Recommended plumbing for swimming pool heating

When you heat your swimming pool not only do you need to choose the most appropriate type of heater to match your needs, you should also think about how the heater will be connected to your pool and the other equipment.

There are three possible plumbing methods for pool heating:

1. In series
2. In series with a booster pump, or
3. Independently plumbed

Some heating types dictate the plumbing method and others you have a choice. For the same heater and the same heat output, the plumbing method can have significant effects on your energy consumption, your power bills, and the ease of operation. In this article we’ll walk through each possible configuration and look at their pro’s and con’s.

In Series

This works for gas and heat pump heaters (for solar heating an additional booster pump is required). Valves either manual or automatically controlled are installed to push water through the heater or to bypass it when not in use.

A by product of salt water chlorinator’s is hydrogen gas which should not be pumped through heaters. When connected in series or with booster pumps chlorinators must always be installed after the heater.

Pro’s	Con’s
Simplest configuration Only a single pump required The cheapest installation cost when adding heating to an existing pool as it uses the existing water inlets and outlets in the pool walls.	The heater cannot be run independently of the filter and chlorinator. The optimum pump speed for the filter and chlorinator is quite slow but it’s forced to run fast whenever the heater is operating resulting in less energy efficiency.

Booster pump

Solar pool heaters always require a booster. More work is required to elevate the water to the roof of the house than can be achieved by a stand alone filter pump. Check (one way) valves are used to prevent water in the hoses on the roof flowing back down when the pumps are not running.

Solar heaters can be configured either as the sole heat source, or boosted by a gas or heat pump heater.

Pro’s

Con’s

Can use existing outlets in the pool, reducing installation cost.

The the filter pump must be run at the same time as the solar booster pump else it blocks or restricts the flow of water. The solar heater must run during the day when the sun is out. For people on time of use power this is also the period when electricity is most expensive (2-4 times that of off-peak). Solar heaters start and stop during periods of sun and shade, synchronisation is required with the filter pump.

Independent system

Regardless of the heating type – solar, gas, heat pump or a combination, we recommend where possible that the heating be connected entirely independently of the water filtration. Doing so requires separate fittings in the walls of the pool to take cold water in and return the heated water.

Pro’s

Con’s

The filter pump is able to operate at an optimal (low) speed when filtering. The heater pump can be set at the optimal speed for water heating. For solar heating – water filtration can occur over night using cheaper electricity (when time of use electricity tariff applies) and water heating during the day when the sun is out. Greatly reduced complexity in pump operation, synchronisation of pumps is not required, heater operation cannot adversely affect water filtration and vice versa. If noise from heat pumps is a concern – operation can be timed to minimise disturbance. Less valves or gates are required, reducing risk of equipment damage due to them being set incorrectly.

Two separate intake pipes and a return pipe must be plumbed into the pool walls. On new pool builds there is a marginal cost increase, for existing pool builds it can be more significant.