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Discussion in 'Cold Weather Camping' started by PopUpSteve, Dec 3, 2018.
The heat exchanger temperature would depend on the camper inside temperature.
Simple way of looking at it. It would depend on the inside temp and air flow (BTU Out) + the BTU produced by the burners - the outside fresh air temp for the burn - the exhaust temp. There is a lot more math to it. but these are the things to take into account for the heat exchanger temp.
That is why a stand alone heater like a big buddy or a wave heater is so efficient. You don't introduce the cold air. You use the room temp air to rise the BTU out of the burn. Where the camper furnace is using the colder outside air for the burn.
But I still prefer the safety of the in-efficient camper furnace. I only bring my standalone wave-8 out for dry camping when I need to conserve my battery.
I am not going to beat this to death but the outside does not have a large effect on the flame temperature.
You are right it will not affect the temp that the propane burns at but by a few degrees. Most fuels have a set temp that they burn at.
But the cold air coming in the intake will make a difference. It will affect the air in the the temp of the combustion chamber. If you look through the small inspection window you will see a small flame in the combustion chamber compared to the size of the chamber. The furnace brings in a lot of fresh air from the outside to have the proper O2 mixture. This air requires being heated up. Since it is colder it reduces the temp the heat exchanger since the heater exchanger is several inches from the burning propane. It is kinda like wood burns at a certain temp depending on type and amount of water in it. During the summer you need to stand 4-6 feet away from the campfire. During the winter at zero degrees, you can have your feet maybe 1-2 feet away from the fire to warm up those cold toes. You have to warm up the air between your feet and the fire. But the wood flame is still t, which is much colder at zero than at 70+ degrees. But the wood flame temp is still about the same.
FYI I just came back from a long trip and had to refill one of my propane tanks. There was a person ahead of me getting a tank full. I asked the person fill the tank what the temp was when propane evaporated. Both the person ahead of me and the employee filling the tank said almost at the same time -44 degrees. The person ahead of me added that he was a delivery person for America Gas. I don't think 22 outside temps at degrees should affect your regulator, unless for some reason the outside vent got frozen up from water getting in it.
But it means that at -45 degrees you would have to pour propane out of the tank as a liquid.
I have never seen a furnace where the heat exchanger had anything to do with the combustion air.
Just try a simple experiment. It will take two different times of the year. Measure the the temps of the intake and exhaust of your furnace. Do it when the inside temp of the camper is at 65 degrees. Do it first when the outside temp is in the 50's to 60's, than do it when the outside temp is in the.
You will see the exhaust temp is much colder when the outside temp is colder. But since the trailer air is at the same temps "65 degrees air circulating over the heat exchanger is same, and as you pointed out propane burns at nearly the same temp regardless of the O2 temp. You have to ask why is it colder?
Now a furnace in a house most of the time is using the inside air to supply the O2. These camper furnaces use the outside air.
The inside air is circulated over the heat exchanger. The only thing that matters is the temperature of air as in enters the heat exchanger. Combustion air plays no part in this.
I will say no more because we are just getting redundant posts.
You could switch to Map-pro gas. It has a slightly lower boiling point and similar (slightly higher) pressure/temperature curves. And it burns hotter.
I wonder if anyone has tried this?
I used Map a lot in my shop. Heats steal up to cherry red 2x as fast as propane. It is much hotter. Not sure about using in a furance unless the specs include the use of it. But it would give you awesome heat.
I'm not sure I'd try it either, but it does raise interesting ideas.
Burn temperature Propane/Propylene (Oxygen): 4579F/5240F
Burn temperature Propane/Propylene (Air): 3596F/4115F (Estimated)
Heat of combustion Propane/Propylene: 2371/2181 BTU/cf
Propylene has fewer BTU/cf, but burns hotter. Hmmm.
Cook faster, fridge cools better, heater heats better? Or would the fridge boiler get too hot, heater exchanger be damaged?
Just for Sh!ts and giggles I looked up the refill cost for a 30# propylene tank. $133. That would be an expensive experiment to see if you burned up anything.
yep that would be great if you could do it.
Yeah. Maybe I'll go with PUGs and some Reflectix.
I would just bring extra propane tanks and switch them out when they start to freeze.