Outdoor Rocket Mass Heater for frozen animal water?

The pens for the goats, pigs and chickens are too far from my house to practically use extensions cords. Has anyone used a Rocket Mass Heater to keep water from freezing in the winter for their farm animals.

I imagine a low mass that could form a heated floor for some metal water bowls or pans to sit on.

A fancier version would have an extra tank of water that would feed the bowls or trough below when the level gets low. The tank would be near the mass to keep it from freezing during cold winter days.

How would you ensure you don't get the water too hot and simply boil it away or make it uncomfortable for the animals to drink from?

How long would I be able to expect the water to remain unfrozen in just under freezing temperatures (25 - 30 deg F)?

I can also imagine some of the mass being above / hanging over the water trough to give radiant heat from above to the water helping to keep it liquid.

Are there examples of RMH's built to not make hot water, but to keep it warm? Is this idea practical or will it cool off to quickly, being outside, that it would not be worth it?

Have you research anywhere?
From; https://www.horsenation.com/2018/01/23/4-low-tech-ways-to-fight-frozen-water-troughs/
The Floating Object
Just as a river rarely freezes compared to a lake, moving water stays liquid longer.
How can we use that to our advantage without leaving a hose running all night long?
The answer is as simple as placing some large floating objects in our stock tanks.
A basketball, tennis ball, or other non-sinking object bobs and floats around in the water, agitating the surface and making it difficult for an ice skin to form over the top of the tank.
Plus there’s an added benefit in really cold weather! If an ice skin does manage to form, the floating object creates a weak spot in the ice that your horse
can more easily break by pushing down on the ball to create a drinking hole."
The Insulated Side Walls
Insulating the sides of our water tanks can keep them warmer which delays or prevents freezing.
How does this work? Heat is lost from your horses’ water to the surrounding atmosphere primarily via the principle of conduction.
Heat energy is transferred from the warmer substance to an adjacent cooler one where they are touching.
In our case, the air is cooler than the water as temperatures drop outside – at night, for example.
The Floating Lid
This is the same principle as putting on a hat to keep from losing heat from the top of your head.
You can do this with your horse’s water by using a floating piece of foam the size and shape of your vessel to insulate the surface of the water
from direct contact with the air, which prevents heat loss much like a pool cover.
When the horse pushes his curious nose on the floating foam, it sinks a bit and water flows over the top for him to drink.
Some commercially available foam water covers even have a bowl shape in the top that water pools in for easy drinking.

And look at this topic
https://permies.com/t/19586/grid-livestock-water-freezing

I'm going to quote myself from another thread (which feels weird) but here it is:

Before electricity, farmers here used a simple immersion heater in their stock tanks. The heater was a heavy cast iron tub that sat right in the water, with a downdraft design and a chimney of adequate height to maintain the draft once established. Both wood and large lump coal could be burned. I'm sure the idea could be adapted to modern materials.

Edit: a search for stock tank heater wood fired turns up some commercial options, lots of discussions, and an example of a DIY project: https://www.backwoodshome.com/build-a-wood-fired-stock-tank-heater/

I can see advantages of using a RMH in some sort of structure or enclosure. Though the water in a large tank is a substantial mass in and of itself.

I am moving forward with experimenting with an outdoor rocket mass heater for animal water warming.

I will post some pictures of what I am thinking in the next few days, but I had a few questions first.

Can the drop after the heat riser (barrel) be lower than your starting firebox? Or would it be better to keep it at the same height as the firebox for draft purposes.

My question stems from the design I am leaning towards. (Pictures to come) I am envisioning a small brick "patio" next to the RMH that would be the mass. I came to putting the mass underground to keep wind from blowing the heat away. Some will conduct into the surrounding ground, but I think it will keep warm longer by putting it low.

So, if the bricks are to be counter-sunk, (This also allows the warmed patio to be located underneath fencing and supply multiple pens with warm water.) that leads to the main question above, do I need to sink the firebox into the ground also or can it be at ground level and after leaving the barrel it drops two brick channels lower into the ground from where it started?

I will also have some above-ground channels for heat before leaving the chimney that will form a small wall that water buckets can be attached to so they can't be dumped over. So the hottest part of the "Heat Mass" will be under-ground, but some will extend above-ground also.

Does anyone see other problems to this approach that I should think about?



Another question I had is on the channels through the heat mass. Do they need to be brick-lined, or can they be metal ducting tubes buried in gravel and sand for the mass? The hottest parts, the firebox leading up to the "barrel" draft chamber will be firebrick. My question is more towards after the barrel when the heat is traveling back and forth through the mass. How heat-proof do you need the passages there.

Thanks

Here is an attempt at attaching some pictures of my thoughts on the Rocket Mass Heater Water Platform.