What this service includes
- System pressure test and diagnosis
- Correctly sized expansion tank supply
- Professional installation on the cold-water line
- Pre-charge set to match your home's pressure
- T&P valve check and replacement if worn
- Post-install pressure verification
What an expansion tank does
Water expands as it heats. In a “closed” plumbing system, that extra volume has nowhere to go, so pressure spikes every heating cycle. Those spikes stress the tank, fixtures, and connections, and they push the relief valve open — the drip you may be seeing. An expansion tank gives the expanding water a cushion of air to push into, keeping pressure stable and protecting the entire system.
Signs you need one
Telltale signs include a relief valve that drips or discharges only when the water heater runs, banging or “water hammer” in the pipes, and fluctuating water pressure. If your home has a pressure-reducing valve or backflow preventer at the meter, you have a closed system and an expansion tank is likely required. A pro can confirm with a quick pressure test.
Signs you need expansion tank installation
- Relief valve drips only when the heater is running
- Banging or water hammer in the pipes
- Fluctuating or spiking water pressure
- You have a PRV or backflow preventer (closed system)
- A recently failed relief valve
- Code compliance for a new water heater install
What affects the price
We never quote a price sight-unseen — our technician gives you an upfront quote after diagnosing the problem. Typical cost factors include:
- Tank size needed for your water heater capacity
- Accessibility of the cold-water connection
- Whether a worn T&P valve is also replaced
- Any pressure-regulator work required