6 Bar Pressure Relief Valve | F0000412 | MK3 Multibloc Circlip

Description

The Caleffi 6 Bar Pressure Relief Valve (F0000412) is a circlip-type replacement safety relief valve designed specifically for the Caleffi MK3 multibloc unvented group set. It opens to release excess pressure once the system reaches 6 bar, then re-seals once pressure has dropped back to a safe level, protecting the cylinder and pipework from dangerous over-pressurisation.

This part is intended as a service replacement for the safety relief valve fitted to an existing Caleffi MK3 multibloc, rather than a general-purpose valve for any push-fit or compression system. Fitting the correct circlip variant for your multibloc generation ensures the replacement seats and locks correctly in the manifold body.

6 bar

Pressure Setting

Circlip

Retention Type

Brass

Body Material

MK3

Multibloc Compatibility

WRAS

Approved

Caleffi

Manufacturer

Please Note

This valve is designed as a circlip-retained replacement specifically for the Caleffi MK3 multibloc. Earlier multibloc generations use different relief valve variants (for example, an O-ring push-fit type for the MK1). Check which generation of multibloc is fitted to your system before ordering to ensure correct fitment.

Important Safety Information

A pressure relief valve must discharge via a suitable tundish and pipework in line with manufacturer instructions and Building Regulations Part G3. Replacement or servicing of components on an unvented hot water system should only be carried out by a G3-qualified engineer.

Good to Know

Keeping the correct replacement relief valve on hand for the specific multibloc generation fitted avoids compatibility issues during servicing and keeps the unvented system's safety devices performing as the manufacturer intended.

Factory-Set 6 Bar Relief

Opens automatically at 6 bar to discharge excess pressure and protect the cylinder and connected pipework from damage.

Circlip Retention

The circlip fitting type is designed to seat and lock correctly into the Caleffi MK3 multibloc body, unlike O-ring or loose-nut variants used on other generations.

Direct MK3 Replacement

A straightforward like-for-like replacement part for an existing MK3 multibloc, simplifying servicing without needing to replace the whole valve assembly.

Brass Construction

A durable, corrosion-resistant brass body supports a long service life in domestic hot water applications.

WRAS Approved

Manufactured to meet WRAS and UK safety standards for potable hot water system components.

Genuine Caleffi Part

Sourced as a genuine Caleffi manufacturer part, supporting continued compliance and performance of the original multibloc assembly.

Valve Specification

Manufacturer

Caleffi

Manufacturer part code

F0000412

Product type

Safety/pressure relief valve, circlip type

Pressure setting

6 bar

Compatibility

Caleffi MK3 multibloc unvented group set

Retention type

Circlip

Body material

Brass

Approval

WRAS approved

What is this valve used for?

It is a replacement 6 bar safety relief valve for the Caleffi MK3 multibloc, an unvented group set used to control inlet pressure on unvented hot water systems.

Will this fit any Caleffi multibloc?

No. This is the circlip-retained variant for the MK3 generation specifically. Earlier multibloc generations use different relief valve types (for example, an O-ring push-fit variant), so check which generation is fitted before ordering.

Can I fit this myself?

Servicing components on an unvented hot water system falls under Building Regulations Part G3, so replacement should be carried out by a G3-qualified engineer.

Does the relief valve need a tundish?

Yes. The valve must discharge via a suitable tundish and pipework arrangement in line with the manufacturer's installation instructions and Part G3 requirements.

BTU Calculator

BTU & WATT Calculator

Room Dimensions

Length (in m):

Width (in m):

Height (in m):

Room Type

Living Room

Bedroom

Kitchen

Bathroom

Conservatory

Hallway

Glazing Type

Single Glazed

Double Glazed

Triple Glazed

External Walls

0 Wall

1 Wall

2 Walls

3 Walls

4 Walls

Insulation Level

Poor

Average

Good (New Build)

Calculate

Required Heating

0

Watts

0

BTUs