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daleslad
Member
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# Posted: 28 Jan 2011 06:16pm
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Hi, great forum and lots of hands-on know-how here.
Got a small cabin at 7300 ft. snowed in every year but like to visit for a day now and them just to enjoy the scenery.
I have a wood stove but I'd like to install a propane heater to have a more instant form of heat.
When I am only there for a few hours I don't want to waste them stoking up a wood fire.
After reading one of the other posts I liked the idea of installing a Williams 14K wall heater but after reading the specs it's only rated up to 4500 feet.
Does anyone have a cabin at the same altitude and if so how do they cope using a propane heater.
Thanks for any suggestions.
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Rob_O
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# Posted: 28 Jan 2011 07:38pm
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There should be a high altitude kit available for that heater. Call the MFG
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daleslad
Member
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# Posted: 28 Jan 2011 08:26pm
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Thanks Rob, I can do that.
The room I am intending to heat up with that heater is about 180 sq. ft. how good a job do you think it will do.
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MtnDon
Member
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# Posted: 28 Jan 2011 08:59pm
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Our cabin is at 8800 feet. We have wood heat and a Housewarmer propane wall heater (from Northern Tool). It's rated at 18000 BTU/hr, at sea level. For every 1000 feet above sea level anything that burns fuel with air at atmospheric pressure loses about 3%. So at 8800 feet our heater is derated to about 13,250 BTU.hr... That 14K unit at 7300 feet would be about 10,900 BTU/he.
For high altitude operation a smaller propane orifice is installed. There's less air, so you need less fuel. Changing the orifice will help prevent the burner from burning rich and producing excessive soot.
I got the correct orifice from the manufacturer at no charge by phoning their customer service number. I had not even bought the heater yet, but on my saying I would they shipped the part n/c. I can't say if everybody's service is as good as that.
For a space of only 180 sq ft that would probably be more heater than you need. Is it insulated? If the heater is too big for the space it will heat up quicker, but there is a downside too. Depending on how much mass there is in the burner combustion chamber you may overshoot the indoor temperature you wanted. When the thermostat cuts off the burner there can be so much stored heat in the burner box that the room keeps warming. I have a friend who ran into that problem and switched to a smaller heater because of it.
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Rob_O
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# Posted: 28 Jan 2011 09:19pm
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Adjusted for altitude and efficiency you should still get 9K BTU output. That's more than enough to run you out of the place if you can keep the wind out
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daleslad
Member
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# Posted: 29 Jan 2011 02:28am
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Thanks fellas, good information. Don could you tell me how large a room you use your heater in and what size pipe you run to it.
My cabin walls are insulated but not the roof and the peak of the roof inside is about 14 - 16 feet high so it takes a bit of time to heat up.
I'm also curious about the safety issues with using the propane tank in the winter when it's piled high with snow.
I normally turn off the gas at the water heater and also at the tank when I close the cabin down for the winter.
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MtnDon
Member
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# Posted: 29 Jan 2011 09:49am
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16x30x8 ft ceiling. R19walls, R45 ceiling, R20 floor
1/2 inch ID pipe
I don't believe snow piled on the tanks is as much of an issue as low temperature might be if you are using small tanks (20, 40 pound) The cold lowers the vapor pressure. The vapor pressure also falls as the tank level decreases and the smaller the tank the less the vapor pressure. This all affects how many BTU's of fuel can be delivered from the tank to the heater. With all the above it is quite possible to have insufficient fuel volume available at the heater. I have charts but will have to look up the link info later.
100 pound tanks and larger are able to deliver enough propane when cold.
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daleslad
Member
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# Posted: 29 Jan 2011 12:54pm
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Thanks Don, I have a 250 lb. propane tank situated about 20 feet away from the cabin.
I was told their is insulation in the walls but no idea how much. There is none in the roof, the floor I insulated last year because 2/3rds of the room is on stilts and exposed to the elements. I have also since then enclosed the stilts with siding so it has to be a lot better than it was.
Do you see any problem with leaving the propane turned on at the tank all winter. It would certainly make it easier with not having to dig the tank out to turn it on if I am up there just for the day.
Would that be black iron pipe or copper tubing you ran to your heater.
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daleslad
Member
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# Posted: 29 Jan 2011 12:56pm
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Quoting: Rob_O Adjusted for altitude and efficiency you should still get 9K BTU output. That's more than enough to run you out of the place if you can keep the wind out
Rob, in your experience with the smaller unit just how long did it take to heat up a room that size.
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Rob_O
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# Posted: 29 Jan 2011 01:49pm
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I have no experience with that unit. I'm just an HVAC guy by trade
The "rule of thumb" for an average older house is 1K BTU for 32 ft^2, or about 6K BTU for your cabin. Using Dons altitude adjustment and 80% efficiency you should get about 8700 BTU output from that heater
As I said before, unless there's a breeze blowing through the cabin it should be enough heat to run you out of the place
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MtnDon
Member
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# Posted: 29 Jan 2011 02:13pm
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I'd leave the tank on.
I used some black iron and some copper with flared fittings. Flared fittings are the only ones approved to propane. (no compression fittings, in other words).
My heater manual came with a chart for different sizes of pipes required for different distances. Be sure to allow for any other appliances that may be upstream of the heater, or downstream of it too.
Your 250 tank should work with no issues.
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daleslad
Member
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# Posted: 29 Jan 2011 03:11pm
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Thanks Rob, I'm looking for the most economical for day use only, the cabin wasn't intended to be a winter cabin. Sounds like the smaller unit should do the trick.
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daleslad
Member
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# Posted: 29 Jan 2011 03:14pm
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I haven't had a chance yet to scope out the sizes of pipe that are in use right now Don but the heater would be only appliance that would be in use during the winter.
The water tank is drained and I'd have no need to use the gas stove.
Thanks for the help and the link I will be checking it out.
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daleslad
Member
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# Posted: 18 Feb 2011 05:59pm
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Was able to gain access to my cabin in the snow and from the inside it looks like I have 1/2 stub up iron pipe to the back of the stove and another 1/2 stub up for the water heater.
Do you see any problem with running 1/2 copper pipe from a tee on the gas stove stub and over the heater I will install.
It would be about a 30-40 foot run under the cabin with difficult clearances.
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MtnDon
Member
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# Posted: 18 Feb 2011 07:16pm
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It should work but to be certain you should add the BTU for both the stove and the heater and check this chart to be sure both could run at the same time. More than likely they bith can.
Notice that iron pipe measurements normally mean I.D. and copper tubing (flexible , comes in a roll) is most often sized by the O.D. and that makes a substantial difference in flow capacity
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daleslad
Member
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# Posted: 18 Feb 2011 08:12pm
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Thanks Don I see by the charts that the pipe I.D. is slightly larger than the 1/2 inch copper tubing I.D., do you think it would be necessary to go to 5/8 tubing.
I can't foresee the stove and the fire ever being on at the same time as it very rarely gets used.
The water heater is drained for the winter so that wouldn't be a problem.
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MtnDon
Member
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# Posted: 18 Feb 2011 08:26pm
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If you have a typical range and a typical small cabin heater you can pretty much be sure it will work.
Look up what the BTU's on the heater is. If you have the installation manual it should list pipe types and lengths of run and what size pipe/tubing is needed. If you have 1/2 iron from the source to the range see what the capacity on that run to the stove would be from the charts.
The numbers in the body of the table are the capacity where, for example, 1/2 iron/steel sched 40 up to 40 feet length can pass 110,000 BTU/Hour. That is likely enough for both the range and the heater ratings. Ranges typically are 50,000 BTU/Hr or so max.
Then 1/2 copper (OD) is good for either 35,000 to 40,000 BTU.he depending on type of copper.
Check the BTU ratings to see if it falls within that range.
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daleslad
Member
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# Posted: 19 Feb 2011 01:23am
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The one I'm thinking about getting if I can physically locate it in a good place is the Williams 14,000 btu/hr, but it will be less than that at the higher altitude so it looks like I will have plenty of capacity.
Thanks for all of the good info. Don.
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