The term 'deep litter' is often misunderstood and misapplied.
I've always liked this explanation:
http://www.backyardchickens.com/t/1075545/can-i-do-deep-litter-method-with-this-coop#post_16440037
Managing a
truly composting deep litter can be tricky, you have to understand what it contains(both materials and the organisms that break it down) and
how it works in order to manage it effectively or it can turn into an unhealthy nightmare. It's not just piling up a bunch of stuff and, viola!
There are many ways to manage the manure your birds will deposit.
This is how I do it:
-I use poop boards under roosts with thin(<1/2") layer of sand/PDZ mix, sifted daily(takes 5-10mins) into bucket going to friends compost.
-Scrape big or wet poops off roost and ramps as needed.
-Pine shavings on coop floor, add some occasionally, totally changed out once or twice a year, old shavings added to run.
-Runs have semi-deep litter, never clean anything out, just add smaller dry materials on occasion, add larger wood chippings as needed.
-Nests are bedded with straw, add some occasionally, change out if needed(broken egg).
There is no odor, unless a fresh cecal has been dropped and when I open the bucket to add more poop.
That's how I keep it 'clean', have not found any reason to clean 'deeper' in 5 years.
As to water heaters, I am unfamiliar with the commercial ones.
Will just say
be careful with your power sources/connections, they can be deadly.
I made my own heated waterer...
https://www.backyardchickens.com/articles/aarts-heated-waterer-with-horizontal-nipples.67256/
....it has to be topped off daily(~1/2-3/4 of a gallon), which is fine with me as I can keep an eye on it and monitor birds consumption.