I might try that.. Its a simple, low cost idea..
And it dont get that cold here.

I built a wooden box lined with that foil covered foam insulation that fits over the anvil with about 4 inches of air space all of the way around. I also cut out two pieces of plywood that fit around the base of the anvil and covered them with the same foam insulation. I have a 60 watt ceramic reptile heat emitter that I mounted through a hole in the top of the box to point down on the face of the anvil.
Check them out here Heat Emitters. it draws only a little more power then a 60 watt light bulb.
It keeps my anvil warm not hot and last year in my shop (unheated) I had temps at -15 degrees
My shop is in the woods in a low spot and in the winter it does not get sun until around 1:00 pm. Lets put it this way this time of year I hang deer and game in my shop and they keep as if in a meat locker.

Here is what I'm doing for mine, just a tarp wrapped over a trouble light and around my 280 lb wright anvil.

I keep a 2"x6"x1/4" piece of plate on my stand that I used as a punching block. On really cold days I throw that in the forge as soon as I light it and once it is hot I just leave it on my anvil face. By the time I get everything else set up it has heated the anvil face enough to help keep smaller pieces from cooling too quickly.

My Buddy Don from FA-WA forge told me he takes a salamander, fires it off, points it at the forge, leaves for about 5 minutes, when he returns, his anvil, and his entire shop is warm, might have to try that one! Course his shop is in and 8X8 shed.

in my experience(which is jus about 8 months, hehe ) a cold anvil will break when hit with a sufficiently large force. thus heating is a very very good idea.

i use the same method as said above in many places of using a heated piece on the anvil and letting it absorb the heat.

I got a chuckle out of construcitng a building and heating it. That's my favorite! lol

I use a natural gas furnace to keep my shop above freezing and to drive out the moisture to keep the metal from sweating. Then the wood stove is fired up for an hour to make it cozy for the blacksmith. I will add a insulated box around the anvil with a light to keep it a bit warmer. I have always been careful not to work on a cold anvil for fear of damage to the anvil. I over looked the cooling of the metal being worked.

Great thread! Always something new to learn everytime I log on.

Thanks folks

Salamander on a timer and thermostat. Starts 1/2 hr early. has my
18X24 shop at 68+ when I get there.
Ken

I guess we're going to have to build little stoves under our anvils and place them on steel frames. Heheh.