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Alpha CD25C/28C/35C Combination Boiler Installation and Servicing Instructions
This document provides the full set of instructions for installing, commissioning, operating and servicing the Alpha CD25C, CD28C and CD35C high‑efficiency condensing combination boilers. It includes technical data, safety regulations, wiring diagrams and fault‑finding procedures.
Key sections cover boiler dimensions, gas and electrical supply requirements, flue system design, central‑heating system setup, boiler location, and routine maintenance. A benchmark checklist and service record form are also provided to help installers verify compliance with UK building and gas regulations.
Alpha 25C specifications
| Central heating load (CD25C) | 5.5 – 19.5 kW |
|---|---|
| Domestic hot water flow (CD25C) | 9.6 L/min |
| Gas rate (CD25C) | 2.55 m³/h (90.1 ft³/h) |
| Electrical supply | 230/240 V ~ 50 Hz, fused at 3 A |
| Pressure relief valve setting | 3 bar |
Source: Alpha CD25C/28C/35C Combination Boiler Installation and Servicing Instructions
All Alpha 25C documents by type
Mounting, wiring and first power-up. Read it before the hardware goes in.
Questions answered in these manuals
What minimum gas supply pipe size is required?
The boiler requires at least a 22 mm gas supply pipe.
From: Alpha CD25C/28C/35C Combination Boiler Installation and Servicing Instructions
What is the temperature range for the Alpha Wire 1181/25C?
The part is rated for temperatures from –20 °C to 80 °C.
What voltage rating does the 1181/25C wire have?
It is rated for 300 Vams.