Downfall of Placing Water Coil Directly in Coal.

Hi Everyone,
What is the downfall of placing a water coil directly into your burning coal?

The only reason I've found is that your water gets "too" hot.

I've seen schedule 40 pipe go through lots heat in commercial boilers, just wondering why people put their coils high up in their stoves instead of directly in the coal?

Thanks for you input.

The temperature of the stove air above the fire is ~1000-1500*, the temperature in the fire when red-white hot is ~2200-2500*. the added temperature and oxygen will errode away the pipe, even if it is SS. Cast iron may last a reasonable length of time,, but the above-fire coils last decades..

Greg L.

Plus in a failure, you will vaporize the water (turn to steam) WAY faster directly in the coals, plus the stokers don't have the room in the burn tray for a coil, most coils are pretty good size, and to get the most heat transfer, you need a very long one.

The Clayton furnaces I believe use a coil within the firebox. See the attachement. THis is a great article on how to install a coil.
I was concerned at first too, but with a pressure relief valve in place I think it would be okay as long as you're hooked up to a water heater.

I'm new here. Hey, thanks all of you for your great info. It got me off and going with coal!