Gabarron MATTIRA MAC15 Installation Instructions And User Manual - page 11

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4.9 (c) DHW CONNECTIONS, DESIGN & REQUIREMENTS 

 CAUTION: This boiler incorporates a 50 litre unvented hot water cylinder. Installation of this appliance must be 

carried out by a Competent Person and in accordance with the relevant regulations. 

In every installation it is mandatory for the Group combination valve to be installed on the mains cold water supply to the 

boiler. This will protect the boiler and prevent constant opening of the 7 bar relief valve (The Group combination valve is 

comprised of a pressure reducing valve, a pressure relief valve, a check valve, a filter and a balanced cold water outlet all 

included in a single valve. These inlet control groups are designed to control the pressure on the mains supply to the integral 

unvented hot water cylinder). 

The installation of a thermostatic blending valve (not supplied) is recommended, as per the diagram shown in 4.7 to ensure a 

safe and economic supply of hot water. 

Maximum inlet pressure to Pressure reducing valve  12 Bar 

Operating pressure (PRV setting)    

3 Bar 

Expansion vessel charge pressure    

3 Bar 

Expansion relief valve setting        

4.75 Bar 

Opening pressure of P & T Relief Valve       

7 Bar 

Opening temperature of P & T Relief Valve   

92ºC – 95ºC 

Energy cut-out thermostat setting   

80ºC 

Immersion heater rating    

2-15kW depending upon setting 

All cylinders are manufactured in accordance with the requirements of BS EN 12897. 

The tundish must be positioned so that it is visible to the occupant and is away from electrical devices. 

Components supplied with Gabarrón Mattira electric combi boiler (incorporating a 50 litre unvented 

cylinder): 

• Cold water inlet PRV combination valve/expansion relief (supplied loose) 

• Pressure and temperature relief valve 

• Control thermostat 

• Energy cut-out thermostat 

• Tundish (supplied loose) 

• Immersion heaters including control and cut out thermostats 

• Expansion vessel 

• Technical/user product literature 

In any situation where the volume of heated pipework (eg. secondary circulation pipes or manifold pipework 

for multiple units) exceeds 10 litres, then an additional expansion vessel must be fitted to accommodate the 

extra expansion volume. 

 CAUTION: Modifications should not be made to this product. Replacement parts, including immersion heaters, 

should be purchased from Elnur UK Limited, or agents approved by them. 

Unvented hot water storage vessels need regular routine checks, and these are detailed below. It is for this reason that this 

manual must always be left with the Gabarrón Mattira combi boiler. 

It is essential that these checks be carried out at the time of boiler maintenance by a qualified installer: 

1. Manually open the relief valves in turn, and check that water is discharged from the valves and runs freely through the 

tundish and out at the discharge point. Ensure that the valves re-seat satisfactorily. (Note – the water may be very hot). 

2. It is important to check that the discharge pipework is carrying the water away adequately. Check for blockages etc. if it is 

not. 

3. Turn the mains water off and remove and clean the strainer element in the Pressure Reducing Valve. 

4. Check the charge pressure in the expansion vessel and repressurise if required. 

5. Re-fill the system and ensure that all relief valves have re-seated. 

6. The Service Record should be updated at each service.