Elwa HOTRUN-VE 38VE Operating And Installation Instructions page 13

The HOTRUN does not switch on when opening the tap fully.
Causes
- This problem is usually caused by lack of water flow problems. Ensure the pressure on the
cold water supply is over 60kPa, while the HOTRUN is in use and the flow rate is
sufficient to turn the heating elements on.
- Too much back pressure in tap-outlets or shower heads after the HOTRUN, causing lack
of pressure differential over the HOTRUN (back-pressure through the cold)
- Maximum temperature/overpressure cut-out switch is activated. This if most likely due to
air in the HOTRUN not cleared before switching on the electrical supply, or the mains
incoming water pressure is too high.
Remedy
- Fix the water pressure problems; remove any flow restrictions fixtures such as shower-
heads and tap outlets.
- Switch the electric power supply off; make sure there is no power on any of the terminals
- Check continuity over the safety switch terminals. If there is no continuity over the
contacts, push the reset button on the safety switch.
- Seek electrical assistance to check power supply on all phases and continuity all the way
to the electric elements, and to measure element resistance.
The water that is coming out of the HOTRUN is not warm enough.
Cause
- The incoming water is very cold (below 12°C) and/or the total flow is too high.
Remedy
- A flow restrictor can be installed or an inline (additional) ball valve in the cold water
supply to the HOTRUN can enable the user to reduce the flow and so increase the
temperature to the maximum temperature programmed in the temperature limiter.
The heating of water stops when trying to mix cold water to get the required
outlet temperature
Causes
- Aerator/restrictor in nozzle of outlet causing too much back pressure
- Incorrectly balanced flow restrictor in the supply line, pressure limiter installed in the
wrong place not reducing the pressure of the cold water to the taps
- Pressure and/or flow in the cold supply line is less than the required minimum pressure for
the HOTRUN to switch on.
Remedy
- Remove the restrictions in the tap-aerator or shower-head.
- Check all other taps or restrictors built into the supply line are not affecting the flow or
reducing the pressure too much.
Trouble Shooting Examples