The second in our series of maintenance articles for rainwater harvesting systems is on pumps. Pumps are one of the expensive and vulnerable elements of the rain harvesting system. It is worth getting a good one and installing it properly.
We had a coffee with Mike Thompson, from Claytech, who took us through some things to think about.
Mains switching device
The big change in the last decade has been the widespread use of mains switching devices usually associated with the pump. These clever devices use rainwater until it runs out, and then automatically switch over to mains water supply. From the household point of view it is seamless, your appliances never run out of water and you maximise efficient use of your rainwater. It is important to understand that leaf litter from the gutters will damage the operation of the switching system. You could clean your gutters or install a leaf diverter on the downpipe.
And now for the golden part. Mike has 20 years experience solving pump problems, here is the good oil for problem solving
It is important that the operation of the pumping system is understood in order to maintain the system and fix problems. If there is a problem with the pumping system then refer to the Operations Manual of the pump and/or mains back-up system.
The table below provide generic troubleshooting, which may or may not apply to a specific model or brand of system:
Table 3 – Trouble shooting guide for pump systems
|Problem||Root Cause||Possible Solution|
|Pump is turning on and off repeatedly||The pump will turn on when the pressure in the discharge piping is low. It will turn off when it has pumped the pressure high. The pressure in the household piping can only go down if there is a tap open or a leak in the system||Check all taps for leaks. Check all toilets that there is no slow leak into the bowl. Check washing machine by turning off water isolation tap. Repair leaks if necessary. If leak cannot be found contact a plumber to investigate leak that may not be visible.|
|Pump continually operates||The pump will operate continually if there is a tap open or a severe leak. If this is not the case then the pump controller may be faulty.||Check for open tap and leaks in system from toilet and pipework. Contact a plumber if there is a leak. If no leak is detected, contact the pump manufacturer, repairer, or retailer.|
|Pump doesn’t operate when rainwater in tank||The pump should operate when a tap is opened or a toilet is flushed. There could be electrical supply problems to the pump or even pump failure.||Turn the pump off and then on at the power point.
a) If the pump does not start, test power point by using another appliance. If other appliance doesn’t operate, check circuit breaker at switchboard. Reset circuit breaker and test appliance again. If circuit breaker trips again contact electrician. If pump is causing circuit breaker to trip contact pump manufacturer or retailer.
b) If the pump starts but doesn’t continue the problem maybe with the switching device. Contact the pump manufacturer, repairer, or retailer.
|No water to tap or toilets or washing machine||Tank top-up systems rely fully on the pump to deliver water to toilets and/or washing machine. Systems that have electronic or hydraulic switching to mains water should deliver water at all times even when there is no rainwater in tank.||Check pump operation and power supply by following procedure in section above.
Clean all filters and strainers to ensure there are no blockages.
Contact the pump manufacturer, repairer or retailer.
|Low flow to tap or toilet or washing machine||There could be blockages in the system that is restricting flow.
It is possible that the pumping system or mains switching system supply is designed for low flow.
|Clean all filters and strainers to ensure there are no blockages.
If the flow is still not acceptable contact the pump manufacturer, repairer, or retailer.
External pump or internal one?
Finally, do you want an external pump or an internal one?
Table 1 : Benefits of Pumping Systems
|Characteristic||External Pump||In-tank Pump|
|Performance||Correctly installed will provide consistent performance. Long or poorly installed suction lines can cause problems||Correctly installed will provide consistent performance|
|Noise||Horizontal Multistage design pumps are extremely quiet but lower cost jet pumps can be noisy||Water in tank will minimise noise|
|Electrical cabling||Can be an issue for children and animals||Less accessible if installed correctly.|
|Weather protection||Needs to be protected from sun and rain||No protection required for the pump but may need protection for external controller (from sun and rain).|
|Maintenance||Easier to maintain||Need to pull pump out of tank to maintain|
|Cost||Usually lower cost||Can be higher cost|
All of this content is on the rainwater harvesting website with our other content on maintaining rainwater harvesting systems
- charge systems
- sizing tanks
Have you had problems with your pump, have we missed something important that happened to you? Let us know and you can help everyone else!