Radiant in floor heat (concrete slab)

CasterTroy said:
Your
but pipe failure under slab,
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This is mentally where I cant wrap my head around it.
I'm not as smart as you or others on these systems but my simple brain says
1) The system depends on close contact between the pipe and the concrete
2) Concrete and the chem reaction deteriorates anything it touches starting from day one.
So when it fails ...you have to bust up the concrete to replace it. and even if you abandon the system you then have cavities and holes in your floor surface...
 
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Ron said:
This is mentally where I cant wrap my head around it.
I'm not as smart as you or others on these systems but my simple brain says
1) The system depends on close contact between the pipe and the concrete
2) Concrete and the chem reaction deteriorates anything it touches starting from day one.
So when it fails ...you have to bust up the concrete to replace it. and even if you abandon the system you then have cavities and holes in your floor surface...
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I have that concern also but from everything I have read it seems that up north it has been used for decades with great success, so thats why Im asking for personal and professional experience.
 
CasterTroy said:
Without a doubt it's the BEST solution for what you are after. Economically though, I have found that unless you do a lot of it yourself, your cost will be in line with conditioning the space. This has just been my experiences in my area. YMMV depending on the experience of local installers
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CasterTroy said:
Your
Mileage
May
Vary



We get hit with vendors pushing "the new hotness" every few months. "SOLAR" was all the rage then heat pump, then VRF, then solar AGAIN, then GAS.

At the end of the day, after seeing all I've seen....SIMPLICITY and the ability to go to ACR on saturday and buy an off the shelf item that's widely available so I can get back online in hours, not days, trumps anything that may or may not be able to be controlled to the Nth degree from my phone.

I say all that to ask: WHEN this system breaks...and it's a mechanical system, it WILL break......what are you willing to do to fix it, and or replace it with something else?

MY big thing was; I was putting a lot of faith in a water furnace, and underground piping. The pumps...they can be replaced...but pipe failure under slab, or the water stove developing a leak....that would be a problem. $1200 wall mounted split systems and/or commercial rooftop units mounted on a slab are like big screen TV's ..they break, replace within hours.
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So its the best solution but you wouldn't do it? The water heater seems like it would be simple to replace if it developed a leak. Everything except the pipe in the slab seems like it would be a simple fast repair. But maybe you are talking about larger more commercial heaters or systems.
 
Ron said:
2) Concrete and the chem reaction deteriorates anything it touches starting from day one.
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Pex lasts the life of the building. Where it gets dodgy was with the link above that recommended splicing the tubing with a quick-connect if you had a puncture pre-pour. The brass will react with the concrete.
 
shawn said:
Pex lasts the life of the building. Where it gets dodgy was with the link above that recommended splicing the tubing with a quick-connect if you had a puncture pre-pour. The brass will react with the concrete.
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Ok I haven't had time to look at the link yet, I didn't know brass would react with concrete other than the natural moisture attacking the brass over time. Good to know the pex is designed to last the life of the building.
 
Stuntman Autoworks said:
So its the best solution but you wouldn't do it?
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No...best solution for YOU

I'm not rolling around on the floor. If I knew I was spending copious amounts of time laying on the floor I would have likely cut other things out to make it happen. As it is..I spend very little time on the ground and the wife walks around in fur lined slippers :lol:

20201207_182311.jpg
 
I’ve dealt with these a few times. A good flat sub grade, good insulation 2” board and proper PEX placement is key. Tape all the seems on the insulation board. Pressure test the system well before you pour. If you have to do any splicing, coat those areas with epoxy. PEX goes on top of the wire mesh (unless you’re going with fiber) and you’ll need to carefully consider the layout in regards to where you’ll have a lift and stuff in the shop.

If you’re gonna do it, I would go ahead and run it under the living portion of the house as well. You’ll really reduce your heating bill in the winter on that side at least. When it’s time, I’d be glad to price you the insulation needed, might be able to save you some coin.

You will have to have a concrete pump truck so be prepared for that extra cost too when pouring.
 
I thought about this for my shop (2520sf), and ran some rough numbers. It just didn't seem worth it.

First, in this area (Stuntman is close by) there just isn't enough heating days in a season. Just a few months you need heat, and compared to up north, not that big of a temp rise. If the shop is 50, I am happy. Doesn't take much propane in a torpedo to do that. I will go for a couple of weeks or more without spending any real time in the shop. With the radiant, you can't just turn it on and go to work a half-hour later...you have to keep the slab warm all the time. Of course, you'll be living in the same space, so that's different.

Only other thing I can think of is that before the PEX is laid, you'll have to know where you are going to place machinery and equipment NOW, for any and all equipment you have or might get in the future that needs bolted down. IIRC, for something like a 2 post lift, you can't have the pex anywhere with in X feet of the post anchors.

For me, I use a couple of LP space heaters. Long-term plan is to put a gas furnace in. My shop is divided into 3 partitioned areas...I plan to put the furnace where the walls intersect, and dump a dampered vent into each area. Might eventually put a mini-split in the welding room, or the loft if I ever build it enclosed, so I have a cool spot to piddle on really hot days. I have also thought about a passive tin-can solar array to help keep it above freezing, at least.
 
I was talked out of this by several water stove manufacturers on my current shop build.
1- amount of heating days vs cost as mentioned by @kaiser715.
2- temperature swings in NC. This was the biggest reason. Probably wouldn't be a big problem in the residential area, but the floor sweating in the shop area. Its a problem in this area as you probably know. Basically the were saying that the slab wouldn't be able to cool off fast enough to compensate even if shut off. Multiple people said the same thing.

I am going with a water stove but just traditional heat exchanger hot air setup.
 
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CasterTroy said:
No...best solution for YOU

I'm not rolling around on the floor. If I knew I was spending copious amounts of time laying on the floor I would have likely cut other things out to make it happen. As it is..I spend very little time on the ground and the wife walks around in fur lined slippers :lol:

View attachment 332595
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Gotcha
 
77GreenMachine said:
I’ve dealt with these a few times. A good flat sub grade, good insulation 2” board and proper PEX placement is key. Tape all the seems on the insulation board. Pressure test the system well before you pour. If you have to do any splicing, coat those areas with epoxy. PEX goes on top of the wire mesh (unless you’re going with fiber) and you’ll need to carefully consider the layout in regards to where you’ll have a lift and stuff in the shop.

If you’re gonna do it, I would go ahead and run it under the living portion of the house as well. You’ll really reduce your heating bill in the winter on that side at least. When it’s time, I’d be glad to price you the insulation needed, might be able to save you some coin.

You will have to have a concrete pump truck so be prepared for that extra cost too when pouring.
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It would deffinatly be in the living area also.

I hadn't thought about having to pump the concrete.
How much more expensive is that?
 
Junkyard Dog said:
I was talked out of this by several water stove manufacturers on my current shop build.
1- amount of heating days vs cost as mentioned by @kaiser715.
2- temperature swings in NC. This was the biggest reason. Probably wouldn't be a big problem in the residential area, but the floor sweating in the shop area. Its a problem in this area as you probably know. Basically the were saying that the slab wouldn't be able to cool off fast enough to compensate even if shut off. Multiple people said the same thing.

I am going with a water stove but just traditional heat exchanger hot air setup.
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Yes my shop floor sweats now badly but it happens more when its cold at night and then during the day I open up the doors and the warm humid air rushes in. So the opposite problem of the slab not able to warm up fast enough and the warm air condenses on the floor.

Good points
 
kaiser715 said:
I thought about this for my shop (2520sf), and ran some rough numbers. It just didn't seem worth it.

First, in this area (Stuntman is close by) there just isn't enough heating days in a season. Just a few months you need heat, and compared to up north, not that big of a temp rise. If the shop is 50, I am happy. Doesn't take much propane in a torpedo to do that. I will go for a couple of weeks or more without spending any real time in the shop. With the radiant, you can't just turn it on and go to work a half-hour later...you have to keep the slab warm all the time. Of course, you'll be living in the same space, so that's different.

Only other thing I can think of is that before the PEX is laid, you'll have to know where you are going to place machinery and equipment NOW, for any and all equipment you have or might get in the future that needs bolted down. IIRC, for something like a 2 post lift, you can't have the pex anywhere with in X feet of the post anchors.

For me, I use a couple of LP space heaters. Long-term plan is to put a gas furnace in. My shop is divided into 3 partitioned areas...I plan to put the furnace where the walls intersect, and dump a dampered vent into each area. Might eventually put a mini-split in the welding room, or the loft if I ever build it enclosed, so I have a cool spot to piddle on really hot days. I have also thought about a passive tin-can solar array to help keep it above freezing, at least.
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Good points on the equipment
 
Stuntman Autoworks said:
It would deffinatly be in the living area also.

I hadn't thought about having to pump the concrete.
How much more expensive is that?
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I would budget $200/hr for a pump truck. It might not be quite that much, but $200/hr will ease the pain if it comes in at $160ish
 
77GreenMachine said:
You will have to have a concrete pump truck so be prepared for that extra cost too when pouring.
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Dude is talking about an 8000sqft shop with heated floors. A days worth of pump truck rental aint gonna matter.
:bling:
 
Junkyard Dog said:
Basically the were saying that the slab wouldn't be able to cool off fast enough to compensate even if shut off. Multiple people said the same thing.
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If you kept the slab at a constant temp... let's say somewhere between 65F and 75F... you could have a boiler failure in Jan/Feb and likely wouldn't know about it for a couple of days.

Unless I'm misunderstanding the point about sweating, that's more of an issue in the summer with chilled slabs. If your slab temperature is less than dewpoint, you'll get condensation on the slab.
Stuntman Autoworks said:
I didn't know brass would react with concrete other than the natural moisture attacking the brass over time.
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It would take years and years and years... figure that they used to do radiant slabs with copper pipe, and those lasted 30-40 years before the copper started to give out.
 
im not trying to be a dick here but have you priced a 8000 sf building yet? i have a feeling a "BASIC SHELL" is going to be pushing 400,000.00 once labor, concrete, insulation, wiring and plumbing are all factored in.
 
Loganwayne said:
im not trying to be a dick here but have you priced a 8000 sf building yet? i have a feeling a "BASIC SHELL" is going to be pushing 400,000.00 once labor, concrete, insulation, wiring and plumbing are all factored in.
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Which is why I will be doing most of the work myself and if I need to pour concrete in stages over a couple years then that will be something I'm willing to do also in order to have enough space in the dry. (Is there such a thing?)
Also I spent some time talking yesterday and found out 70ft is the largest clear span wood truss so the dimensions may change. I may only do 60 or so wide with two 15ft sheds down each side that get closed in. Or maybe one gets closed in and one is open to the outside for parking. 80x100 is the general size I'm shooting for.
 
Stuntman Autoworks said:
The reason I was considering the in floor heat is because in a shop you are usually close to the floor working and if the floor is warm when you lay on it then everything seems much better even if the air temp isn't as warm as it could possibly be.
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It would be cheaper to install a couple lifts
 
Loganwayne said:
im not trying to be a dick here but have you priced a 8000 sf building yet? i have a feeling a "BASIC SHELL" is going to be pushing 400,000.00 once labor, concrete, insulation, wiring and plumbing are all factored in.
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I am in the process of building a 60x100 red iron building. 25x100 lean to off one wall, I am less than $20/sqft. with concrete, building package, labor to erect building. Have not bought doors yet or wired it. The cost of a building like this goes up tremendously when a GC gets involved. As in probably doubles, its ridiculous.

@Stuntman Autoworks if you want to check it out sometime it aint but 4 miles from your work. Might give you some ideas about what you do or don't want in yours.
 
Junkyard Dog said:
I am in the process of building a 60x100 red iron building. 25x100 lean to off one wall, I am less than $20/sqft. with concrete, building package, labor to erect building. Have not bought doors yet or wired it. The cost of a building like this goes up tremendously when a GC gets involved. As in probably doubles, its ridiculous.

@Stuntman Autoworks if you want to check it out sometime it aint but 4 miles from your work. Might give you some ideas about what you do or don't want in yours.
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Not going to disagree that cost goes up with a GC, most will charge 10-20% of total cost.

Cost also has a lot to do with the county your in as well. Concrete up here is probably 20 dollars a yard more. Also a building that size would require engineered drawings here $.

There are also usually size slots that they engineer to which if you go small on that slot the building cost more per sq ft than doing a bigger building in the same slot size.


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