Plumbing UV sterilizer back to return

RaymondsWorlddd · Jun 29, 2020

Total plumbing noob here! I’m planning on installing a UV sterilizer on my Reefer 350. I’ve read that having the water return to the return pump chamber would just recirculate some water. So I thought about plumbing the water from the UV sterilizer back to the return line to prevent recirculating. Would this work or would there be problems with pressure?
Note: This isn’t the final set-up, just a quick rough draft to get the point across. Thank you!

Mastiffsrule · Jun 29, 2020

Hello,

Sending the uv return back to the pump will do what you describe. I am not familiar with RSR plumbing so I am not sure how you are referencing the plumbing. If you have 2 returns you could branch them off. 1 for the UV and one for straight return. If you have 1 return you could still plumb it returning the UV back into the return line, I would assume.

I bet there are lots of RSR folks tonight that have put in UV around tonight to help.

RaymondsWorlddd · Jun 29, 2020

Mastiffsrule said:
Hello,

Sending the uv return back to the pump will do what you describe. I am not familiar with RSR plumbing so I am not sure how you are referencing the plumbing. If you have 2 returns you could branch them off. 1 for the UV and one for straight return. If you have 1 return you could still plumb it returning the UV back into the return line, I would assume.

I bet there are lots of RSR folks tonight that have put in UV around tonight to help.

Oh sorry. So with the plumbing, the far right pipe is the drain. The middle is the emergency drain. So only the left is the return.
The way I want to set it up is from the return pump, have the water go through a manifold. The last port on the left on the manifold will be for the UV sterilizer. So the water will go from the return pump, through the manifold, to the UV sterilizer, and return to the return pipe via a WYE piece. When the water from the UV meets the water from the return pump, will there be a problem with pressure there making this not a feasible idea?

RaymondsWorlddd · Jun 29, 2020

I’ve seen several people running their water from the return pump all through the UV sterilizer back to the tank. That confuses me because isnt the flow through the UV sterilizer dependent on why you’re running the sterilizer? I want to keep a steady flow to the tank

RaymondsWorlddd · Jul 3, 2020

Any other opinions?

Billdogg · Jul 3, 2020

If I were to plumb a UV, I'd run it on it's own pump, from the drain area of the sump to the return area. Keep it simple, keep it out of sight.

DCR · Jul 3, 2020

There will not be a pressure problem where the two steams join together, but it is going to be hard to balance the flows through the sterilizer and the normal return without gate valves on each circuit and probably a flow meter on the UV.
Otherwise you will really be guessing how much flow you have through the UV.
You will have to have a valve on the return downstream of the manifold take-off, and upstream of where they rejoin together, to throttle down on the return flow and force water through the UV. Otherwise it is going to take the path of least resistance which is going to be the return and you will get very little flow through the UV.

DSEKULA · Jul 3, 2020

Your UV flow should be based on the UV unit usually this is slower or faster than general flow through the sump. My UV runs on a submersible pump in my return chamber and it flows back to the beginning of my sump. The flow in my sump is quite slow ensuring that water circulates through my UV unit 2-4x before returning to the dt. This is where your UV contact time vs concentration comes into play for different uses. You should read up on the manufacturers recommendations for flow and sterilizing effect for what ever your trying to accomplish.

RaymondsWorlddd · Jul 3, 2020

DCR said:
There will not be a pressure problem where the two steams join together, but it is going to be hard to balance the flows through the sterilizer and the normal return without gate valves on each circuit and probably a flow meter on the UV.
Otherwise you will really be guessing how much flow you have through the UV.
You will have to have a valve on the return downstream of the manifold take-off, and upstream of where they rejoin together, to throttle down on the return flow and force water through the UV. Otherwise it is going to take the path of least resistance which is going to be the return and you will get very little flow through the UV.

So should I put a gate valve between the two wye fittings? Without the valve there, the path of least resistance will be to return to the tank and not through the manifold? I was planning on putting gate valves on each output on the manifold, will that do anything to the water flow?

I was planning on hopefully fitting a flow meter for the sterilizer. If I can’t fit the flow meter on the intake side, I was thinking of putting it on the output side before the wye fitting.

DCR · Jul 4, 2020

RaymondsWorlddd said:
So should I put a gate valve between the two wye fittings? Without the valve there, the path of least resistance will be to return to the tank and not through the manifold? I was planning on putting gate valves on each output on the manifold, will that do anything to the water flow?

I was planning on hopefully fitting a flow meter for the sterilizer. If I can’t fit the flow meter on the intake side, I was thinking of putting it on the output side before the wye fitting.

Yes, I would put a gate valve between the wye fittings for the manifold take-off and the wye where the UV returns. With that and a flow meter you should be able to achieve what you are looking for. Keep the valves on the manifold to adjust flows to whatever other devices you connect to it. Flow meter can go on either the input or the output of the UV.

RaymondsWorlddd · Jul 4, 2020

DCR said:
Yes, I would put a gate valve between the wye fittings for the manifold take-off and the wye where the UV returns. With that and a flow meter you should be able to achieve what you are looking for. Keep the valves on the manifold to adjust flows to whatever other devices you connect to it. Flow meter can go on either the input or the output of the UV.

I’m not understanding why I should also put one on the output side of the UV, if there will be one on the intake side. The intake one will control the flow that is in the UV. What will the output one do?

WVNed · Jul 4, 2020

If you come off the return and then back to the return there will be no flow through the UV. You must have a pressure differential. A manifold can limit flow but it doesn't make pressure.

DCR · Jul 5, 2020

RaymondsWorlddd said:
I’m not understanding why I should also put one on the output side of the UV, if there will be one on the intake side. The intake one will control the flow that is in the UV. What will the output one do?

You don't need two gate valves on the UV circuit for throttling. I apologize for that misunderstanding. That is not what I was trying to say. You need one to throttle the UV, either on the inlet or the outlet side (you could probably just use the valve you have on the manifold, and one to throttle the return flow that is bypassing the UV. Ideally the one on the UV would be almost wide open and could be a ball valve, and you would control the UV flow by throttling the gate valve on the return circuit that bypasses the UV. You may still want additional valve on the outlet of the UV with unions to isolate the UV for periodic bulb replacement.

01xp · Jul 5, 2020

I have my uv plumbed from the return pump with a single gate valve (for flow restrictio) then the drain I made a little manifold thing and placed in my refugium to help tumble the chaeto.

RaymondsWorlddd · Jul 17, 2020

How does this look? The plan is to hopefully fit a ghl flow sensor at the top left on the manifold before the last gate valve.

mcshams · Jul 17, 2020

Do you plan to remove the entire UV unit when it is time to replace bulb and/or clean?

RaymondsWorlddd · Jul 17, 2020

mcshams said:
Do you plan to remove the entire UV unit when it is time to replace bulb and/or clean?

Yeah. It’s my first time with a uv but I’m thinking it’ll be easy to disconnect at the unions to remove?

mcshams · Jul 17, 2020

RaymondsWorlddd said:
Yeah. It’s my first time with a uv but I’m thinking it’ll be easy to disconnect at the unions to remove?

Give yourself enough room to lower the unit after the unions are unscrewed and you are likely ok. Practice once to see, because the bulb will likely be 12-14 months only. I like the plumbing btw.