Shop Floor Heat

Jaden

Member
Location
Eastern Nebraska
Referring to the post below, If I left my heat on 24/7, the room would be way too warm for comfort. Because of the slow response, I don't have an auto thermostat set up yet.
 
Just get a cheap thermostat and hook it to the circulating pump I just used one from the house that I replaced with a programmable. Just make sure it can handle 120 volts.
 
I heat 1500 sq ft shop floor to 75 degrees with a wood boiler. Some days if its sunny and calm it will get to 70 in the shop. Cold windy days it may get down to 60. I will have to turn it down when we start getting 50s outside. I love the warm feet and how you can have a door open and not be cold. I did 2 inch foam under nothing on the sides but a block wall. I loose some heat cause of that. It takes a half if not a full day to get a noticeable air temp change. I think with your system you need to let the floor temp alone and if you want to regulate heat you will need to do it with a hot air heater.

I did figure with my system running I was putting 60000 btu to the floor. I don't have a timer to tell me how long it runs so I don't know how many but I really put into the shop in a season.
 
I use the thermostat from a junked water heater glued to the lower tank of 1 of my shop radiators to control the draft blower and chimney check to keep my outdoor boiler at a constant water temp.
 
Install a thermostat and set it to a cool but comfortable temperature, and leave it there. The more stuff you put in the shop, it will retain the heat longer as well. For radiant heat like in-floor to work correctly, you need to have it consistent. I heat a 40'x40' shop with 12' ceilings using in-floor heat, run from a wood fired boiler that I also use for heating the house. I leave the thermostat at 60F and the circulating pump probably kicks on about once a day. If it's below zero, the pump may turn on more and run longer. I run the boiler from October to mid-April, and I never change the thermostat.
 
jaden,
Bet once you get the concrete warm, it will stay warm for a while. I think the specific heat for concrete is about 0.5. Water is 1.0. What this means it is it takes the same energy to heat 2 pounds of concrete as it takes to heat 1 pound of water.

Your slow response is because you have tons of concrete, thermal mass, to warm up.

If it require 24 hours to recover, water heater not shutting off, it would cost me about $15.

Could see the advantage of having dry floors.

I was working in my 24x24 garage today, not shop, which is attached to my house. I can heat it with a 1500 watt baseboard heater. However, I haven't had the heater on in years. The garage temp was 45. Last night it was about 20. My garage has over R20 walls, R50 ceiling, Anderson windows, insulated doors. Leave windows cracked open a little to keep it dryed out. I think the reason my garage stays warm is because it is south facing, brick on the outside, some heat comes through the insulated wall from house and the main reason is my 6 inch concrete floor is resting on 8 inches of pea gravel. The gravel acts as an insulator.

Hope your heating works well for you. Like you said, you could heat the water with anything. May find out propane is cheaper.

George
 
(quoted from post at 11:13:21 03/06/13)...Like you said, you could heat the water with anything. May find out propane is cheaper.

George

That is what most people do. An electric water heater is the least cost effective method.

Go to AgTalk for WAY more info on what people are doing with in floor heat. It is a good idea if you are going to be in a shop everyday. If you are only there on nights or weekends radiant tubes seem much better.
 
sflem849,
Decided to crunch some numbers. My 30x40 pole barn has a 6 inch floor. Using my floor, it will take 444,444 BTU's to change concrete just 10 degrees. If I used a 5500 watt electric water heater, it would take 23.7 hours to do the job. Not factoring in any heat losses. SOOOOOO, it will cost me $15 to change my floor temp 10 degrees.

If anyone wants to check my calculations:

specific heat for concrete is 0.5
1 yard of concrete is 4000 pounds.
these numbers may not be exact, but close.
I was trusting my old memory.

George
 
I heat my 42 X 62 shop with in-floor heat from a natural gas boiler. 2" foam underthe floor, 6" in the walls and 18" blown in in the ceiling. Keep it 60 degrees all winter.
Usual gas bill for the winter is around $900.00. Last years was 621.00
 
As some of you noted, the floor is also very slow to cool down. That's why after opening a door, the air warmth returns quickly.
There are some studies that show that the depth of pex piping in the concrete affects warm up and cool down. Mine are probably below half way.
 
GordoSD,
Heat loss is calculated by knowing the R rating of walls, ceiling, windows, doors, loss through ground, not to mention air infiltration. You also have to know the delta temp between inside and outside temps. Windows are rated in U ratings which you convert to R. R = 1/U Oh, you also need to know the surface area of each part of the building too, doors, windows, walls, ceiling, floor.

Give me that, the rest is very simple.

It's very cheap to heat just air.

George
 
(quoted from post at 13:20:29 03/06/13) sflem849,
Decided to crunch some numbers. My 30x40 pole barn has a 6 inch floor. Using my floor, it will take 444,444 BTU's to change concrete just 10 degrees. If I used a 5500 watt electric water heater, it would take 23.7 hours to do the job. Not factoring in any heat losses. SOOOOOO, it will cost me $15 to change my floor temp 10 degrees.

If anyone wants to check my calculations:

specific heat for concrete is 0.5
1 yard of concrete is 4000 pounds.
these numbers may not be exact, but close.
I was trusting my old memory.

George

So wouldn't this be true for propane? There are 91,300 btus in a gallon of propane. Propane is around $3/gal right now. So it would cost $14.60 to heat the same floor with propane. About the same.

Don't you need to account for efficiencies somewhere in the calculations?
 

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