We stock a wide range of water feature low voltage transformers in various sizes to suit your requirements, ranging from 2.4VA up to 60VA. If your transformer needs replacing, the VA rating must be equal to or greater than your existing transformer (eg. If your existing transformer is 10VA then you would need a 10VA or greater as your replacement).
If you purchase a smaller transformer then this would simply burn out and blow.
If you do not have the original transformer you can work out the size of the transformer you require.
You would need to take the Wattage of the pump and any lights that run off the transformer then work out the size that is needed. The sum is very basic, one watt equals one VA. E.g. a 10 watt pump and a 5 watt light would need at least a minimum of a 15VA transformer.