S T I E B E L
E L T R O N
DHC
Single phase hydraulically controlled
instantaneous hot water system
Single phase electric
DHC 4 – 4.4kW / 19amps 230V
DHC 6 – 6.6kW / 29amps 230V
DHC 8 – 8.8kW / 39amps 230V
No temperature adjuster on the outer unit.
Able to adjust flow rate under the cover.
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Trouble Shooting DHC
1. Unit not heating…. water coming out the tap but no temperature rise on the
cold at all.
a. Check power and circuit breaker to the unit are correct.
• DHC8 230V 39amp
• DHC6 230V 29amp
• DHC4 230V 19amp
b. When the hot tap is opened does the flow switch activate – a click is
heard and the “power” light will show on the front cover?
If yes proceed to C, if no follow the steps below.
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•
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Ensure the flow rate is greater than the minimum required - brochure
Ensure hot and cold pipe-work is correct – hot left, cold right when
looking at the unit.
Check inlet filter for blockages – located in flow switch (see fig20 in
instruction manual)
•
Remove any restrictors from tap-ware and outlets.
If the pressure switch will still not activate, unit possibly requires new
flow switch.
c. The safety thermal cut-out may have switched the unit off.
•
Press the reset button on the safety thermal cut-out located on the
side of the tank (fig 21). Isolate the power to the unit first.
If the cut-out wasn’t activated the unit may require a replacement element.
2
Trouble Shooting DHC
2. Unit only warm…. warm water only coming out of the tap, will not get hot.
a. Check the hot water flow rate, cold water temperature and hot water
temperature.
• Check the flow rate with a flow cup or bucket e.g. 6ltr min
• Take the cold water temperature away from the hot to get the
temperature rise. e.g.hot = 36oC, cold = 20 oC / temp rise = 16 oC
• Match unit, flow rate and temperature rise to the chart on the
brochure e.g. DHC6 matched the above example.
Does the flow rate, temp rise match with the unit installed?
If yes – the unit is operating correctly. Adjust the flow rate down via the
flow rate screw in the unit to desired temperature. Shown in fig18.
If no proceed to b.
b. Check power and circuit breaker to the unit are correct.
• DHC8 230V 39amp
• DHC6 230V 29amp
• DHC4 230V 19amp
If not rectify.
If ok proceed to C.
c. Check the amp draw when the unit is operating.
If the amp draw doesn’t match as per above – replace the element.
If amp draw correct proceed to d.
d. With power off and cold water isolation valve turned off remove the
outlet pipe and fit a flexi to run into a bucket or floor drain. Open isolation
valve to run water through the unit and switch power on. Re-check
temperature.
If temperature correct, there is an issue with the plumbing after the hot
water system. Rectify plumbing and re-test.
If temperature still not correct – replace unit.
3
Trouble Shooting DHC
3. Unit fluctuating…. Unit fluctuating hot and cold at outlet.
The DHC units do not have a thermostat in them to control the temperature.
Fluctuation only occurs when the water flow increases or decreases. See below for
trouble shooting.
a. Is the unit installed with a tempering valve?
If yes proceed, if no go to “b”.
•
Ensure the tempering valve is a high performance model suitable for
instant hot water units. If the wrong valve is installed the unit will fluctuate.
If correct proceed.
b. Check outlets to remove any restrictors. Note most outlets now have a
restrictor located in them somewhere to comply with “WELS”. This MUST be
removed as it may cause the unit to fluctuate.
If restrictor found, remove and re-test. Restrictors can cause back pressure on
the unit causing it to switch on and off.
If no restrictor proceed.
c. With power off and cold water isolation valve turned off remove the outlet pipe
and fit a flexi to run into a bucket or floor drain. Open isolation valve to run
water through the unit and switch power on. Check for temperature
fluctuations.
If no fluctuating occurs there is a restriction further down the hot plumbing pipework. Rectify and re-test.
If unit is still fluctuating – replace.
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