Posts Tagged ‘Boiler Tanks’

Is a hot water storage tank required?
It is highly recommended because it increases overall system efficiency, is more convenient and minimizes the possibility of creosote build up.

Hot water storage tank before it was insulated

Efficiency:
A properly sized hot water storage tank can lessen your wood usage. The average American house uses about 82 Million Btu’s annually. Assuming the boiler system is 85% efficient, 82 Million Btu’s translates into 4 – 5.25 hardwood cords or 6.5 to 11.75 softwood cords.

The increased efficiency is due to the fact that the boiler is designed to operate best when burning at full pace. The hot water tank stores heat for later, and allows the boiler to continue to burn for a longer period of time at maximum output. Once the demand is finally met, the boiler will idle.

Convenience:
Because the heat is stored in the tank, the heat is retained long after the wood or coal is depleted (the length of time is variable based on demand and on the volume of water in the tank). This means that you don’t have to reload your boiler until your tank temperature drops to an unusable temperature (the unusable temperature varies based on your heating system. Typical unusable temperatures are below 140 degrees for baseboard and below 110 for radiant floor).

Starting the fire once every few days is sufficient during warmer months in fall and spring or in the summer when using the boiler only for domestic hot water. So ultimately, even though the boiler will produce heat without the additional storage tank, the added efficiency and convenience exceeds the initial investment of a tank.

Creosote:
When you size your boiler, typically you are trying to size it for the coldest temperature your area sees in the winter. Our area is 0 degrees. We may see 0 degrees for a week or two out of the year, so that means that 90% of the time our boiler is “over sized”. This means that in the spring and autumn months the boiler will tend to idle more if no storage tank is used.

When the boiler is idling, you have the potential to build up creosote in your primary chamber and chimney. If a hot water storage tank is in use, it allows the boiler to burn at full capacity for a longer period of time when first lit. This allows the tar and creosote causing agents to be burned off during the gasification. If system demand is met near the end of the burn, the fuel left is in a charcoal state.  If the boiler idles at this point, it will not cause any creosote.