Overview of a Pool Plant System
In later sections of the course, we’re going to be going into some detail into all the main components of a pool plant system. For now though, we need a basic overview. See below for a diagram of a typical swimming pool. Click on the ⓘ symbols for more info. on the various components of a typical pool plant system.
For the purposes of this course, we can consider the circulation system as everything the pool water flows through as it makes its journey from the pool to the plant room, and back to the pool again. Substances for disinfection, pH correction and coagulation are injected into the pool water as it travels through the circulation system.
Main Components (in sequence)
- Strainer basket(s)
- Pump(s)
- Filter(s)
- Heat exchanger
Chemical Injection Points
- Coagulant – prior to filter(s) but after auto chemical monitoring sample point.
- Disinfectant – can be prior to or after filter(s) if no UV system fitted but always after UV if fitted.
- Acid (pH correction) – usually after the heat exchanger.
Plant room components
Some of the images and diagrams you quite often come across in formal courses and textbooks depict the type of pool plant system that you would have in an ideal world (like in the diagram above!). But the real world of pool plant operations means that you might well need to get to grips with a treatment system that is old, possibly neglected and not always well-designed. The slides below show a series of photos of a swimming pool water treatment system for a hotel pool. Follow the slides along, click on the blue icons to drill down into more detail and see if they help you recognise and identify some of the equivalent components in your own plant room.
All about valves
There are several types of valve you might come across in a typical plant room, some images and descriptions of the more common ones are provided below. Click on the images to enlarge.
Check Valve – used to ensure fluid travels in one direction only. 
Gate Valve – opens by lifting a barrier out of the path of the fluid. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened. 
Multiport Valve – acts as a manifold on smaller systems and combines the function of several valves into one. 
Butterfly Valve – one of the most common on swimming pool systems. Turning the handle rotates a disc within the pipework, thus opening or closing the valve. 
Ball Valve – quite similar to the butterfly valve, except the disc is replaced with a ball with a hole in it which restricts or allows flow according to its position.
How to survey your own plant room
1. Figure out the direction of flow
Once you know the direction water is flowing through the system, things become much easier, so it makes sense to figure this out first.
The two most fundamental components of a pool plant system are the filter(s) and the pump(s) that push the water through them.
Identifying either of these components is quite easy in most plant rooms. The filters are usually the largest component on a pool treatment system and the pumps are the noisiest.
The pumps always push water through the filters (they don’t pull the water through). This means that, in terms of how the pipework connects the filters to the pumps, the pumps will always be ‘upstream’ of the filters. Once you know where your pumps and filters are, you can easily track the pipework connecting them and thus establish the direction of flow.
2. Find the incoming pool water pipework
Once you’ve figured out the direction of flow, track the pipework backwards (i.e. against the direction of flow). The objective here is to go all the way back until you get to the point where the pipework comes into the plant room from the pool itself. This will be pipework coming through a wall, the floor, or a ceiling (it depends on where your plant room is in relation to the pool).
This can sometimes be tricky as pipework may well be located adjacent to or behind other pipework and various other components and building features, making it difficult to keep track of it. This is par for the course of being a pool plant operator, so welcome to the club!
3. Go with the flow from A to B
Point A is the incoming pool water pipework (discussed above). Point B is where the pool water exits the plant room and is returned to the swimming pool. Like with the incoming pool water, the outgoing water will be pipework going through a wall, the floor, or a ceiling (it depends on where your plant room is in relation to the pool).
Start at point A and follow the pipework in the direction of flow. Along the way, you will see that there are peripheral systems and components connected to the main system pipework. When you come across one of these items, develop a curious frame of mind and set out to identify what it is.
You should expect to encounter things like pipework, chemical feed lines, sample feed lines, flow meters, injectors, heat exchangers, ultraviolet systems. It depends how your system was designed, what was included in the original specification what additional systems may have been added on over the years. Don’t be surprised if you discoiver that you are missing some components!
Bear in mind that the pipework ‘upstream’ of the pumps is under suction and pipework ‘downstream’ of the pumps is under pressure. This might help you when it comes to identifying the automatic monitoring system sample flow and return lines.
Plant room tour
This video will take you through a system comprising 2 x full duty pumps and 3 x filters servicing a fairly large (875 cubic metre) deck-level pool. Don’t worry if it seems a bit confusing at first, your understanding of all these different functions and components will increase as you progress through this course and remember, you can come back and re-watch the video any time you like.
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