New garage time!

[fatjay]

This is the tubing I was looking at. I figure 2 spools of that will put me at 500' to spare: 1/2" x 1ft roll of PEX Tubing with Oxygen Barrier - PexUniverse

The manifold would be something like this to bring it together: 8-Port Stainless Steel Manifold for Radiant Floor Heating - PexUniverse

This is the hot water heater I liked: https://www.homedepot.com/p/EcoSmar...ectric-Tankless-Water-Heater-ECO-18/203316216

I was thinking of this pump: Taco 7-F5 Cast Iron Circulator Pump, 115V - PexUniverse

And this to control the pump: Taco SR51-4, 1-Zone Switching Relay - PexUniverse

So I can hook any old thermostat up. Plumbing this is going to be fun, I am looking forward to this one.

 

[ovrszd]

I'm concerned about the water heater. Not sure it can keep up. Your pump will run somewhere around 2.8 gpm. Your heater produces 3.5 gpm at 35F temp rise. You need your water temp to be 110 or so. If your water source temp is 55F and you are trying to heat it to 110F you have a 55F temp rise. Your heater won't be able to keep up with the flow rate of the pump and maintain 110F. You'll end up moving water that might be 80F. That won't work. It'll run non stop and never reach thermostat setting.

Understand, the heater does not regulate flow. If pushed beyond it's abilities it simply puts out water at a cooler temp.

You need a heater in this category. Not pimping the brand or model. Just showing you an example of the size you need.

Stiebel Eltron Tempra 36 Plus, Whole House Electric Tankless Water Heater - PexUniverse

Also, you need an expansion tank and an air burper. Depending on how you plumb it you may also need a one way valve and a pressure regulator.

Not trying to talk down to you. Just not sure what you know.

These systems work pretty simple. Thermostat demands heat, it activates the pump, heater sense water movement and fires up. When demand is met thermostat disconnects, pump stops, water movement stops and heater shuts off. The expansion tank is needed to handle the expansion and shrinkage of the water. Burper continually removes any air that forms thru the heating/cooling process. One way valve and regulator is needed if you want to create an open system that constantly has water service pressure against it.

 

[ovrszd]

Oh, forgot to mention pex pipe. You need a foot of pipe for every square foot of floor space in your building.

 

[ovrszd]

Here's a pic of my shop setup. Again, not pimping anything. Just offering ideas.

 

[aczlan]

I'm concerned about the water heater. Not sure it can keep up. Your pump will run somewhere around 2.8 gpm. Your heater produces 3.5 gpm at 35F temp rise. You need your water temp to be 110 or so. If your water source temp is 55F and you are trying to heat it to 110F you have a 55F temp rise. Your heater won't be able to keep up with the flow rate of the pump and maintain 110F. You'll end up moving water that might be 80F. That won't work. It'll run non stop and never reach thermostat setting.

Understand, the heater does not regulate flow. If pushed beyond it's abilities it simply puts out water at a cooler temp.

You need a heater in this category. Not pimping the brand or model. Just showing you an example of the size you need.

Stiebel Eltron Tempra 36 Plus, Whole House Electric Tankless Water Heater - PexUniverse

Also, you need an expansion tank and an air burper. Depending on how you plumb it you may also need a one way valve and a pressure regulator.

Not trying to talk down to you. Just not sure what you know.

These systems work pretty simple. Thermostat demands heat, it activates the pump, heater sense water movement and fires up. When demand is met thermostat disconnects, pump stops, water movement stops and heater shuts off. The expansion tank is needed to handle the expansion and shrinkage of the water. Burper continually removes any air that forms thru the heating/cooling process. One way valve and regulator is needed if you want to create an open system that constantly has water service pressure against it.

Except that if the water is recirculating in the system the temperature of the water coming in will rise as it brings the floor up temperature.
So in theory, the only temperature drop should be the amount of heat that the water gives up to the floor.
Definitely will need a check valve and a pressure regulator to prevent back feeding and drop the system pressure from whatever house pressure is set to.

Aaron Z

 

[ovrszd]

Except that if the water is recirculating in the system the temperature of the water coming in will rise as it brings the floor up temperature.
So in theory, the only temperature drop should be the amount of heat that the water gives up to the floor.
Definitely will need a check valve and a pressure regulator to prevent back feeding and drop the system pressure from whatever house pressure is set to.

Aaron Z

Excellent point Aaron. I forgot to factor that. I've never checked the temp of the water coming into my heater. Dang it, that would be good information right now. I'd guess that it will be similar to the thermostat setting or just above.

If it's really cold out my building is losing heat. So my floor will be warmer than my thermostat setting. I use a thermostat with a concrete probe. It detects both temps. Causes the system to run on shorter cycles more often which is good. I have my thermostat on 68F. The max concrete temp set on 75F. My probe is about 6ft from my manifolds. Really cold days it will cycle.

So if my floor temp is 72F (guessing) and my heater is on 120F (which it is), I'm warming the water 48F. Still exceeds his heater by 13F. Not going to keep up. At the end of a cycle he may be down to 80F or 90F water going into his loops.

 

[civilian]

Not sure if this is a factor in h OP's area, but our building dept will not allow water heater to be used to heat floors. It has to be a boiler system. Fuel or wood boiler. Just saying. Jon

 

[fatjay]

Finished parge coat, put on termite guard, got another 13 ton of stone to level it out and built a rake that will level the stone out. It sits on the outside 12's and drops down 2" where the stone needs to be.

Side note, I noticed a robin fly out of my backhoe. Turns out they built a nest in the boom.

 

[dragoneggs]

Mr. Fat, I continue to be impressed with your build and progress. Keep it going and keep posting the great pics!

 

[fatjay]

The $8200 for the floor is out. The guy wanted to do wire/pex sitting on the insulation, then 3x3 grid of rebar on top. Everything I researched said pex needs to be 1-2” from the top. So I’m doing 2’x2’ rebar on chairs at 3”, then wire on top of that, then pex ok top of that, which should put the pex about 1.5” from the top. Also priced rebar and wire plus concrete to come out to $3200, $5000 for a days labor for 2 guys is a bit much. I picked up the wire today and am picking up 60x 20’ pieces of rebar tomorrow. I have to decide if I want to do 6” or 12” spacing on pex because I’m going to tie it to the wire mesh and it’s 6” square. I know I’ll be putting in 2 lifts so I need to drill the concrete for anchors. So I’m thinking 12” in those areas, 6” in the rest.

 

[EddieWalker]

How will they spread the concrete and walk on the 6 inch wire and not push the wire to the bottom of the pad?

 

[fried1765]

How will they spread the concrete and walk on the 6 inch wire and not push the wire to the bottom of the pad?

I think wire mesh rests along the very bottom of 90% of most slabs.
Even pulling the wire mesh, with slots cut in shovels, or using a hook, is not all that good, because it often gets walked on again.

 

[Pixguy]

More chairs?

 

[fatjay]

How will they spread the concrete and walk on the 6 inch wire and not push the wire to the bottom of the pad?

We are probably going to end up doing it ourselves. We'll drill the block on the side to stick the rebar in 3" up, and for chairs I was thinking of using 2"x3" angle iron, cut in 2" sections, and welded to the rebar every other joint, so hopefully it'll support it. That way the pex sitting on the wire will be at ideal height.

 

[ovrszd]

I think you missed Eddie's point. A point I also wanted to bring up.

With 6" mesh above the rebar with the pex tied to it 1.5-2" from the top of the pour you can't walk on the pad when pouring. There's no way to screed the concrete?

Secondly, I've never heard of installing the pex 1.5-2" from the top? What is the purpose of doing that?

Again I say, the mesh is unnecessary. If you want the pex embedded in the middle of the concrete tie it to the rebar.

As for rebar chairs. Buy the plastic ones. They are dirt cheap.

 

[fatjay]

Apparently we’re doing the pour ourselves. We have 2 helpers as well so 4 people total. One truck gets to the rear, one in the front. We found 3” rebar chairs in plastic and will have them at every intersection. Then tie the mesh to the rebar, then pex clips on the mesh. All the pex guides I’ve read say 1-2” from surface so the heat doesn’t have to go through 5” of concrete to get to the surface. We’re figuring it out as we go, I think the goal is not to step in but pull from the outside. The concrete guy we talked to said we should go with mesh as it’s a lot easier to tie the pex to and the spacing is taken care of for you. Mesh isn’t expensive and it’s not hurting anything. We’re still learning as we go.

 

[ovrszd]

Yeah, definitely do it however feels right to you. There are some "rules" in laying the pex but I think you've got them covered. Laying it in the upper half of the slab is not one of them. Most pex is laid on the pinkboard and stapled.

The heat you get from floor heat is what's stored in the slab. The slab provides continuity and even heat. The idea that it'll work better being in the upper half of the slab is simply wrong. I'm not saying it's a bad idea. Just saying it won't work better. Heat rises. The heat source being at the bottom of the slab is most logical.

Whatever you do try to follow the rule of a foot of pex for every square foot of floor. Make sure all of your loops are the same length.

I'm not sure how you are going to lay the pex since you can't walk on the elevated mesh. But you'll figure it out.

Looking forward to pics as you go. If you have a Drone take a pic straight down on your floor before you pour. This will be a guide as to the location and routing of the pex.

Take your time when laying out areas for your lift to sit. Take detailed measurements. I know of a commercial shop that drilled thru a loop when installing a lift. Their failure was to move the lift from it's original location. They moved it 6".

 

[Citydude]

Im not getting the 1 and 1/2 inch below the surface in a 6 inch slab for pex placement. Isn’t this not using the principles of heating with mass? 1 and 1/2 inches of concrete heated is not the same thermal retention as 3-4 inches.

 

[fatjay]

A lot of the information I'm getting is from here: How to install PEX Tubing in a concrete slab

It makes sense to me at least. Maybe for a 4" pad it wouldn't be bad but 6" is a lot of concrete to heat before it hits the surface. Their suggestion doesn't seem to be driven by sales as they wouldn't make anything extra regardless of where you put it, and they even sell staples to staple it to the insulation. I mean if it's dead wrong, it's dead wrong, it seems to make sense to me though.

Today was the leveling of the gravel and digging out the front course of block so we can lay the final course of 12's tomorrow. The stone leveler worked great and gave a real nice consistent level. I had a spare 24' 2" square tube steel so I picked up a 20' section of 2" angle iron and welded it to the bottom. Attached fork attachments to it. But I found that it was fairly unstable, I would dig in any time i hit a mass of stone. So I smoothed it as much with the bobcat's bucket, then shuffled the leveler on the ground forward a few feet to get my new level, then back on the bobcat to pull the stone away. Repeated the process many times, and even welded a piece of tube steel on the front to keep it from tipping forward. I'm happy with the results.

Clearing out the stone #3 stone that we've been driving over for the past week was a pain, basically hand picking boulders out of the holes. Got the new block in place for tomorrow. Sand, lime, and mortar next to the bin as well. Will lay the last course of 12's, finish the ends, put in the center post, pour concrete down the middle, put in the J bolts and some rebar down the middle for strength. When I was 14 I was pulling my mothers car around and mistook the clutch for the brake and smashed the center post of my fathers garage with the volvo. It didn't move. So over the course of the next 50 years, I'm sure the center post will be smacked and I'll be safe.

 

[aczlan]

Once it gets up to temperature, your entire slab will be the same temperature from top to bottom (within a degree or two).
It may heat up faster with the PEX in the top couple inches, but once the slab is up to temperature it shouldn't matter where in the slab your PEX is sitting.
If it's further down the slab, it'll be a little bit harder to hit on accident which is where I would put it.

Aaron Z