Help me with heater bypass

Billrector

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Nov 3, 2013
134
Fort Worth, TX
I received my new Hayward heater yesterday and had the gas hooked up today by our gas company. Now I am working on the plumbing and I've decided to install a heater bypass for those times the heater is leaking or my chemicals are not ideal for whatever reason. Desperate, I went to Leslie's and purchased a generic 3-way valve. I also have a Pentair check valve. I plan to install the plumbing following the schematic that is attached. I have several questions regarding the 3-way valve. First, can this valve be turned anyway I want to turn it. One port is labeled "input".....but does that matter? Looking at the schematic, it would appear that I should be able to set the valve where it can go straight through the valve (180 degrees) and cut off the 90 degree port. This does not seem possible. On my valve, there is an inlet port and by turning the handle, I can get 1) both of the two other ports open, 2) the left 90% port open, or the right 90% port. So, on my valve, if I want to follow the schematic I would have to make one of the other ports the "inlet" and I would have to have both the 180 degree and 90 degree ports open. My concern is that setup this way, water will go to both the heater and through the bypass. What am I missing? I had assumed that I could configure the valve to close off the 90% and just open the 180 degree port? Hope this makes sense!
 

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mas985

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First, can this valve be turned anyway I want to turn it.
Depends on the valve you use but most have stops so they prevent the inlet labeled port (center port) from being closed. However, you can remove the lid and rotate it 90 degrees counter clockwise so the true inlet port as per your diagram is the only port that cannot be closed. This way you can close the heater, close the bypass or leave both open (normal operation).
 

Billrector

Well-known member
Nov 3, 2013
134
Fort Worth, TX
Depends on the valve you use but most have stops so they prevent the inlet labeled port (center port) from being closed. However, you can remove the lid and rotate it 90 degrees counter clockwise so the true inlet port as per your diagram is the only port that cannot be closed. This way you can close the heater, close the bypass or leave both open (normal operation).
Can you please elaborate on the "normal operation". Why would you want both the bypass and the heater open?
 

jseyfert3

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If I’m understanding this diagram correctly the “off” position should open up the 180° path and close the “inlet” side, allowing you to plumb it like you wanted.


Interesting how those work. Simple, and clever. I don’t have any of them myself yet, my experience to this point was your basic three-way ball valve which just has a 90° hole through the ball, so it’s only either/or, it doesn’t allow partial splitting of the water flow between two outlets like a pool 3-way valve.
 

mas985

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Can you please elaborate on the "normal operation". Why would you want both the bypass and the heater open?
I would only fully close the heater for maintenance purposes. You want some water to flow through it all the time. As for the bypass, that would only need to be closed when using the heater. Otherwise, you will get a maximum flow rate with the heater and bypass fully open.
 

Billrector

Well-known member
Nov 3, 2013
134
Fort Worth, TX
Is there an issue with just connecting the filter output to the inlet of the valve?
If I connect the inlet to the filter output, the water will need to make a 90 degree turn.....there is no way for it to go straight through. I'm just concerned that all the 90 degree turns in my plumbing will cause additional resistance. I would think a straight through (180 degree) flow from the filter to the heater would be better.
 

proavia

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If I connect the inlet to the filter output, the water will need to make a 90 degree turn.....there is no way for it to go straight through. I'm just concerned that all the 90 degree turns in my plumbing will cause additional resistance. I would think a straight through (180 degree) flow from the filter to the heater would be better.
You won't see a measurable difference. Just plumb the easiest way possible and then be sure 'INLET' is on the side closest to the pump/filter. Easy to change by removing the screws, lifting the lid and rotating it to align 'INLET' to the correct location.
 

Turbo1Ton

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I would only fully close the heater for maintenance purposes. You want some water to flow through it all the time. As for the bypass, that would only need to be closed when using the heater. Otherwise, you will get a maximum flow rate with the heater and bypass fully open.
I don't want to hijack this thread, but I am curious about this. @mas985 - Can you elaborate a little bit on why there should be a slipstream of water always flowing through the heater? I have my heater bypass programmed to fully shut the heater off. I schedule my spa to turn on once a week to exercise the heater and flush the stagnant water from the exchanger.

In the Pentair bypass kit instructions, it states to set the valve so it allows a small amount of flow through the exchanger at all times. After seeing your comment, I wonder if I should change my configuration.

Mods - if this needs to be moved, no problem but I thought it would still be relevant to the OP's subject.

--Jeff
 

ps0303

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I don't want to hijack this thread, but I am curious about this. @mas985 - Can you elaborate a little bit on why there should be a slipstream of water always flowing through the heater? I have my heater bypass programmed to fully shut the heater off. I schedule my spa to turn on once a week to exercise the heater and flush the stagnant water from the exchanger.

In the Pentair bypass kit instructions, it states to set the valve so it allows a small amount of flow through the exchanger at all times. After seeing your comment, I wonder if I should change my configuration.

Mods - if this needs to be moved, no problem but I thought it would still be relevant to the OP's subject.

--Jeff
If you leave stagnate water in the unit it could cause the heater exchanger to get destroyed. If the water became acidic, bye bye heat exchanger.
 

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Turbo1Ton

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If you leave stagnate water in the unit it could cause the heater exchanger to get destroyed. If the water became acidic, bye bye heat exchanger.

Right I understand that. Which is why mine is programmed to open and run at least once a week. Does the water become acidic just sitting there? Should there be a continuous flow of water through there or is a once a week flush enough? And during the winter I force the valve so that all flow goes through the heater, for freeze protection.

--Jeff
 

mas985

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There is also and advantage to head loss by leaving both fully open so you can run at lower RPM for the same flow rate. No good reason to close off the heater except for maintenance reasons.
 
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ps0303

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Right I understand that. Which is why mine is programmed to open and run at least once a week. Does the water become acidic just sitting there? Should there be a continuous flow of water through there or is a once a week flush enough? And during the winter I force the valve so that all flow goes through the heater, for freeze protection.

--Jeff
Yes running water thru it once a week should be ok. Its just leaving it for a long period of time is what could cause an issue. I usually tell my customers to maybe run water thru it as well as run the heater at least a few times per month.
 
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