CONNECTIONS – PLUMBING
47
PIPE SIZES
The pipe sizing for hot water supply systems should be carried out by persons competent to do so, choosing
the most suitable pipe size to ensure adequate flow for each individual application. Reference to the
technical specifications of the water heater and local regulatory authority requirements must be made.
To achieve true mains pressure operation, the cold water line to the water heater should be the same size or
bigger than the hot water line from the water heater. The minimum recommended cold pipe or solar preheat
pipe and hot pipe size is DN20 for a single water heater installation. If more than one water heater is
installed, refer to the table of
minimum header pipe sizes
on page 53.
IN-SERIES BOOST WATER HEATER
The pipe work between the solar storage tank (if one is installed) and the in-series gas booster has a
minimum recommended pipe size of DN20,
MUST BE
of copper and be fully insulated in accordance with
the requirements of AS/NZS 3500.4.
The insulation must be weatherproof and UV resistant if exposed. The insulation must be fitted up to the
connections on both the solar storage tank and the in-series gas booster. A full flow isolation valve must be
installed on the water line to the in-series gas booster.
CONDENSATE DRAIN
This high efficiency model has a condensate discharge outlet marked “condensate drain” on the underside of
the water heater. A DN15 UPVC drain line is recommended to be fitted to the condensate discharge outlet.
Copper pipe must not be used. Connect the drain line to the outlet using a disconnection union. The drain
line from the outlet to the point of discharge should be as short as possible, have a continuous fall all the way
from the water heater to the drain line outlet and have no tap, valves or other restrictions in the pipe work.
A drain line must be no longer than 9 metres with no more than three bends greater than 45° before
discharging at an outlet or air break. The maximum length of 9 metres for a drain line is reduced by 1 metre
for each additional bend required of greater than 45°, up to a maximum of three additional bends. Where the
distance to the point of final discharge exceeds this length, the drain line can discharge into a tundish.
The outlet of a drain line must be in such a position that flow out of the pipe can be easily seen, but arranged
so discharge will not cause injury, damage or nuisance. Drain lines must not discharge into a safe tray. The
termination point of a drain line shall be:
•
between 200 mm and 300 mm above an unpaved surface, or
•
between 75 mm and 300 mm above a gravel pit of not less than 100 mm diameter in a paved surface.
In locations where water pipes are prone to freezing, the drain line must be insulated, must not exceed
300 mm in length and is to discharge into a tundish through an air gap of between 75 mm and 150 mm.
If a drain line discharges into a tundish, the drain line from the tundish must be not less than DN20. The drain
line from a tundish must meet the same requirements as for a drain line from the condensate discharge
outlet.
GAS INLET
The gas connection is made at the underside of the water heater. The pipe work must be cleared of foreign
matter before connection and purged before attempting to operate the water heater. An isolation valve and
disconnection union must be installed to allow servicing and removal of the water heater (refer to the
diagram on page
46).
Note:
Refer to the Gas Installations Standard AS 5601 or AS/NZS 5601.1 or NZS 5261 for the correct
method of sizing the gas supply pipe to the water heater. The pipe size selection must take into account the
high gas input of this water heater
(refer to table on page
43
)
as well as all of the other gas appliances in the
premises.
Warning:
Always isolate the water heater before pressure testing the gas supply system. Disconnect the
water heater after the isolation valve to prevent the risk of serious damage to the gas control. The Rheem
warranty does not cover damage of any nature resulting from failure to observe this precaution. Refer to
rating label for gas types and pressures.
