radiant floor heat
Thread Starter
|
Senior User
Joined: Apr 2002
Posts: 196
Likes: 0
From: chicopee us
radiant floor heat
Anyone know the formula or the pattern to run the tubing for radiant floor heat in a 24x26 garage slab?
How many feet of tubing would be needed, what size tubing 1/2"? How many loops? I'm thinking that one large loop (one input and one output) for the entire floor would not be desirable. I would think multiple loops would be better in case of a leak you wouldn't lose the whole project.
Any help would be appreciated
How many feet of tubing would be needed, what size tubing 1/2"? How many loops? I'm thinking that one large loop (one input and one output) for the entire floor would not be desirable. I would think multiple loops would be better in case of a leak you wouldn't lose the whole project.
Any help would be appreciated
Senior User
Joined: Aug 2000
Posts: 153
Likes: 0
From: Ossipee, NH
There is a vast amount of web info on radiant heat. The actual amount of tubing you need will be based on heat loss calculations for your application. 1/2" PEX tubing should be OK. The spacing is normally about 12" on center, but 6" near the outside walls. The total length of run for 1/2" should be limited to around 300 - 400 feet. Your garage (~700') will need at least two loops to keep the run within limits. A Taco 008 pump should work OK to pump the fluid around both loops.
I have two zones in my 2,200 sq ft house, all with 1/2" PEX, broken down into 250 - 350 foot loops. Each zone uses a Taco 008 pump. No problem down to -20 F this winter.
Fran
I have two zones in my 2,200 sq ft house, all with 1/2" PEX, broken down into 250 - 350 foot loops. Each zone uses a Taco 008 pump. No problem down to -20 F this winter.
Fran
Tuned
Joined: Dec 2001
Posts: 431
Likes: 3
From: Saskatoon sk
The above post from fran is bang on my installation. Great form of heat. I also put the airfoil insulation (air pockets wrapped in foil) underneath the concrete. This sends the heat up rather than down and up.
PREMIUM SPONSOR
Joined: Sep 2003
Posts: 2,630
Likes: 217
From: North East Ohio
What are you guys using for a boiler? I've been told a large Hot water tank works well, and this is something I want to consider in the construction of my shop this spring.
I've done a few of these years ago but all were large garages with a huge boiler. We zip tied the tubing to the wire mesh with nothing under it. I like the idea of using the foil.
I've done a few of these years ago but all were large garages with a huge boiler. We zip tied the tubing to the wire mesh with nothing under it. I like the idea of using the foil.
__________________
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
Senior User
Joined: Aug 2000
Posts: 153
Likes: 0
From: Ossipee, NH
In order to figure out what size boiler, hot water tank, etc you need will be based on a heat loss calculation for your application. For my 2,200 sq ft house, which is heated to 68 F and designed for -20 F, I am using a Boch 50 gallon, 150,000 BTUH, oil-fired hot water heater for both the house heat and domestic HW. The domestic hot water is run direct through the Boch and the house heat is run through a heat exchanger off of the Boch. Normally, a 40 gal, 40,000 BTUH gas water heater is OK for domestic water, but I have 2 1/2 baths with one of them having a Jacuzzi bath tub of about 55 gallons. The big Boch will handle it great and at the same time keep the house toasty warm.
Depending on the size of the garage, how well it is insulated, the expected inside and outside temperatures, will determine the size of the heat source. A hot water heater works great for this application, because the floor water temperature is normally below 120 F.
Do a search on radiant heat. There is a ton of info out there. Find out how to insulate below the concrete slab for best results. This is how I did my homework to design and install my house floor heat.
Fran
Depending on the size of the garage, how well it is insulated, the expected inside and outside temperatures, will determine the size of the heat source. A hot water heater works great for this application, because the floor water temperature is normally below 120 F.
Do a search on radiant heat. There is a ton of info out there. Find out how to insulate below the concrete slab for best results. This is how I did my homework to design and install my house floor heat.
Fran
5th Wheeling
Joined: Oct 2002
Posts: 49
Likes: 0
From: Somewhere USA
I just got done doing this on my shop. A good rule of thumb is to use one foot of tubing for every square foot of floor space you will be heating. Keep the tubing lengths shorter at 250 feet, and use a cheaper smaller pump. Taco 007 is much cheaper than 008, and can push 250' loops just fine. Shorter loops reduce the "head" on the system, and make it easier to pump. A well insulated building is key, and insulate under the slab and at edges. I used 2" dow blue board. You'll have to do the heat loss calculation to determine how big a heat source you need.
A water heater may be highly illegal to use for heating in your area. Check this out before you do it. Efficiency of a water heater is low at 50% or so. A boiler is higher at 85% or more. Boilers are really the right thing to use here, but can be costlier. DO NOT plan on using a setback thermostat with this system, it won't work. Plan on heating it full time, and just insulating well. The thermal mass is too high, and you'll take about 2-3 days to get it toasty. If you want to know more, go to www.heatinghelp.com and hang out there for a while. The wetheads there really know thier stuff.
A water heater may be highly illegal to use for heating in your area. Check this out before you do it. Efficiency of a water heater is low at 50% or so. A boiler is higher at 85% or more. Boilers are really the right thing to use here, but can be costlier. DO NOT plan on using a setback thermostat with this system, it won't work. Plan on heating it full time, and just insulating well. The thermal mass is too high, and you'll take about 2-3 days to get it toasty. If you want to know more, go to www.heatinghelp.com and hang out there for a while. The wetheads there really know thier stuff.
Tuned
Joined: Dec 2001
Posts: 431
Likes: 3
From: Saskatoon sk
I used two 60 gallon electric water heaters. What I found is the one 60 gallon water heater would cycle on and off (as it should) up until about -25 F keeping my 18 x 24 x10 shop toasaty at 70 F I thought adding a second heater would give me more hot water capacity (storage capacity) It did but it really wasn't necessary. When we had a week of -48 F both units were working regularily but it seem to have dropped the room tempeture to 65F since the weather has warmed up to zero both units are hardly on yet maintains 70 F I do have good insulation so that is also a fact. the posts above are in my opinion good advice. ( Except the one about illlegal not me
not me
Trending Topics
Posting Guru
Joined: Jan 2004
Posts: 1,232
Likes: 0
Me and my dad helped a friend install a home made system a long time back. We used a huge (guessing industrial) boiler and copper piping, we laid it out in the zig zag pattern, and continued right on down his driveway. He never has to shovel and the boiler is so efficient that he had a 2 dollar a month jump in energy costs, although he doesn't use his shop too much
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Senior User
Joined: Feb 2004
Posts: 139
Likes: 0
I think the suggestion to keeping the tubing shorter is the right way to go. I think most tubing packages come in 300 ft rolls and if you need more you can terminate them at a manifold, not supposed to splice them. That way you are getting more even heat through out the slab by sending multiple equal temp loops. Insulate under the concrete with 2" rigid, fasten the tubing down then the rebar or mesh over the top of that, then pour the concrete. Old school was to heat the ground under the slab and let it heat the slab longer after the heat was shut off. Why? Heat the space, it will warm up faster and not cost extra because there are no savings. Takes longer to cool off in the spring too. Unless you are a gopher living under the slab. Consider putting it on off peak electric or gas and getting a reduced rate. Use a small boiler, don't mess with water heaters. You can get buy with one pump for all the loops or multiple zones for that matter. I am heating 2600 square feet of basement and greatroom and 1100 square feet of garage on one 7kw boiler one pump and 8 zones and pay 2.6 cents per killowatt, cheap to heat. It takes about 7 hours to bring the garage from 40 to 62 degress.
Last edited by 04-HD4U2NV; Mar 22, 2004 at 03:54 PM.
Senior User
Joined: Feb 2004
Posts: 139
Likes: 0
I think a couple of the real positives of radiant that may get overlooked is that if any solvents or paints etc are being used it doesn't make the smell worse by running it through a plenum. No blower noise, no real cold spots. But you do have to plan ahead to get the temp up. Maybe a small propane or nat gas until to supplement would be nice to get things started, it is only money.
Junior User
Joined: Sep 2003
Posts: 65
Likes: 0
From: Ottawa Canada
multiple loops are best, one long one will loose too much heat at the end of the loop cause an imbalance of heat and your boiler/heater will run continuosly. Don't forget that you will be heating the whole slab as well as some of the ground below the slab, so a quick temp change will be imposible.
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
All,
There are a few basics to get started:
1. Calculate your heat loss (Q). Get your number (i.e. 100,000 BTU/hr.)
2. Calculate your flow. Flow should be in gallons per minute, (GPM).
3. Do not allow for more than a 20 degree F temperature drop.
4. Formula; Q = 500 * GPM * ( Tin - Tout) OK - 100,000 / 500 * 20 = 10 GPM
What size is your radiant heating line?
Rule of thumb: 100 ft. of 1/2" line will carry 1.5 GPM with 6 ft. of head loss. 100ft. of 3/4" line will carry 4 GPM with 6 ft. of head loss. These parameters should get you far enough to do a radiant heat design layout and size a pump that will do the job. Don't forget to calculate head loos through your heater, valves, and manifold.
Good Luck,
KingFisher
There are a few basics to get started:
1. Calculate your heat loss (Q). Get your number (i.e. 100,000 BTU/hr.)
2. Calculate your flow. Flow should be in gallons per minute, (GPM).
3. Do not allow for more than a 20 degree F temperature drop.
4. Formula; Q = 500 * GPM * ( Tin - Tout) OK - 100,000 / 500 * 20 = 10 GPM
What size is your radiant heating line?
Rule of thumb: 100 ft. of 1/2" line will carry 1.5 GPM with 6 ft. of head loss. 100ft. of 3/4" line will carry 4 GPM with 6 ft. of head loss. These parameters should get you far enough to do a radiant heat design layout and size a pump that will do the job. Don't forget to calculate head loos through your heater, valves, and manifold.
Good Luck,
KingFisher
Thread
Thread Starter
Forum
Replies
Last Post
AZ2000EX
Bed Covers, Tonneau covers, Toppers/Canopies & Bed liners
0
Oct 31, 2015 11:02 AM
tonyjklh
Clutch, Transmission, Differential, Axle & Transfer Case
1
Mar 15, 2015 10:26 PM
