View Tankless Products. Businesses that depend on hot water rely on Rinnai. Our latest news New at Rinnai. Register your product Register Now. Are you a plumber? Visit PRO Site. Become a PRO. Refer C in Figure 2. The DDHEX 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.
Contact Rinnai Commercial for further information. Operating and over-temperature control of any external heat source will be part of any approval. This sensor detects potable water temperature under flow and no flow conditions. The Thermostat then either shuts off the pump in the primary heating circuit when the temperature reaches the set point or restarts the pump if the temperature falls below set point and differential.
Refer to Figure 3. All valves, controls and pumps etc must be easily accessible. Ensure components are not allowed to stand in water. In wet areas it is recommended to place spacers under the tank.
It must be installed in a vertically upright position. The water heater must be accessible without the use of a ladder or scaffold. For external installations, the water heater should be mounted on a concrete base at least 50 mm thick. Ensure the water heater does not stand on wet surfaces. Potable hot water outlet and vent fitting are on the right hand side of tank when viewing from the front. Particular care must be taken with the location of flue terminals.
All systems, skids and components should have the wrapping carefully removed and checked for any transport damage. Inspect for any transport damage. DO NOT install if any components are damaged. DO NOT install if any of the components are damaged. The only Non insulated lines should be the potable cold water supply up to the non return valve.
Replace lid ensuring EPDM seal is properly located. Latch lid in place. If required, fit feet to base of tank and fix tank to floor Refer Figure 4. The outlet should remain visible for detecting overflow. To reduce heat loss it is recommended that this line should be lagged.
Leave sensor sheath and electrical cable packaged. When mounting the location Tank or otherwise you must consider the routing length of the pump power feed and the control power feed. The length of both of these cable is 2 m. Refer Figure 5. This can occur at commissioning stage. This may change depending on desired position of flue terminal.
Install isolating ball valves on suction and supply side. Mount pump on absorption isolators and fix pump cover. Supplied in fitting kit. Pipe drain valve to drain. Ensure power cable enters pump from below and that it is not a track for water to enter pump. Connect the building return to the potable water supply line using another isolating valve.
Ensure the sensor is inserted all the way to the end of the thermowell then fix in place by applying silicone in and around the thermowell.
Refer Figure 7. Pumps should be sized for minimal temperature loss around the ring-main. Pumps must have a isolation valve on the discharge. Manifold pack includes a gas isolation valve for each unit. Pipe size used on inlet fitting is no indication of pipe size required. When the primary water circuit is ready to be charged, open the cold water line which will supply potable cold water to the coils and to the make-up float valve fitting.
Open the primary water circuit to the HD units for both flow and return. Water will begin to fill the tank via the float valve until the factory adjusted level is achieved approximately 40 mm below the vent fitting. Refer Figure 9. System will fill slowly to correct volume. Operate primary pump for several minutes and check air is bled from pump. Check all relevant valves, water and gas, are opened on the primary circuit and ensure no blockages or restrictions are present. Check all relevant branch outlets are closed on the ring main flow and return circuit.
Primary circuit will be activated and HD units will fire as the primary circuit pump starts. You may need to bleed the pump of air, to do this: a. Disconnect power to pump and close the isolating valve on the discharge side of the pump. Open the isolating valve in the suction pipe completely before starting the pump. Remove the filling plug A. B is the pump drain plug. See Figure Fill the pump housing and the suction pipe completely with liquid until a steady stream of liquid runs out of the filling hole.
Fit and tighten the filling plug A B E. Slowly open the discharge isolating valve while the pump is running. This ensures venting and pressure build-up during start-up. As the system is filled from cold a small quantity of water may drain from the overflow as the system comes up to operating temperature. Once the primary circuit is commissioned open flow to the building hot water supply, and open the isolating valve on the return circuit.
Open an outlet load and observe system for 30 minutes to ensure system is functioning satisfactorily. Check gas supply pressure whist operating. Clear strainers on HD cold inlets. Adjust float valve if required. Check float valve operation. Wet pump electrics may cause failure.
Water can run along power lead so keep the lead looping under the pump and curving upwards toward the electrical box. DO NOT aim shaft upwards or downwards.
Note that this is an 'O' ring seal and does not need to be excessively tightened. Just make sure 'O' ring is engaged inside machined surface in brass housing. Isolate circulating water supply before removing filter for cleaning and inspection. Ensure water in storage cylinder is not excessively hot before removing HD inlet filter.
These units are not staged. Refer to a full list of fault codes. Refer to page This may be indicated by fault Contact Rinnai Service. This can be caused by the flueing not being pushed together properly and exhaust gases are re-entering the inlet air.
Push the flue together to remedy this. Also inspect flue terminal for any cause to divert exhaust air back into the inlet air.
If a fault occurs, an Error Code will flash on the Digital Monitor.
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