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My brother-in-law wants to update his garage heating system. He’d like to add a hydronic radiant heating system to the existing concrete slab floor. However, he needs to be able to drive vehicles in and out of the garage on this floor. Has anyone done this successfully and if so, would you briefly outline how you did it?
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Hi Lisa,,
The smart thing might be to remove the existing slab and prepare the base for the new slab c/w tubing and re-enforcing. You don't want a crack in your new slab so ya gotta do it right.
Technically, if the existing slab is stable, you can add another layer, but the layer will add a few inches to the elevation of the floor. If this isn't a problem, not a big deal.
Gabe
*Gabe, this goes back to that heat sink thing where she might want to divorce the two slabs to keep from heating the one below? I would think the smart way would be to get out the old and prep properly for the new. Just sitting here thinking with the warm floor below my toes. What do you think?
*Thanks, guys. I don't think he's going to go for replacing the original slab. It makes sense that he'd have to put insulation between the old slab and the new to avoid heating the old slab. There's still the question of whether or not you can safely drive a vehicle over the second layer.
*Hard to say Calvin,Heat rises. What percentage would be used to heat the lower slab and what harm or loss would it have on the overall concept?Having a 4 inch slab with heating pipes vs an 8 inch slab with heating pipes. Obviously, the 4 inch slab would come up to temp. faster but would also cool down faster and startup more often. So, common sense would dictate that the differences would be minor.Cost?Cost to take out and repour a new slab would be much higher than simply topping off the old AS LONG AS THE OLD IS STRUCTURALLY SOUND.In a new slab, by adding 2" of styrofoam, would you recover the cost in a reasonable amount of time?In a moderate temperature zone, highly unlikely.In my neck of the woods, highly likely.Regarding the same scenerio by pouring over the existing slab.Probably less effective to add the 2" and only require 1 inch to achieve the same effect and you would loose the mass effect.Bottom line...I think I would pour over the old concrete over a slip sheet of 6 mil poly and isolate the slab from the perimeter with 1" styrofoam.Gabe
*Thank you. Now, with your expertice, tell me why we always (most) froze our butts off watching my daughter skate? Who dreams up the alum. seating? And does anyone ever turn on those radiant heaters up near the ceiling? Not being a smart ass, just always had those questions and who better to ask than someone that builds em. Thanks again. By the way, the best rink for comfort we sat in had mini basebd heat under the seat and at the floor. Now that was sittin'.
*Lisa, if he doen't insulate the slab, he'll lose heat downward; heat migrates to cold. If he does use foam, he'll need another structural layer of concrete to keep the new slab from deflecting, while gaining at least 5-6" in height by now which messes with the apron height, steps into the house, and door closures. It's safe, to answer your question, but not convenient. Hot water heat is a pretty expensive and cumbersome retrofit for a place to park cars. In case he hasn't considered any others types of heat, there are overhead electric radiant panels that are easy to install and out of the way, if he doesn't want baseboards and/or objects to blown air. Also, there are small oil/gas stoves that are cheaper to install and operate and take up little space, but need to be vented.
*Hi Calvin,Can't say who would dream up aluminium seating but I do know that vandalism is a major problem in public arenas.I prefer wood planking in vandal resistant seating.In properly designed arenas, the individual infrared heaters are the best for spectator comfort. The tube type are not as efficient. The operators of your arena may be too cheap to turn them on without threat of bodily harm.The best arenas are the smaller facilities for under a 1000 spectators. Best seating, view and comfort.Chat laterGabe
*Thanks Gabe, Calvin and SplinterG. I will relate this accumulated wisdom to my brother-in-law.
*DF why don't you stick to subject matter you know and stop trying to impress with BS. You know nothing about concrete or radiant heat, other than what you have read in magazines. Before you cause anyone to do damge to their homes, go back and play in your art and craft shows.Gabe
*Gabe, at the risk of becoming another of your enemies, I must take exception to your coment that heat rises. While I'll agree that hot air rises, radiant heat goes in all directions. That's why foam is used under snow-melt systems, and foil faced Celotex is used under staple-up systems indoors.
*bearmon,Not to worry about joining the list of enemies unless you attack me personally like DF did and if you monitor this board for any length of time you will know that she hasn't a clue and only mimics others.Let's stay to the subject.While radiant heat can be directed, it still prefers to move upward when it meets resistance. Foam is used to resist change in temperature between the two masses and to concentrate the effects of cooling or heating to one of these masses.The basic here is "is it worth it, IN THIS CASE?And the answer is......not likely. You would have to use high density foam to balance the load in order for the slab not to crack, especially at the entry as the wheels would first put pressure on the new slab.It's a lot easier and safer to cap over the existing slab, ASSUMING that it is stable and is not cracked.Now that didn't hurt.....did it?Gabe :)
*Well, thank-you, Gabe!!! I see you've moved me up from "flea markets" to "art and craft shows"! I just knew all that sweet talk would get to you sooner or later!PS: Kathryn was wondering if she could get her shovel back...
*i While radiant heat can be directed, it still prefers to move upward when it meets resistance.So i guess that's definitive proof of which end of the solar system is up!radial: characterized by divergence from a center, developing uniformly around a center axis, moving along a radius, etc. (Webster)But then, with slab-on-slab/no insul, there's some conduction going on, too, i reckon.
*DF I don't debate with idiots.Gabe
*Gabe - I think we have a problem here with strict sematics vs more common usage. Strictly speaking, radiant heating is the generation of electromagnetic waves, primarily in the infrared region, that then warm an object in the path of these waves. Gravity has almost no effect on these electromagnetic waves* so they generally travel in straight lines from the radiation source until they encounter some object that absorbs them - the "generally" being added because electromagnetic waves can be reflected or can be bent by some objects such as lenses or prisms. Thus, for radiant heat in a strict sense, "up" or "down" has no effect. The problem is that many of the heat sources that we term "radiant heating" supply much of their thermal energy by conduction and convection. And once the infrared radiation hits an object, the heat from that object is conducted to the surrounding air and is dispersed by convection. Traditional "radiators" actually disperse heat much more by conduction and convection than by infrared radiation and I would guess that the so called "radiant floor heating" acts similarly. Thus most of the dispersed heat would be by convection and thus the effect would be along the lines indicated by Gabe. Of course, I got my worst grade in college in thermodynamics, so what do I know...(*Einstein did predict that gravity does bend electromagnetic waves and astronomers have verified that light waves do get bent, but it takes a very very large mass to do it.)
*Lisa: I'll add my vote to the consensus that you could insulate (adding cost and height but being quicker to come to temperature and lower energy bills) or not insulate between pours (less concrete, height, cost, but more thermal inertia and more energy usage). I've got 2" of blue foam under my radiant garage floor, but with a 4" pour on top of it (6"x6" #10 WWF plus glass fibers in the mix). But I've got pretty cold ground underneath and while heat losses decrease after the upper ground is warmed, they would always continue.One point not addressed yet is that as you increase the thermal inertia of the system, it becomes more difficult to hold a steady temperature. Especially if you pour directly on top, I'd spend an extra $30 and get a thermstat with a 1 degree F hysteresis instead of the usual 2 to 3F. Imagine pushing a big truck around - once you get it moving, it keeps going. You want to make small adjustments and stop pushing earlier than if tossing around a Geo Metro. I haven't found any PID (Proportional, Integral, Differential) temperature controllers that look like a normal thermostat. Anyone know of one? I've only found ones that look like the chemical process equipment that they are.Splinter: Yes there are many ways to heat a garage. But radiant is really sweet in snow country. The car melts and drys really quick with the heat coming from underneath and the resulting pool of melt water evaporates quickly instead of running under my storage boxes or towards the front (freezing the garage door to the slab). I'm using a direct-vent hot water heater ($450, 42,000 BTU/hour) for the garage radiant heat source - works very nicely, easy installation, no air leakage through the flue and much less ignition hazard than an open flame.Casey: Thanks for the physics lesson. So if I had a large enough gravational lens, could I focus all the 4 degree Kelvin background radiation left over from the Big Bang and heat my garage for free? How many black holes would that take?
*David, i was pondering radiant heat for my new shop in a walk-out basement, what the realtor will call a two-car garage. I decided against it because i'd be committed to keeping the door shut in cold weather and to continue heating even though i travel a fair amount, and in truth i couldn't figure out if the cost of that would be exorbitant. Do you by chance have a separate meter on your water heater, or any idea what it's running you in BTU's to heat? I wouldn't do this as a retrofit, but maybe the next shop...
*Splinter: I calculated the house at 18,000 BTU/hour at -40F (worst case) and confirmed at -25F last winter a natural gas usage of 11,000 BTU/hour so the estimate seemed right on. For the 728 square foot garage, I figured 21,000 BTU/hour at -40F (less insulation and more leakage at the doors). $225 a year for 590 therms of natural gas in my extreme climate, but with cheap natural gas.For the radiant sidewalk, it's about $4 per usage. Sure beats me shoveling it or trying to find a neighbor kid and give him $10. And it leaves it dry and ice-free. The sidewalk has gycol in its loop, seperated by a heat exchanger from the water in the other loops. It is only run after a snow event, then allowed to cool down, once clear and dry. If you ran gycol in your garage, why not let it get cold in your absence? -David
*David, sorry but my Pocket Ref doesn't seem to give me the answer to that one. However, I would guess that if you would just get yourself a small black hole and jump in, the resulting compression would warm you up in a hurry...
*Yikes! 91,547 BTU/gal of propane @ ~ $1.00/gal for 590 therms for 728 s.f. works out to approx. $600 per winter just for my garage, and the entire space devoted to shop is even larger. We get down to -20* on a regular basis, so not much difference there. Don't suppose i'll even consider the glycol stream until i get back to civilization and NG... Been wanting to know this for a long time--big thanks, David!
*Splinter: Garages are tough to keep warm in extreme climates with those leaky doors. If you're willing to caulk all around the door each time you use it, those energy figures could be halved. Rather a pain through. With a newborn son, a doctor wife who gets called in at all hours, cheap natural gas, and two professional incomes, the heated garage was never in question. -David
*Gabe,The only attacking I seen was you doing it to others.I think that you are a rude jerk that thinks he knows it all and thinks other opinions are useless
*Wacker,And you would be............not that it matters a pinch of coon shit what you think or if you can think, for that matter.We have to know history so that we can appreciate the present and prepare for the future.Learn the history BEFORE you put you foot in your mouth.SmuckGabe
*I can see you know all about coon shit it's all you have inside that thick skull of yours.Just trying to let you know your not the only one with an opinion.
*Wacker, you may have noticed that I don't debate with idiots, so have a good day.Gabe
*I don't mind debating with idiots,I was debating with you
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My brother-in-law wants to update his garage heating system. He'd like to add a hydronic radiant heating system to the existing concrete slab floor. However, he needs to be able to drive vehicles in and out of the garage on this floor. Has anyone done this successfully and if so, would you briefly outline how you did it?