Buffer Tanks are rarely larger than 120 gal, 30-50gal being most popular for residential, until you get into comercial /industrial applications. Either way you want it in the house since there are more benefits this way other than eating space.
I hear alot of CAN'T,,,, but yes you can improve your system using storage. Not everyone can afford to just upgrade. Storage DOES NOT have to be these 1000 gal ideas. Bigger only means longer between burn times, but also means more standby losses. Whats the difference between a Froling 20 @ 102kbtu and this empyre 100 @ 120kbtu. Cant he run it just like these indoor boilers?
If you go thru and verify everything in current system is at optimum then you can move onto calculations to see what size tank will suit you. No matter what you will have to burn the required wood to produce the target BTU you need. The tank will cover the very high demand periods. That 100 only holds 60 gallons, so you will have to figure what it will put out on a flat out burn for GPM with a 20-35 degree differential. If your getting 70kbtuh at the 6hr burn rate then thats atleast 7 GPM to charge your tank. Maybe someone else can help with the math also.
How much to upgrade anyways?
and how much can you add storage and efficient pumps and controls for? Alot less for sure.
Ive seen plenty of LP tanks, SS tanks etc for sale from $100 to $500 on CL. say $600 for 3 new top of the line Delta T ECM pumps(if necessary) and $350 in wood and Roxul to do the tank down to .5deg/hr stdbyloss. your labor and materials or a contractor for another $200-$1500 depending what you have them do.
You will have to do max burns while you are home tending, the benefit is you will be burning more efficient to charge tank and now when the tank calls for heat it will also run max for longer times charging the tank. You Might find yourself operating more like an indoor gasser than an OWB. Your empyre 100 claims a 120kbtu max burn rate, not far off of many of these fancy systems with crazy amounts of storage. It comes down to how much time you wanna spend at the stove.
if your trying to charge and calling for max load heat at the same time......see the problem, of course its a loosing battle. Think you should use the backup while charging or maybe there is a design flaw. Nothing wrong with 250 gal either.
Have you done a proper test on the heat loss of your underground lines? This is where I see alot of problems. Should be less than 1 degree loss per 100' with low gpm flow. logstor and uponor have this in their test specs and brochures.
