Rinnai HOTFLO EHFA Series

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Overview

Function Description
Operational Overview
Important Technical Specifications
Usage Features
Maintenance Features
Installation Requirements

The Rinnai HOTFLO (EHFA/EHFD) Series is a range of mains pressure vitreous enamel electric storage water heaters designed for domestic hot water supply. These appliances are certified products, complying with current AS 3498 standards and bearing the WaterMark certification (WMKA00169) and regulatory compliance mark N10378.

Function Description:

The Rinnai HOTFLO electric storage water heaters store water in a vitreous enamel lined steel cylinder and heat it using thermostatically controlled electric heating elements. They are designed to provide a continuous supply of hot water for various household needs, including kitchens, laundries, bathrooms, and ensuites. The system operates under mains pressure, connecting directly to the main water supply.

Operational Overview:

Single Element Models: These models feature a single heating element located at the base of the cylinder. The element is thermostatically controlled and can be connected to either a Continuous or Off-Peak electricity supply. Continuous supply is suitable when the water heater capacity is less than the daily hot water usage, while Off-Peak supply is appropriate when capacity exceeds daily usage, allowing heating during set periods, often at a lower tariff.
Twin Element Models: These models incorporate two thermostatically controlled heating elements: one at the base and another near the top of the cylinder. The bottom element heats the entire cylinder contents, typically connected to an Off-Peak supply. The top (booster) element operates during high-demand periods to heat the upper portion of the cylinder, usually connected to a continuous electricity supply. The two elements are wired for non-simultaneous operation, meaning only one can operate at a time.

Important Technical Specifications:

Cylinder Rated Pressure: 1000 kPa for all models (EHFD 160, EFHA 250, EHFA 315).
PTR Rated Pressure: 1000 kPa for all models.
ECV Rated Pressure: 850 kPa for all models.
PLV Fitment: A Pressure Limiting Valve (PLV) is recommended if mains pressure exceeds 680 kPa (for ECV Fitted) or 800 kPa (for ECV Not Fitted). The recommended PLV pressure rating is 500 kPa.
Rated Capacity Hot Water Litres:
- EHFD 160: 160 litres
- EFHA 250: 250 litres
- EHFA 315: 315 litres
Heating Element (W):
- EHFD 160: Lower 2400W or 3600W.
- EFHA 250: Lower 2400W, 3600W, or 4800W. Upper 3600W, 4800W (for twin element models).
- EHFA 315: Lower 3600W or 4800W. Upper 3600W, 4800W (for twin element models).
Inlet/Outlet Connections: 3/4" (20 mm).
Dimensions (mm):
- EHFD 160: A=1313, B=600, C=537, D=1107, E=186, F=110. Weight: 51 kg.
- EFHA 250: A=1484, B=674, C=605, D=1248, E=210, F=135, G=985. Weight: 71 kg.
- EHFA 315: A=1770, B=674, C=605, D=1541, E=210, F=135, G=1225. Weight: 91 kg.
Ingress Protection Rating: IPX4, suitable for internal or external installation.
Electrical Supply: Single phase 240 Volts, AC mains electrical operation.

Usage Features:

Water Temperature Control: The thermostat is factory pre-set to 70°C but can be adjusted by a qualified electrician between 60°C and 70°C. Stored water temperature must not be less than 60°C to meet regulatory requirements.
Scald Prevention: The water heater can deliver water at scalding temperatures. Rinnai recommends fitting an approved Temperature Limiting Device (TLD) in the hot water pipework to areas used for personal hygiene (e.g., bathrooms) to reduce water temperature to safer levels (e.g., 45°C or 50°C), especially for children, the disabled, and the elderly.
Hydrogen Gas Accumulation: If the water heater is not used for two weeks or more, flammable hydrogen gas may accumulate. To dissipate, turn on a non-electrically operated hot tap for several minutes.
Turning ON/OFF: The water heater is typically switched on/off via an isolating switch in the electricity meter box. When turning on, it may take several hours for hot water to become available.
Draining: Draining must be performed by a qualified person. This involves isolating electricity, closing cold water isolation valve and hot water taps, and operating the PTR valve easing gear.

Maintenance Features:

Sacrificial Anode: Fitted to extend cylinder life. It should be inspected and replaced by an authorised person at least every 5 years. Magnesium anodes are standard, but an aluminium-based anode is required for water supplies with total dissolved solids (TDS) exceeding 600 mg/L.
Pressure & Temperature Relief (PTR) Valve: This critical safety device is supplied with the water heater and MUST be fitted. It should be checked for performance or replaced at intervals not exceeding 5 years, or more frequently in areas with high water deposits. The easing gear must be operated gently at least every six months to dislodge deposits and verify operation.
Expansion Control Valve (ECV): Recommended in areas with scaling water (total hardness > 200 mg/litre or Saturation Index > +0.4), and may be required by local authorities. If fitted, its easing gear should be operated at least every six months and checked/replaced at intervals not exceeding 5 years.
Water Quality: If sludge or foreign matter is present in the water supply, a suitable strainer or filter should be incorporated.
Periodic Servicing: Rinnai recommends that the appliance be inspected and serviced by a qualified person every 12 months.
Drain Lines: Copper drain lines (DN15) MUST be fitted to the ECV (if applicable) and PTR valve, configured with a continuous downward slope, no restrictions, and a maximum length of 9 metres with no more than three 45° bends. Termination points must comply with local regulations and AS/NZS3500.4.
Insulation: Cold supply and hot water pipes from the heater MUST be insulated according to AS/NZS 3500.4 and local regulatory requirements. The PTR valve and ECV bodies MUST also be insulated.
Over-temperature Cut-out: To ensure this safety feature is set, the red 'reset' button on the thermostat must be pressed after any adjustment or electrical work.

Installation Requirements:

Installation MUST be carried out by a qualified person in accordance with:

Manufacturer's Installation Instructions
Current AS/NZS 3000 Wiring Rules
Current AS/NZS 3500.4 Plumbing and Drainage - Heated Water Services
All local regulatory requirements, including OH&S. The water heater should be installed as close as possible to the most frequently used hot water outlet, in a vertically upright position, at ground or floor level, and be accessible for service. A safe tray and drain are required where property damage from leakage could occur. Valves with pressure ratings other than specified are unsuitable and MUST NOT be used. Disconnection unions are required between the water heater and isolation valves.