If you’re maintaining a tankless water heater, the right service kit can make flushing, isolation, and pressure relief much easier and safer.
This roundup of isolation valves with pressure relief valves focuses on practical options for homeowners, installers, and DIY users who want dependable shutoff performance and straightforward servicing.
Best 10 Isolation Valves with Pressure Relief Valves Picks for 2026
Tankless Service Kit
HYDRO MASTER Brass 3/4-Inch Valve Set
- Includes hot and cold isolation valves plus PRV
- Lead-free forged brass with factory testing
- Fits standard 3/4-inch IPS tankless setups
Best For: Complete service kit buyers for major tankless water heater brands
Tankless Isolation Kit
EFIELD 3/4-Inch Service Valve Set
- Hot and cold 1/4-turn full-port isolation valves
- Includes drain valve and brass safety cap
- Pressure relief valve rated 150 PSI / 200,000 BTU
Best For: Tankless water heater servicing with a full 3/4-inch valve kit
Sweat-Fit Service Kit
Libra Supply FNPT x Sweat Valve Set
- Includes pressure relief valve in a compact kit
- DZR brass with double O-ring stem seal
- Made for FNPT x sweat tankless connections
Best For: Tankless installs that need sweat-fit service valves and PRV
Premium Brass Pick
3/4 Inch IPS Tankless Water Heater Valve Kit
- Thick forged lead-compliant brass construction
- 3/4-inch IPS with NPT-standard end connections
- Hot and cold valves rated at 500 WOG
Best For: Standard residential tankless water heater installs
Most Versatile Set
8-Piece Brass Valve Kit with Adapters
- Includes 3/4-inch and 1/2-inch NPT adapters
- Lead-free brass parts for potable water systems
- Hot/cold valves plus pressure relief valves included
Best For: DIY or pro installs needing extra size flexibility
Reliable Standard Fit
3/4 Inch IPS Service Valve Kit
- 3/4-inch size for most residential usage
- Lead-free brass meets federal and state standards
- Full-port ball valve design supports better flow
Best For: Common 3/4-inch tankless heater brands and installs
Premium Brass Service Kit
3/4 Inch IPS Tankless Valve Set
- Hot and cold isolation valves with relief valve
- Lead-free brass with CSA certification
- Threaded IPS fittings for solder-free install
Best For: Tankless heater maintenance with integrated overpressure protection
Reliable Maintenance Kit
- Hot, cold, and pressure relief valves included
- Colored handles and drain valve aid servicing
- Lead-free brass with CSA certification
Best For: Simple, service-friendly tankless water heater maintenance
Heavy-Duty Brass Set
3/4 Inch IPS Service Valve Kit
- 3-piece kit with hot, cold, and relief valves
- Forged brass body with leak-free focus
- Full-port design for better flow
Best For: Durable tankless service and maintenance with broad compatibility
Tankless Service Kit – HYDRO MASTER Brass 3/4-Inch Valve Set
If you want isolation valves with pressure relief valves for a tankless setup, this HYDRO MASTER kit bundles the core service parts into one lead-free brass package. It includes hot and cold isolation valves, a 150 PSI / 200,000 BTU pressure relief valve, and full-port ball valves for strong flow during maintenance.
Best For: Homeowners or installers wanting a complete 3/4-inch service valve kit for major tankless brands.
Pros:
- All-in-one kit with hot and cold isolation valves plus a pressure relief valve
- Forged lead-free brass construction and factory-tested reliability
- Full-port ball valves help maintain maximum water flow
- Color-coded handles simplify hot/cold line identification
Cons:
- Designed around standard 3/4-inch IPS connections, so fitment is specific
- More kit than needed if you only want a standalone relief valve
This is a practical pick when you want a durable, code-conscious service kit that keeps tankless maintenance straightforward. The included pressure relief valve and broad brand compatibility make it a solid all-in-one option for common residential installations.
Cold Water PRV – Merrill 75 PSI Brass Relief Valve
For cold-water systems that need a dedicated pressure relief valve, this Merrill brass model offers a simple 75 PSI solution in a compact 3/4-inch size. It uses lead-free brass with stainless steel control springs and is IAMPO certified, making it a straightforward choice where a standalone relief valve is all you need.
Best For: Cold water systems that need a compact, standalone 75 PSI pressure relief valve.
Pros:
- Lead-free brass body with stainless steel control springs
- IAMPO certified and RoHS listed
- Compact 3/4-inch line connection for tight installs
- Simple standalone design for excessive pressure protection
Cons:
- Not for use with water heaters
- Cold water systems only, so application is narrow
- No isolation valves included
This valve makes sense when your project calls for a basic pressure safeguard rather than a full service assembly. It is best treated as a specialized cold-water component, not a general-purpose tankless heater valve kit.
Tankless Isolation Kit – EFIELD 3/4-Inch Service Valve Set
This EFIELD kit is built for buyers comparing isolation valves with pressure relief valves in a single tankless service package. It combines 1/4-turn hot and cold full-port isolation valves, an integrated drain valve with brass safety cap, and a pressure relief valve rated for 150 PSI / 200,000 BTU.
Best For: Residential or commercial gas tankless water heater servicing with 3/4-inch NPT connections.
Pros:
- Includes hot and cold 1/4-turn full-port isolation valves
- Integrated drain valve with brass safety cap for maintenance
- Pressure relief valve rated 150 PSI / 200,000 BTU
- Lead-free brass construction for the main kit components
Cons:
- Limited to 3/4-inch NPT applications
- Less specialized if you only need one replacement part
Overall, this is a strong all-in-one maintenance kit for tankless systems that need both shutoff and relief features. The integrated drain hardware and full-port valves make routine servicing easier without adding extra parts.
Sweat-Fit Service Kit – Libra Supply FNPT x Sweat Valve Set
If your installation needs isolation valves with pressure relief valves and a sweat connection, this Libra Supply kit is designed for that exact style of tankless water heater hookup. It uses DZR brass, a compact body, and a pressure relief valve included in the package, with 100% leak testing noted in the product details.
Best For: Tankless water heaters that use FNPT x sweat connections and need a compact service kit.
Pros:
- DZR brass construction for corrosion resistance
- Pressure relief valve included with the isolation kit
- Double O-ring stem seal and stainless steel ball
- Full-port drain outlets and 100% leak testing
Cons:
- Connection style is specific to FNPT x sweat installations
- Standard brass version may not suit every material preference
This kit is a good fit when compact plumbing layout and sweat-joint compatibility matter as much as shutoff performance. Its blend of DZR brass, leak testing, and included relief valve makes it a practical service-oriented choice.
Premium Brass Pick – 3/4 Inch IPS Tankless Water Heater Valve Kit
If you’re comparing isolation valves with pressure relief valves for a tankless water heater, this 3/4-inch IPS kit is built around durable brass construction and standard residential sizing. It combines hot and cold service valves with a pressure relief valve, making it a practical choice for flushing, isolation, and routine maintenance on compatible systems.
Best For: Homeowners or installers who want a standard-size brass service kit for common tankless water heater setups.
Pros:
- Thick forged lead-compliant brass construction for durability and reduced leak potential
- 3/4-inch IPS size with NPT-compliant end connections for common residential installs
- Includes hot and cold valves rated at 500 WOG with 1/4-inch red and blue handles
- Full-port ball valves support better flow during flushing and service work
Cons:
- Designed around 3/4-inch installations, so it may not suit systems needing adapters
- Routine maintenance is required, including yearly valve operation and periodic inspection
This kit focuses on the essentials: sturdy materials, standard sizing, and a service-friendly valve layout. If your system matches the 3/4-inch format, it offers a straightforward path to isolation and maintenance.
Most Versatile Set – 8-Piece Brass Valve Kit with Adapters
This tankless water heater kit is geared toward buyers who want isolation valves with pressure relief valves plus extra adapters for a wider range of setups. With 3/4-inch and 1/2-inch NPT options, it is built to simplify installation, flushing, and routine descaling on compatible tankless water heaters.
Best For: DIY users or pros who need adapter flexibility for different tankless water heater connections.
Pros:
- Includes 3/4-inch and 1/2-inch NPT adapters for broader compatibility
- Complete kit adds hot and cold isolation valves, pressure relief valves, and sealing tape
- Accessible service valves support easy hose and pump connection for flushing
- Lead-free brass construction is intended for potable water systems
Cons:
- More parts may be more than needed for simple, standard 3/4-inch installs
- Compatibility still depends on your heater’s inlet and outlet configuration
If you want one kit that covers more installation scenarios, this is the most adaptable option in the group. The included adapters make it especially useful when you are matching different connection sizes.
Reliable Standard Fit – 3/4 Inch IPS Service Valve Kit
For shoppers focused on a straightforward tankless water heater setup, this 3/4-inch IPS service kit covers the key needs: isolation, flushing, and pressure relief. It uses a full-port ball valve design and lead-free brass components, making it a practical match for many residential and light commercial tankless systems.
Best For: Buyers who want a simple, standard-size service valve kit for common tankless water heater brands.
Pros:
- 3/4-inch standard size fits most American residential usage
- Lead-free brass components meet federal and state lead-content standards
- Full-port ball valve design supports better flow rate during service
- Clear red and blue handles make hot and cold valves easy to identify
Cons:
- Best suited to systems that already use a 3/4-inch setup
- Does not include the broader adapter set found in some competing kits
This is a no-frills option that leans on standard sizing and proven brass construction. If your heater already matches the 3/4-inch format, it should be an easy fit for maintenance and service tasks.
Premium Brass Service Kit – 3/4 Inch IPS Tankless Valve Set
If you want isolation valves with pressure relief valves for a tankless heater install, this 3/4-inch IPS kit is built for straightforward maintenance and safer operation. It combines hot and cold shut-off valves with an integrated pressure relief valve, plus lead-free brass construction and CSA certification for potable-water use.
Best For: Homeowners and installers who want a lead-free brass service valve kit with universal compatibility and integrated pressure protection.
Pros:
- Includes hot and cold isolation valves plus an integrated pressure relief valve
- 3/4-inch IPS threaded fittings support fast, solder-free installation
- Lead-free brass body with CSA certification for potable water applications
- Color-coded handles and full-port ball valves make service easier
Cons:
- Sized specifically for 3/4-inch IPS connections
- Designed for tankless water heater service use rather than general plumbing
Overall, this kit is a practical pick if you want a single package that handles isolation, drainage, and overpressure protection. The combination of durable brass construction and universal brand compatibility makes it a solid service upgrade.
Reliable Maintenance Kit – Clean Brass IPS Isolator Set
For shoppers comparing isolation valves with pressure relief valves, this 3/4-inch IPS tankless service kit offers a simple setup with colored handles, a drain valve, and a pressure relief valve. The clean brass construction and lead-free certification make it a strong fit for routine tankless water heater maintenance.
Best For: Users who want an easy-to-identify, lead-free brass service valve kit for common residential tankless water heaters.
Pros:
- Includes hot isolation valve, cold isolation valve, and pressure relief valve
- Colored handles help identify hot and cold lines quickly
- Full-port ball valve and integrated drain valve support maintenance
- Lead-free brass construction with CSA certification
Cons:
- No electric use is specified in the product details
- Primarily aimed at 3/4-inch tankless water heater service applications
This kit keeps the feature set focused on serviceability and safety rather than extras. If you want a straightforward brass valve set for compatible tankless systems, it covers the core needs well.
Heavy-Duty Brass Set – 3/4 Inch IPS Service Valve Kit
If you need isolation valves with pressure relief valves for a tankless system, this 3/4-inch IPS kit focuses on durability and strong flow performance. It includes hot and cold isolation valves, a pressure relief valve rated to 150 PSI, and a full-port design with thickened forged brass construction.
Best For: Buyers who want a heavy-duty brass tankless service kit with proven leak-free construction and broad brand compatibility.
Pros:
- 3-piece kit includes hot and cold isolation valves and a pressure relief valve
- Full-port ball valve design supports better flow rate
- Thickened, one-piece forged brass body is built for long-term use
- Lead-free certification and CSA marking on the relief valve
Cons:
- Rated for 150 PSI, so it may not suit every higher-pressure use case
- Sold as a dedicated tankless water heater service kit, not a general-purpose valve set
Among the three, this one leans hardest into rugged construction and a leak-resistant design. It is a sensible choice if you want a dependable service valve kit for regular tankless maintenance and shutdown.
How We Picked the Best Isolation Valves with Pressure Relief Valves
We focused on Isolation Valves with Pressure Relief Valves that are built for tankless water heater service, with attention to valve materials, compatibility, ease of installation, and common maintenance use cases. Preference went to kits that include the essentials for isolating hot and cold lines and supporting routine flushing.
Quick Comparison
Most options in this category fall into two groups: complete service kits for installation and maintenance, and standalone pressure relief valves for replacing or upgrading a specific part. Full kits are better if you want a one-box solution, while single valves make sense when you only need a replacement component.
Key Buying Factors for Isolation Valves with Pressure Relief Valves
Connection Type and Size
Check whether your system uses IPS, sweat, or FNPT connections before buying. The wrong connection style can add extra adapters, cost, and leak risk.
Material Quality
Brass and lead-free brass are common choices because they hold up well under regular use and repeated servicing. Look for solid construction if you plan to flush the system often.
Pressure Rating
Make sure the pressure relief valve matches your heater’s requirements and local code expectations. A valve rated too low or too high may not be appropriate for your setup.
Serviceability
Good isolation valves should allow clean shutoff for both hot and cold sides so you can flush mineral buildup without disturbing the rest of the plumbing system. A well-designed kit can also save time during winterization or replacement work.
Included Accessories
Some kits add extras such as drain ports, handles, or installation tools. These can improve convenience, but only if the core valve quality is strong.
Who Should Buy Which Isolation Valves with Pressure Relief Valves?
DIY homeowners who want a simple maintenance setup should look for a complete all-brass kit with clear sizing and easy-to-use shutoffs. Professional installers may prefer kits with a cleaner fit and more durable components for frequent service calls. If you only need to replace a relief component, a standalone pressure relief valve may be the most efficient choice. For most buyers, the best option is the one that matches the plumbing connection type first, then the pressure and material specs second.
