30,000 btu direct vent to much?

[akdube]

got a insulated 8x12. floor walls roof all insulated. The lake this shack is going on hits -30 almost nightly coldest we saw it last year -54. 30k btu to much or not enough?

[Melbs7]

it can always get turned down.... also... I would assume that it has a built in T-Stat....

[akdube]

Built in but on a wire probably 3 foot long. How low could I turn it down and guess on propane usage?

[mud_n_fun]

I sure hope your using a 100lber for it! Otherwise your going to go through alot of 20's.

[Melbs7]

Built in but on a wire probably 3 foot long. How low could I turn it down and guess on propane usage?

Well as long as you're using the T-Stat.... most of them turn "down" themselves and then of course cycle off when not needed.... so the size of the unit is irrellevent as long as it is big enough.... which I am sure it is.

[Nor Easter]

You could always use 30 or 40 pounders as well

http://www.propane101.com/consumerpropanecylinders.htm

[Melbs7]

30,000 BTU's isnt all the excessive for a 20 ln tank guys. Think about it..... if a big buddy at 18,000 BTUs last around 5 hours on 2 lbs of propane a 30,000 BTU heater should last about 27 hours (since they only fill them to roughly 18 lbs) on a 20 lbs tank.......

[mud_n_fun]

He said -30 nightly! That heater will be on alot.

[Nor Easter]

(since they only fill them to roughly 18 lbs)

See the dimensions chart in my above link. A 20lber weighs 18LBS empty and it weighs 38LBS full according to them.

A reason I have felt unfavorable to LP in the past was due to it`s inability to work properly at very cold temps when you need it the most. See the 1st chart here and also note the statement just below:

In cold climates, in order to keep vaporization of LP-gas at the highest level, keep the fuel levels above 50%.

This is where Coleman/unleaded fuel and kerosene appliances (torpedoes but more-so wick burners) quickly get ahead of propane (a wood stove is nice here also, probably KING!  ), basically at 0°F and below, I begin bringing out heaters that won`t let me down. I`ve seen times I can light a propane torch or torpedo heater but it soon malfunctions as the frost begins to form on the tank. Not a welcome feeling when you are shivering almost uncontrollably!    MAPP and Acetylene do not have this problem.

Also, while LP`s BTU rating per gallon is 91,500, a gallon of #1 kero is 135K so it is ~50% more efficient if you are considering the weight as part of your transportation for the day let alone cost per BTU. On average in my area at present, kero is about 5% more expensive than LP so the difference is negligible although the BTU advantage is still substantial.

I think I`ll stick to what I already have which is a variety of Coleman and kerosene fueled devices starting from 7,500 BTU to about 22,000 BTU per heater. If I need more heat, I`ll bring more than one heater...  8)

[poorfisherman]

Ive had alot of trouble with propane in those cold temps.  It seems to gel up on a guy.  I stick to wood now.

[ice dawg]

I have a 6 1/2' x 12' drop down shack and it heats very well with a 15,000 BTU direct vent heater. The walls and ceiling are insulated but not the floor. I think you will be ok with a 30,000. If you have a problem with the propane not wanting to vaporize, you can keep a tank inside to keep it warm and switch them if you need to. I would be sure the tank inside isn't leaking. Are you talk ing about heating it only when you are using it???

[akdube]

yeah only when there will I be heating it. Aproblem we had in the past was the propane "geling" but we will keep the tank inside and a co2 moniter at about 3 foot level. are you guys calling a 20lber a gas grill tank? Thanks.

[ice dawg]

A twenty pounder is a gas grill tank. Here is a chart that I found that may be of some help. I also read that if you hook two tanks together in a Y configuration going to a regulator, you would get double the vaporization of one tank.


Vaporization Rates of Cylinders   

Output in BTU's per hour - Vertical Cylinder 25% full - Minimum Cylinder Pressure 10 PSI

 

                                                          Cylinder Size

Outside Temperature 20 30 40 100 200 420
+60F 24,000 32,000 40,100 79,700 125,900 185,500
+50F 21,200 28,300 35,500 70,600 111,500 164,300
+40F 18,450 24,700 31,000 61,500 97,200 143,100
+30F 15,700 21,000 26,400 52,400 82,800 122,000
+20F 13,000 17,300 21,800 43,300 68,400 100,700
+10F 10,250 13,700 17,200 34,200 54,000 79,500
0 7,500 10,000 12,600 25,000 39,500 58,300
-10F 4,780 6,400 8,000 16,000 25,300 37,100
-20F 2,050 2,700 3,400 6,800 10,700 15,900

[Tainterslayer]

What kind of insulation do you have in that shack?? 1" foam board? 3.5" fiberglass?? Your r-value is going to make a huge difference.

Don't buy the bare minimum because you will always want to get that shack heated up fast. A 10k btu heater would keep it warm but it obviously won't heat it up as fast as a 30,000 btu model. What kind of levels does it have, 30k and 15k btu? Make sure you get something that would have a real low level of heat because you really dont want to have to get up every 5 minutes to turn it on/off when its NOT 50 below

[akdube]

Well I have 1 1/2" foam board throughout then I chalked all the seems in the shack not to concerned with the shack holding heat as the floor has never kept ice or water onit for that fact for anyamount of time. I also run 2 battery fans on the lid to keep the air moving. Thanks again for all the replies.

[phredder]

What kind is the make and style of the heater?  I use a B.D.Wait 30,000 BTU space heater to heat a 12 x 6 x 6 Clam Command Post pop-up.  The heater is either full-on or off and is controlled by a hydraulic thermostat run off the valve assembly (looks like a copper bulb attached to a copper wire).  So far the one 20lb propane tank has run a turkey fryer for 2 hours and has heated my pop-up for 12-13 hours.  Your shelter is insulated, mine is just material walls so the heater is full-on quite a bit of time.  Not sure how much longer the tank will go but I would think the same size of propane tank in your set-up would last a few days of steady use.

Mike

[DRR324]

Just to offer up some experience here, I work in the propane industry, and use it in my perm shanty as well.
My shanty is 5' x 8' by 6'6" tall.  My heater is a metal box 14" x 14" by 14" tall- I installed the burner out of a bradford white water heater inside.  This is the cast iron job, with an output of 34,000 btus on high.  I ran a small wheel valve to it, just open the valve to light it, and then adjust from there.  Wide open- it only runs about 3/4 of what it normally would.  So, figure 24,000 btu or so.  I also run two paulin gas lights.  I run the system off of a 30lb cylinder, and fish many late nights.  Lowest temps encounter here in central michigan while in use have been -15.  Some frost showed on my cylinder, but not cold enough to stop it from working.  Propane will slow and quit vaporizing near -40.  My trick is to mount my cylinder bracket on the side of the shanty close to my vent pipe (on the outside) this enables my cylinder to contact the wall where it is considerably warmer than the outside air.  The cylinder will absorb some of the heat- and thus continue to work until it is empty.  I can run the 30 lb tank for a solid 40 to 50 hours of run time.  If you are in a colder climate, use a 30 or 40lb tank, and mount it on the wall nearest your heat source for the best case scenario.
Also, the other night was 8 degrees outside, with solid 10 mph winds, and running the lights and heater on just less than 1/2- it was a balmy 75 degrees in the shanty.  Only insulation is 1" blue board on the lower 1/2- just on my backside, and on the roof.  Sides and front are not insulated.
Hope this helps someone!

[Drifter_016]

I heat my house with propane here in the NWT.
I have not had any problems with gelling even at temps down to -52C.
The reason I have not had any problems is due to where my tank is located.
It is at the bottom of a 10' slope and because of this it gets burried with snow.
The snow works as a really good insulator. You Alaskan guys get lots of snow don't cha?
When you put your bottle outside shovel a bunch of snow over it and you should be ok.   

[akdube]

Installed and holey cow way to much. But it does have a therostat so we just crank it down a bit, works great got 3 day out of a 30lber just ran the heater. And it was cold maybe -20 highs and low -30's at night. Thanks for the help guys...Dube