Semi On Topic: Heating my shop

No you don't....

There's this great gadget called a "relay".... It has a 24VAC coil, and can switch 120 or 240VAC or even more.

Some are "solid state" - really triacs.

I'd like something that meets whatever rules my home insurance policy expects to see in my dwelling.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

one's choices.

to see in my

You can buy an integrated HVAC relay / transformer combo that mounts in place of a cover on a 4" square electrical box and provides screw terminals on the outside for the 24VAC connections. This will certainly meet all electrical codes for controlling resistance heaters up to the rating of the relay.

Use a standard low voltage thermostat and a contacter. (HD relay) Usually cheaper than line voltage stats. ANd easier to find too.

one's choices.

to see in my

There are units made exactly for that purpose that no insurance company could legitimately complain about.

one's choices.

natural for my

> 69.95 with free shipping.

>

The Grainger URL you cite displays a non-programmable stat.

If you don't mind doing a bit of artificing, you could use a 24-volt xfmr, a relay with 24-volt coil or a solid-state relay (about $25) and one of many good choices of residential programmable stats.

This approach probably wouldn't save you any $ but it would probably work noticably better. Line volt stats tend to have rather large differentials as RoyJ observed. There are other reasons to avoid them as well.

By the way, I was a scientist/engineer at Honeywell in a previous life.

I heated my shop with a torpedo heater with no thermostat, I had an old thermostat in my misc. pile. I used a small 24VAC transformer and a relay with 24VAC coil IIRC, line voltage went to the transformer and relay contacts, transformer voltage went through thermostat to relay coil. Gave me great temperature control of my torpedo heater, should work with a programmable thermostat too. I made my entire assembly with a line cord to plug into an outlet and a length of cord with receptacle to plug the heater into.

RogerN

69.95 with free shipping.

My error.

That one goes for 78.90, which still has me scratching my head.

Too late to make changes now since I have it in hand.

I see on the small print at bottom of the box that it uses 15 minute heating cycles. I assume (dangerous) that that means it will turn the internal contactor on / off once during a 15 minute window to regulate heat. Likey they do that to maximise the contactors life.

Maybe with the 4000# of metal in the room, the temperature swings won't be too wide.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

I did that too! I also added a catalytic screen on the heater to mitigate those "kerosene farts" it produced when starting each time.

I now use a natural gas unit heater vented to outdoors.

Right. With all that thermal mass, the room's thermal time constant should be quite long.

On Sat, 17 Oct 2009 11:58:07 -0500, the infamous Don Foreman scrawled the following:

With proper insulation, a 1,500W ceramic disc heater would be able to provide and maintain warmth in most climes. It might take a while to ramp up, but once warm, it'd stay toasty.

-- The blind are not good trailblazers.

-- federal judge Frank Easterbrook

I've got a 40' container color dark blue on the south side of my shop. By

10' am I can't put my hand on the inside wall and leave it there for long. There ought to be a way to harness that heat and use it to at least warm my 40x48 shop. I know that the air inside the container gets above 120 quickly. Since we only get about 372 days/yr of sunshine.....Any ideas? I've thought about recirculating the air but don't have any heat transfer data on the time required to heat up the container air in a circulating environment. Should be an excellent place for heating water also...

On Sat, 17 Oct 2009 13:39:38 -0700, the infamous "Stu Fields" scrawled the following:

Sure. Paint it flat black and fill it with 55 gallon water drums. Seal the door openings well.

Now add outgoing air ducting on the bottom of one end and return air ducts on the top of the other end, using thermostatically controlled (only working when the air temps are a set amount different) fans to draw the hot air out the top, into your shop. In the summer, put a white tarp over it and use it for cooling (once or twice, before it stays warm for the duration. ;)

-- The blind are not good trailblazers.

-- federal judge Frank Easterbrook

On Sat, 17 Oct 2009 13:39:38 -0700, the infamous "Stu Fields" scrawled the following:

Oops, forgot to address this part:

Drop by your local library and grab some books on passive solar heating and thermal mass. Note with a grin that most are from the 70s and 80s.

-- The blind are not good trailblazers.

-- federal judge Frank Easterbrook

Not counting other losses, the heater being on for 6 minutes will only raise the temp of the machines one degree. I realize there is more to it but It gives me a feeling that temperature swings won't be a big issue.

Oh well, I shall soon see how this works out in practice.

Wes

What's that Lassie? You say that snipped-for-privacy@snyder.on.ca fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Fri, 16 Oct 2009 22:38:13 -0400:

to see in my

Got any names? I've been wanting to do this since the first winter in my apartment. I think my thermostats are mounted in standard switch boxes, so something that needs a 4" square box wont work.

I forgot to think about the concrete floor, I have a feeling that is going to add greatly to the thermal time constant.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Concrete has considerably higher thermal resistance than metal so it doesn't take much heat flow to get surface temp up near ambient. A big chunk of metal needs to be warmed clear thru before it'll feel warm.