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Strong, Silent, and an Important Part of Your HVAC System: The Buffer Tank
Has your plumber mentioned your buffer tank, or suggested that you could use one? Since it is an unfamiliar part of heating and cooling systems for many homeowners, let’s talk.
A buffer tank quietly solves problems in your hot water system that you probably weren’t aware of, so it doesn’t get much credit. You may not have heard the term even though you’ve owned your home for years. At bluefrog Plumbing + Drain, our plumbers want you to make informed decisions about your home and its plumbing, so let’s talk about your hot water system and see how buffer tanks fit into the picture.
You Might Have a Buffer Tank and Not Know It
Many homeowners focus on the basic functions of their heating and cooling systems and don’t notice the support equipment such as buffer and expansion tanks, or even a tankless water heater associated with your furnace. Your plumber can guide you through identifying each tank and its purpose. It’s also possible that you might have a similar-looking expansion tank for your well system in another location.
The Buffer Tank’s Purpose
A buffer tank serves a purpose similar to a battery or flywheel — it holds energy or “thermal mass” so the heating or cooling equipment doesn’t have to operate as frequently. This saves wear and tear on your expensive machinery while keeping a supply of hot (or cold water, usually in commercial systems) available for use. The buffer tank is insulated to ensure that the temperature is maintained, and it is also pressure rated according to the application.
Expansion Tank versus Buffer Tank
Though they might look similar, expansion tanks serve a different purpose from buffer tanks. Your plumber can tell you about the pressure issues that put stress on the plumbing of your heating systems, and how an expansion tank absorbs the stress. The primary issue is the expansion of heated water, a basic principle of physics. The expansion tank provides a mechanism that adapts to the pressure dynamically as part of the system, rather than just using an external relief valve every time your heating system cycles. In case of trouble, your system should have a relief valve as well.
Other stresses that the expansion tank handles include valves opening and closing throughout your heating system, and pumps starting and stopping. You could have both types of tank in your system, and your plumber can tell you if adding one or the other could be beneficial, as sometimes they are omitted during construction for cost savings, possibly reducing the lifetime of your mechanical components.
Your Plumber Might Recommend Adding a Buffer Tank
Since one of the buffer tank’s main benefits is reducing “short cycling” of your equipment and the related wear and tear, leaving it out of your heating system design can provide savings when your home is built or a new system installed, but possibly at the cost of a reduced lifetime of other system components. Your plumber might begin a conversation about buffer tanks by asking how long you plan to live in your home, since adding a buffer tank could provide long-term cost savings.
Working in Conjunction with Your Water Heater
Buffer tanks can provide a dual benefit, storing heat for your various heating systems such as room heat, radiant floor heating, and also for hot water for your faucets and appliances. Your plumber can explain how the system works to support your heating and hot water supply together and discuss the benefits and drawbacks of tying the two systems together.
What a Buffer Tank Looks Like
Most buffer tanks look like a typical pressure vessel-style tank, with at least two sets of pipes entering and exiting from the top or bottom. The size of the buffer tank can vary depending on your application and the size of your building, from a compact model for basic residential use to hundreds of gallons for commercial use.
Buffer Tanks for Chilled Water
Buffer tanks can be used for cold water when an HVAC system uses it to provide cooling throughout the building. This is more common in commercial installations. The tank will be designed with insulation as in the hot water buffer, but with different temperature parameters for operation. It will perform the same task, saving cold instead of heat in the thermal mass provided, and allowing it to be distributed when needed without having to run equipment on-demand to reduce the chilled water temperature.
Maintenance, Repair, and Replacement of Buffer Tanks
During your regular inspection and maintenance visits, the plumber will ensure that your buffer tank, related plumbing, pumps, and regular and relief valves are in good shape. If they identify any repair needs and longer-term concerns, you can schedule downtime for that work. If replacement is necessary, it might be helpful to discuss whether the capacity of the tank could be adjusted for even better system performance.
Renewable Energy Hot Water Heaters and Buffer Tanks
These days, homes and commercial systems use much more than simple standalone water heaters or furnace-based hot water systems. In buildings with geothermal or solar heating, the hot water system may use a buffer tank to store the energy extracted from the earth or sun. In the case of solar heating, you are reliant not on the furnace cycling time, but on the cycle of available solar heat energy to keep the hot water supply plentiful.
Your Full-Service Plumber at bluefrog Provides Plumbing Knowledge, Too
At bluefrog Plumbing + Drain, you may see our plumbers most often for basic drain cleaning and leaks, but we have a wealth of knowledge about residential and commercial plumbing. If you’re a homeowner interested in how the heating, cooling, water supply, and drain systems function in your home, we’re glad to help you learn about them and provide suggestions on how to maintain and improve them. Give us a call for all your plumbing needs.
