Propane Supply For Garage Heater

[dwall174]

I'm looking to install a 45,000 BTU heater in my insulated 2 -1/2 car garage. Can this be ran off of two 100lb. propane tanks?
And if so, approx. how long would they last?

 

[Steve W.]

CAN it be done? Yes.

SHOULD it be done? Maybe.

How well is the building insulated?

Will you warm it for use or keep it warm?

How warm do you want?

.

 

[dwall174]

The Walls are insulated with standard 3-1/2" insulation & covered with 1/2" OSB. I still need to finish some framing on the ceiling area above the overhead garage door, but once finished I'll have 6" batt insulation in the ceiling. Ceiling height will be about 7-1/2 feet, garage area 24' X 20'. 7' X 16' fiberglass panel & foam insulated overhead garage door.

As far as my heating needs goes. I figure on keeping it just above freezing (40~45 degrees) while not in there, and probably about 60 degrees while working out in the garage.

 

[zak77]

I have a 50K Big Maxx in my garage(24x24). i go through about 1 100lb tank per year and that's using it mostly on the weekends and very rarely during the week. My garage is uninsulated(walls and ceiling).

 

[dwall174]

I have a 50K Big Maxx in my garage(24x24). i go through about 1 100lb tank per year and that's using it mostly on the weekends

I currently have a DIY jury-rigged RV heater in the garage right now, but I'm looking for a permanent set-up.
I have a used 30,000 BTU RV furnace that came out of my old camping trailer, I installed it somewhat like a window AC unit in my garage.

It works ok, but it can't really keep up that well when it gets below 30 degrees outside.
I'll go through about (6~8) 30lb. tanks a year mainly using the garage during the weekends, & that's without having the ceiling finished/insulated.

Now that I'm retired & I'll be spending more time out in the garage, I want to install a more permanent garage heater.
I looked into getting a natural gas line installed out to the garage, but that's currently not within my budget!

​

 

[dcg9381]

I'm looking to install a 45,000 BTU heater in my insulated 2 -1/2 car garage. Can this be ran off of two 100lb. propane tanks?
And if so, approx. how long would they last?

I run a 30k BTU unit off a 100 lb tank. No problem. It's just about the regulator.

Apparently propane is 21500 BTU per lb. 95 hours or so... At full output.

 

[PoorUB]

It will run it just find unless it is -40F

A gallon of propane has 91,200 BTU,so one gallon will run your 45,000 BTU heater two hours. A 100 pound LPG tank holds about 19 gallons of LPG, so two tanks, 38 gallons, about 76 hours of running time.

Don't forget, your 100 pound tank can only be filled to 80%.

 

[Jackfre]

I can handle an empty 100#er myself. I can no longer handle a filled 100 tank. Oh, how the mighty have fallen Can you? Are you driving these tanks to the fill station or will your LP supplier fill the 100’s for you on site. Many will not. I would suggest that you contact a couple LP suppliers and see what the rental cost of a 250 or more is. It will be much less of a hassle for you and them. Also, you are buying at rack rate when you drag those 100’s in so gas cost rides the market over a heating season. So, Get a bigger tank, keep the 100’s for back-up or perhaps at the end of the season to avoid another fill

 

[dcg9381]

I have 2 100lb'ers. They will not fill them on site, so I have to transport them, upright, to Tractor Supply. They are literally at my limit to handle by myself when full. We would get about 3-4 months per bottle when living in the shop - but use was just hot water and gas clothes dryer. We only use propane as supplimental heat when it goes below freezing and our mini-split output drops substantially (ours were not designed for cold weather efficiency).

 

[dwall174]

I can handle an empty 100#er myself. I can no longer handle a filled 100 tank.

Same here!
I can handle them empty & full I would ether get my neighbor to help, or I can use my Harbor Freight shop crane/lift.

Are you driving these tanks to the fill station or will your LP supplier fill the 100’s for you on site.

I would have to take them to get filled. I have a small drop-axle utility trailer so they wouldn't be as high as say getting them out of a pick-up truck.

There is a LP supplier near me that will lease 100lb tanks & they offer a pick-up & exchange service, but that's based on a yearly contract. The extra cost for the service would not make it worth paying for during the warmer months.

see what the rental cost of a 250 or more is.

I live in a residential neighborhood that has access to natural gas, so they don't allow the larger tanks.
As I mentioned before I looked into having a natural gas line ran out to the garage, but I was quoted around $2000 a few years ago. I imagine that price has gone up quite a bit with these so-called Covid prices.

Even the 100lb. tanks are generally frowned about in the neighborhood, but if their kept out of sight in a lean-to style shed their usually not a problem.

 

[fitter30]

How Many Gallons of Propane in a 100 Pound Propane Tank? - Powerblanket

Propane tank and other gas cylinder sizing is not as easy as it appears. How much propane is in your 100 pound tank? We have the answer for you.

www.powerblanket.com

 

[dwall174]

We only use propane as supplemental heat when it goes below freezing and our mini-split output drops substantially (ours were not designed for cold weather efficiency).

I'm starting to think that may be the way to go?
They have some newer style mini-splits that supposably heat down to around "0" degrees *F

 

[beemerphile]

Another consideration with propane at low temperatures is the vaporization rate. It may tank a larger tank to get a vaporization rate that is adequate for your usage rate.

 

[pcmeiners]

"They have some newer style mini-splits that supposedly heat down to around "0" degrees *F"

Zero, try -26 at full rating. Propane is 3-4 times the cost of a very efficient min split to run on average.

Heating costs spreadsheet. You need to replace dated fuel costs with today's...as to the percent efficiency fill in 300% for average minisplits -400% for very efficient minisplits.

https://www.maine.gov/energy/sites/maine.gov.energy/files/inline-files/Home-Heating-Calculator.xls

 

[dcg9381]

I'm starting to think that may be the way to go?
They have some newer style mini-splits that supposably heat down to around "0" degrees *F

They certainly have some that will likely work great... It's been discussed many times. Spreadsheets have been provided on using those over LPG / NG also... Cold weather performance was not something that we typically care about down here, then we had an all time record cold storm.

 

[dwall174]

Cold weather performance was not something that we typically care about down here, then we had an all time record cold storm.

The opposite usually applied here in Michigan at least as working out in the garage goes. Generally, with the doors opened & a few fans running it wasn't too bad. Lately though we have been having a lot more humid weather which makes things a lot muggier.

 

[pcmeiners]

"The opposite usually applied here in Michigan at least as working out in the garage goes."

That is why the SEER numbers are not that important in half the states, the HSPF numbers rule in cooler climates. Seer numbers rule in hot states such as TEXAS

Minisplit running cost compare, you can compare SEER and HSPF ratings.....

https://www.energystar.gov/sites/default/files/asset/document/ASHP_Sav_Calc.xls

 

[Jackfre]

If you have the capacity in your elec. panel, pass go and directly to a mini-split or dig the trench and buy some 1” poly and run the gas line to the house. Hire someone to terminate the line if you are unable to do so. Propane should be your last option, imho. The mini-split will be spendy, but you will love it and it will take care of the humidity/cooling as well as the heat. Check for local rebates.

 

[PoorUB]

As I mentioned before I looked into having a natural gas line ran out to the garage, but I was quoted around $2000 a few years ago. I imagine that price has gone up quite

Are you willing to work a bit? I have done my share of underground gas for customers. Trenching is the hard part. Get a price to do the NG hook up and offer to dig the trench. It should drop the price by half if not more.
I would give a customer a quote if we dig, or they dig. I rarely dug the trench.
Natural gas is generally about 1/3rd the price of LPG per BTU. If you plan on being around for a while, the the NG hooked up!

 

[Firebrick43]

Same here!
I can handle them empty & full I would ether get my neighbor to help, or I can use my Harbor Freight shop crane/lift.

I would have to take them to get filled. I have a small drop-axle utility trailer so they wouldn't be as high as say getting them out of a pick-up truck.

There is a LP supplier near me that will lease 100lb tanks & they offer a pick-up & exchange service, but that's based on a yearly contract. The extra cost for the service would not make it worth paying for during the warmer months.

I live in a residential neighborhood that has access to natural gas, so they don't allow the larger tanks.
As I mentioned before I looked into having a natural gas line ran out to the garage, but I was quoted around $2000 a few years ago. I imagine that price has gone up quite a bit with these so-called Covid prices.

Even the 100lb. tanks are generally frowned about in the neighborhood, but if their kept out of sight in a lean-to style shed their usually not a problem.

Vaporization rate at 0 degrees for a 100lbs cylinder is 113,000 btus. So two manifolded together would be good for a 45,000 btu heater.

However

You can not put the cylinders/regulators inside a shed like that. They have to have one side open by code. Also note that the regulators must be outside. The regulators/tanks must be set away from windows, flues, AC, and other sources of ignition.

 

[dwall174]

Vaporization rate at 0 degrees for a 100lbs cylinder is 113,000 btus. So, two manifolded together would be good for a 45,000 btu heater.

Thanks, that answered another question I had!
On my DIY RV heater set-up (34,000 btu unit) I'm just using the two 30lb. tanks with the auto switching regulator set-up that I originally had on my old camping trailer. The tanks will freeze up at about 1/2 full when it gets below about 20 degrees.

You cannot put the cylinders/regulators inside a shed like that. They have to have one side open by code.

Thanks!
I didn't know about the shed needing to be open on one end.

 

[Firebrick43]

Thanks, that answered another question I had!
On my DIY RV heater set-up (34,000 btu unit) I'm just using the two 30lb. tanks with the auto switching regulator set-up that I originally had on my old camping trailer. The tanks will freeze up at about 1/2 full when it gets below about 20 degrees.

Thanks!
I didn't know about the shed needing to be open on one end.

vaporization of a 20lbs cylinder at 0 is 36000. I should have explained that that is full, as the level drops so does the vaporization rate, not quite proportional but not to far off either.

Technically it needs still to be open on two sides but the code is changing next year. I don't know if you state adopts the new code with every update or waits several years.

 

[alwaysFlOoReD]

I wrap a battery blanket around my tank when it's below freezing.

 

[dscheidt]

Don't forget, your 100 pound tank can only be filled to 80%.

80% of the volume. the 100 lb rating is the actual propane capacity of the tank, already accounting for the require free head space. If you look at a small propane tank, they will have a water capacity stamped on them, WC and a number. For a 100 lb tank, the WC is 239. That's the weight of water the tank holds, full to overflowing, in lbs. 239 pounds is about 28.5 gallons. 28.5 * 80% = 22.8. 100 lbs of propane is 22.9 gallons. (20 lb tanks are the same way, 20 lbs is their actual capacity. Anyone who says it's less is either a lying tank exchange company, or someone suckered by the exchange companies. )

 

[PoorUB]

80% of the volume. the 100 lb rating is the actual propane capacity of the tank, already accounting for the require free head space. If you look at a small propane tank, they will have a water capacity stamped on them, WC and a number. For a 100 lb tank, the WC is 239. That's the weight of water the tank holds, full to overflowing, in lbs. 239 pounds is about 28.5 gallons. 28.5 * 80% = 22.8. 100 lbs of propane is 22.9 gallons. (20 lb tanks are the same way, 20 lbs is their actual capacity. Anyone who says it's less is either a lying tank exchange company, or someone suckered by the exchange companies. )

Ok, I am not overly familiar with LPG tanks.

I dealt with refrigerant recovery tanks and we could fill the to 80%. We had to do the math and figure it out. I figured a LPG tank was figured the same, but apparently a 100 pound LPG tank is really a 125 pounder. Probably the same tanks we used for refrigerant recovery. We called them 125's, but could only put about 100 pounds in one.