Commissioning Of The Boiler; Initial Flushing; Gas Supply; Electrical Installation - Keston Celsius 25 Installation And Servicing Instructions

WD209/1/2000

4. COMMISSIONING OF THE BOILER

Important:
This condensing boiler contains components which could be damaged or blocked by grease, dirt,
solder etc., from the water system. The following commissioning procedures must be followed
precisely.
It is essential that combustion is checked at high and low rate , as per Section 5.7, using a
calibrated flue gas analyser set for the relevant gas type.
4.1

INITIAL FLUSHING

All waterways within the Keston Celsius 25 are either copper, high alloy stainless steel or
aluminium. As a result water treatment chemicals for central heating boilers such as
Fernox MB1, or equivalent, are suitable. In any event reference must be made to BS 7593
: Treatment Of Water In Hot Water Central Heating Systems.
a. Disconnect the boiler from the system at the flow and return connections and
temporarily link the flow and return pipes on the system.
b. Flush the entire system until clean water is discharged, free from dirt, flux, solder
etc. The use of a flushing chemical is recommended, e.g. Fernox Supafloc, or
equivalent.
Sludge and scale must be removed from an existing system. Boiler failure due to
system debris or sludge shall invalidate the guarantee.
c. Connect the system to the boiler and fill in accordance with Section 2.7 - Water
Systems. At this stage, for sealed systems, fill to a pressure of about 2.7 bar.
d. Check the complete system for water soundness. If leaks need to be rectified
using flux and solder, the system must be flushed cold again before proceeding.
e. Reduce the pressure to the Initial System Design Pressure for sealed systems, if
applicable. Vent the system
4.2

GAS SUPPLY

The complete gas installation up to the boiler service cock must be checked for
soundness. BS 6891.
4.3

ELECTRICAL INSTALLATION

Carry out preliminary electrical safety checks, i.e. Earth continuity, Polarity, Resistance to
Earth, Short Circuit using a suitable test meter.
4.4 LP GAS
The Keston Celsius 25 is supplied preset for the gas designated on the boiler packing. No
field conversion is possible. LPG installations must use Celsius 25P models only.
4.5 INITIAL FIRING
Important
Checking the gas pressure to the pre-mix burner requires a special procedure, outlined
below, which must be carried out.
a. Purge the gas supply in accordance with BS 6891.
b. Vent the water system.
Important:
The Celsius heat exchanger consists of crossflow tubes which can trap an air
pocket. Great care must be taken to ensure that water flow has been established
through the heat exchanger and thus ensuring no air pockets remain in the heat
exchanger and pipe work. Firing the boiler while an air pocket exists in the heat
exchanger could damage it.
c. Turn the gas service cock to ON.
d. Turn on the electrical supply, setting any external controls to call for heat.
e. Set the boiler user control knob clockwise to the desired temperature setting. The
mains LED (green) will illuminate continuously. After approx 10 seconds the
boiler fan and pump will start on ignition rates. After a few seconds the yellow
Boiler ON LED will flash and a spark will light gas at the main burner, provided all
Installation & Servicing Instructions
Chapter 4 : Commissioning The Keston Celsius 25 & 25P
Page : 19