UV Sterilizer Plumbing Question

[pianosdr]

I’m in the process of mapping out the plumbing for a Pentair 25W UV. I believe the best approach here is to install a ball valve (Cepex) both before AND after the UV, both to control the flow as well as to be able to fully isolate the UV from water for maintenance purposes. Is this correct?

I also have a flow meter I want to install. Does it matter at all whether I install this on the inlet or outlet side?

thank you in advance

 

[KrisReef]

If you run the UV on it's own return, you only need one (supply) valve to control flow. IF you put a second valve in up hill of a union connection you can drain the UV/return before you disconnect. HOpe that makes sense. I gotta go to the dentist now.

 

[rsumner]

I’m in the process of mapping out the plumbing for a Pentair 25W UV. I believe the best approach here is to install a ball valve (Cepex) both before AND after the UV, both to control the flow as well as to be able to fully isolate the UV from water for maintenance purposes. Is this correct?

I also have a flow meter I want to install. Does it matter at all whether I install this on the inlet or outlet side?

thank you in advance

If you don't have a separate return path for the UV and you feel like you will need to have it shutdown for extended periods, you may want to install a bypass loop. A bypass loop has 3 valves: one on the inlet of the UV, one on the exit of the uv, and one in the middle. I have a single return path on my small 5ft tank, so I have a bypass loop installed and I I've never used it. Even when I need to clean the quartz sleeve, it only takes about 15 minutes, so I shutdown my return pump and pop open the UV. When I'm in normal operating mode, 100% of my return goes through my UV, so I didn't need to use a ball valve to adjust flow (DC controllable return pump).

As for the flow meter, it's more important to make sure that it has straight pipe runs before and after the sensor that equal to 5x the diameter of the pipe. So, for a 1" sensor, you should have 5" of straight pipe before and after the sensor before you start to do any bends. This will help you yield the most accurate flow calculations out of the flow sensor. On my new build, I'm planning for 30" of straight pipe for my 2" flow sensors before dealing with any change to direction or pipe dimension. My sensors will be installed before the UV.

 

[pianosdr]

Great info thank you both

 

[Sean Clark]

I have mine on a separate DC pump and on its own loop. Setup this way there is no effect on return flow balance and you can adjust the speed higher or lower depending on what you are trying to go after.

 

[pianosdr]

I have mine on a separate DC pump and on its own loop. Setup this way there is no effect on return flow balance and you can adjust the speed higher or lower depending on what you are trying to go after.

Right, though the reason I was thinking I should put a valve on each side of the UV is specifically for maintenance purposes -
i.e., whenever I might need to disconnect the UV from the water supply, understanding that only one valve is required for simply controlling flow rate.

do you find yourself ever having to isolate the entire UV unit from the water supply for any reason?

 

[Sean Clark]

Right, though the reason I was thinking I should put a valve on each side of the UV is specifically for maintenance purposes -
i.e., whenever I might need to disconnect the UV from the water supply, understanding that only one valve is required for simply controlling flow rate.

do you find yourself ever having to isolate the entire UV unit from the water supply for any reason?

I change the bulb regularly which does not require a flow shutdown. If you needed to pull the quartz sleve for cleaning then I would just shutdown the DC pump and drain what was left in the loop. This might be a half gallon at most.

I have found that if you do not run aggressive additives and high end levels for Ca, Mg, and ALK that your sleeve will stay nice and clean for years due to the lack of precipitation that will collect on your equipment.

 

[rsumner]

Right, though the reason I was thinking I should put a valve on each side of the UV is specifically for maintenance purposes -
i.e., whenever I might need to disconnect the UV from the water supply, understanding that only one valve is required for simply controlling flow rate.

do you find yourself ever having to isolate the entire UV unit from the water supply for any reason?

Are you planning on having a separate pump dedicated to the UV? This would either be a secondary return or a closed loop.

See this thread back from 2018 for details on the bypass loop. Having the bypass in place gives you a few advantages:

• when using the same pump for your UV that you use for the return, the bypass will allow you to tune how much of the return water will be processed by the UV. The bypass is critical here because you will close the exit valve on the UV and the inline valve (the one that is between the inlet and exit of the UV) creating a balance between the loop and back pressure.
• completely bypassing the UV if you want to completely shut it down or remove it for extended periods of time and cannot have your return pump shutdown for that long

As I mentioned in my earlier reply: I don't find much value in having a bypass loop if you have a dedicated pump for the UV or you have multiple return pumps. One major exception to this statement: if you remove the UV, will you have a flood without the valves?

I hope to have a detailed post on my build thread regarding my plumbing setup soon if you want to check that out. One important thing that I'm installing in my new plumbing setup is way to drain the UV easily in times of maintenance.

 

[ShepherdReefer]

We have two tanks. Both tanks use a UV, and both tanks have two pumps. One pump for the DT and one pump for the UV, and only using one valve to control the flow located at the UV inlet. No issues with the setup or performance.

 

[pianosdr]

All excellent info thank you everyone. I think I got what I need here.

 

[jmatt]

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