A new water heater may need an expansion tank, but not every installation does. It depends mainly on whether the plumbing system lets heated water expand back toward the supply, along with the rules and manufacturer instructions that apply to that installation.
This question often comes up when an installer recommends an expansion tank that the old setup did not have. Understanding why it may be suggested can help you make sense of the quote.
What Thermal Expansion Means
Water takes up a little more space when it gets hot. In a storage water heater, that extra volume has to go somewhere each time the tank heats up.
In some homes, the extra water can move back toward the city supply line. In others, a device on the supply side stops water from flowing backward. That is sometimes called a closed system. When the system is closed, the expanding water has no easy place to go, and pressure in the pipes can rise.
What an Expansion Tank Does
An expansion tank is a small tank connected to the plumbing near the water heater. Inside, a cushion of air gives the expanding water room to go. This can help keep pressure from rising too much each time the water heats.
Without that extra room in a closed system, rising pressure may lead to problems such as a relief valve that drips, extra strain on fittings or a toilet fill valve that runs on its own. Those symptoms can have other causes too, so they do not prove an expansion tank is needed.
How the Decision Is Made
An installer may look at several things before suggesting an expansion tank:
- whether there is a backflow preventer, check valve or pressure-reducing valve on the supply
- the water pressure in the building
- the size and type of the new water heater
- the manufacturer’s installation instructions
- the code requirements that apply to that property
Because these differ from one property to another, there is no single answer for every Bronx home. An expansion tank is mostly a storage tank question. Tankless units work differently, so the need may not be the same.
Questions to Ask Your Installer
If an expansion tank is part of your quote, ask why it is recommended for your system, where it will go and whether it needs any upkeep. If it is not included, it is fair to ask whether your setup was checked for it.
In apartment buildings, central water heating systems are usually designed and maintained by the building. Tenants should direct questions to the super or management.
Planning a replacement and wondering about expansion tanks? Our water heater installation in the Bronx includes a look at how your system is set up. Call (929) 209-6183 with your questions.
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