[EricR]

Finally got my radiant tube heat installed in my shop/garage. It's a 32'x48' pole building and they spec'd a 40', 80,000 BTU natural gas unit. I thought that was a little low on the BTU side but two different companies that I had provide a quote spec'd the same size unit. I don't have any insulation in that building yet (other than one small area) but it is on my list to get done. Both companies based the unit size on an un-insulated building and being able to maintain 70 degrees. I told them it might be a while until I get the insulation done so wanted the heater to still be able to get it into that ballpark until I could get around to insulating.

They just finished the install and it has been running for about 3 hours now. Outside temp is 35 degrees and the pole building has only got up to 48 degrees. It actually got to 48 degrees about an hour after it was first started and has not gotten any higher. Not sure what to expect since I have never had one before so looking for some others with experience.

Does the BTU sound a little low?
Does anyone have a similar building with a similar size tube heater?
Does it just take a while to get all the "things" in the building up to temp before they start radiating back?

Any advice or experience is appreciated.
Thanks in advance!

 

[bloodrunsgreen]

That little small white thing can't heat that size building!!! Oooops, that's a garage door opener, Sorry. Do the doors have a decent seal, I know my garage doors tend to move in the wind and let snow/wind penetrate past the seals on the side.

Just remembered seeing one setups of those but it runs the whole length of the building on both sides, about half way on each side of the peak, with multiple service doors (auto service center)

 

[Dr Maphesto]

I LOVE the feel of radiant heat!

 

[rtgt]

It will take it a while to get everything warmed up.

 

[Rasman]

Once the concrete warms up it should be ok.

 

[Kennyd]

You'll spend more money in fuel than you would on decent insulation, I think you will go broke trying to heat that large space to 70* without it.

 

[Dr Maphesto]

I agree with Kenny.

You'll be money ahead hiring someone to come in and insulate if you cannot get it done yourself.

 

[ttazzman]

+2 ^^^^ insulation is the cheapest smartest thing you can ever do to a conditioned building ....because eventually it is free and starts paying you dividends......do it soon ...do it right.....

 

[Sharpie]

Not sure what your options are for roof insulation with the ceiling already being in place. The cap insulation is most important when it comes to heating the building. You need to foam anything in the walls that needs to be sealed prior to placement of any fiberglass batts.

 

[BWV]

Is your ceiling insulated? Looks like you have an interior ceiling surface...

Great idea to insulate... especially in a metal building, as in addition to fuel savings, it will help reduce condensation too.

I insulated my garage when I built it... 32'x24' with 10' ceilings, r19 walls r38 ceiling, I'm in upstate NY, it costs me about $180 a year in electric, using a little ceiling mounted 4800 watt electric unit to keep it 45-50 degrees. (It's 8 degrees F out right now...)

Eventually I may do an LP unit, but the cost of the heater, roofjack or wall thimble, gas plumbing, etc... might never offset the payback period (meaning.. $1000 worth of LP stuff and installation vs $90 electric heater.. if it saves me $80 a year.. would take 11 years to payback.. and the electric heater takes up very little space)

 

[iamrfixit]

A metal building in cold climate, you'll NEVER get that warm without insulation and you could go broke trying. A thin layer of steel wall rapidly transfers heat so every square inch of tin is essentially a giant heat sink. You'd have to pour heat into it faster than it dissipates against the cold wall surface. You'll probably get a ton of condensation in the process. As warm moist air hits the cold steel it will condense and pretty much rain down the inside of the walls.

Radiant can work because it heats objects instead of the air, so when you work in front of it you can feel warm, but actually heating the uninsulated space is expecting way too much. Hopefully the ceiling was insulated before the interior liner was installed, otherwise that will be difficult with the finished ceiling, unless you have an attic space above to blow in a layer. Typically about 80% of heat is lost through the ceiling so it needs a much thicker layer of insulation.

Insulation is always the best place to start when you decide to heat a building, in the case of a metal building it's absolutely essential.

 

[EricR]

Thanks for the input everyone... insulation is definitely on my list of things to get done. I can do it myself but will have to chip a way at it as time permits. There is about a 3' air void between the inner ceiling and the roof but it is not insulated yet either. It will need to be blown in so will be hiring a contractor to come in and do that part. I can do the walls myself and already have one section about 20' done (not pictured). Guess I'll get the wall insulation started next weekend since I tend to have more time in the winter than I do in the warmer months for projects like this. I do need to seal up any air leak on the walls before I put up the insulation though. As a friend of mine said who owns an insulation company: "think of the space as a boat and you need to seal it up to keep water from flowing in".

My brother-in-law has a much larger metal building for his fab/welding shop. It too is not insulated and he has two radiant tube heaters that do a fantastic job of keeping it in the 60's even when it is close to 0° outside. But that building is full of very large and heavy metal fabrication equipment so I am sure that is absorbing the radiant heat and convecting it back into the space.

Thanks again.... I was pretty sure I knew what I needed to do but figured I would tap the vast knowledge pool on this forum!

 

[Tractor Tim]

There is about a 3' air void between the inner ceiling and the roof but it is not insulated yet either. It will need to be blown in so will be hiring a contractor to come in and do that part.

I find blowing in insulation to be quite simple..and believe it or not, ENJOYABLE.

Here is our video showing our insulating work:

 

[sennister]

Does it just take a while to get all the "things" in the building up to temp before they start radiating back?

Radiant heat will heat you to a point but it will heat objects better. This will take time. Radiant heat isn't very good if your intent is to turn the heat down all day as you are busy at work and turn it on at night. That is where forced air heaters work best. Even if you are not in the shop all week and turn it on in the weekends, you will turn it on Friday and it might be warm by Sunday if not too cold.

I don't have heat tube as I went in floor hydronic heat but it has the same issue. Slow response to temp change. Where these systems shine is where you want them warm all the time. Once the slab which had a huge thermal mass heats up, it takes a long time to heat but it also takes a long time to cool down. That means that unlike forced air systems, if you open a door you may loose all the heat but it will be back in a couple minutes as the slab will warm it back up quickly.

As for 70F you can do that but I keep mine at 60 or 65. You can always put on a light jacket or sweat shirt and be really comfortable when working at cooler temps. It will be easier to hit that target as well when cold out.

My only experience with heat tubes are in the military. When I had a few years in aviation we heated our hangers with them and we kept them in the 60s. We would open huge hangar doors, wheel out the helicopters. Once the doors were shut, the heat would be back in that huge space after a couple minutes. Since I wasn't paying the bills, I don't know what they cost to run. I will say that so far we have been happy with the cost to heat with in floor. However we insulated pretty well.

It looks like it has been 3 days since turning the system on. Has it warmed up in there yet?

 

[snowdoggie]

Well I have a radiant tube heater in my recently built pole barn, at the present time it's also non-insulated too. Will be doing the insulation soon, I hope. Anyways, it's a two stage furnace 40' long and 150,000 / 100,000 BTUs, The barn size is 40 x 60, with 5 garage doors and +10 windows, along with a 12 foot leanto. I've only been running it on the weekends and at daytime. I'm in SE Michigan, it was 14 degrees earlier last week and it took about 4-5 hours to get to 40 degrees. So, it needs to be insulated for sure. Hope this helps. Oh, on warmer days like 30 degrees it just takes just couple of hours to get it up to 45-50 degrees. For what I'm doing out there I really don't need it any hotter.

 

[sennister]

Well I have a radiant tube heater in my recently built pole barn, at the present time it's also non-insulated too. Will be doing the insulation soon, I hope. Anyways, it's a two stage furnace 40' long and 150,000 / 100,000 BTUs, The barn size is 40 x 60, with 5 garage doors and +10 windows, along with a 12 foot leanto. I've only been running it on the weekends and at daytime. I'm in SE Michigan, it was 14 degrees earlier last week and it took about 4-5 hours to get to 40 degrees. So, it needs to be insulated for sure. Hope this helps. Oh, on warmer days like 30 degrees it just takes just couple of hours to get it up to 45-50 degrees. For what I'm doing out there I really don't need it any hotter.

Out of curiosity, what do you have for floor in your new PB at the moment? Do you have a slab poured yet?

 

[nastorino]

Yikes I couldn't imagine eating a metal exterior shop that has zero insulation value on the walls. I have a two car 23'x23' attached garage what is 2x6 construction insulated on the walls and ceiling...that I haven't heated yet. Only reason is the garage doors are cheap steel and have zero R value. Sure I replaced the weatherstripping at the edges and snugged it up well. There is too much thermal loss with uninsulated steel.

 

[TDavis1992]

I didn't see it anywhere else in the responses, so figured I'd drop it. Maybe it was said, but what about your eves? We just closed up the eves in our shop last month, uninsulated 60x40 metal barn. Made a massive difference, we can now keep it at hoodie temps while its 10 °F and breezy out with a single 80k btu diesel/kero heater.

Sent from my SM-N950U using Tapatalk

 

[snowdoggie]

Out of curiosity, what do you have for floor in your new PB at the moment? Do you have a slab poured yet?

It's poured, for the record, I always planned on it being insulated, eventually it will be insulated, just ran out of time before winter hit. Just using it now to take the chill out of the air. I understand the concrete will be a nice thermal mass when I finish insulating it and leave the furnace on. Just trying to give the OP an idea on if the his furnace is sized right.
t

.

 

[sennister]

Nice build snowdoggie.

We had to heat our garage all of November without door seals but the rest of the insulation was all done. The temps were in the low 40s to mid 30s most the month and the boiler ran almost non-stop as soon as the wind would blow it would cool off the garage enough that the thermostat would call for more heat. This happened because the garage doors were installed before the buck boards were up. I had two contractors (general and siders) that kept pointing fingers at each other saying it was the other guy's job to do the buck boards. I finally did them myself then I had to get the garage guys back to do the seals but they didn't want to come out until my openers where in. For some reason that took 6 weeks.

Without the seals the boiler was running so hard my slab was a little over 100F. At least the glycol return lines were showing around 105F. When out in there working, after 30min-1hr my feet would be sweating but we could maintain 60-65F for doing mudding and taping. Now that it is sealed up, even with air temps outside well below 0F the slab isn't nearly as hot and the boiler seems to run once every couple days.

You can kind of make out the gaps.

We also ran out of time in the winter and couldn't pour the apron or do the driveway work. I think that was better as it gave us time now to use the apron area and now realize that we need to go bigger with the apron and need to change the grade. That would have been an expensive change later on.

For the OP. I wonder if when they did the sizing calculations that they most likely did them based on insulation being in place. I do know that was part of the calculation when we did out sizing. The hard part now is once the space is filled, it is a lot harder to take everything back out and do the insulation.

The original plan for our build was to have the contractors insulate and put the sheetrock up on the wall where it touches the house and ceiling as they need to be fire rated anyhow for the building permit as well as the wall with the garage doors as I didn't want to have to work around them. We were going to do the back wall and end wall and all mudding, taping and priming. Turns out we were running so far behind in our build and with winter on our heels, we bit the bullet and had him do it all. That added another $5k but I knew it still wouldn't be done at this point had we not spent the extra money. It would have been done if we were on schedule with the overall build but we were several months behind at that point.