Help understanding what valve is doing

dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#1
New user here finally taking control of my pool. I am working at understanding how everything is working in my system. I can't figure out why the valve in the picture below is there. It is between the outlet of my filter and the gas heater. Also right before the Swg and return to the pool. As you can see it is now partially closed. To me it seems that would be restricting flow back to the pool. Help please.
 

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JamesW

TFP Expert
Mar 2, 2011
13,067
#3
Looks like it's a bypass to control how much water goes through the heater. You don't want too much or too little flow through the heater.
 

bdavis466

TFP Expert
Platinum Supporter
In The Industry
Aug 4, 2014
4,344
San Clemente, CA
#5
There would be less resistance in the path of the bypass than what would be encountered through the heater. It is there to reduce the flow through the heater since some older models were susceptible to damage if they encountered high flows. The back pressure from the heater basically gets dumped to the bypass.
 

JamesW

TFP Expert
Mar 2, 2011
13,067
#6
If the valve is fully open, most of the water will bypass the heater. If the valve is fully closed, all of the water will go through the heater. If the valve is partially open, a portion of the flow will go through the heater.
 
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dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#7
If the valve is fully open, most of the water will bypass the heater. If the valve is fully closed, all of the water will go through the heater. If the valve is partially open, a portion of the flow will go through the heater.
ok ,so dumb me, that explanation finally makes sense to me.
 
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dooger54

Well-known member
Apr 21, 2017
81
Tucson AZ
#11
It's summer here in Tucson, pool temp up to 88 already. I have my heater turned off, gas valve is off, any reason why I can't move this valve so no water runs through the heater? Seems like there is no reason for water to be circulating through the heater now.