(Pressure Switches, Gauges, Tank Tees, Air Volume Controls and Safety Valves)
If a well tank starts acting up, the problem usually comes down to a handful of parts. The pressure switch, pressure gauge, tank tee assembly, and, in older steel tanks, the air volume control all play a part in keeping pressure steady and the pump running efficiently. When one of them fails, you can end up with short cycling, weak pressure, or no water at all.
In this guide, you’ll learn how each part works, the signs it is failing, and exactly how to replace it. You’ll also find direct links to Well Tanks & Parts, Pressure Switches, Tank Tee Packages, Temperature & Pressure Gauges, and Relief Valves so you can source replacements quickly when the time comes.
Table of Contents
Tools
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- Adjustable wrench, channel-locks
- Multimeter or voltage tester
- Teflon tape or pipe thread sealant
- Screwdrivers (flat and Phillips)
- Bucket or towels for controlled draining
- Tire gauge for checking pre-charge on bladder tanks
Video Walkthrough
Preventative Maintenance Checklist
| Part | What it does | Quick check | Replace when… | Where to browse |
| Pressure switch | Starts and stops pump at set PSI | Inspect contacts and cover every 6 months | Contacts burnt or pitted, erratic cut-in or cut-out | Pressure Switches |
| Pressure gauge | Confirms system PSI | Compare to known pressure, drain to 0 | Needle sticks, fogged, will not return to 0 | Temperature & Pressure Gauges |
| Tank tee | Hub for ports and drain | Check for corrosion or leaks annually | Corroded threads, leaking, no spare ports | Tank Tee Packages |
| Air volume control (non-bladder) | Maintains air cushion | Older steel tanks only, check quarterly | Waterlogging, air spitting, failed float or vent | Johnson Controls AVC |
| Safety relief valve | Releases over-pressure | Test annually | Dribbles or leaks, stuck, corroded | Relief Valves |
Quick Compatibility Reference
| Component | Typical thread | Common ratings | Notes |
| Pressure switch | ¼” NPT | 20/40, 30/50, 40/60 PSI | Match cut-in and cut-out to pump capability, low-pressure cut-off available |
| Gauge | ¼” NPT bottom or back | 0–100 PSI | Liquid-filled helps with vibration |
| Tank tee | 1″ or 1¼” MPT tank side | — | Brass or stainless, union styles speed service |
| AVC | ½” or 1¼” NPT | Shallow or deep well styles | Only for non-bladder tanks |
| Relief valve | ½” NPT | 75–150 PSI | Set above switch cut-out, follow local code |
Pressure Switch
What it does
Acts as the control center for the pump, turning it on and off at pre-set pressures like 30/50 or 40/60 PSI. For help choosing the right pump to match your pressure settings, see How To: Choose a Well Pump.
When to replace
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- Pump will not start or stop at correct pressures
- Burnt or pitted contacts
- Rapid clicking or chattering
- Erratic pump cycling
Replacement steps
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- Turn off power at the breaker.
- Open a faucet to drop pressure to zero.
- Label and remove wires from the old switch.
- Remove the switch from the ¼” nipple and clean the sensing port.
- Wrap threads on the new switch and install.
- Reconnect wiring to the same terminals.
- Restore power and verify cut-in and cut-out.
Browse Pressure Switches at Supplyhouse.
Pressure Gauge
What it does
Provides a visual reading of current system pressure, helping with troubleshooting and verifying switch operation.
When to replace
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- Needle stuck or fogging display
- Reading does not drop to zero after draining
- Slow response from pulsation
Replacement steps
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- Turn off power and drain system to zero.
- Remove gauge with a wrench on its hex.
- Clean the port if clogged.
- Wrap threads and install the new gauge.
- Refill and power on to verify readings.
Browse Temperature & Pressure Gauges at Supplyhouse.
Air Volume Control
Older non-bladder steel tanks need an air volume control to maintain the air cushion. Bladder or diaphragm tanks do not use an AVC. For a full primer on how different types of tanks work, read Expansion Tanks: What Are They and Why Are They Important?.
When to replace
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- Frequent short cycling
- Spitting air at fixtures
- Waterlogged tank
Replacement steps
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- Turn off pump and drain tank to below AVC level.
- Disconnect tubing if present and remove old AVC.
- Wrap threads and install the new unit, reconnect tubing or vent.
- Refill and power on, watching cycle length.
Browse Air Volume Controls at Supplyhouse. 
Tank Tee
A tee assembly ties the tank to the system and provides ports for the gauge, switch, relief valve, drain, and sometimes a check valve.
When to replace
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- Corrosion, leaks, or stripped threads
- No free ports for accessories
- Swapping tank size and need a new layout
Replacement steps
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- Turn off pump and drain the tank fully.
- Disconnect lines to house and pump.
- Remove tee from tank and clean threads.
- Pre-assemble new tee with gauge, switch, relief valve, and drain valve.
- Tape or paste threads and install into tank, aligning ports.
- Reconnect lines, refill, check for leaks.
Browse Tank Tee Packages at Supplyhouse.
Safety Relief Valve
Relief valves are low-cost protection against over-pressure. Test annually and replace if the valve dribbles, sticks, or shows corrosion. For potable well use, select potable-rated products and setpoints above switch cut-out.
Browse Relief Valves at Supplyhouse.
Pro Tips
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- Set pre-charge on bladder tanks 2 PSI below switch cut-in.
- Keep the sensing port clean to prevent false readings.
- Label wires before disconnecting anything.
- Use a glycerin-filled gauge where pump pulsation is heavy.
- Union tees make future service easier.
- Keep spare parts in the truck to prevent downtime.
FAQs
What PSI should a well system run?
Common setups run 30/50 or 40/60 PSI. Match the switch to pump performance and tank pre-charge.
How do I pick 30/50 vs 40/60?
Choose based on fixture expectations and pump capability. If the pump struggles to hit 60 PSI, stick with 30/50.
How is tank pre-charge set?
Power off, drain to 0 PSI, set air charge 2 PSI below cut-in.
Can a 40/60 switch go on a small tank?
Yes, if the pump can hit 60 PSI.
Low-pressure cut-off: worth it?
Helps protect a pump if the well runs low. Many models have a manual reset lever.
Is a relief valve required?
Check local code, but it is smart practice on pressure vessels.
Do bladder tanks use an air volume control?
No, only non-bladder steel tanks use one.
Where does the gauge go?
Any open ¼” port on the tee or manifold, ideally close to the switch.
How often should parts be replaced?
Switches when contacts pit or burn, gauges when inaccurate, relief valves per code or if leaking, tees with tank replacement or damage.
Wrap-Up
A well-tuned system comes from keeping core components in good shape: a clean sensing port, a reliable pressure switch, an accurate gauge, a solid tank tee, and a functional relief valve. Regular checks and timely replacements mean longer pump life, consistent pressure, lower repair costs, and better safety.
The best time to replace a suspect part is before it fails. Stocking a spare switch, gauge, and sealant can turn an emergency into a quick fix.
Browse Supplyhouse’s well parts categories to get what you need:
When you understand how each part works and keep spares on hand, you control the repair, the schedule, and the outcome.
