RADIANT HEAT for shop

[Ted Baxter]

I am looking for heating options for a 400' sq ft shop. Anyone have experience using Radiant heat? I don't understand how it works. Will it heat the whole space or just what is in front of the unit?

[Mike Kees]

Ted ,I have no idea where you live . I live in southern Alberta and heat my 2800 square foot shop with natural gas fired overhead radiant tube heaters. They work excellent in a shop, no air movement to stir up dust and even heat. I even plumbed my floor for in-floor heat during construction. Ended up with the overhead because my budget was shot at the end of building my shop and I needed heat. I have insulation everywhere even under my entire floor slab. Snow melts on my floor and it will dry up by morning. Radiant heat heats up surfaces that release heat to air around them.

[John TenEyck]

Radiant heat heats objects, not air. Whatever is in a direct line of sight from the heat source will absorb heat and then re-radiate some of that heat again. In that way, most everything eventually gets heated, even stuff that's not in direct line of sight from the heater. Response time from a cold start is pretty slow compared to normal convective air furnaces, however, except for stuff in direct line of sight.

John

[Jack Frederick]

It is really hard to advise without location. Minot or Miami. It makes a difference. Mike refers to the OH radiant and I can’t expand on that other than it does work well. I think you are referring to the warm floor radiant. Yes? Is it new construction? Slab or raise foundation wooden floor. 400 sq ft is pretty small for radiant imo. Reason being in a new or totally refurbished place you can detail it so you have little heat loss. the problem with small space stand alone radiant is it is difficult to match the heat source to the load. Small wall hung boilers are being built today, many firing from about 10-60 kbtu. Were you to buy one I suspect in that well built space you would never get over the 20-25 kbtu input and perhaps less. It is working, but loafing along, which is not good for modulating equipment.
My shop is 960 sq ft in a moderate climate. I have installed miles of radiant tubing, can buy better than wholesale, do the work myself and still felt it was to spendy, mostly from the time standpoint. You have to really want it. Yes it is wonderful heat, but for your space I would look at a mini-split. It will give you heat and ac and perhaps better for you as you are in Miami, dehumidification. I chose the heat only option and have a Rinnai Energysaver direct vent wall furnace and it heats my shop perfectly. If in Minot it is an excellent choice for straight heat and you can install it yourself in about 2 hrs.

[Ted Baxter]

I am trying to heat a "400" sq. ft. insulated shop. It was heated by gas but that is no longer avalible.

I was thinking about a celing mounted unit. I live in OKLA US and it gets very cold here.

[Lisa Starr]

I heat 530 sq feet with radiant using in floor pex tubing. I installed mine at the time my shop was built. Basically, it is made up of 3 layers of wood. Subfloor, plywood sleepers with the tubing running between them, and finished floor. We have something over 2000 heating degree days here and it keeps my shop a very comfortable 68 degrees very economically. Here's a photo of the install:
cherry street 257 (2).jpg

I'm happy to answer any questions anyone has about this.

[David Zaret]

i have in-floor, high-mass radiant in my shop, run by a single boiler. it's wonderful. in your case, it sounds as though you aren't thinking in-floor, because my guess is you already have a floor. you could (though i am not entirely sure it makes sense) use a radiant coil setup, which is effectively a big fan behind a coil, radiant fluid pumps to the coil and the heat is transferred to the air. i use such a system in my house as a secondary heat source - it kicks on only on the coldest days to supplement the in-floor. if you already had a boiler, and were looking to heat 400 sqft, such a unit might work just fine. if you don't already have a boiler, i'm not sure this is the best approach, but it's one way to use radiant when you can't bury it in concrete.

fwiw, my shop is ~2800 sqft of floor space, and my radiant keeps it at 64 easily during the coldest michigan winters.

[Jim Barstow]

I use radiant in my shop (approx 500 sq ft) which sits over a basement that contains the dust collector and all duct work. It is provides a very stable and comfortable environment but is very slow to heat up when I turn the heat off and let the space cool down. I'm in northern CA where we get occasional frost in the winter but we are at this house only 4 days a week. We came up mid-afternoon yesterday and the shop was still warming up when I quit for the night. If you think you may need to cut into the floor, make sure you have a map. I specified an 18" wide perimeter and a 3'x3' center section to be tube free so I could penetrate the floor with the vacuum ducts.

Other than the slow response, the only other thing that I dislike is that since it is virtually invisible, it is hard to tell if there is a problem. There is no fan, the pumps are silent, and the temperature differential is pretty low. We had a failure and it was hard to detect at first, then hard to diagnose. I had to call in a pro who tracked it down to an intermittent solenoid valve failure.

[Earl McLain]

I took a look at overhead radiant a few years ago (24' x 36' garage/shop, concrete floor, with snow that would come in on wife's car--my car lives outside). I liked the idea, but if i recall correctly-- with 10' wall height i was only marginal on having a tall enough ceiling for it to work well. I still haven't come up with a good solution, other than building a dedicated shop with floors like Lisa Starr has!! Then my feet would be warm--which i like.
earl

[Mike Kees]

Earl ,I have two heaters running the length of my shop down the center. One came out of my old shop ,it was in a space with a 8' ceiling. I used to get fairly hot on the top of my head if I was at the burner end. It heated the space just fine though.

[Bruce Wrenn]

I'm on the other end of the spectrum on radiant heat. i have a wall mounted, ventless propane gas heater. It's the kind with the ceramic briques, instead of an open flame. It produces both radiant and air heat. Over unit on ceiling, I have a thermostat that activates the air cleaner when heat is on. Circulates warm air around shop. Also have a small fan mounted near ceiling that blows down toward bench 24/7/365. When heat comes on, I can instantly feel heat if I'm in line of site of heater. Heat is set to 57-60 degrees which when working is more than comfortable. In my 960 sq ft shop, I use about one and one half 20# cylinders of propane per week, which works out to about $60 / month. A small price to be comfortable. I have never had a problem with condensation from the burning of the propane

[Jim Becker]

Radiant heat warms up objects, not the air. For in-floor, it heats the slab which in turn radiates to other objects, both of which then help to heat the air. Direct gradient (over head gas) is more targeted but the really good gas units typically installed parallel to the roof ridge can be very efficient if sized correctly. Electric radiant will take all your tool money when the bills come in...

Best thing I ever did for my shop was install the minisplit. My shop is 64-68ºF constantly winter and 74-76ºF constantly summer.

[Earl McLain]

Earl ,I have two heaters running the length of my shop down the center. One came out of my old shop ,it was in a space with a 8' ceiling. I used to get fairly hot on the top of my head if I was at the burner end. It heated the space just fine though.

Great to know--thanks Mike. I'll have to revisit that in the spring--it's only about 50' to run an underground natural gas line from the house.
earl