In floor heat question

I am in the process of finishing up my new building and radiant heat is an option to me.

My question is has anyone had any problems with the foam under the pad with heavy machines on the floor. I have 2 10,000 pound machining centers (soon to be 3 ) and a 6500 pound CNC lathe.

I post this in here because I want people who have CNC machines/Heavy machines with experience with in floor heat.

Or any other issues that may come up with in floor heat.

Thanks in advance

Jason,

Have a plan to repair the water lines if you ever need to cut a hole in the concrete for some type of foundation. Know the location of the lines so you can miss them when installing anchor bolts if/when needed. Go thicker on the concrete if you are worried but with 6 in. you should be ok with those machines. Disclaimer; I pour concrete for a living but have never done the radiant heat. Not much need for it here but I have spent a lot of time thinking about it just in case it comes up. I have used the foam boards under the slab for freezers and my clients have installed full pallet racks and mid-sized forklifts on top of them with no problems.

When I bought my foam from a local producer, it was available as 1 lb and 2 lb.

The 2 lb will withstand more weight.

Aside from machines that need a special foundation, the foam has the same bearing capacity as the dirt below.

use the pex with the oxygen liner, it really never dies

I will say the shop local to me had issues with temperature control, our machines generate so much heat they add more than you need, and they ended up opening the door in the winter a lot.

If you ever need AC, it is a second system, so ponder that.

I love it in a garage because you actually have to lay on the floor sometimes


insulate the floor anyway, it makes a huge difference. I would insulate 2 inches around the edges in any building, including door openings[add a cover plate] An inch under the floor at least. You will find the floor is no longer 'cold'

The tube is pretty cheap and if you get a basic idea of how to run it you can do it yourself in a few hours, you just ty wrap it to the wire or rebar. Basically you want to run it to one or two common locations for manifolds and each run should only be so many feet, depending on tube size. The truth is for a shop space you do not need every square foot of the floor with tube, it is just math as to water temp and btu output, the more tube you have the lower the water temp you can run and the more efficient it is. In a shop you are not worried about a cooler spot on the floor like in a house. So if you were nervous about some future dream machine being too heavy, it is not going to matter if you delete the tube in that area. The foam is not IMHO an issue either, but if you deleted some towards the middle of the building it would not have much affect

I love radiant heat[grew up with it] and tubed my current house at great effort when laying hardwood over the concrete downstairs.

I have never hooked it up because the insulation value of the wood and plywood below makes the floor feel warm enough.

To directly answer your question, no, you will not have any issue or concerns having foam under your slab, even with major weight on it.

However, you did not disclose any construction details and if any one of those is not up to snuff, you "may" have issues. With those weights, technically even a 4" floor can be made to work, but 6" is a bet. You do NOT need to buy extreme XPS foam, EPS will do at 1.25lb density. With or without foam, you want the subgrade RIGHT as rain! Seen this many times where someone breaks the floor and says it was not thick enough. bullshit. Its sitting on uncompressed clay.

All that being said, I have had loads in excess of 30,000lb sitting on 3" of DIY POS concrete without issue. I did not pour it but seemed to work.

If you want more safety, use a dual pneumatic tire forklift. The guaranteed worst case situation is a fork holding a machine. But your weights don't concern me in the least.....

I moved into a building with in flour heat in June. I've got a 10000lb and two 8000lb machines. Hasn't been a problem. What i have noticed is that the floor transmits vibrations. Everytime my apprentice drops something it feels like the machines are crashing but i came from a shop that was Sitting on 40' of sand over top of bedrock. That floor was really solid. I turned the heat on a couple weeks ago and the floor feels more comfortable than the old shop.

Sent from my LG-H831 using Tapatalk

JasonE said:

To directly answer your question, no, you will not have any issue or concerns having foam under your slab, even with major weight on it.

However, you did not disclose any construction details and if any one of those is not up to snuff, you "may" have issues. With those weights, technically even a 4" floor can be made to work, but 6" is a bet. You do NOT need to buy extreme XPS foam, EPS will do at 1.25lb density. With or without foam, you want the subgrade RIGHT as rain! Seen this many times where someone breaks the floor and says it was not thick enough. bullshit. Its sitting on uncompressed clay.

All that being said, I have had loads in excess of 30,000lb sitting on 3" of DIY POS concrete without issue. I did not pour it but seemed to work.

If you want more safety, use a dual pneumatic tire forklift. The guaranteed worst case situation is a fork holding a machine. But your weights don't concern me in the least.....

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the floor will be 6" thick and all the prep work is done my father owned a construction company ( retired now ) he handled it all so its all good I just had a question about the foam and weight.

Thanks for the responses

Jason,

25psi foam is what I would put under there. I have seen a few machine shops run the XPS 25psi and have bigger machines. If you need to put in a lift or a machine below grade now would be a good time to plan for it.

alliancefab said:

I am in the process of finishing up my new building and radiant heat is an option to me.

My question is has anyone had any problems with the foam under the pad with heavy machines on the floor. I have 2 10,000 pound machining centers (soon to be 3 ) and a 6500 pound CNC lathe.

I post this in here because I want people who have CNC machines/Heavy machines with experience with in floor heat.

Or any other issues that may come up with in floor heat.

Thanks in advance

Jason,

Click to expand...

At my Ranch I have in floor radiant heat, but travertine throughout the house (rather than wood) etc. [Really kills your feet and joints]. The one thing about in-floor radiant heat is that it's not very responsive to ambient whether and temperature needs. So if its been off for while and winter time rolls around it may take about two days to heat up that thermal mass to ambient temperatures... So it becomes a pretty massive thermal load that is not very responsive IME. [I don't have good AC or base board heating]. Not really sure about how thermal expansion in a floor will affect your machines given that they may be on the "smaller" side (under 20,000 lbs) probably OK/not a problem for 6000 lb to 10,000 lb machines.

Main thing depending on construction technique do whatever you can to prevent future cracking and various parts of a slab pitching or rolling/inevitable movement and subsidence for a "New-build". I have known some builders that have lost their shirt on larger developments as the didn't do the proper "Soil work"/engineering. So do remember ultimately you are building on dirt/soil and depending on where you are that stability can vary considerably.

I used HighLoad-40 under my shop slabs, its not much more $ than the hardware store pink/blue stuff but way better. You can also get it in 60 and 100psi, its psi rating is also based on I think 5% compression vs 10% for cheap consumer stuff.
My heaviest machine is about 5500lbs, no issues on (6-7" concrete in old shop). Next machine will likely be in the 10,000lb range and I'm not worried, but I've got bedrock close under so that's a good base and 9" of concrete and rebar in the new shop.

alliancefab said:

I am in the process of finishing up my new building and radiant heat is an option to me.

My question is has anyone had any problems with the foam under the pad with heavy machines on the floor. I have 2 10,000 pound machining centers (soon to be 3 ) and a 6500 pound CNC lathe.

I post this in here because I want people who have CNC machines/Heavy machines with experience with in floor heat.

Or any other issues that may come up with in floor heat.

Thanks in advance

Jason,

Click to expand...

My shop floor is 6" thick concrete (4000psi with fiberglass) with a 24" grid of #4 re-bar and re-mesh. That sits on 2" of XPS-25 structural foam.

For heating, I used 1/2" oxygen barrier pex. There are 10 circuits, each about 225 feet long on a 12" grid.
Hot water comes from a 4 ton ground-source heat pump. In the summer, I can cool with a couple of 20" radiators that are plumbed in to the ceiling.


I have a 13000 lbs VMC, 8000 lbs turning center, as well as an old 16" B&E lathe weighing roughly 6500 lbs on my shop floor.
Note that I set these machines on skates at the door and rolled them across the shop floor to their places in the back.

No issues at all in the couple of years since I stood up the building and I love the radiant heat.
Should I build anything in the future, it will be slab on grade with radiant/hydronic and a geothermal heat pump.

IME with any on the floor heat source you don't want it controlled by a room air thermostat, you want it set at a given point based on a floor temperature measurement. Get that about right and the machine load won't have all that much effect, put simply as the air heats up the floor loses less heat and simply does not get any hotter.

Measure air temp and over night your heating ramps to max, then you add heat and the flywheels totally out of whack.

Under floor heating and trying to turn it up and down temp wise will fail, you will never hit a good point, set the floor to be a few degrees above - at your chosen air temp and it will work a whole lot better!

Hopefully you put in AC as well, Ductless heat pumps are awesome.
I ran the Pex in my new shop, but I got no plan to hook it up, 18k/btu heat pump should keep up.

adama said:

IME with any on the floor heat source you don't want it controlled by a room air thermostat, you want it set at a given point based on a floor temperature measurement. Get that about right and the machine load won't have all that much effect, put simply as the air heats up the floor loses less heat and simply does not get any hotter.

Measure air temp and over night your heating ramps to max, then you add heat and the flywheels totally out of whack.

Under floor heating and trying to turn it up and down temp wise will fail, you will never hit a good point, set the floor to be a few degrees above - at your chosen air temp and it will work a whole lot better!

Click to expand...

I agree about using the floor temperature as your main set-point. That's basically the way I programmed my system, but with a little added functionality.
The trick is to consider the difference between the shop air temp and the outside air temp. With no insulation, you have to crank up the heating source to push enough heat through the floor to keep your shop warm. Each system is different, but you basically have to increase the floor temperature at the thermostat as it gets colder outside.

You can program an electronic thermostat to do that calculus for you. I believe the HVAC industry calls that feature "Outdoor Reset".
I simply built my own using some PLC units and off the shelf single-board computer.

Here's what the temperatures look like in my shop today with the heat-pump set on low output and the floor-temp set at 63.0°F.



SWIT = Source Water Inlet Temp (water coming into the heat pump from my buried ground-loops)
SWOT = Source Water Outlet Temp (water returning to ground loops)
LWIT = Load Water Inlet Temp (water coming out of my concrete slab)
LWOT = Load Water Outlet Temp (water leaving the heat-pump on it's way to the concrete slab)

Last 3 shops I worked in had in floor with a very standard thermostat on a wall at about 5 foot high

I have 6" slab, I believe the foam was called hiload rated at 6000 pounds/sq foot, do notice a little vibration when 10000 pound haas is doing heavy cutting, no accuracy issues though. I have a tekmar controller that looks at outside air temp and inside temp and varies the water temp going into the slab by calculating what the building heat loss will be. I works very well, none of that afternoon "overshoot" where you have to open all the doors. I love it

I did my addition last winter with infloor. I used the regular Pink foam from big box store, some farm shops will go to the higher psi stuff in areas where a loaded semi might sit, but I think its generally considered overkill given a good base.

While its not "perfect" it helps in other areas, use the plastic staples and staple pex right to foam, dont tie to rebar that will be held in middle of slab like everyone says is the best way. If you put pex in middle of slab you are going to hit it with anchors at some time or have to use infrared camera to find the tubes before you drill. With the tubes stapled to the foam I know I can drill anywhere in my floor for an anchor bolt, so long as I set the max depth of the drill to like 3". It still heats just as well as the insul underneath does its job and the pex still heats up the whole slab thickness. And its alot easier to put the staples in than wire tie to rebar, plus I feel less chance of getting poked when pouring. And put some air pressure on the lines when pouring, unless your like me and pour in middle of winter and wind up running 65 deg water through the lines to help set the concrete

One other thing, add an extra pex line, capped off with a steel plug about maybe 15-20' long in total that comes up out of slab the same as the rest. This can be stuffed with a in floor heat sensor later that some of the better thermostats use.

rbdjr59 said:

Have a plan to repair the water lines if you ever need to cut a hole in the concrete for some type of foundation. Know the location of the lines so you can miss them when installing anchor bolts if/when needed.

Click to expand...

I second that... we have had installers hit a line and it's not pretty. If you could mark the locations it would be best. Also, unlike electrical, home runs in plumbing can create a nightmare in the future. Don't skimp on valves and junctions.

In situations we don't know the location we have had to use a laser temp gauge, but its not the most precise means of locating.

Zachsdaniel said:

I second that... we have had installers hit a line and it's not pretty. If you could mark the locations it would be best. Also, unlike electrical, home runs in plumbing can create a nightmare in the future. Don't skimp on valves and junctions.

In situations we don't know the location we have had to use a laser temp gauge, but its not the most precise means of locating.

Click to expand...

Thermal camera works very well for locating the pipes. Let the slab cool down a bit and then hit the water temp setting higher than usual and the piping lits up in hour or two like lit cristmas tree.

Jorgo said:

I moved into a building with in flour heat in June. I've got a 10000lb and two 8000lb machines. Hasn't been a problem. What i have noticed is that the floor transmits vibrations. Everytime my apprentice drops something it feels like the machines are crashing but i came from a shop that was Sitting on 40' of sand over top of bedrock. That floor was really solid. I turned the heat on a couple weeks ago and the floor feels more comfortable than the old shop.

Sent from my LG-H831 using Tapatalk

Click to expand...

I know one shop where the VMC would poop the surface finish if someone was driving a forklift around in the same time. Afaik they ended up splitting the floor slab to independent islands or pouring foundations under the machinery without insulation layer.