Expansion Tank Size Calculator

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Need a little help?

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Our Expansion Tank Size Calculator walks you through a quick set of questions, starting with whether you're working on a heating or plumbing system. In less than a minute, you'll have a recommended tank size to keep your system running smoothly.

Why the right size matters

Keeps system pressure stable during heat-up and cool-down.
Protects valves, pumps, heat exchangers, and piping from stress.
Cuts down nuisance relief events.
Helps extend service life with less wear and tear.

Questions? View the Expansion Tank FAQs below

Next steps

Take the number the calculator gives you and pick an expansion tank that meets — or better yet, exceeds — that capacity.

Expansion Tanks — hydronic heating and accessories.
Water Heater Expansion Tanks — for domestic hot water systems.
PLT Potable Water Expansion Tanks — potable applications.
Extrol Expansion Tanks for Hydronic Heating — popular hydronic models.

Expansion Tank FAQs

What does an expansion tank do?

It's the pressure shock absorber for your system. As water heats up and expands, the tank takes the hit so your system pressure stays in the safe zone.

What size expansion tank do I need?

That depends on your system. Instead of pulling numbers out of thin air, our calculator can walk you through a quick flow and hands you a recommended capacity you can actually shop with.

What happens if the tank is too small?

Pressure spikes, relief valves popping, and parts wearing out faster than they should.

Is oversizing a problem?

Not really. Going bigger usually just costs a little more upfront. Undersizing is where you’ll run into trouble. Aim for a tank that meets or just edges past the recommendation.

Do potable water systems use a different tank?

Yep. Domestic hot water needs a potable-rated tank. Our PLT line is designed for exactly that.

Do brand and style matter?

They do. Pay attention to diaphragm vs. bladder construction, pre-charge pressure, working pressure rating, and whether it’s built for your application. Those details make all the difference in performance and lifespan.

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