Grant Diaphragm Kit Mpcbs33 Combi

Includes Silicone Grease Suitable for Grant Combi MKII, Grant Combi V3 Boiler

Genuine Diaphragm Replacement Kit for Grant Vortex Combi Boilers

The Grant MPCBS33/A Diaphragm Kit is a genuine manufacturer-approved replacement for the domestic hot water (DHW) diaphragm in Grant Vortex Combi oil boilers. This critical component controls the flow of mains water to the heat exchanger, triggering the boiler to heat domestic hot water on demand.

A worn or split diaphragm can lead to reduced hot water flow, fluctuating temperatures, or failure to ignite the burner during hot water use. Replacing it with the MPCBS33/A restores proper function and helps maintain efficient and reliable performance from your combi boiler.

Key Features & Benefits

• Official Grant Part – MPCBS33/A
  OEM replacement part designed specifically for Grant Vortex Combi boilers—ensures perfect fit and function.

• Restores Hot Water Performance
  Triggers the boiler to fire when hot water is demanded at the tap or shower.

• Prevents Lockouts and Flow Failures
  Replacing a damaged diaphragm helps prevent DHW interruptions and boiler ignition issues.

• Made from High-Quality Elastomer Material
  Built to withstand constant pressure changes and hot/cold water cycling.

• Cost-Effective Repair Solution
  Avoids the need to replace the entire diverter or water section assembly.

• Straightforward Installation
  Can be replaced during routine servicing by qualified engineers or experienced DIY users.

 Compatible Grant Boiler Models

The MPCBS33/A Diaphragm Kit is compatible with:

• Grant Vortex Combi 21kW

• Grant Vortex Combi 26kW

• Grant Vortex Combi 36kW

• May also suit selected Grant Vortex Pro Combi models using the same water flow assembly

Need help confirming compatibility? Contact us with your boiler model or serial number and we’ll verify it for you.

 When to Replace the Diaphragm Kit

Replace the diaphragm if:

• The boiler fails to ignite during hot water use

• You notice inconsistent or reduced hot water flow

• There are frequent hot water lockouts

• The diaphragm appears cracked, perished, or deformed during inspection

• You're carrying out a full service or refurbishing the hot water section

A failed diaphragm prevents the boiler from responding correctly to hot water demand—timely replacement is essential for system performance.

Technical Specifications

• Part Number: MPCBS33/A

• Manufacturer: Grant UK

• Type: DHW flow switch diaphragm kit

• Material: Flexible heat- and pressure-resistant rubber

• Application: Triggers burner activation on hot water demand

• Includes: Replacement diaphragm and fitting components (check packaging contents)

• Installation: Fits inside water flow valve housing (refer to boiler manual)