Summer boiler operation
GBA Editor
| Posted in Energy Efficiency and Durability on
I presently use an electric hot water heater for use as a domestic hot water source in the summer months. I have been told that I cannot shut down my oil fired boiler in the summer months as it will leak from the gaskets and cause corrosion of the heat exchanger. The boiler is installed in the living space of the home (not below grade) and I turn off the power to the boiler in May and turn it back on in the fall. I feel that I save fuel oil by doing this – am I wrong?
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Replies
Dwight,
There are two ways to produce domestic hot water from a boiler. Older boilers had tankless coils; such coils required the boiler to fire every time there was a call for domestic hot water.
Newer boilers are usually equipped with indirect water heaters that include an insulated hot-water storage tank with a heat-exchange coil. An aquastat in the tank controls a circulator that circulates boiler water through the heat-exchange coil whenever the hot water in the tank drops below a certain temperature. Such a set up requires a boiler to fire far less frequently and is therefore more efficient.
Here's my advice:
1. Whether you have an indirect water heater or a tankless coil, you probably aren't saving any money by switching to an electric water heater in the summer. Electricity is a more expensive fuel than oil. It makes more sense to obtain your hot water from the boiler.
2. If you have a cast-iron boiler that you turn off during the summer, it is indeed possible that the boiler's gaskets will leak when the boiler cools off. That's why it's safer to keep the boiler warm during the summer -- especially if it isn't located in the basement.
3. If you have a steel boiler, there are no gaskets to leak (except gaskets around the tankless coil if the boiler has one). A steel boiler without a tankless coil is not at risk of developing leaks during months of idleness.