This brass pressure relief valve is a direct-fit safety component for electric storage water heaters, combining three essential safety functions in a single compact unit: overpressure relief, controlled drain-down, and non-return (check valve) protection. Set to open at 0.8 MPa (8 bar), it protects the cylinder and connected pipework from damaging pressure build-up as water is heated, while its integral check valve stops heated water flowing back into the cold mains supply.
Fitted with a 1/2" male thread x female BSP thread connection, it is manufactured from solid brass for long-term corrosion resistance and reliable operation under sustained pressure and temperature cycling. It is a straightforward like-for-like replacement part for electric water heaters specified with an 0.8 MPa safety valve, and doubles as a maintenance drain point when the system needs to be emptied down.
0.8 MPa
Relief Set Pressure
8 Bar
Relief Set Pressure
Male x Female
BSP Connection
Good to Know
This valve performs three safety functions in one fitting: it relieves excess pressure caused by thermal expansion during heating, provides a drain point for servicing or decommissioning the cylinder, and acts as a non-return valve to prevent hot water backflowing into the cold mains.
Important Safety Information
Pressure rating must match the water heater it is fitted to. This is the 0.8 MPa (8 bar) version — do not substitute a 0.7 MPa (7 bar) or other rated valve, as the relief point must correspond to the maximum working pressure stated by the water heater manufacturer. Installation and replacement of pressure/safety valves should be carried out by a competent person in line with the water heater manufacturer's instructions.
Please Note
Confirm the thread size and pressure rating printed on your existing valve or heater data plate before ordering, as electric water heaters in this class are also supplied with 0.6 MPa and 0.7 MPa rated valves depending on model and market. This listing is for the 1/2" BSP, 0.8 MPa variant only.
Key Features
Combined Safety Valve
Integrates an overpressure relief valve, a drain valve, and a non-return (check) valve into one compact brass fitting, reducing the number of separate components needed on the cold feed.
0.8 MPa Relief Setting
Opens at 0.8 MPa (8 bar) to release excess pressure generated by thermal expansion as the water heater cycles, protecting the cylinder and pipework from damage.
Backflow Protection
The built-in check valve stops heated water in the cylinder from flowing back into the cold mains supply, protecting the freshwater system from contamination.
Solid Brass Construction
Manufactured from brass for strong corrosion resistance and dependable long-term performance under repeated pressure and temperature cycling.
1/2" Male x Female BSP
Fitted with a 1/2" male thread on one side and a female BSP thread on the other for straightforward in-line connection to standard UK water heater pipework.
Compact, Easy-Fit Design
A small, lightweight footprint makes it simple to install, service, or replace without disturbing surrounding pipework.
Technical Specification
| Performance |
| Relief Set Pressure |
0.8 MPa (8 bar) |
| Maximum Working Temperature |
100°C |
| Function |
Pressure relief, drain valve, non-return (check) valve |
| Connections |
| Thread Size |
1/2" |
| Thread Type |
Male thread x Female BSP thread |
| Construction |
| Body Material |
Brass |
| Compatibility |
| Suitable For |
Electric storage water heaters requiring an 0.8 MPa rated safety valve, including. AIZO Technologies, ELDOM, Thermex and QH (Quality Heating) models |
What's Included
- 1 x Pressure Relief Valve — 1/2" Male x Female BSP, Brass, 0.8 MPa
Frequently Asked Questions
What does this valve do?
It performs three functions in one fitting: it releases excess pressure from the water heater once it reaches 0.8 MPa (8 bar), provides a drain point for servicing the cylinder, and includes a non-return valve to stop hot water flowing back into the cold mains.
Is this the same as a 0.7 MPa valve?
No. This is the 0.8 MPa (8 bar) rated version. The relief pressure must match the rating specified for your water heater — fitting the wrong pressure rating can either cause nuisance discharging or fail to protect the cylinder correctly.
What thread size does it use?
A 1/2" male thread x female BSP thread connection, sized for standard UK electric water heater pipework.
Can I use this to drain my water heater?
Yes — the valve's drain function allows a controlled release of water from the cylinder during servicing, maintenance, or decommissioning.
Is this suitable for any electric water heater, or only ELDOM models?
It is a standard 1/2" BSP, 0.8 MPa brass safety valve and will fit any electric storage water heater specified with this thread size and pressure rating, not only ELDOM units. Always check the pressure rating on your existing valve or the heater's data plate before ordering.
Who should install this valve?
Fitting or replacing a water heater safety valve should be carried out by a competent person following the water heater manufacturer's installation instructions, to ensure correct operation and continued compliance with the appliance's safety requirements.
