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Re: Heating a garage or hanger

Posted: Wed Jan 03, 2018 1:50 am
by Bruce Fenstermacher
Thanks Brian. That’s a good data point. I’m probably over thinking the calculations.

Re: Heating a garage or hanger

Posted: Wed Jan 03, 2018 6:48 am
by DaveF
When I spec-ed the radiant floors heating for my house I was amused to see how "real" HVAC guys do it -- room size, wall insulation, and delta-T, then look up a BTU number in a table, add 50% and you're good! Or maybe it was 100%, I don't remember. :roll:

Re: Heating a garage or hanger

Posted: Wed Jan 03, 2018 1:18 pm
by Bruce Fenstermacher
Dave, in my experience installing a heat pump and retro fitting my house with air vents, and then a few years ago replacing that heat pump with a geothermal system, HVAC guys are not interested in the detail work necessary to calculate heat loss when installing a system. They pretty much swag it. For example my house could use either a 2 or 3 ton pump system. One would be a few dollars less efficient over a year than the other but it might heat and cool slightly better on 3 or 4 extreme days of the year. Splitting hairs really and that is reality. To a T, every installer I had bid on the job based on a 15 minute walk through. Little measuring. In fact, I had more bidders come cause I was dissatisfied with their method of determining what I really needed. I ran out of contractors I was willing to call.

However if you want an HVAC guy to do a better heat loss calculation call him in to trouble shoot someone else's work that is not working well. They will generate numbers showing the system is under/over size and how you can spend money with them to fix it.

I have a brother-in-law in the heating business. He sells fuel as well as maintains various heating systems. He knows heat loss and how to calculate it. I called him for his expert help on the subject and all he could say is he has a 4 car garage twice the size of mine. He has two 75,000 BTU heaters. He can pull his car in the garage being dead cold in Pittsburg winter and be washing his car in a T-shirt in 15 minutes. He says I should install 150,000 btus in my garage and I won't be cold. Now that's a swag. He also gets his energy fuel at cost so go big is his motto.

Re: Heating a garage or hanger

Posted: Wed Jan 03, 2018 4:06 pm
by GAHorn
Bruce Fenstermacher wrote:... go big is his motto.
Engines, anchors, bilge-pumps, etc.... bigger is better.

Re: Heating a garage or hanger

Posted: Thu Jan 04, 2018 1:15 am
by sfarringer
I would consider a mini-split heat pump, but it would probably be higher in initial cost than the other options you are considering.
However, it would be more efficient than electric heaters, and you would get cooling/dehumidification in the summer.
Some of them have quite good efficiency ratings, and work at quite low outside temperatures.

I bought mine from Surplus City Liquidators, and installed myself. https://surpluscityliquidators.com/
They buy excess inventory, seconds, etc, and inventory is constantly changing.

Re: Heating a garage or hanger

Posted: Fri Jan 05, 2018 7:23 pm
by hilltop170
Bruce-
I heated my Alaska cabin with this 80,000 BTU propane heater for several years before I tied-into the electric grid. The coldest trip was +10°F and it took several hours to heat up the cold-soaked 16’x32’ stick-built cabin with a loft. Did I mention that was +10°F in Alaska and not Texas? Oh yeah, I did, in case it makes a difference. 8O

It provides instant heat in great quantities, it’s safe (within limits but more-so than a salamander), it’s fast, and it’s cheap. I think that covered all your bases.

On the negative side, it’s direct-fired, exhausts into the heated space (does not smoke tho), and is definitely a fire hazard (if combustable gasses are around).

It will put a lot of water vapor into the garage but once heated up, that water does not condense on anything and the heat output can be controlled at a comfortable temp. The vapor can be vented out by opening the garage door when finished with it.

In my cabin, at the time, there was enough air leakage in the structure I never had to worry about lack of oxygen or venting exhaust. (I did not build it, I bought it like that and it is sealed very well now).

And, you can get one today at the home improvement or hardware store and use it until your long-term solution is operating. You could be machining in comfort in a couple of hours. :D
80,000 BTU propane construction heater
80,000 BTU propane construction heater
Just make sure you don’t set anything on top of it before it cools off, especially a black plastic bag full of garbage!

Re: Heating a garage or hanger

Posted: Fri Jan 05, 2018 9:47 pm
by Bruce Fenstermacher
Before George asks, that propane heater Richard pictured IS NOT hanging off the wall. And if all but George click on it, it will rotate to the floor. It is a magic picture unless you are George.

Richard, would you believe I own one of those propane heaters. it was given to me to make a airplane preheater out of which I did by removing the 12" chimney, blocking 3 of the 6 jets and installing a 6" dai, 2' tall chimney with a 3" flexible aluminum heater duck out the side. Opposite the 3" heater duct, I installed a 12v electric squirrel cage type fan to force air up and out the duct. It was one heck of a preheater.

I had a Cherokee at the time. I'd sit the heater next to the Cherokee at the fire wall. Run the flexible duck under the cowl and point it up at the engine. Engine was warm in no time no matter how cold. When I got the 170 I did the same thing but the cowl being higher off the ground the duct barely made it to the bottom of the cowl leaving a large gap. Still so much hot air the engine was warm in no time. Later I was given a old Red Dragon heater that stood up and installed a T for two ducts to the front cowl openings of the 170. I retired this heater before I melted an airplane.

Last year I decided, as of course I kept all the original heater parts, to reinstall the original chimney and drill out the closed jets. I thought burning propane might be more pleasant to Teresa's nose than kero/jet A. I fired up the heater in the garage for a test run and asked Teresa if she smelled anything. She said besides the propane, no and asked what I burned? I asked her if propane, which I have to buy was more pleasant than the free JetA I have to burn. She said no. As I needed to work on the propane heater to make it safer, I had to temporarily remove the safety for the test, it was easier to just burn JetA in my torpedo heater.

Teresa has a very very sensitive nose.

Re: Heating a garage or hanger

Posted: Fri Jan 05, 2018 9:51 pm
by GAHorn
Bruce Fenstermacher wrote:...Teresa has a very very sensitive nose.
I think you've just got the perfect aviation-oriented wife..... She likes the smell of Jet-A! :P

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 9:30 am
by hilltop170
OK Bruce, here is some real-world data to use in your decision process.

My buddy here in Alaska has a 22’ x 24’ detached garage that is insulated, with two insulated 8’ overhead doors, and concrete floor.

He has a discarded 80,000 Btu natural gas forced air heater he got for free that stands in the garage with the intake above and two 8” discharge ducts below pointing up. The combustion exhaust is 3” sch 40 PVC and the condensate drain goes thru a hole in the slab (may not be to code). He said the heater could be converted to propane with different gas jets. I would prefer the intake below, to pull cold air off the floor, but free is free and you take what you can get.

It was -5°F outside and the garage was at 60°F. The heater cycled on about every 10 minutes for about 5-8 minutes but I didn’t time it. We were casting lead bullets and had a 1000cu.ft./min maximum rate exhaust fan running on low at the same time above the lead pot so there was continual heat removal.
80,000 Btu natural gas forced air heater
80,000 Btu natural gas forced air heater
Heater data plate
Heater data plate
22’ x 24’ detached garage
22’ x 24’ detached garage
-5° oat at 3:00pm looking due south, 35 miles north of Anchorage
-5° oat at 3:00pm looking due south, 35 miles north of Anchorage

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 12:08 pm
by sfarringer
Good to know that there's another bullet caster around here!

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 8:42 pm
by hilltop170
:wink:

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 8:55 pm
by GAHorn
Last time I witnessed Richard casting bullets.... he was casting them at the rate of 650 rounds-per-minute .....out the barrel of my Sten. :twisted:

Now THAT'S A HEATER!

BTW... I have an almost identical furnace/air-handler I'll give to anyone who'll pick it up or pay shipping. It's also rigged for nat gas.
I don't believe the comment about simply converting it to propane by changing the jets tho'. Nat gas runs a different regulator also and that costs over $120. I know because I was planning the same thing and decided I'd rather spend the $120 toward a new overhead furnace.

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 9:05 pm
by hilltop170
That was fun George, I still have a few thousand 9mm left if you want to do it again.

You're probably correct about converting to propane, he never did it, just speculated it was just the jets that needed changing.

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 9:14 pm
by GAHorn
The regulator must be "convertible" already. If the existing regulator is only NG or only LP... it's not economical.

You can come shoot hogs anytime you want to sit up late with a spotlight and a goofy dog.... I'll be sleeping until you "let 'er loose!" They seem to show up between 10PM and 4AM. My runway's a mess and now they've even begun to tear up my yard. The dog sleeps thru it or runs away...won't alert me at all.

If you REALLY want to spray that ammo away you can use the M-11. It runs at 1100 rounds/min. I'm going to sell it 'cause I can't afford to feed it. :lol:

Re: Heating a garage or hanger

Posted: Thu Jan 11, 2018 9:22 pm
by Bruce Fenstermacher
Thanks for the additional data point Richard. Adds towards the fact I'm on the right track about 50000 BTU.