contractor

rst64

Hello,

I am a long time radiant heating contractor in N. California. This is my first post. I am wondering if anybody out there has any experience with using reflective insulation and PEX tubing to create a low temp infared type heater. The application is an old poorly insulated metal gymnasium with a very cool old surplus Navy basketball floor made with modular floor panels. This is owned by a school district who is spending $6000 per month trying to keep the place heated with a large hanging propane furnace. The building measures about 70' x 110' x 20'-24' height. They called me in to see how much it would cost to install a radiant heated floor. My initial conclusion is that would be a bad idea for several obvious reasons like floor height,  floor temperature issues not to mention high cost but not huge savings.

The ceiling is insulated with the type typical in metal buildings, fiberglass with white vinyl backing. My idea is to install exposed reflective insulation on the ceiling (below the existing stuff) and install a bunch of loops of 1/2" or maybe larger PEX-AL PEX just below the reflector. Using a mod-con boiler would allow a wide range of temperature adjustability based on outside (or maybe even inside) temperatures. I don't know if the tubing would be hot enough or too far away to do much good, but the idea of no thermal mass seems appealing since the response time would be fast.

Any comments will be appreciated!



Thanks, RS

nicholas bonham-carter

chilly basketball

why not start with the insulation first, and then supply the heat. maybe the floor also needs some insulation.

some of those gas fired radiant heaters, with a very long flue pipe running throughout the building might give the radiant heat for a lower installation cost than hot water with a mod-con. also the players must be putting out some heat!--nbc

RobbieDo

Radiant floor heat

I have installed radiant in a barn with 20' ceilings and outside temp of 0, it works fine. John Siegenthaler is great with radiant heating and spoke with him before I did this project. Remember, radiant stops heating around 8 or less and that is where you want the heat, not at the ceiling. Look up Siegenthaler online and he has a lot of articles on this same situation your in, that is what I was in with this barn. Good luck

Gordy

Hot athletes

 Yeah I do not think a radiant floor would be best for the athletes interest in comfort.



 Also RFH would not do much good for the spectators if there are bleachers involved, if that is a factor.



 Ceiling radiant would have its limitations also.



 I think some insulation need be investigated first. Plus the possibility of getting off propane, and on NG.



 

Gordan

I'm willing to bet a large sum of money that this would not work

The small surface area of pex tubing would simply not be able to radiate very much heat at any temperature that's compatible with pex. Radiant ceilings work because heat passes from the tubing to the ceiling panel through conduction, not radiation, and then the large surface radiates heat into the space. Distance from heated objects also plays a large role with radiant heating.

RobbieDo

Floor Heating

I thought that is wouldn't work either as the floor was 20' high in the barn I installed it in. I had many reservations and a lot of people told me this would not work. The roof had R30 insulation and the walls approx. R19. The main source of heat is a wood outside boiler with a Buderus as a backup and if the wood can't keep up. The temp in the barn stays at 68 when it's 0 outside. It works in this application that I did but every situation is different.

rst64

contractor (I thought it was asking for my title!)

I appreciate the comments!  Obviously the insulation and infiltration issues in this building are of primary concern. You would think that somebody paying $6000 per month would jump right on that. The reflective-PEX idea is just a wild brainstorm I had, so I wouldn't try it without testing it first somehow- maybe in my garage!  There is no natural gas available in this area, unfortunately. Propane is the only way to go in this case. Propane gas infared heaters are probably the best option for them, strategically located to heat the fans in the bleachers less that the basketball players. Plus, anything above the court is subject to getting hit by an errant pass. They did mention needing to keep the building warm enough to prevent damage or warping to the wooden floor.

icesailor

Radiant Gym Ceiling:

I'm not too sure either how well this will work.

But, from what you describe with a Propane heater in the ceiling, I've dealt with this problem before. What often happens with these high ceiling buildings with heaters in the rafters is that all the heat collects in the ceiling. The more it heats, the hotter the ceiling gets. You may need to connect some form of return that will and up on the floor to get cold air off the floor to be heated by the ceiling heater. It may be fine for cooling but not for heating. Hot air rises. You can put ceiling fans to push it down but a return to the floor will do a better job.

Myself, personally, I would look at something like this passive solution before I went out on a limb with an unproven design like you suggest.

A number of years ago, the town that I work in built a big maintenance building with a herd of doors to bring trucks in. At one of the building, they put a giant warm air horizontal furnace in. They ran duct work to the other end of the building and cut round holes in the bottom of the duct work and blowing down. The bay spaces were always cold. I was doing some work there and someone was grousing about how cold it was in the building and they were going to need to replace it with a bigger unit. I suggested that they build a plywood box that went from the ground and got a piece of sheet metal to connect to the heater. That it would suck up the cold air from the floor and increase circulation. They tried it and didn't need to replace the heater. There was plenty of heat. It just wasn't 100 degrees at the roof peak any more.

Look at it, it might work for you.

Don't underestimate the effect of a lack of circulation and the fact that how hot air doesn't want to go down. Think of it as what happens with a monoflow hot water system with cellar radiators below the main. Hot water/air doesn't want to go down.  

bruce_21

I did a similar job

about 20 yrs ago in an old barn like place. I used I think 4 unvented propane radiant heaters that had ceramic burners that got very hot. The heaters were hung about 15' off the floor (the space was used as a dance studio). The heat was only turned on when there were people in there and maybe 20 minutes before a class. You might have to go higher to miss the high arching balls. There is also a system made by Reznor the VR series which is a burner that shoots into a long tube which gets hot and radiates down with reflectors above it. It is vented which is a big plus. My son has one in his farm's vegetable washing building that is hung about 15' above the people working and does a nice job. I don't know what you have for equipment wholesalers there but this is the Reznor catalog page to look at:



https://www.rezspec.com/catalog-15_Gas_Infrared.html



Their rep should be able to help you size it and lay it out.

Good luck.

Gordy

Not so sure

 I think that they could do the job, BUT. They would be a nightmare to strategically place for comfort to bleacher occupants, and floor athletes. I see stair stepping Banks of heaters lots of gas plumbing etc. Safety would be a big concern, seen a lot of wild balls that you would never think would go where they do. All it takes is one.



 Been in my share of gymnasiums while there is an event always hot, and humid for obvious reasons. Control could be challenging with a straight forward radiant type heating system.



 Next would they cost less to operate than the present system? Breaking even would not be acceptable at the least even if comfort were up graded. 



 I'm still stuck on the envelope. If they are heating now, but just costing a ton of money, and no other fuel choice then I would stick money in to the envelope. The heating system is all ready in place. You are still going to burn the same fuel unless you go with an electric format. If you could save even 1000.00- 2000.00 a month that's a chunk of change.



 I do have a radical thought though. Radiant bleacher seats if they were aluminum, and did not get folded back after every event heat right where you need it. More then likely they are wood or plastic though, and do get folded away for more practice area.

David Sutton_6

Ambirads

 I Did a building about the same size maybe a bit bigger, it was 4 tennis courts.  i used Ambirads

http://www.ambirad.com/ambiradUS/php/index.php



They worked really well and the cost was good

David

Aka Dr Pepper