OT - Shop insulation

[50BMG DUDE]

Don't forget one of the best ways to insulate and heat a shop: fill it full of equipment and stuff!
A shop full of iron will acts as a slow-loss heat sink for the airspace and the concrete floor.
A lot less airspace to heat. A lot more concrete covered with iron.
For simplicity of install and ability to throw a lot of heat, one of the hanging unit-type natural gas heaters is hard to beat.
Since 2001, we've had a 175k natural gas unit here at the 4,000 sq.ft. shop (14-16' ceilings and basic insulation package), and the heater does a good job at countering our higher-elevation southwest-Virginia winters.
We run the heat on 68 during the day and 60 at night, with the monthly flat-pay gas bill averaging $150. Although nat. gas has gone up recently, I've yet to see much change on the gas bill...yet.
An overhead ceiling fan diffuses the warm air nicely.
So, with a building full of equipment and efficient heat, you can get by with a basic-insulation package.

ToolCat

This is one reason I started heating earlier this year. Started Nov 1 last year,

Thought maybe that the machinery picked up a chill that cost me $$ to warm back up once we started heating. There are 20pcs of machinery in the shop weighing more than 6K

There are no gaping holes in the structure. I have one 4" exhaust for a smaller CO2 laser that has a damper on it and enters into the fully enclosed machine

 

[Garwood]

Hydronic loops are stapled to the foam. Poly sheeting went under the crete as a moisture barrier, but is is on top of a raised pad of 80 yards of crushed limestone and 4" of sand that was compacted with a real deal big ass roller compactor. Floor is 6" thick ,6000 PSI crete.

I am not a radiant floor heat expert, but I do hope to use it in my next shop expansion. The research I have done says you can't run the pex down that deep. It will suck, you'll just heat the ground regardless of below slab insulation.

The pex is supposed to be closer to the top of the slab.

That could be your problem. All that heat is going right through your R10 slab insulation into all that rock you piled up.

 

[newtonsapple]

" If I update the HDD to cover the Oct. 17th - Nov 19th I get 809. With an annual 5570 HDD, that works out to 4634 gallon or $11,121. It would be interesting to know how that compares to the gallons used last year."

Last year I spent $10K and change, but took the month of Dec off so was not heating the shop above 50 deg for that month I was gone.

There are not any likely leaks in the loops as the FTVN boiler is a pressurized system and I have not has any pressure drop in over a year. When it was installed I was told I may have some in the first couple months as there can be small pockets of air trapped or entrained in the water that are removed by the air purge valve. There is a 2 Gallon (aprox) surge tank in the system that maintains pressure. I added about a quart of water to the system a year ago to make up for any bubbles that came out.

Hydronic loops are stapled to the foam. Poly sheeting went under the crete as a moisture barrier, but is is on top of a raised pad of 80 yards of crushed limestone and 4" of sand that was compacted with a real deal big ass roller compactor. Floor is 6" thick ,6000 PSI crete. Shop sits about 20" higher than surrounding grade, we did this due to the fact we are on a bench on the side of a mountain and spring breakup sends a good deal of water down the mountain.

As far as builder liability, I was the "builder" - I had the slab and hydronics done, but my family and I put up the pre-engineered building from a kit. We have a crane and necessary equipment to assemble.

As far as your calculated air infiltration, that is tough to believe if could be that high - As stated above the 2 overheads are high end doors and the only spot I think I could have a air leak would be at the tops of the doors. The Insulation blanket, as poor as it is/was is all joint taped continiously so there should be an air barrier throughout. There are 2) 36" man doors that are Jeld-Wen standard flush steel doors from HD and there are 3) 36"x48" Jeld-Wen Low-E glass sliders about 2' down from the eve along the west side for ambient light. (and to let me know when it's time to go home)

Any other thoughts are appreciated.

How many gallons did you use last year? Lots of price changes in the past year.

I would definitely get someone in that can do a blower door test and thermal camera analysis. They will tell you exactly where the leaks are, both air and conduction.

You can also spot some issues after light snow or heavy frost (thermal bridging):


Is that raised 20" exposed on the outside as bare concrete or buried? You said the slab insulation went 24" down. Do you have any vertical slab edge insulation going up to insulate the exposed edge of the slab (see the slab detail a few posts back with a floating slab)? Your concrete thickness may bump up the heat loss a bit.

How is the sheathing sealed to the slab or curb wall? How about seals at the corners and roof to wall? Is the insulation faced on one side only? Thin layers of low density insulation can experience some infiltration loss if exposed to airflow in places like the panel corrugations. Do the wall or roof permit airflow in the corrugations?

 

[newtonsapple]

I am not a radiant floor heat expert, but I do hope to use it in my next shop expansion. The research I have done says you can't run the pex down that deep. It will suck, you'll just heat the ground regardless of below slab insulation.

The pex is supposed to be closer to the top of the slab.

That could be your problem. All that heat is going right through your R10 slab insulation into all that rock you piled up.

Radiant floors are pretty expensive. In most scenarios, you are better off putting the extra money into the enclosure. This is particularly true if you need AC as you will need an air based system anyways (unless you live a super dry place and can radiant cool).

The whole warm feet radiant effect is a myth in the context of a well insulated house. The heating loads are so small, that the slab will never really feel warm without overheating the place.

If your design temps are above 5F and you have cheap electricity, inverter heat pumps are the way to go in many scenarios now. The higher your design temp, the stronger the case is for this. Cost are much more 1:1 with capacity though compared to gas where a 100K boiler is much cheaper than a 200K one.

 

[Garwood]

Radiant floors are pretty expensive. In most scenarios, you are better off putting the extra money into the enclosure. This is particularly true if you need AC as you will need an air based system anyways (unless you live a super dry place and can radiant cool).

The whole warm feet radiant effect is a myth in the context of a well insulated house. The heating loads are so small, that the slab will never really feel warm without overheating the place.

If your design temps are above 5F and you have cheap electricity, inverter heat pumps are the way to go in many scenarios now. The higher your design temp, the stronger the case is for this. Cost are much more 1:1 with capacity though compared to gas where a 100K boiler is much cheaper than a 200K one.

What does that have to do with the pex being 6" down in the slab?

It's been a bit since it was fresh in my head, but 2-3 inches down sticks in my head. There were several articles I read where big projects were done with pex laid 6" down in the slab and it was a total failure, didn't heat effectively at all.

 

[lucky7]

Respectfully disagree. Radiant floors in a shop are not expensive. Long term, they are cheaper as less btu’s need to be used. The heat is down low were the people and machines are. What they are poor at is rapid temperature changes- best to set at beginning of heating season at minimum comfortable working temp and forget. What too many people forget is they need a good amount of insulation under slab and at periphery of foundation going down to expected frost depth. In my case 6” below slab and 4”, four feet deep around perimeter. Yes, the tubes should be mid slab. Tied to rebar worked well for me. In the fifteen years I’ve had this current shop it has been far cheaper to heat than previous same size shops in same town.

This is my experience with a machine shop. I have limited experience with a home and radiant heating so won’t comment on that.

And just for giggles, ask how many guys prefer working under something laying on a cold concrete slab in the winter vs a radiant heated floor.

 

[newtonsapple]

What does that have to do with the pex being 6" down in the slab?

It's been a bit since it was fresh in my head, but 2-3 inches down sticks in my head. There were several articles I read where big projects were done with pex laid 6" down in the slab and it was a total failure, didn't heat effectively at all.

Sorry I wasn't clear what that I was commenting on new construction with radiant floors.

I believe you are correct that the location of the tube at the bottom of the slab would increase losses. I am not sure how to quantify the difference, but with R10ish below, I think it would still work. In residential applications, people put hardwood floors on top of radiant, which is a lot more insulating than a few more inches of concrete.

 

[Garwood]

Sorry I wasn't clear what that I was commenting on new construction with radiant floors.

I believe you are correct that the location of the tube at the bottom of the slab would increase losses. I am not sure how to quantify the difference, but with R10ish below, I think it would still work. In residential applications, people put hardwood floors on top of radiant, which is a lot more insulating than a few more inches of concrete.

OK, so you are not any more familiar with any of this than I am then?

I'm not finding them right now, but I vividly recall reading numerous articles in my radiant floor viability research phase that proclaimed the installed depth of the pex tubing was critical to heat effectively. Basically, you get past a few inches depth and you can't get the heat in the space. It doesn't transfer effectively enough and if you just staple the pex down to foam and pour 6" of concrete on top you are totally wasting your time- Just heating the dirt below.

 

[newtonsapple]

Respectfully disagree. Radiant floors in a shop are not expensive. Long term, they are cheaper as less btu’s need to be used. The heat is down low were the people and machines are. What they are poor at is rapid temperature changes- best to set at beginning of heating season at minimum comfortable working temp and forget. What too many people forget is they need a good amount of insulation under slab and at periphery of foundation going down to expected frost depth. In my case 6” below slab and 4”, four feet deep around perimeter. Yes, the tubes should be mid slab. Tied to rebar worked well for me. In the fifteen years I’ve had this current shop it has been far cheaper to heat than previous same size shops in same town.

This is my experience with a machine shop. I have limited experience with a home and radiant heating so won’t comment on that.

And just for giggles, ask how many guys prefer working under something laying on a cold concrete slab in the winter vs a radiant heated floor.

Less BTU's are not used with radiant floors as that is determined by how much energy is leaving the structure and the efficiency of the boiler or furnace. The one caveat to that is that in poorly designed forced air systems, user sometime increase the setpoint to compensate for poor air distribution or cold areas of the enclosure. In a constant set point scenario though, there is no difference in energy use.

Now in a well designed enclosure, the heat needs are low enough that the floors don't even get that warm. Even in the OP's shop, he's got 8000SF and 200,000BTU. His floor temp at a 60F setpoint tops out at about 72F, which isn't exactly cozy warm. Most of the time in winter it is probably like 67F. You can do tricks like concentrate the piping where you are laying on the floor.

If you reduce the enclosure losses, the average floor temp is even lower.

Consider that a radiant system might cost 30%-40% more than forced air and sinking the savings into more insulation and you will use less power with forced air.

 

[gustafson]

Radiant floors are pretty expensive. In most scenarios, you are better off putting the extra money into the enclosure. This is particularly true if you need AC as you will need an air based system anyways (unless you live a super dry place and can radiant cool).

The whole warm feet radiant effect is a myth in the context of a well insulated house. The heating loads are so small, that the slab will never really feel warm without overheating the place.

If your design temps are above 5F and you have cheap electricity, inverter heat pumps are the way to go in many scenarios now. The higher your design temp, the stronger the case is for this. Cost are much more 1:1 with capacity though compared to gas where a 100K boiler is much cheaper than a 200K one.

Agree and disagree. The lack of warm floors in a well insulated house is a myth. If you retrofit superinsulation in a previously radiant heated house, yes, the floors will never be warm. However, the struggle in a normally/poorly insulated house actually becomes how to keep floor temps low enough. If designing a radiant heated well insulated house, one simply cuts down that amount of tubing such that warmer water temps and thus higher local floor temps are required to maintain room temp. Then one locates the tubing where ones feet are bound to be located. Rather than a 7 inch grid in the bath, a loop in front of the sink, another in front of the toilet, and one under the feet in the shower. A loop a foot from the counter in the kitchen. A loop under the dining room table etc etc.

Radiant in slab is super cheap as it is just a roll of PEX, and a few valves.

It is however, no more efficient than any other heating system. As you say, its about boiler efficiency. I think there are subtle advantages to hydronic heat, but whether they amount to money is another question. Heat pumps are really the way to go. Heat, AC, relatively inexpensive to run.

The problem with radiant in a machine shop is the added load of the machines in the shoulder seasons. Only shop I know with radiant had to open the doors in the fall and spring, but I have no idea if that system was set up properly

 

[gustafson]

What does that have to do with the pex being 6" down in the slab?

I 'think' the only problem with deep pex is response time. I don't 'think' it really affects efficiency

 

[gustafson]

This is one reason I started heating earlier this year. Started Nov 1 last year,

Thought maybe that the machinery picked up a chill that cost me $$ to warm back up once we started heating. There are 20pcs of machinery in the shop weighing more than 6K

There are no gaping holes in the structure. I have one 4" exhaust for a smaller CO2 laser that has a damper on it and enters into the fully enclosed machine

Look, aside from the shell insulation, you appear to have done things right, and I don't think you are paying this dearly for that mistake.
Put it this way, a 1/16 gap on the entire perimeter of your building is a hole the size of a man door.
Another gap at the top of the wall is another door with a 24 hour convective breeze between the two. Imagine heating your building with two doors on opposite walls open 24/7 and a fan in one of them.

Commercial overhead doors are rarely set up right, everywhere I go I see that plastic trim loosely nailed and wavy.

I bought one of those little cameras that plugs into my iphone, and it gives pretty good thermal images. Couple weeks propane bill for you, might be worth it.

 

[50BMG DUDE]

I am not a radiant floor heat expert, but I do hope to use it in my next shop expansion. The research I have done says you can't run the pex down that deep. It will suck, you'll just heat the ground regardless of below slab insulation.

The pex is supposed to be closer to the top of the slab.

That could be your problem. All that heat is going right through your R10 slab insulation into all that rock you piled up.

Could be the case, although you still cant convince me that the shitty insulation is helping matters

This was also a compromise, since I needed to be able to bolt down barfeeders, tumblers. etc

The hydronics guys said this is how they normally install tube up here, just don't know about a 6" slab

 

[50BMG DUDE]

Look, aside from the shell insulation, you appear to have done things right, and I don't think you are paying this dearly for that mistake.
Put it this way, a 1/16 gap on the entire perimeter of your building is a hole the size of a man door.
Another gap at the top of the wall is another door with a 24 hour convective breeze between the two. Imagine heating your building with two doors on opposite walls open 24/7 and a fan in one of them.

Commercial overhead doors are rarely set up right, everywhere I go I see that plastic trim loosely nailed and wavy.

I bought one of those little cameras that plugs into my iphone, and it gives pretty good thermal images. Couple weeks propane bill for you, might be worth it.

I have a buddy with a thermal NV scope he said I can borrow. I'll check it out with that. I know the bottom purlin is tapconned into the crete with a double layer of sil-sealer under it.

The top edge of the wall-roof joint is a double purlin with the wall batts and roof batts overlapping

 

[50BMG DUDE]

How many gallons did you use last year? Lots of price changes in the past year.

I would definitely get someone in that can do a blower door test and thermal camera analysis. They will tell you exactly where the leaks are, both air and conduction.

You can also spot some issues after light snow or heavy frost (thermal bridging):
View attachment 380527

Is that raised 20" exposed on the outside as bare concrete or buried? You said the slab insulation went 24" down. Do you have any vertical slab edge insulation going up to insulate the exposed edge of the slab (see the slab detail a few posts back with a floating slab)? Your concrete thickness may bump up the heat loss a bit.

How is the sheathing sealed to the slab or curb wall? How about seals at the corners and roof to wall? Is the insulation faced on one side only? Thin layers of low density insulation can experience some infiltration loss if exposed to airflow in places like the panel corrugations. Do the wall or roof permit airflow in the corrugations?

The 24" of foam is vertical around the outside perimeter footing as a thermal break. Outside the building is graded from a couple inches below the top of the slab sloping out about 12' for drainage away from the building.

We got about 2" snow early this morning, I all burned off in a couple hours and slid off. When I get frost I can see the roof purlins like your picture.

I don't know how many gallons I burned last year, the wife just looked up the Co-op payments for last year to get the total price. I do know it was $2.60/gal last spring. and about $2.00ish last fall.

 

[50BMG DUDE]

My main driving reason for going hydronic was being able to use an outdoor wood boiler, just didn't get one in time for this year.

 

[Speedie]

11K to heat a 8K shop in the winter is insane. You did the floor correctly. Do not float pex on a floor unless it is thicker than 8". You should beg, borrow steal for spray foam and for cripes sakes get a ceiling. Move that air around. My last job had a shop that was 25000sq ft in Wisconsin with 18' ceilings but spray foamed, ect and was $7K annually to heat @ 1.96 gallon

 

[Speedie]

Consider you have gradient heat loss if you do not seal that lid and walls. A good shop will get hotter as height increases without major loss.

 

[CarbideBob]

For $25 dollars one can buy a laser pointed thingie.
Then you can point it your thermal break floor.
This is so much diffent from Michigan to Florida or Texas.
Mother nature is a bitch. She will not be denied.
Bob

 

[newtonsapple]

My main driving reason for going hydronic was being able to use an outdoor wood boiler, just didn't get one in time for this year.

If you tried to heat 100% with wood, you would use 17 cords (oak) per year. I didn't even factor in the lower efficiency of most wood boilers, which would make that number 20-40% higher...

That's a LOT of wood, wouldn't leave much time to run a shop.