EHC Comet - Water Supply Requirements

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7. Installation: Plumbing
Water supply requirements
The Comet Combi operates at 3 bar (controlled by the inlet set) and is capable of delivering over 50 litres per minute. The high quality
inlet control set has been designed to make the most of the ow rates available, however the performance of the system is only as
good as the mains water supply to the unit. The maximum possible water demand should be assessed by taking into consideration
that both hot and cold services are supplied simultaneously from the mains. The water supply should be checked to ensure it can meet
these requirements. If necessary consult the local water company regarding the likely pressure and ow rate availability.
If measuring the water pressure, please note that a high static (no ow) mains pressure is no guarantee of a high ow rate.
In a domestic installation 1.5 bar and 25 l/m should be regarded as the minimum. The maximum recommended mains pressure for
the inlet control set is 16 bar. Consideration should be given to upgrading existing ½” (15mm) cold mains pipework to a larger size if
the recommended minimum pressure / owrate is not being achieved.
Cold mains pipework
1. Run the cold water mains pipework to the location of the Comet Combi. Take care not to run cold pipes close to hot pipework as
this will cause thermal transfer.
2. Install an isolating valve (not supplied) before the combination valve. A 22mm BS1010 stopcock can typically be used, however
a 22mm 1/4 turn full bore valve is preferable as it is less likely to restrict the ow. Do not use“screwdriver slot” or similar valves.
3. Allow space for a 22mm x 22mm x 15mm tee between the combination valve and the boiler heating return connection for the
system lling loop. This must be disconnected after the system has been commissioned.
Balanced
Mains Outlet
Hot
Water
Return
Inlet c.h.
Flow outlet
c.h.
Cold Mains
Inlet