38 TECHNICAL
additional expansion relief . There is no energy efficiency in terms of SANS 10400-XA .
The design has to provide that where there is a series of cylinders and one were to pop , the bypass could be opened so as to prevent the whole hot water system being interrupted . That ’ s why there are additional valves and the design .
Adriaan Myburgh
Points to consider when installing cylinders in series :
• System operates equally well under low or peak demand ( it does not affect supply )
• A bypass must be installed so that any faulty tank can be replaced without interruption of supply
• Different types of cylinders may be used , but the one with the highest kW rating must be first in line ( that is , the one which heats up the water fastest )
• Pipe sizing is limited by the inlets and outlets of the cylinders – also beware of dead legs being created
• Consider accumulative pressure drops through each unit ( diffusers vary from model to model ) – add all together , difficult to maintain balanced pressure
• SANS 10142 – isolator per geyser – may lead to increased wire thickness , possibly additional breakers at DB . This must be referred to a licensed electrician
• Being a rational design , safety requirements are that all valves are to be labelled , special operating instructions are to be provided and relevant warning signs be installed
• Most new electrical-only geyser installations will not comply with XA2 from the National Building Regulations
The regulation states that only one geyser is allowed per three trusses . These installations will therefore require placement that will in turn require longer pipe work between cylinders , excluding anti-syphon loops . Given cramped space in a roof and the long distances , this is likely an arduous task .
SABS
In terms of geyser installations – be careful when signing off on these types of installation that may or may not be compliant – by making sure they are compliant . Series connections of hot water cylinders are not covered by SANS 10254:2017 . Each installation will be unique , with different layouts , different flow rates , space for working , demand from building occupants , and more . PA