Positive seal check valve

moore887

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Aug 14, 2018
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CAPE CORAL
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Good morning,

I took a photo of this device attached to my friend's pool heater as I hadn't seen one before. This is a new build and a very high end one at that. After some research I have found that this is some sort of check valve which I presume is designed to stop high levels of concentrated chlorine from the salt cell from going back into the heater when the pump basket lid is removed. There seems to be a bit of debate whether this is needed or not as I thought titanium core heat pumps were resistant to corrosion.

My question is, why is it plumbed in this way across the inlet and outlet of the heater and not inline with the outlet?
 

Jimrahbe

Mod Squad
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Jul 7, 2014
15,757
Bedford, TX
Dave,

My guess is it is a heater by-pass that opens when the flow gets too high for the heater...

A salt system has zero "high levels of concentrated chlorine" it is impossible for it to leak back into the heater.. And, it is not so much the chlorine but the very low pH that causes damage to a heater.. You need a check valve when you use a tablet feeder because when the pump stops, the tablets and water around them, which are very acidic, can leak back into the heater..

Thanks,

Jim R.
 
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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
12,845
Northern NJ
Post a wider view for context of where that valve is being used.

I agree with Jim it looks like the valve is being used to bypass the heater and limit the water flow through the heater core.
 

JamesW

TFP Expert
Mar 2, 2011
17,335
It's a 5 psi bypass check valve. It opens at 5 psi to help limit the amount of water flow going through the heater.

Heat pumps are usually not well suited for high flow rates. The tubing inside tends to be relatively small diameter, which creates high head loss at high flow rates.

Many heat pumps have a check valve bypass inside.

If you get the model number of the heat pump, you can check the parts diagram for an internal bypass.

In any case, I think that it's a good idea to install a check valve bypass on any heat pump installation where the flow will exceed about 40 gpm.
 

moore887

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Aug 14, 2018
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CAPE CORAL
Hi James,

Great information there. On my own heater, there is a Jandy check valve and a manual bypass. I like the idea of the one of the photo that opens by itself. I guess it's needed in that particular pool as there's two bubblers on the shelf as well as three spills on the back wall of the pool.

On a new build pool which I have just got the contract to clean, the owner went to recreational warehouse and bought an Aquacal heater but there is no bypass or checkvalve so there's someone coming on Friday to fit that. The end result (we hope) that there will be enough head to properly power the two deck jets. One draws a ton of pressure which weakens the second one so the first one has to be barely open while the second one is all the way open. I think when the check valve is installed, a flo vis flow meter could be a nice retrofit.
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JamesW

TFP Expert
Mar 2, 2011
17,335
AquaCal STK0135 Heater bypass External.

Install a bypass check valve (AquaCal P.N.: 2556, or equal to Del Industries P.N.: CO-0103) whenever water flow rate may exceed 70-GPM.
 
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