Common Valve Types Reference
Why this matters
Customer's "water won't shut off" OR "this valve is leaking" requires identifying valve type + selecting correct replacement. Wrong valve = wrong function OR leak. The tech who knows valves cold serves quickly. This is the field card.
Valve categories
Shutoff (isolation): full-flow OR no-flow. Ball, gate, butterfly.
Throttling (regulating): variable flow position. Globe, needle.
Check (non-return): prevents reverse flow. Swing check, spring check, lift check.
Pressure-regulating: reduces incoming pressure to set output. PRV.
Pressure-relief: opens at over-pressure. T+P (temp + pressure), safety valve.
Mixing: blends hot + cold to target temp. Thermostatic mixing.
Backflow prevention: prevents contaminated water entering supply. RPZ, double-check.
Ball valve
Quarter-turn handle: quick on/off.
Full-bore: minimal restriction.
Body: brass, stainless, PVC.
Most common shutoff in modern residential install.
Lifespan: 15 - 30+ years; minimal maintenance.
Gate valve
Full-bore: same as ball when fully open.
Slow operation (multi-turn): not for quick shutoff.
Stem packing leak: common after years; needs re-packing OR replace.
Older homes: gate valves common.
Falling out of favor: less reliable + slower than ball.
Globe valve
Throttling: variable flow position.
More flow restriction than ball OR gate: even full open.
Better for partial flow control.
Uses: hose bib, garden valve, throttling applications.
Angle valve / supply stop
Under fixture (toilet, lav): isolates that fixture.
1/4-turn: ball-valve style; replacing older multi-turn.
Sizes: 1/2" sweat OR FIP × 3/8" compression (toilet/lav).
Common replacement: when corroded OR seized.
Check valve
Swing check: hinged disc; swings open with forward flow, falls closed on reverse.
Spring check (silent check): spring-loaded disc; quieter than swing.
Lift check (in-line): vertical lift; small flow.
Foot valve: check valve at bottom of pump suction line; keeps pump primed.
Backflow preventer (more complex): RPZ + double-check for code-required protection.
Where required: above pumps, dishwasher discharge, ice maker, irrigation.
Pressure-reducing valve (PRV)
Installed at incoming service line: when supply > 80 PSI.
Reduces to 45 - 60 PSI typical residential.
Common brands: Watts (LF25AUB), Wilkins (NR3XL), Apollo.
Sized to incoming line: 3/4" typical.
Pressure regulator = same as PRV.
Pressure-relief valve (T+P)
Water heater: T+P (temperature + pressure) valve at top OR side.
Discharges if T > 210°F OR P > 150 PSI.
Required by code: not optional.
Open-ended drain pipe to safe location (drain pan OR exterior).
Mixing valve / scald protection
Thermostatic mixing valve (TMV): blends hot + cold to target output temp.
Installed at water heater outlet (whole-house) OR at individual fixture (shower, sink).
Required by code for new shower install (anti-scald). ASSE 1016 (shower) OR 1017 (whole-house).
Common brands: Watts, Apollo, Bradley, Cash Acme.
Hose bib
Threaded male hose connection for garden hose.
Frost-free / freeze-proof: longer body with shutoff inside building; outdoor-rated for cold climates.
Vacuum breaker: built-in OR added; prevents back-siphon (required by IPC).
Standard sizes: 1/2" + 3/4" supply; 3/4" hose thread.
Stop + waste valve
Shut off + drain feature: turn off + drain remaining water in line.
Use: irrigation, outdoor lines, freeze protection.
Older installations: common; modern use ball valves + separate drains.
Backflow preventers (potable water protection)
RPZ (reduced pressure zone): highest protection class; commercial + irrigation.
DCV (double-check): medium protection; residential.
AVB (atmospheric vacuum breaker): hose-bib level; lowest protection.
Required: irrigation, boiler feed, commercial dishwasher, some chemical mix.
Testing: annual inspection by certified tester required commercial.
Solenoid valve
Electrically actuated: 24V common HVAC + appliance.
Common uses: irrigation zones, dishwasher fill, washer fill, ice maker, refrigerator water.
Normally closed (NC): opens when energized (most common).
Normally open (NO): closes when energized (specialty).
Tank-fill float-controlled valve: not solenoid; mechanical.
Common valve sizing
1/2" supply branch: most common residential.
3/4" main supply: from incoming line.
1" + larger: commercial OR main supply 4+ bath home.
Always size to pipe + flow demand: undersized valve restricts flow.
Common valve mistakes
Wrong type (using gate where ball needed; gate stems break + leak). Stem packing not maintained (leak through stem; tighten packing nut OR rebuild). Mineral buildup (hard water; clean with vinegar OR descaler). Forcing seized valve (breaks stem; replace). Skipping isolation valve at fixture (cannot isolate for service). Wrong PRV direction (won't function). T+P discharge pipe routed wrong (closed end = catastrophic failure point).
Valve diagnostics
Won't shut off: debris in seat; flush + reset OR replace.
Leaks at stem: packing failure; tighten OR replace.
Leaks at body: cracked body; replace.
Slow OR partial flow: mineral buildup OR partial close; clean OR replace.
Stuck handle: mineral buildup OR corrosion; PB Blaster + careful work.
Truck stock
Ball valves (1/2", 3/4", 1" brass), angle stop (1/2" × 3/8" compression), PRV (3/4"), T+P (water heater), check valve (1/2", 3/4"), hose bib (frost-free), TMV (thermostatic mixing), assorted unions + couplings.
Service workflow
- Identify valve type + size + connection method
- Source replacement (same type OR upgrade to ball valve)
- Shut off upstream water
- Drain remaining water
- Disconnect + remove old
- Install new (proper sealant on threads)
- Slowly turn water back on; check for leaks
- Test full operation
The single most-useful valve habit is the EXERCISE THE MAIN SHUTOFF on every plumbing service call. Walk over to the customer's main water shutoff (typically at meter OR at incoming pipe entry to home) + turn it off + back on once. Many shutoffs sit decades without being moved + the valve seats up + breaks when finally needed. Exercising annually keeps it functional. If it doesn't turn cleanly OR stops the water, customer needs a replacement BEFORE they have a real emergency. Sell the proactive replacement; customer thanks you when the burst pipe happens at midnight + the main shuts off as expected.
References
- IPC + UPC plumbing codes
- ASSE 1016, 1017, 1070 (mixing valve standards)
- AWWA C500 (gate valve), C507 (ball valve)
- Manufacturer technical data (Watts, Apollo, Nibco, Honeywell)
- Manuall internal: Common Pipe Fittings, Water Pressure + Flow