In-Floor Heating

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af2
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Re: In-Floor Heating

Post by af2 » Sat Dec 14, 2013 8:50 pm

les327 wrote:My 40 x60 shop in sc Pa. Has 8- 300 ft. Loops of 1/2 in. Pex pipe and a Munchkin M140 boiler in parallel with a tarm 140k btu wood boiler. I keep floor at 60 degrees F love it. Aprox 200 gal propane 4 cord wood Nov to March. Set up if to lazy to feed wood M140 takes over. So far so good 5 years running i have 6000.00 in heat system. 6`` concrete 1`` extruded foam 6 mill black plastic under 4500 lb. Fibermesh concrete.
That is about right right but the fact you have 2400' feet of tubing in 2400 sq' shop is spot on. The biggest mistake is not enough tubing and to far distance between loops. The underlay is important and the sides are way more critical..

I just had to replace a Munchkin 140 that I installed in 2003 due to maintenance (lack of). The new owners of the house have a new outlook...

I would never build a slab house without radiant.
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Re: In-Floor Heating

Post by Warpspeed » Mon Dec 16, 2013 11:04 pm

In floor heating is great if you plan to run it 24 hours, and there is good insulation UNDER the slab floor.
But heating anything 24 hours in a very cold climate is not going to be cheap...

If you switch it off overnight, it will take hours to heat up that concrete floor, and then heat the air above.
You could try turning it on at 4am, and off at 4pm, or something like that, but its still not an efficient way to heat up a space that may only be occuped during the day.

It can be made to work, but its probably about the most expensive way to go about it, especially if you use electric power.
Cheers, Tony.

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Re: In-Floor Heating

Post by crazyman » Fri Dec 20, 2013 12:09 am

These bad boys throttle the flame from a log based upon call for heat. http://www.centralboiler.com/models.php My mom used to have one at her old house. One log would provide for all day's heat.

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Re: In-Floor Heating

Post by jsgarage » Mon Dec 23, 2013 3:44 am

A few tips that worked for me. RE radiant floor heating, I owned an 'Eichler' home in N Ca for quite a while. They all had radiant floor heating. The first batch built in the '50s used black iron pipe in a concrete slab. 10-20 yrs down the road, everyone realized that concrete is acidic and also slightly moist....pipes corroded through & leaked. Many of those early homes had their concrete floors jackhammered up to replace failed heating pipe. The second and third batch of Eichler homes used copper pipe; they have so far lasted 50 yrs. Incidently, they also found that running galvanized steel conduit for electrical wiring in concrete also corrodes thru, often shorting the wires.

In my 10,000 square foot shop I use a 30,000 btu natural gas space heater hanging on the drywall. It has a thermostat and a small distribution fan built in, and keeps the place at 60F when its zero-to -10F outside. I used as much insulation as I could stuff into 2x6 walls and ceiling & an insulated roll-up door and man-door. Natural gas is easy to work with- about like automotive fuel lines. You should use black iron pipe as gas will react with copper, and since it only comes in at 2-1/2 psi from the street, its simple to deal with. I tapped our house gas line for a tee, added three shut-off valves to isolate sections, and ran a line 100 ft out to the building. A tap along the way supplies a smaller space heater in the wife's greenhouse. Her tropical plants are all happy and so is she. Talk about making points!!! I'm now going on 12 years of warm winter shop work near Lake Tahoe in N. Nevada.

Second, in the shop walls, I suggest also using sweat-soldered copper pipe for a built-in compressed air supply. Poly tubing will fail at one or more glued joints from the constant stress of containing 90-120 psi. So unless you vent the air system each night, you'll be in your walls fixing poly air leaks before too long.

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Re: In-Floor Heating

Post by jeff8407 » Tue Jan 14, 2014 7:03 pm

I have a 24 x 66 garage/shop that uses radiant heat here in the mountains of CA. It is fabulous. I have 2" of foam underneath the 6" slab. I have one single 7/8" loop at just under 500 ft. in length. I heat the entire shop with a 30 gallon water heater with an open loop and and variable speed pump--my garage is also spray foamed. It is great for keeping a constant temperature. My entire system was just under $2K DIY, excluding insulation.

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Re: In-Floor Heating

Post by af2 » Wed Jan 15, 2014 9:48 pm

jsgarage wrote:. The second and third batch of Eichler homes used copper pipe; they have so far lasted 50 yrs.
.
Awe the EICHLER HOMES.... Copper and concrete make a lot of work for me! LOL
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Re: In-Floor Heating

Post by af2 » Wed Jan 15, 2014 9:59 pm

jeff8407 wrote:I have a 24 x 66 garage/shop that uses radiant heat here in the mountains of CA. It is fabulous. I have 2" of foam underneath the 6" slab. I have one single 7/8" loop at just under 500 ft. in length. I heat the entire shop with a 30 gallon water heater with an open loop and and variable speed pump--my garage is also spray foamed. It is great for keeping a constant temperature. My entire system was just under $2K DIY, excluding insulation.
Jeff, spill the beans on the insulation... People crap when they find out the cost. I am glad you used 7/8" because you would not get there with 1/2" pex. :mrgreen:
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Re: In-Floor Heating

Post by jeff8407 » Tue Jan 21, 2014 5:15 pm

The 7/8 PEX has about triple the heat transfer of 1/2--I did the math! Plus, my slab is 6" instead of the usual 4", helping with the heat retention. It is great for keeping the garage at a constant temperature, but it takes a long time, 4-6 hours, to significantly change the temp inside.

The insulation is not cheap, but worth every penny! A barrel set runs about $2600 and is enough to do about 4500 square feet 1" thick on the closed cell and about 14000 square feet 1" thick with the open cell.

I own a Graco E-10 that I bought used for my house and decided to use it in the garage too. I have now done my house, garage, parent's attic , in law's attic and sub-floor, and 1 sister's attic.

I used one barrel set of closed cell and one set of open cell in my garage. Even owning the machine, it is still cheaper to use board stock (2" iso foam) and cut it to fit in between the joists, then top with a 1.5" layer of closed cell(creating a vapor barrier) and fill the remaining voids with the open cell on a 2X6 wall--same treatment in between the roof trusses/ceiling joists except you build up the open cell foam to get your final R-value desired. The trick is how well the spray foam stops all air infiltration. I will never own a home again that does not have spay foam. It is fantastic. As an example, I sprayed one barrel set in my folks attic in Bakersfield--I added about 5" of open cell foam on top of fiberglass in the attic(Yes, I know I was supposed to remove the fiberglass; but my dad is cheap and didn't want to remove it). Their AC bill is now less than half. This was using the cheaper foam, not the good closed cell stuff!

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Re: In-Floor Heating

Post by af2 » Tue Jan 21, 2014 8:20 pm

jeff8407 wrote:The 7/8 PEX has about triple the heat transfer of 1/2--I did the math! Plus, my slab is 6" instead of the usual 4", helping with the heat retention. It is great for keeping the garage at a constant temperature, but it takes a long time, 4-6 hours, to significantly change the temp inside.

The insulation is not cheap, but worth every penny! A barrel set runs about $2600 and is enough to do about 4500 square feet 1" thick on the closed cell and about 14000 square feet 1" thick with the open cell.

I own a Graco E-10 that I bought used for my house and decided to use it in the garage too. I have now done my house, garage, parent's attic , in law's attic and sub-floor, and 1 sister's attic.

I used one barrel set of closed cell and one set of open cell in my garage. Even owning the machine, it is still cheaper to use board stock (2" iso foam) and cut it to fit in between the joists, then top with a 1.5" layer of closed cell(creating a vapor barrier) and fill the remaining voids with the open cell on a 2X6 wall--same treatment in between the roof trusses/ceiling joists except you build up the open cell foam to get your final R-value desired. The trick is how well the spray foam stops all air infiltration. I will never own a home again that does not have spay foam. It is fantastic. As an example, I sprayed one barrel set in my folks attic in Bakersfield--I added about 5" of open cell foam on top of fiberglass in the attic(Yes, I know I was supposed to remove the fiberglass; but my dad is cheap and didn't want to remove it). Their AC bill is now less than half. This was using the cheaper foam, not the good closed cell stuff!
That is why I posted to you. Good job!!!!
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Re: In-Floor Heating

Post by wagspe208 » Tue Jan 28, 2014 11:41 pm

So, I have 1.75' fonm r10 (roofing foam) to go under slab. I was told this is aweosme. NOW, some dude tells me bubble wrap is better. This does not make sense. He wants 3k to do bubble wrap and tubing only. I can buy tubing, manifolds (have foam already) for 2100. Sure, his time is worth something.... but bubble wrap has r fucking nothing in this application.... so , WTF?
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Re: In-Floor Heating

Post by blockislandguy » Wed Jan 29, 2014 12:50 pm

Gee, 200 gal of propane at $4 a gal and 4 cords of wood, say at $125 retail value , cut, split and delivered totals $1300. That sounds high for small shop in PA.

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Re: In-Floor Heating

Post by jeff8407 » Wed Jan 29, 2014 1:41 pm

Bubble wrap is not better. However, most slabs lose their heat from the edges ,and if you use bubble wrap under the footings and up the sides of the slab the heat will be forced up instead of out. Insulating the sides of the slab is of the utmost importance either way you go. Remember, heat like water, and money in politics, will find the path of least resistance and go where it is easiest to "flow." Insulation just directs the "flow".

The idea behind the bubble wrap is to force the heat up or down instead of out the sides. Even if heat is transferred under the building the idea is that the soil will act as a huge heatsink and eventually it will come up into the building--in some areas it can be typical to leave the center section of the slab uninsulated--I do not know why, but have a few ideas.

Personally, I would insulate the floor and sides with foam and footings with either(bubble wrap is easier to lay into the footings and pour concrete into). I think using the foam you have is a no brainer.

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Re: In-Floor Heating

Post by blockislandguy » Wed Jan 29, 2014 9:48 pm

@jsgarage.

A 10,000 square foot shop is a serious shop. Congratulations. I assume that you are running a company and not a hobby shop.

I wouldn't tell too many people , least of all the IRS , that your company's nat gas (a legitimate business expense) is heating your house.

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Re: In-Floor Heating

Post by Dan Timberlake » Thu Jan 30, 2014 12:56 pm

I think I want my floor slab and especially footings resting on something substantial. Codes have wording like "undisturbed or thoroughly compacted soil" as a required base for footings for a reason.

These guys are not keen on bubble wrap under slabs, for undisclosed reasons.
http://www.radiantcompany.com/details/grade.shtml

Dow corning's "high load" foam insulation is rated for 40 psi at which point the thickness deformation is 5-10%. And a 5-1 safety factor for dynamic loads, and 3-1 for static loads
http://building.dow.com/na/en/products/ ... load40.htm
There are some differences how load is applied with a 4 or 6 inch thick slab on top, but a 4000 lb car resting on its wheels applies something like 40 psi to it's 5" X 5 " tire contact patches.

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Re: In-Floor Heating

Post by af2 » Thu Jan 30, 2014 5:28 pm

wagspe208 wrote:So, I have 1.75' fonm r10 (roofing foam) to go under slab. I was told this is aweosme. NOW, some dude tells me bubble wrap is better. This does not make sense. He wants 3k to do bubble wrap and tubing only. I can buy tubing, manifolds (have foam already) for 2100. Sure, his time is worth something.... but bubble wrap has r fucking nothing in this application.... so , WTF?
Wags
Foam under slab is NOT the way. On the sides it is the best..
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