Heating and cooling recommendations

[nukefission]

This forum is a great resource, but looking to refine my choices by asking about my specific situation.

Garage:
-Detached 24x30x11, concrete slab, framed walls/roof, unfinished, one 16' garage door and one entry door, vented soffits and one turbine vent in the roof, built in 1990.
-I'm working on insulating it with R-13 in the walls (2x4, 24" o.c. construction) and minimum R-38 in the attic (trusses are also 2x4, 24" o.c.). Because the roof trusses are 2x4, I plan to put the same R-13 batts in the joist cavities and then roll some unfaced R-30 on top and perpendicular.
-I have 50A service to the building. There also happens to be a 500gal propane tank situated right next to it which serves as the dual-fuel source for my house when it gets below freezing.

Region:
-Zone 4, northern VA (mid-atlantic). At the extremes, temps can get down to 0*F in the winter and up to 100*F in the summer.
-It's usually pretty humid, which is a big concern. In fact, one of my project cars that has been sitting in this garage for a number of years has a mold problem in the interior.

Goals:
-Looking for a moderately-controlled climate in the garage year-round. 50*F or so in the winter, 80*F or so in the summer, with humidity under control (not to exceed let's say 75% R/H).
-Some ventilation capability would be nice (for welding/fab work/carb cleaner stink), but opening the big door is never out of the question.

The most important factor is COST. Constraining the budget to shoe-string so that there's something left over for the cars.

Originally I was looking at this through-the-wall unit for both heating and cooling. I'm concerned that the electric heating element in that thing won't be up to the task and that it will be costly to run continuously to maintain a minimum temp in the winter.

Then I was thinking of splitting up the heating and cooling duties and going with this in-wall ventless propane unit for heat that I happened to see at the hardware store. Fuel source would be easy since the big tank is right next to the building. But I'm concerned about long-term CO exposure and moisture (humidity) from the lack of external vent. Plus the thing has gotten some poor reviews. Cheap, though!

Clicking around in this forum led me to this vented propane heater which many of you appear to be happy with. It's relatively inexpensive and doesn't have any of the negatives of the ventless unit.

With the latter two options I would have to get a dedicated air conditioner separately, which isn't too big of a concern.

Thoughts?

Thanks for the space.
Victor

 

[matt_i]

If I were you I'd try a ductless mini-split for that size of shop and your needs. I can't comment directly on tonnage but I'd WAG at 1.5-2 tons of A/C.

You will still get heat but might suffer in performance during certain very-cold snaps, possibly enough to cause you discomfort. At that point I'd get something like a 5-7.5kW electric heater for either a boost or completely shutoff the mini and go full electric.

Whatever you do, I would personally add a ceiling fan, whatever suits your budget from the box store. The air circulation, even on low speed, will keep the mold growth down, even when humidity gets high. It picks up condensation back into the airstream faster than an organism can start using it to make a home. I leave my fans in the shop on low speed nearly year round.

I also see that your trusses are open and it appears to have a ridge vent. I would add some sort of a ceiling whether that be metal or drywall or osb/ply or ? Being able to enclose your own microclimate is the first step.

 

[DC73]

A mini-split would probably be the easiest.

You could also source a new Goodman 1.5 Ton AC w/ furnace online and have a standard house type system. This might work out to be less costly than a mini-split if you can do all the work yourself (except for charging the system with refrigerant). You'll need a licensed HVAC tech to charge the system and sign off on the installation to get the factory warranty.

The cheapest option might be to install some type of window or thru-wall AC unit and a vented propane heater as you described. You could go electric heat but that can sure be costly to operate. Might depend on the cost of propane for you.

DC

 

[trythis]

For heat, I recommend these kinds of tube heaters. They make everything warm, no blowing air and low electric load. I dont know the best one to suggest, but this one would be great. Set it 50 and you'll feel great, like the sun is over your head.
https://www.farmtek.com/farm/supplies/prod1;ft_heaters-ft_tube_heaters;77ed2f2c_103192L.html
You only need one hole in the roof or wall, but if you use fresh air intake, your paints and solvents wont foul the tube.



I dont have any suggestions for AC except a couple window units or just a simple AC unit.

 

[uberschall]

Mini-splits and radiant tube heaters are excellent options but also several times the price of the heaters you're currently considering.

Unvented propane heaters are cheap and good to have around for emergencies, but not for permanent installation or continuous use. They'll introduce moisture, and you have to be careful about oxygen levels.

I learned the hard way after going through several versions of ventless propane heaters before finally getting a wood stove.

The combination AC/heater looks like a compelling option if electric rates are reasonable in your area - you can use the specs to calculate the difference in running costs of electric vs. propane - but I don't have any personal experience with a unit like that.

I'd say the vented propane heater is your best bet if you've already got a tank and it hits your budget target.

 

[theoldwizard1]

The most important factor is COST. Constraining the budget to shoe-string so that there's something left over for the cars.

There are 2 costs to consider. The cost to install and the cost to operate. If you have access to free/low cost wood, it is by far the lowest cost to operate.

Originally I was looking at this through-the-wall unit for both heating and cooling. I'm concerned that the electric heating element in that thing won't be up to the task and that it will be costly to run continuously to maintain a minimum temp in the winter.
At the other end of the scale is electric resistance (unless your PoCo has some special deal). Run away from this option !

Then I was thinking of splitting up the heating and cooling duties and going with this in-wall ventless propane unit for heat that I happened to see at the hardware store.

Ventless propane puts a huge amount of moisture INTO the building.

With the latter two options I would have to get a dedicated air conditioner separately, which isn't too big of a concern,

As others have said, go with a mini-split heat pump. Yes, it will cost a lot more than what you are looking at, but that is INSTALLATION cost, not operational cost. Shop the internet. There are some lower cost units. Most of the lower cost units do NOT do well when the temperature drops below freezing, so having some kind of portable heater might be a good idea.

 

[theoldwizard1]

For heat, I recommend these kinds of tube heaters. They make everything warm, no blowing air and low electric load.

They work very well, especially in very cold climates. Don't they tend to concentrate the heat in one area so that a fan is required to spread it around ?

 

[nukefission]

Whatever you do, I would personally add a ceiling fan, whatever suits your budget from the box store. The air circulation, even on low speed, will keep the mold growth down, even when humidity gets high. It picks up condensation back into the airstream faster than an organism can start using it to make a home. I leave my fans in the shop on low speed nearly year round.

I also see that your trusses are open and it appears to have a ridge vent. I would add some sort of a ceiling whether that be metal or drywall or osb/ply or ? Being able to enclose your own microclimate is the first step.

I do plan to add a fan or two. Although it does look like the roof has a ridge vent, in fact it does not. Just the turbine. I'll be insulating & OSBing the ceiling just like the walls.

Thanks for the feedback. I looked at mini-splits early on but a) the size I need exceeds my budget and b) the strong possibility of needing an auxilliary heat source defeats the purpose. Both HVAC systems in my house are new, high efficiency (21 SEER), and equipped with--and make regular use of--auxilliary heating (electric on one, propane on the other), so I imagine a mini-split would as well. I hear you about being a cheapskate, but it is what it is. All that said, due to their relative simplicity I could always add a mini-split later when I can afford it, and if the cheaper near-term options aren't panning out.

Electricity in my area is around $0.1018/kwh in the winter. Propane can get upwards of $3+/gal in the winter, but if I'm smart enough to plan and budget in advance I can defray that cost by filling up in the summer for half the price (~$1.60/gal). Some simple online calculators tell me propane wins the operational cost battle as long as I buy gas during the summer, which I should be doing regardless.

 

[Mike.VA]

Have you decided on your heating/cooling unit?

I have the same issue and thinking of installing a 4 zone mini split.

 

[nukefission]

I decided on the Mr. Heater 50k BTU unit linked above, but haven't purchased it yet because I've been preoccupied with other things in the space (wiring, insulation, paneling, painting). At the rate things are going and because this winter has been so mild in my area, I'm thinking I can put off the purchase until next winter.

I haven't completely ruled out a mini-split but still not too hot on those for the reasons stated above.

 

[Mike.VA]

This is the unit I am thinking about. I need to keep everything from freezing, (plan to maintain at 45-50 in winter) and the two other rooms (shop and kitchen area/ManCave) I would like to a/c and heat.
I don't have an issue running duct work, so I could even consider a standard heat pump, but have not priced one of those out.
Since the use of the unit would be small, I am thinking this would handle the space well.

Product Details ; Pioneer Air Conditioner Inverter, Ductless Wall Mount, Multi Split System Air Conditioner & Heat Pump Full Set, Quad (4) Zone, by PIONEER Air Conditioner, $3,251.50