It is important that you follow the simple drawings that you will be supplied with when you are fitting your Elecro Heater into your system.
The reason for this is to ensure that the body of the actual heater is always full of water - thus preventing half the heating element to be out of water which would, of course, cause the element to overheat and burn out ..
You can either choose to use 90 degree bends or 45 degree bends which are a little gentler with the interrupted flow..
this then means that water will flow out of the upper section of the pipework return to your pond ... this in turn ensures that there will always be water in the heater covering all of the element ....and if possible the Heater should be placed before the Ultra Violet Clarifier as this then prevents and single cell algae that has been 'zapped' by the UV rays from collecting on the 'Flow Switch' contained within the body of your new heater unit .. which is of course one of the built in safety trips in this piece of equipment ..
The drawing below is for a 'Gravity Fed' system where the 'clean water' is being returned to the pond after passing through the filtration system..
If you have a 'Pump Fed' system, where the water is being pumped to the filter from the bottom of the pond then you should also make the provision for de mounting the unit so that you can regularly flush it through to remove any possible build up of debris from round the element. This is easily done by plumbing in with hose tails if you are using flexible pipe – or when using rigid pipe work (which is what we would recommend) installing unions or better still double union ball valves before and after the unit.