Test Thermal Expansion Bypass — Final Checks and System Purge
Part of project
How to Replace a Well Pressure Tank · Step 10 of 10
In this video
This test applies to open plumbing systems with a regulator that has a thermal expansion bypass. Close all faucets and trigger the hot water heater to begin a heating cycle. You can do this by briefly running hot water or by temporarily raising the thermostat setting. As the water heats, it expands, causing the pressure to rise. Watch the gauge. The pressure should rise but not exceed the municipal supply pressure by more than 10 PSI. In the video, the pressure rises from the 50 PSI static pressure to 95 PSI, which is only 5 PSI above the 90 PSI municipal pressure, confirming the bypass is working.
Goal: Verify thermal expansion bypass functionality
- This test is for open water systems where the regulator has a built-in thermal expansion bypass. Closed systems require a separate thermal expansion tank.
Used in this video
- Water Pressure Test Gauge (brand: Watts, Tool Type: Measuring Tools) — To monitor the pressure increase caused by thermal expansion.
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FAQs
What are the most critical safety steps I must take before beginning to replace my well pressure tank?
Absolutely always turn off the power to your well pump at the main electrical panel first. Then, fully drain the entire water system to relieve all pressure. This prevents electric shock, water damage, and injury from pressurized components.
How long should I expect this well pressure tank replacement to take, and what's the approximate material cost for a DIYer?
For a beginner, plan for 2-4 hours, assuming you have all tools and materials ready. The material cost, primarily for the new pressure tank and fittings, can range from $200 to $600, depending on the tank size and brand, plus a few dollars for tape and rags.
Why is correctly pre-charging the new well pressure tank so important, and what pressure should I set it to?
Pre-charging with air prevents the tank from becoming 'waterlogged' and ensures your pump cycles efficiently, extending its lifespan. Set the tank's air pressure (when empty) to 2 PSI below your well pump's 'cut-in' pressure (the pressure at which your pump turns on).
Which specialized tools are absolutely essential for replacing a well pressure tank, beyond basic household tools?
You'll definitely need a sturdy pipe wrench (like the 16-inch self-adjusting one mentioned) for plumbing connections, a tire pressure gauge to check the tank's pre-charge, and a water pressure gauge to monitor system pressure. Slip-joint pliers are also very helpful for various fittings.
Test Thermal Expansion Bypass — Final Checks and System Purge
Part of project
How to Replace a Well Pressure Tank · Step 10 of 10
In this video
This test applies to open plumbing systems with a regulator that has a thermal expansion bypass. Close all faucets and trigger the hot water heater to begin a heating cycle. You can do this by briefly running hot water or by temporarily raising the thermostat setting. As the water heats, it expands, causing the pressure to rise. Watch the gauge. The pressure should rise but not exceed the municipal supply pressure by more than 10 PSI. In the video, the pressure rises from the 50 PSI static pressure to 95 PSI, which is only 5 PSI above the 90 PSI municipal pressure, confirming the bypass is working.
Goal: Verify thermal expansion bypass functionality
- This test is for open water systems where the regulator has a built-in thermal expansion bypass. Closed systems require a separate thermal expansion tank.
Used in this video
- Water Pressure Test Gauge (brand: Watts, Tool Type: Measuring Tools) — To monitor the pressure increase caused by thermal expansion.
Frequently Asked Questions
What are the most critical safety steps I must take before beginning to replace my well pressure tank?
Absolutely always turn off the power to your well pump at the main electrical panel first. Then, fully drain the entire water system to relieve all pressure. This prevents electric shock, water damage, and injury from pressurized components.
How long should I expect this well pressure tank replacement to take, and what's the approximate material cost for a DIYer?
For a beginner, plan for 2-4 hours, assuming you have all tools and materials ready. The material cost, primarily for the new pressure tank and fittings, can range from $200 to $600, depending on the tank size and brand, plus a few dollars for tape and rags.
Why is correctly pre-charging the new well pressure tank so important, and what pressure should I set it to?
Pre-charging with air prevents the tank from becoming 'waterlogged' and ensures your pump cycles efficiently, extending its lifespan. Set the tank's air pressure (when empty) to 2 PSI below your well pump's 'cut-in' pressure (the pressure at which your pump turns on).
Which specialized tools are absolutely essential for replacing a well pressure tank, beyond basic household tools?
You'll definitely need a sturdy pipe wrench (like the 16-inch self-adjusting one mentioned) for plumbing connections, a tire pressure gauge to check the tank's pre-charge, and a water pressure gauge to monitor system pressure. Slip-joint pliers are also very helpful for various fittings.