An introduction to backwash valves.
If you have a DE (diatomaceous earth) filter or a sand filter, your filter has a backwash valve on it. There are four different types of valves, but they all do the same basic thing – they control the flow of water through your filter.
How are the valves different?
There are two main differences between the valves:
Check out this chart that compares the different types of backwash valves
|Backwash Valve Type||Feet of Head||PSI Loss||2″ Pipe Equivalent|
|Push Pull (Plunger)||10.3||4.5||128 Feet|
- At a flow rate of 100 gallons per minute, a multiport backwash valve creates as much resistance to flow as adding 171 feet of pipe to the system! By comparison, the diverter style valve adds only as much as resistance as 34 feet of pipe, which is obviously a LOT less.
- Please note that at lower flow rates (i.e. variable speed pumps) the resistance will be significantly decreased and the differences between the different styles of valves will be much less dramatic.
What are the valve settings?
When you are in filter mode, the water goes “forward” through the filter and the particulate is filtered out and the clean water goes back to the pool. When you are in “backwash” mode, the water goes through the filter in reverse direction and flushes the dirt and sediment out of the filter and sends it to the sanitary sewer line. There are other settings on some valves as described below.
Backwash valves are “manufacturer specific” which means that you must purchase the valve that your manufacturer makes and specifies for that filter. There are some universal valves made, but it is always best and easiest to just get the valve made specifically to fit your filter.
Push Pull Valves
The push pull valve is the most common backwash valve for several reasons:
If you have a DE filter, typically, the handle is down in filter mode and up in backwash mode, but there are some valves that operate opposite, so ask a qualified professional if you are unsure.
The mutiport is the second most common valve. It is different from the push pull valve in these respects
- Options – there are several other settings besides filter and backwash. If you have a sand filter, the “rinse” option is really helpful.
- Cost – it is more expensive to purchase and maintain
There are several different settings on this valve. We will discuss these in greater detail in the page that is dedicated to multiport valves.
Diverter Style Valves
This is a newer style valve that is offered by several manufacturers. It uses the same type of diverters as you find in Jandy valves. Here are the advantages of this type of valve:
- Best Flow – these offer the best flow rate with the lowest friction loss of any backwash valve.
- Automation Ready – these can be fitted with a valve actuator for systems that facilitate automatic backwashing (primarily sand filters)
These are primarily used in applications where the highest possible flow rate is needed.
It is an interesting concept. Thankfully none of the other manufacturers have seen fit to include it in their filter designs. It is difficult to use and difficult to repair because it requires taking the entire filter apart to get to the valve portion. Parts are not always readily available at our local friendly pool store.
NEED HELP? Having problems with your backwash valve? Contact Pool Stop today! Give us a call
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