Specifications

Rinnai Australia 8 Owners Guide & Installation Instructions
GENERAL INSTALLATION INSTRUCTIONS
These instructions apply to the Rinnai DDHEX250 High Efficiency Heat Exchange Hot Water System.
Rinnai DDHEX250 High Efficiency Heat Exchange hot water system must only be installed,
commissioned, serviced and removed by an authorised person in accordance with these instructions,
AS/NZS 5601, AS 3000 & AS/NZS 3500.4 and local regulations.
Rinnai DDHEX250 High Efficiency Heat Exchange hot water systems are not suitable or approved as
a pool heater.
Read these instructions carefully before proceeding with the installation.
The Rinnai specified heat sources (Rinnai HD200 series continuous flow water heaters) must be
installed and commissioned in accordance with the relevant section of the operation and installation
manual supplied with these appliances.
DDHEX250 High Efficiency Heat Exchange Hot Water Systems Principle of Operation:
The DDHEX250 Vented Tank is certified to AS/NZS 3498 as a heat exchange water heater with
external energy sources. It consists of three main components:
1. DDHEX250 - 250 Litre heat exchange Vented Tank. (Refer
in Figure 1).
2. Fitting Kit - Kit includes Primary Circulating Pump, Thermostat and all connections. (Refer
in
Figure 2).
3. Manifolded HD200 Gas Continuous flow water heaters (1, 2 or 3), Internal or External NG or
LPG. (Refer
in Figure 2).
The DDHEX250 Vented Tank is designed to separate potable hot water from the primary heat source
by locating a set of heat exchange coils inside an open vented storage tank. This keeps any
contaminants in the potable water separated from the external heat source, while maintaining high
efficiency and long life.
Potable cold water enters the coil set where it flows to the bottom of the tank, it is then heated as it
rises through the coils.
Primary water fills the tank itself. It is pumped from the base of the tank to an external heat source and
returned to the top of the tank in a counterflow heat exchange design. The primary pump is switched
by a thermostat that measures the outlet temperature of the coil set, energising the primary pump
when the coil outlet temperature is below the desired temperature.
Primary water levels are maintained in the tank by an internal float valve that admits make up water
as required under normal conditions etc.
When an external heating circuit is present, any thermal energy used in this process will result in a
lower performance for potable water flowing through the coils.
Fitting Kit - Kits included = primary circulating pump, thermostat and all connections.
When an external heating circuit is used in conjunction with the DDHEX250 High Efficiency Heat
Exchange Hot Water system, expansion of the water in the heating circuit must be allowed for to
prevent water overflow from the DDHEX250 Vented Tank. Contact Rinnai Commercial for further
information.
• Other external heat sources can be used to heat the primary water, subject to
approval from Rinnai. Operating and over-temperature control of any external
heat source will be part of any approval.
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WARNING