Water from the relief pipe? Start here
What to do if it is discharging
Keep clear
Water from the relief pipe can be very hot. Keep people and pets away from the outlet.
Hands off
Do not touch the valve, lift its lever, or cap, plug or reroute the pipe.
Note the pattern
A steady flow, an occasional drip, or a drip after the heater runs each point in different directions.
Call
A steady discharge needs prompt attention. An occasional drip should still be looked at soon.
If there is any smell of gas in the cellar, leave the building and call the gas utility and emergency services from outside.
If a carbon monoxide alarm goes off, get everyone out of the house and call emergency services from outside.
What the relief valve does
Every storage water heater has a temperature and pressure relief valve, usually on the top or upper side of the tank, with a discharge pipe running down toward the floor or to a drain. It is designed to open if the temperature or pressure inside the tank goes beyond what it is set for, releasing water so conditions return to normal. It is a last line of protection, which is why it must always be free to open and its pipe free to discharge.
Why it must never be capped
Capping, plugging or blocking the valve or its pipe removes the heater's protection against excess temperature and pressure. A drip can be annoying, but it is a symptom. The fix is always to find and deal with the cause, never to silence the valve.
If you find a capped relief pipe
Do not try to remove the cap yourself with the heater running. Call and describe what you have found, and a technician will deal with it.
Why a relief valve drips or discharges
Thermal expansion in a closed system
Very common on Connecticut well systems and on town water with a pressure-reducing or backflow valve at the meter. Heated water has nowhere to expand, pressure rises, and the valve lets a little out. An expansion tank is the usual answer.
Water too hot
A thermostat or control that is stuck or set too high can drive the temperature up. That needs a technician promptly.
High supply pressure
If the household water pressure is high, the valve may open more readily. The technician can measure it at the heater.
A worn valve
Relief valves wear, and sediment or mineral deposits can stop one sealing. Replacement is straightforward once the cause is confirmed.
On a private well?
Relief valves on well systems
Many well systems are closed by a check valve, so thermal expansion is a leading cause of relief valve drips in well homes. Pressure also swings as the pump cycles. Mention the well and whether there is an expansion tank near the heater when you call.
Well homes often need an expansion tank.
How the technician deals with it
They check the water temperature and the heater's controls, measure the supply pressure, check whether the system is closed and whether an expansion tank is present and working, and inspect the valve and its discharge pipe. They explain the cause and the fix, and give the price before doing anything. The fix might be a control repair, an expansion tank, a new relief valve, a correctly routed discharge pipe, or a combination.
The cause and the fix are explained first.
The discharge pipe
The pipe that runs from the relief valve matters as much as the valve. It should carry discharged water to a point where it can be seen and where it will not harm anyone, typically running down toward the floor or to a suitable drain. It should not be reduced in size, blocked, capped, or routed where it could freeze or be hidden. Over the years, discharge pipes get cut short, extended through walls, or tucked away out of sight during basement finishing. The technician checks the pipe as well as the valve, and reroutes it where needed so a discharge is always noticed.
When relief valves are replaced
A relief valve that has been discharging repeatedly, is weeping, or has mineral build-up around its seat is often replaced once the underlying cause has been dealt with. A new water heater comes with its own relief valve, fitted by the installer. On an older tank, the technician may suggest replacing the valve at the same visit as an expansion tank or a control repair, so the whole arrangement is sound.
Relief valves on boiler-fed systems
Where hot water comes from an indirect tank, the tank has its own relief valve on the household water side, separate from the boiler's relief valve on the heating side. Water from the indirect tank's valve is a water heater question; water from the boiler's valve is a heating question and outside this service. The technician can tell you which is which if you are unsure.
Relief valves near finished spaces
When a basement is finished around a water heater, the relief valve discharge pipe is sometimes shortened, hidden behind a wall or routed somewhere it will not be noticed. A discharge that nobody sees can soak flooring or walls unnoticed. The technician checks that the pipe still discharges somewhere visible and suitable, and reroutes it if the finishing work has hidden it.
What affects the cost of pressure relief valve service
- Whether the valve itself, the controls, or the system pressure is the cause
- Adding an expansion tank
- Rerouting a discharge pipe that has been altered
- Emergency hours for a steady discharge
How long pressure relief valve service takes in Connecticut
Diagnosis and most fixes, including valve replacement and adding an expansion tank, are usually completed in one visit.
Relief valve questions
Should I worry about a dripping relief valve?
It should be looked at. A drip means the valve is opening, and the reason needs finding. Do not cap or plug it. Call and have a technician check the temperature, pressure and the valve itself.
Can I test the relief valve by lifting the lever?
We do not recommend it. Lifting the lever on an older valve can release very hot water and sometimes stop the valve from resealing. Leave testing to a technician.
Why does it only drip after the heater runs?
That pattern often points to thermal expansion in a closed system. An expansion tank on the cold supply usually solves it.
Water is pouring from the relief pipe. What should I do?
Keep clear of the discharge and call straight away. Leave the valve and the heater's controls alone. If you smell gas, leave and call the gas utility and emergency services from outside.
Can the relief valve just be replaced?
If the valve is worn, yes. But if it is opening because of expansion, temperature or pressure, a new valve will open too. The technician finds the cause first.
Where should the relief pipe go?
It should discharge to a safe point where the water can be seen and will not harm anyone. The installer routes it to suit your space.
Do indirect tanks have relief valves?
Yes. Indirect tanks have their own relief valve on the household water side, separate from the boiler's. The local installers service the tank's valve.
We found a cap on the relief pipe. What now?
Do not remove it yourself with the heater running. Call and describe it, and a technician will deal with it safely.
Is a relief valve on a new heater likely to drip?
It should not if the system is set up correctly. A new heater on a closed system without an expansion tank may start dripping soon after installation, which is why installers check for thermal expansion when fitting a new tank.
Can a relief valve be replaced without draining the tank?
It usually means relieving pressure and lowering the water level in the tank. It is a job for the technician, who can do it safely during the visit.