OWB has anyone added pressurized storage tanks to one of these?

[2.beans]

a freind of mine wants to add 500 gallons of pressurized storage to his system. he currently has a classic owb tied to his system thru a hx. he wants to put the 500 gallons on the pressurized side of the system (thats all he has room for). has anyone tried this. is it worth it? no boiler bashing please i dont want his feelings to get hurt.

 

[jebatty]

a freind of mine wants to add 500 gallons of pressurized storage to his system. he currently has a classic owb tied to his system thru a hx. he wants to put the 500 gallons on the pressurized side of the system (thats all he has room for). has anyone tried this. is it worth it? no boiler bashing please i dont want his feelings to get hurt.

"Worth it" is an opinion, not a fact, so can't answer that question. Without bashing the poor efficiency of the OWB, and assuming that the OWB produces more btu's than can be used without the boiler going into idle, the 500 gal of extra storage will serve as a buffer or storage to allow longer burn times between idles, and should increase poor system efficiency to less poor system efficiency. If the storage is located in the structure to be heated, the storage also can serve as a radiator to heat a basement, for example, with extra heat convecting and radiating throughout the structure.

Since it appears he has a pressurized side of the system already, I assume he has another oil or gas boiler. How does he connect those now and deal with the pressure differential? One way of course would be with a coil or plate hx to isolate the OWB from the pressure side. With 500 gal of pressurized storage a large expansion tank also will need to be added.

I believe the efficiency gain will be minimal, although the comfort gain may be more. The inherent burn inefficiency of the OWB cannot be improved upon, although reducing idling, start-up and shut-down will be of some benefit.

 

[Nofossil]

There migt be some conflict. One of the primary benefits of storage is that you can run your boiler hot and efficient, then let it go out and live off of the storage for a while. One of the benefits of an OWB is that you can load it with a huge amount of wood at a feeding and never let it go out.

The storage would make sense if it stores enough usable heat to enable a more efficient or convenient boiler firing schedule.