Rheem 21V30-6 30-gallon power miser v gas water heater Parts

Replacing a 30-gallon gas water heater like the Rheem 21V30-6 typically costs about $1,200 to $3,000 installed in the U.S. Total price depends on venting, gas-line work, local labor rates, and any required plumbing or safety updates.

Typical cost breakdown (what you are paying for)

• New 30-gallon gas water heater (tank): $500 to $1,200
• Labor for removal and installation: $500 to $1,500
• Materials and incidentals (connectors, shutoff valve, vent parts): $100 to $500
• Optional code or safety upgrades (as required): $100 to $800+

What makes the price go up or down

• Venting changes (draft hood, flue sizing, chimney liner work)
• Gas piping updates (new shutoff, sediment trap, resizing)
• Water piping work (corroded fittings, valve replacements, rerouting)
• Location and access (tight closets, attic installs, stairs, haul-away difficulty)
• Emergency replacement vs. scheduled work

Repair vs. full replacement: quick comparison

If the tank is not leaking, a repair is often far less expensive than replacing the entire heater.

Symptom	What it often points to	Common next step
Pilot will not stay lit	Flame-sensing safety issue	Replace the thermocouple (match by model)
Not enough hot water	Control or hot-water delivery issue	Check thermostat and dip tube
Slow draining or will not drain	Drain valve clogged or failed	Replace drain valve 100108605

Why it matters

Installed price varies because the job often includes bringing gas, venting, and water connections up to current standards, not just swapping tanks. An itemized quote helps you compare labor, materials, and upgrade costs accurately.

Last updated: February 2026

A Rheem gas tank water heater like model 21V30-6 has a typical life expectancy of 8 to 12 years. Consistent maintenance (especially flushing sediment) and keeping the temperature set reasonably help you reach the upper end of that range.

Typical lifespan ranges

• 8 to 12 years: normal service life for many gas tank water heaters
• 12 to 15 years: common with regular flushing and low-sediment water
• 5 to 8 years: common with heavy sediment, corrosive water, or frequent overheating

What shortens (or extends) tank life

Factor	What you may notice	Impact
Sediment buildup	Rumbling or popping, slower recovery	Overheats the tank bottom and burner area
High temperature setting	Very hot water, faster scaling	Accelerates mineral buildup and wear
Pilot or burner issues	Pilot will not stay lit, inconsistent hot water	Causes repeated cycling and stress on components
Tank corrosion/leak	Rusty water, moisture at base, active leak	Tank is at end of life once it leaks

Maintenance that helps you get the full lifespan

• Flush the tank periodically to remove sediment
• Keep temperature steady (many homes use about 120°F)
• Address pilot outages and burner problems quickly
• Drain a few gallons occasionally to check for heavy sediment

Parts that often restore performance (not tank life)

If you are troubleshooting poor hot water delivery or temperature control, these model-related service parts are commonly involved:

• Drain valve 100108605
• Dip tube SP11248R
• Thermostat SP12258B

Why it matters

Once a tank starts leaking, replacement is the correct fix. If the tank is sound but performance is slipping, replacing wear parts (like a thermostat or dip tube) can restore reliable hot water and help you get the full 8 to 12 years.

Last updated: February 2026

The model number for your Rheem gas water heater is printed on the rating label (data plate) attached to the tank. On model 21V30-6, this label is typically on the outside of the jacket near the gas control area or along the side of the tank.

Where to look on the water heater

Check these common spots first:

• Side of the tank jacket (mid-height)
• Front of the unit near the burner access door
• Near the gas control valve/thermostat area
• Around the lower portion of the tank above the drain valve
• Inside or near the outer access panel/door area

What the label looks like

The rating label is usually a rectangular sticker or metal plate with multiple lines of information. Look for fields such as:

• Model (this is the model number you need)
• Serial (serial number)
• Gas type (natural gas or LP)
• Capacity (often 30 gallons for this unit type)
• Input (BTU rating)

Model number vs. serial number (quick check)

Use this to avoid mixing them up:

Item	What it’s used for	Example format
Model number	Identifies the exact design for parts lookup	21V30-6
Serial number	Identifies the production run/date	Letters and numbers

Why it matters

Using the exact model number ensures you get the correct Rheem water heater parts and diagrams for your unit, especially for fit-critical items like a thermostat or dip tube.

If you are ordering parts, match your label to the parts list for model 21V30-6, such as the dip tube SP11248R or thermostat SP12258B.

Last updated: March 2026