Geysers in series
TECHNICAL
37
Edited by
Eamonn Ryan
The following is a summary of an IOPSA / PIRB Tech Talk by Adriaan Myburgh relating to pitfalls and potential mistakes in installing geysers in a series .
Multiple water heater installations are predominantly used in commercial or industrial applications where a high volume of heated water may be required during peak hours , or where insufficient planning was done to supply hot water to a new build in order to comply with XA 2 .
There are two main methods of interconnecting these hot water cylinders :
• Series connections
• Parallel connections
This means if a plumber gets a job falling outside the scope of this standard , he / she needs to ensure the job is based on drawings , even if just the manufacturer ’ s layout of how the system is to be connected , and that the plumber is satisfied with the drawing . Installation of shut off valves , vacuum control valves & expansion control valves must always comply with SANS 10254 .
This Technical article will deal with Series connections and next month ’ s issue of Plumbing Africa will deal with Parallel connections .
In a series connection , cold water is fed through each tank – one after the other – with the hot water outlet from the first tank becoming the cold supply to the next tank . Geyser installations are governed by a single regulation , SANS 10254:2017 : The installation , maintenance , replacement and repair of fixed electrical storage water heating systems . This document covers the safe installation of new and replacement fixed electric storage water heaters , complete with all the relevant and applicable safety and hydraulic control units . However , this standard does not cover the sizing or hydraulic design of the storage water heating system or the design and installation of industrial hot water systems .
In other words , it is for simple off-the-shelf units installed onto a client ’ s premises . Section 4.1.1.2 of SANS 10254 states , ‘ Where some of the provisions of this standard cannot be applied , the installation shall comply with the details given in a rational design developed by a professional engineer on acceptable installation drawings , and such rational design shall not compromise the safety and performance principles incorporated in this standard .’
Myburgh described the reason for the Tech Talk as being the following sub-section 4.1.1.4 : ‘ On completion of the installation , a certificate of compliance from the professional body for plumbers registered in terms of the relevant national legislation [ in this instance the PIRB ], shall be issued to the owner of the installation or to the body requiring such a certificate .’
SABS
SANS 10106:2014 states : ‘ a ) Solar pre-heater retrofit : There will be no continual circulation of hot potable water between the solar water heating system storage tank and pre-existing electric storage water heater . The cold inlet to the solar pre-heater is connected downstream of the existing pressure control valve , and the hot outlet of the solar pre-heater is connected to the inlet connection of the existing electrical storage water heater , not into its hot outlet pipe . Flow of solar heated water to the preexisting electrical storage water heater only occurs when the hot water is drawn off at terminal fitting . This option may negatively affect flow pressure performance at terminal fittings due to the addition in-line friction pressure losses .’
Myburgh illustrates this with the following for a non-residential application , which he emphasises is a not a design : Myburgh says the above has a few extra valves on the system which are always closed . If there is a valve between the geyser and the pressure control valve it will require
November 2020 Volume 26 I Number 09 www . plumbingafrica . co . za