Efficient hot water heater

My Pocos do great duty in the winter but in the summer they just sit around. Thx to the simplistic installation with a PV I would like to carry them down to the barn where the trainer who leases the barn washes his show horses all day after riding. I know all about hot water coils but I am sure there is mostly hot air coming out of the stove and it is therefore mostly wasted in this app. I see some people use say a EFM just for water would that be more efficient? Of course, I would like to get a much longer coal and extract all that heat as HW. Come winter time when he goes to FL then I would blank it off, drag it back up the hill and use it just to heat. Efficiencies? outputs? coil types? advice!!! I am trying to avoid buying another stove.

The only way to semi-efficiently generate DHW during the "off season" is with a boiler; even then, it's marginal savings---and directly proportional to what 'yer paying for coal, electricity, natural gas, LPG, etc.

I'm upgrading to a boiler and plan to run the boiler 24/7/365 to generate tons of heat and DHW during the heating months; and, "limitless" DHW during the off season.

Forget about using a stove with DHW coil during the off months; unless, you have access to free coal.

Plug your numbers into Microsoft Excel and see what happens...

Electric hot water heaters are 100% efficient. They convert 100% of the BTU energy in the electricity to BTU heat in the water. I suspect what you are really asking is nothing to do with efficiency, but economy. Economy of operation. Selecting the lowest cost water heating method is highly dependent on your local fuel costs and your tolerance for work. No work solutions are more expensive, sometimes very much so.

Thx yanche,

Of course, a poor choice of vocabulary. Given what I think is about to happen in the oil market a Back to the Future on your coal pile seems very appropriate. Tolerance for work is the issue but of course when you are working on your coal stove you are not doing other things that perhaps you have to pay big time for also.