outside air are important as it is likely that on any given day finishing vapors may be present. Im really not sure what the advantages of a non-venting type unit are? How is a rinnai much different from the dayton I posted. Both will do the job and both can vent outside. What are its advantages and what makes it more efficient?

As far as climate, I live in Tenn and we have pretty mild winters. Usually looking at the 40's to 50's during day and 20's to 30's for night. Sumers can be a bit warm in the low to mid 90's.
 
#8 ·
In short yes. Not so much for the finishing aspect but primarily for the wood aspect. If moisture/humidity fluctuates too much then wood moves too much. I guess as far as control goes, I need to be able to maintain a pretty constant moisture level. Ideally were lookin at something like the typical residence in Tenn.
 
#7 ·
The one you posted is power vented, not direct vented. Direct vent is just easier and usually means the unit is more efficient. It will be as simple as drilling a 3" circle hole in your wall.

The one you posted uses room air for combustion, I think. I am not sure. You probablyt want to check on that. The Rinnai is sealed combustion chamber and definitely brings cold air in.

The advantage of non-vented is 100% efficiency, the disadvantage is moisture and carbon monoxide. I am thinking that by design, any non-vented units could be sealed .....since they use room air for combustion.

Not sure how electric rates compare to LP rates - you might look more into the advantages of that Friedrich?
 
#9 ·
What exactly does power vented vs direct vented mean. Ideally I woudl rather not be circulating air from inside the shop. Can't see the advantage to having dust and fume filled air going over or through burner. Sounds like I definately want something vented then?
As for propane, costs about $2.75 a gallon for 120 gallon tank. People tryin to get me hooked up with 500 gallon tank! Lord I could heat for years!
 
#10 ·
The details!

Maybe I should start over and give you the logistics and you all can tell me what would be appropriate.

Average temp - Jan 30/47
July 69/88

Shop size - 18x24 w/10' ceilings with good insulation, two south facing windows and one east facing. Only one door which is fairly well insulated.

Would like to maintain about 60 in winter and 75-78 in summer. Will most likely adjust temp in shop accordingly when I'm not in there. As for humidity, would like to be able to maintain an average seasonal humidity somewhere along the lines of the normal residence. As for safety, I would prefer to not have flames exposed to fumes etc (I think Im saying that the right way). Will consider all types of heat but have some limitations when it comes to electric. 220/20A is the extreme. Certainly cant be hooking up any 440! Propane seems to be fairly expensive but not sure how to compare it with the cost of electric. That should cover it!
 
#11 ·
Since you want heating, cooling/humidity control, safety against open flame, modest OD temps year round, and your propane is pricey vice electric (can't be sure but you are in the TVA area, no?), it would seem a no-brainer to go with a PTAC or split system with electric strip backup. That's my $.02
 
#12 ·
Hi,
go here and have a look, i've installed a few of these in 1 & 2 car garages and they work very well, as for AC get a $100.00 5000 btu window unit from wal-mart and install it in a window or a wall sleeve, wahs the filter a few times a season and hose the evap coil out at the end of season.
You will not go wrong with this combo.

hope this helps. :thumbup:
 
#15 ·
Poster above me forgot to add a link.

Direct vent means there is a pipe from the unit to the outside. Power vent means there is a pipe from the unit to the outside, that has a fan in it. Power vent is usually only required if there is a long distance between the unit and the outside. Not the case here.

It's really ok to have flames in the shop. But most people feel a little safer with electric. Since you've not yet bothered to give us an idea of what your electric vs propane rates are, we can't tell you whats most cost effective. But so far all signs are pointing towards electric heat. You really don't need a HUGE heater, living in Tennessee and all.

Having my own hobby shop, my opinion is you just need something that helps take the chill out of the air. Something that makes it comfortable to work in pants and a long sleeve shirt, once you get moving around a bit. So I think your 20 amp 220v service should handle your heating needs. Just get the biggest electric heater you can afford.

You may want to consider a humidifier if you have a water line handy. Will help keep the humidity up in the winter.

As for cooling, you have lots of options, from cheap window units, ductless split systems (which should be a good solution if you can afford it) all the way up to a small residential system (which you might be able to find used and be a good deal, but be careful of buying too big a unit which won't provide decent dehumidification).

Really one of the biggest constraints is your budget and exactly how much room you have available in your shop. You really need to make this decision yourself, IMO. You gotta be comfortable with the space your going to give up.

So things to think about - probably electric heat, humidity control both under heating and cooling, get a humidistat on your wall, consider an exhaust fan for finishing vapor removal, consider an air filtration unit (along with good dust collection, not in leu of it), and decide how much room you want to give up and how much money you want to spend.

If you are clever and handy, it may be possible to dream up a custom solution, even using used parts, that accomplishes all those things.
 
#17 ·
Since you've not yet bothered to give us an idea of what your electric vs propane rates are, we can't tell you whats most cost effective. But so far all signs are pointing towards electric heat. You really don't need a HUGE heater, living in Tennessee and all.

Looks like electric rate is a little over 9 cents per kilowatt hour and propane is $2.75 a gallon. Given those, how in the heck do you determine which will be most cost effective?


Really one of the biggest constraints is your budget and exactly how much room you have available in your shop. You really need to make this decision yourself, IMO. You gotta be comfortable with the space your going to give up.

as far as budget goes, we're lookin at around $2000 to insulate and heat/cool. It looks like that will be plenty. With regards to space, I'd prefer to have something ceiling or wall mounted as 10' ceilings allows for greater wall space


So things to think about - probably electric heat, humidity control both under heating and cooling, get a humidistat on your wall, consider an exhaust fan for finishing vapor removal, consider an air filtration unit (along with good dust collection, not in leu of it), and decide how much room you want to give up and how much money you want to spend.

Have both an air filter and cyclone dust collector.

If you are clever and handy, it may be possible to dream up a custom solution, even using used parts, that accomplishes all those things.[/QUOTE]
 
#19 ·
Looks like electric rate is a little over 9 cents per kilowatt hour and propane is $2.75 a gallon. Given those, how in the heck do you determine which will be most cost effective?
Well I gallon of LP gas is 91,500 BTU, although the appliance will probably be 80% efficient, so 1 gallon of propane will really only produce 73,000 btu's. So you are paying 0.0038 cents per btu.

With electric, 1 kwh is 3,413 btu's. So you are paying 0.0026 cents per btu of electricity.

Add to that there will probably be first cost of buying a propane storage tank, as well as a service fee for filling it, and it seems pretty obvious to me, unless I've made a glaring math error, that electric heat is the way to go.

Frankly I can't make heads or tails of what pcambell posted. Someone check my math though.
 
#23 ·
Originally Posted by Garasaki
Well I gallon of LP gas is 91,500 BTU, although the appliance will probably be 80% efficient, so 1 gallon of propane will really only produce 73,000 btu's. So you are paying 0.0038 cents per btu.

Ok reedy to let your head spin?

LP burns at 80% so if you have 91,500 btu per gal you will only produce 73,000 btu. of which 20% will go up the chimney on an 80% or 15 % on a 90%

Remember AFUE (annual fuel usage efficiency) factors in an 80% fuel efficiency to start with. :lol:
 
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