Having a cost effective heating system for the coop means you have to seal it up tight, and that means bad ventilation. The hens will die more quickly from respiratory problems caused by poor ventilation than from the coldest Wisconsin winter.

If your hens don't stay in the heated area, they probably don't care about the cold.

I don't heat my coop but I'm considering heating the nest box so the eggs won't freeze. I'm going to try using a soil heating cable attached to chicken wire and buried in a few inches of sand. The straw for the nest will be on top of the sand. The cable, which has a built in thermostat, is safe to use in wet or dry situations (they are used in greenhouses). It can also be used with a timer to come on only during the morning hours. This is the cheapest way I can think of to keep the nest above freezing.

I use an electric water bowl to keep the water from freezing.

The only hens I have had frozen comb problems with are the Production Reds (Warrens) and the Broilers. My Leghorn's combs never freeze (which is weird because their combs are huge). I really like the Aruncana's small combs and they are good winter layers.

Hi, Thanks for your opinion. I have Japenese Phoneix. My rooster disappeared last night. I hope he's is still around some place, but I have coyotes, fox and red tailed hawks. Possibly, even a large cat. He was the one with the beautiful comb as well as feathers. I am very sorry to lose him. He had a tolerent personality unlike his brothers. I suppose that is the price of freedom. I have aruncanas this year, too. I have a few of a number of breeds as well as mutts.
Do you know anything about small heaters? I mean, do you know if any of them would be safe in areas with straw and hay? The cable probably wouldn't work under rest of the floor. Do you think?

The cable won't heat an area with a large headspace, but in a space that is about 2 ft high and well insulated, it works fine.

I use them in my hotbeds for starting tender plants in the early spring.

I guess you only keep the Phoenixs in the cages? And the others are allowed to roam in the coop?

One thing you could consider, and that would be perfectly free for you would be to make use of that horse manure you have. If you put it in large covered barrels in your coop it will give off alot of heat for about 5 weeks. Then you have to change it. It's best to use 3/4 fresh and 1/4 partially composted horse manure. Just dump it on your garden when it's spent.

Cows are supposed to give off alot of heat... lol.

You should read up on inexpensive heating over on the Greenhouse and Structures Forum. They have lots of ingenious ideas over there for heating as cheaply as possible.

How about finding an old electric blanket at a garage sale and putting it under the roof up where your chickens like to roost? It might not heat up too much, but it might be enough to keep the combs from freezing. Electric blankets don't draw much electricity.

Or make a hot compost pile inside the coop in the fall and that might help heat the coop. They used to grow wintertime vegetables in "cold frames" that were heated with compost.