19.01-20
SS-plus installation 130906.p65
Email: sales@solastat.com
SolaStat Distributor.
SolaStat-Plus Plumbing Issues, Cont.
To minimise cavitation.
Mains pressure solar hot water systems are less susceptible to cavitation than low pressure systems as the
extra pressure will make it less likely that vapour bubbles will form.
As cavitation gets worse, less and less water is moved, often reaching a point where no water at all moves.
Since the solar hot water controller is still reading a ‘differential’ requiring water to flow then the pump stays
on until the vapour point drops. The vapour point drops either by water pressure increasing or water
temperature decreasing. When the pump is cavitating it may run continuously for several hours.
1. Make sure the pump is appropriate for the installation.
2. If a variable speed pump then select the best setting (a slower speed that still has enough head
pressure is best as this will create the lowest pressure difference in the pump).
3. Mount the pump as low as is possible to achieve highest water pressure out of the tank feeding into
the pump.
4. Lower the resistance to water flow into the pump, such as less bends or more gradual bends, or wider
diameter pipes. Recommended minimum diameter pipe 1/2”.
5. In exceptional cases a larger pump with a larger impellor may need to be fitted to reduce vacuum at
the impellor.
6. Convert the system to mains pressure.
The SolaStat-Plus controllers have an optional factory setting called ‘Pump Timer’ to assist in pump cavita-
tion recovery. After the pump has run continuously for approximately ten minutes, it will turn off for one
minute. This cycle is repeated as long as the pump is required to run and will not affect normal operation in
a standard hot water collector and cylinder installation. The one minute turn off period helps any accumu-
lated air to escape from the pump and has been effective as a backup in exceptional conditions. This
should not be considered a substitute for the afore mentioned best plumbing practices. This feature can
help prevent the pump running for hours in a ‘locked up’ state, increasing the installation reliability.
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