Hangar heat

[N8293A]

I am trying to decide what type of heater to install in my hangar. I have narrowed my search to either a forced air ceiling mount heater, or an infrared "tube" style heater. I have done some research on this and understand the principle pros and cons of both styles but still am having a hard time deciding. I have experience with the forced air style from my previous hangar. My concern with the forced air unit is, you are heating the air and when you open the hangar door all that air is lost, and recovery time is greater. With the tube style I understand you are actually heating the objects in the hangar. With the tube style, since you are heating the objects (airplane) is there any concern about heating the airplanes surface and then exposing that surface to extremely cold outside air? Is anybody out there using the infrared tube heaters in their hangar? The hangar is 50X60, well insulated, and has a bathroom, loft, and office. Any advice or comments to aid in my decision making process would be appreciated

[canav8]

Steve my concern is UV light ageing everything it is exposed to. Forced air can be more expensive but it just depends on your climate. I am for forced air. I have a suntaned airspeed indicator face for proof of long term infrared exposure.

[DaveF]

Steve,

My hangar is 42x50 and has overhead IR tube style heat. For just a hangar you want IR, not forced air. You can open the door and within a minute of closing it you're comfortable again. If you're trying to make the entire space livable then forced air might seem like the way, but I think IR is so superior that I'd choose it. I once put my airplane in a hangar heated by a forced air box, and 20 minutes later the place was still cold.

Is the office a separate enclosed space that you could heat? My mechanic's hangar is 80x100, heated by overhead tubes. It's very comfortable to work in, but his office is enclosed and heated with a couple of small electric space heaters, which make it very cozy.

My airplane sits directly under the heat tube and gets warm to the touch if we turn the heat up beyond 60, but normally it's set at 50 and the airplane stays cool. I don't know if the temperature is a problem, but if you're worried about it you can turn the heat off when you start the preflight, and by the time you're done the airplane will be at the air temperature, and cooler than it would be with forced air heat.

Dave

[hilltop170]

Steve-
My 45'x45'x20'h hangar in Anchorage, Alaska has a Reznor overhead gas fired forced air heater hanging in the back corner near the roof. If sized correctly, a Reznor will easily heat any size hangar to whatever temp you want. I have a 500sq.ft. loft office as well. The Reznor heat stratifies warmer air high and the hangar floor stays cooler without some additional circulation such as ceiling fans.

I am ok with that as when I am upstairs I prefer to stay warmer and when I'm working below, I prefer to stay cooler. Because of that, I don't particularly like the feel of the radiant heat directly warming my body. The hangar is polyurethane spray foam insulated all around and is very tight. My gas bill in the winter is around $40/mo with the thermostat located at 4' above the floor set at 45°F. The forced air blows directly down to the area where the plane sits and it will deice my plane in short order. I have supplemental gas heat upstairs but have never even hooked it up, the Reznor keeps the temp at 65°F upstairs when the floor is 45°.

The radiant gas tube heaters work very well also so I can't really say one works better than the other. It depends on the situation. If your hangar is not insulated well and sealed up tight, the radiant might be better for you. The hangar behind mine has radiant heat and it works very well for him as he works on the floor most of the time. The radiant heat will also warm the air inside the hangar which will be lost when the hangar door is open just like the forced air units. Recovery time is probably shorter wih radiant but I don't have any experience with it.

Air does not hold much heat on its own so even when I open the hangar door on a cold day, the ambient heat in the hangar warms it back up fairly quickly. I would suggest you try to compare initial and operating costs of both systems as part of your research. I have no idea of radiant operating costs, maybe someone will post their radiant system costs. Then figure in how well your hangar is insulated and sealed up. Personal preference also figures in. The Reznor provides even heat to the air mass, the radiant heat heats objects directly even when the ambient air is cooler.

As far as pulling a warm plane out into the cold, that is not a problem in itself, the plane doesn't care about the temp change. However, if there is freezing precip going on when the plane is pulled out, it will melt on the warm plane then re-freeze as the plane quickly cools off. If that happens, you are back into the hangar to de-ice. Good luck.

[flyboy122]

Steve,

We had both, and after experiencing the radiant we would never go back. The forced air heater only heated the air 4 feet and higher. Your feet froze, etc.. and when you opened the door it was all gone. The tube heater solved all that. Plus, it was amazing how fast it could heat the hanger. The neat part was that it heated the floor, tools, plane, etc... You would be surprised how much warmer 55 deg feels with warm floors vs warm air. I seem to remember Dad saying it was cheaper to run. We never had a problem cooking the plane.

You do need at least a 12 foot ceiling, and a couple inexpensive ceiling fans do help even things out. (For example: it will be cold under the wing of your 170.)

DEM

[edbooth]

We have a four ton heat pump that does an acceptable job in our 50x60x16 insulated hangar. I do have to run an auxiliary fan to help circulate the air. A couple ceiling fans would work better. I don't think heat pumps work too good in your harsh environment Steve.

[wingnut]

Next hangar will have a heated floor. One of the paint shops here has this system and it is superior in every way.

[N8293A]

Thanks guys for all the replies. My old hangar had a Reznor unit and it worked fine. I have the option in this hangar to do either so I thought I would tap some of the forums collective wisdom. If I were building a hangar I would definitely do radiant floor heat, unfortunately that is not an option. I will likely not heat it above 40 or 45 degrees on most days anyway. The loft and office can easily be supplemented with a space heater. I am leaning toward the radiant tube heater right now.

Thanks again guys!

[jrenwick]

Hi Steve,

Here at Lake Elmo, MN (21D) it's very common to see the radiant tube-type heaters mounted above the hangar door, across the front of the hangar. There was one in the hangar you used when you were here for hockey a few years ago. I've never heard anyone here raise cautions about using them.

Mine is 150,000 BTU for a 40x60 hangar with a 12-foot ceiling, and next door to me in the same size hangar is a 125,000 BTU unit. They both work well for that size building, but I think mine warms the place up faster than the smaller one. I keep the thermostat at 46 degrees when I'm not there, and I don't preheat the airplanes. When I'm in the hangar I raise it to 60 degrees. My thermostat is in the rear corner, but my neighbor has his on the front wall below the burner unit, and he says that works the same (the reflectors direct the heat away from it, so it probably responds to the floor temperature more than anything else.

The radiant units seem to heat the floor, which is very nice -- almost as good as in-floor heat, and the inside air temperature seems to recover pretty fast if you have to open the big door. I installed the two fans you see in the photo, but I find they're not needed and I very seldom turn them on.

[N8293A]

John,
Thanks for the advice. I am definitely leaning toward the radiant tube heater. Now the question is where to locate the tube. I've seen just about every type of installation. Down the middle, sides, and like yours across the front. My gas service enters the hangar near the back of the hangar so that will likely play a role in locating the unit. It seems to me it would be better to locate it so that it has a clear view of the floor area, so that the heat is concentrated on the concrete floor rather than the airplane, or other objects in the hangar.

[jrenwick]

Steve,

The radiant heater heats unevenly when it's burning. You'll feel the most heat at the end of the tube closest to the burner, less at the far end, and of course less radiant heat as you move farther away from the tube. This is less prounounced once the hangar is up to thermostat temperature and the floor is warm. In my setup, the hot spot is to the left of the photo, in front of the Swift's left wing. The service door is there, and I have a table and chairs. It's nice to sit under the fire -- the toasty warmth helps me relax and think better when it's cold out. I've never been concerned about too much heat hitting the airplanes; The fabric-covered one might be more sensitive to that, but it's usually in the back. As I said before, there are a lot of these setups on the airport, and I've never heard anyone worry about overheating airplanes.

The installation I have is the most common one here. My gas meter is at the back of the hangar, so there's a length of black gas pipe along the ceiling from the back to the front of the hangar. The radiant tube expands and contracts a few inches each cycle. It's suspended with chains that allow it to move, but because the cold end is fixed to the exhaust port on the far wall, it's the burner unit that moves the most. I use a 360-degree loop of soft type K copper pipe to connect it to the black pipe, which is flexible enough to allow movement. When I bought the hangar, there was a flexible hose there -- the corrugated metal kind, if you know what I'm talking about. The rate of flow through it for 150,000 BTUs was enough to make it whistle like one of those plastic tubes they used to sell that you swing around your head to make a noise, and it was very annoying. Don't do that! Combustion air comes from above the ceiling insulation through an insulated flexible duct, so the unit has no effect on the air pressure inside the hangar.

I hope this helps!

[flyboy122]

If I were building a hangar I would definitely do radiant floor heat, unfortunately that is not an option.

I used to think so too, but then I put in floor heat in my house. I love it, but....it has some quirks. The biggest is that it does not like to change temperature. We set it at 70 in September and don't touch the t-stat until May. If you want to go from say 65 to 70 it can take hours. This is fine for my house because it's very efficient, and we are there every day. Unfortunately, I'm not in my hanger every day (oh how I wish! ). I'm not going to keep it at 60 for the few hours a week I'm there, but if I keep it at 45 then I shiver when there or wait a day for it to warm up. Hence the tube heater provides the best compromise of quick, efficient, radiant heat.

It may be right for you, and God willing someday it will be for me, but just like airplanes look at your mission and pick the heat that matches.

DEM

[GAHorn]

When Dubya (W.J.Langholz) came down to TX two years ago and expressed his opinion as a Minnesota farmer... he thought more of radiant heat than forced air... and the major reason I got from it was dust. Forced air will move dust...if you have a problem with that. (Did I get that correct, Dubya?)

[hilltop170]

Another viewpoint, forced air heats the air that circulates wherever the air flow takes it. When the heater fan turns off, the warm air naturally stratifies in the middle to top of the air mass inside an enclosure. Without constant circulation of some sort, the air at the floor will always be cooler, which translates into less heat lost to the ground. That is how I choose to heat my hangar in Alaska. My gas bill runs around $40/mo thru the winter set at 45F.

Radiant heat warms all objects within direct line of sight of the radiant source, it does not warm the air much and does not go around corners. Then by convection, the warm objects transfer heat to the air and other objects. It warms the objects in line of sight very quickly.

In-floor heat warms the concrete in which it is encased. The heat then warms the rest of the area by convection. It is slow to react both ways, warming up and cooling down due to the large thermal mass of the concrete. Part of the heat will always go down into the ground which is a huge heat-sink, no matter how much insulation is below the slab, so that heat is effectively lost.

What kind of heat is best for any situation depends on how the area is going to be used. Drafty, less well insulated areas or short-term or infrequent use might be best for radiant heat. Well insulated areas and the need for constant use might be best for forced air or in-floor. Where ambient temps vary frequently, in-floor cannot react quickly enough to stay comfortable. Any type heat will work in any situation but efficiency of each system is different depending on how it is used.

[GAHorn]

Yeah... I want heat in my hangar only about week or two in winter. When I want it warm out there, I want it warm NOW....not necessarily continuously. I'm not trying to keep things warm. I'm trying to do some work out there for a few hours and not freeze myself.

I think that speaks well for forced air heat, which is what I will probably do if I can ever find a second-hand propane 100K btu heater from a warehouse, etc.