New Construction Started - Willis, TX (north of Houston)

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Duffatola said:
Issue averted. PB says they only use Jandy CV's!
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Ok, the Pentair check valves look acceptable as well.

The Mastertemp bypass check valve is optional and not necessary.

If you do want to do a bypass check valve, check with Pentair for the recommended check valve spring strength.

I suspect that they will recommend the 12 lb spring since it is what they use on the Mastertemp, but it seems too strong to do any good in my opinion.
 
For example, a 3.5 lb spring on an UltraTemp heater would allow 35 GPM and a 5 lb spring would allow about 41 GPM.

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I can't find a head loss chart for the Mastertemp, but if it is similar to the Jandy JXi, then about 2 psi would allow 40 GPM.

A 3.5 lb. spring should be enough flow for a Mastertemp with a safety margin.

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The Jandy JXi is a similar design to the Mastertemp.

If the head loss is the same, then the head loss created just by the heater will be about 20 feet at 120 GPM, which the pump can do since it can do 120 GPM at about 78 feet of head (total system head including all suction and all return side head loss including all equipment).

If you added the check valve bypass, the heater head loss would drop to about 8 feet of head, so about 12 feet savings, which is not a lot, but it does help reduce wear on the heater at high flow rates.

The CCP520 creates about 20 feet of head as well for a total of 40 feet for the filter and heater at 120 GPM.

That leaves about 38 feet of head for the rest of the system if you want 120 gpm for the spa jets.

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JamesW said:
When the heater is on, part of the water flow goes through the bypass and part goes through the heat exchanger, which has a thermal regulator at the exit.

So, you're trying to push 120 GPM through a relatively small internal bypass, which is a spring bypass, and a small thermal regulator.

The extra bypass relieves the heater's internal bypass from excessive flow.
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JamesW said:
You don't have to do a spring bypass on the Mastertemp as the flow will not exceed 120 GPM as specified in the manual.

However, in my opinion, putting anything over 60 GPM is unnecessary and it can create extra wear on the heater components.

Below is the MasterTemp internal bypass that all of the water need to flow through when the heater is not on.

When the heater is on, part of the water flow goes through the bypass and part goes through the heat exchanger, which has a thermal regulator at the exit.

So, you're trying to push 120 GPM through a relatively small internal bypass, which is a spring bypass, and a small thermal regulator.

The extra bypass relieves the heater's internal bypass from excessive flow.
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In other words, by installing the CV bypass, there will be less stress & wear and tear on the heater? Is this the correct placement of the CV and pipe routing? I assume the valve is a 2.5" 7307?

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Duffatola said:
In other words, by installing the CV bypass, there will be less stress & wear and tear on the heater?
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Correct. I also recommend a flow switch at position F.
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I also highly recommend that you install a flow switch as shown in this thread.

I got lucky...now I need help adding a flow switch

Evening, TFP World! We have an autocover that stays closed except when the pool is in use or needs to be left open to breath. Today, it was a beautiful day, so I left it open most of the day. I did not appreciate how much Crud was coming off the trees, and allowed both skimmer baskets to get...
www.troublefreepool.com www.troublefreepool.com
 
6/17 - Day 15
Gunite Day 3 (complete) - 7:00 a.m. - 10:30 a.m.
Soakin' that sucker for 10 days.
 

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wgipe said:
Okay....so because I'm paranoid and don't want to risk my heater starving for water again...and because I like to tinker with stuff....I did some research on the proper flow switch and thought I'd document it here since I see it mentioned in several other threads, but haven't seen a project documented here where the pressure sensor was swapped out for a flow switch. Below is the email I received from Harwil. I ordered the switch today and will document the installation here so that future folks have something to refer to. I've also attached the flow switch data sheet for the recommended switch here.

======================================================================================
Hi Wes,

A flow switch that is commonly used for that application is our Q-8N series flow switch.
The part number I would recommend based on plumbing size and flow rate is Q-8N/2/2/A/VITON.
This flow switch is an adjustable flow switch with an ON set point at minimum is 44 gpm and can be adjusted up to 65 gpm in a 2” pipe.
Attached is a data sheet.

The current price for the flow switch is $148.76 each.
We do have a minimum order value of $150, so either 2 units would need to be ordered or we can round up to $150.

You are welcome to purchase direct from Harwil. For purchases we accept Visa, Mastercard, and American Express.
The shipper we use is UPS, if you have an account with UPS we can use that to ship with or just add the cost to the order total.

The email to send orders to is: [email protected]

If you have any questions just let me know.

Best Regards,
​
Kyle Acres
Engineering Technician
[email protected]
Ph: (805) 988-6800


Please know your ordering from us is tantamount to reading and accepting our Standard Terms & Conditions which can be found at the link below.

Harwil Standard Terms and Conditions


From: Wesley Gipe
Sent: Saturday, May 28, 2022 6:29 AM
To: Orders <[email protected]>
Subject: Which Flow Switch?

Hello,

I have a residential inground pool with a Pentair MasterTemp 4000BTU heater that I installed last year. These heaters have a pressure switch to sense flow, and for a number of reasons, I’d like to replace that with an inline flow switch. The heater manual shows 45GPM for minimum flow to operate. My plan is to place a threaded in the 2” PVC line to hold the flow switch and run the leads to the control board of the heater.

Based on that application, could you suggest and provide pricing for the flow switch that would be best for that application? Thanks!

Wes
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Check with @wgipe for the specifics on the flow switch.

Here is a different model.

Raypak Flow Switch Kit - 007142F - INYOPools.com

Flow Switch Kit - 007142F
www.inyopools.com www.inyopools.com
 
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JamesW said:
Hayward has a flow switch for their heaters, which is the one below.
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Thanks for the info. The Raypack and Hayward switches are $150-$200 costlier than the Harwil. I need to do more research to learn about the benefit of having a flow switch. I've read: "If water flow is interrupted, it will turn the heater off to ensure that it stays in optimal condition and doesn't damage any other surrounding equipment." Does the heater not have a built in mechanism to do this?
 
Duffatola said:
Does the heater not have a built in mechanism to do this?
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It has a pressure switch, which is not the same thing as a flow switch.

A pressure switch was ok for old single speed pumps and simple systems.

Today, the systems are too complicated to rely on a pressure switch.

You can get pressure with no flow.

Only a properly calibrated flow switch can ensure that the flow is above the heater’s minimum required flow rate.

Below, you can see Wgipe’s pressure switch that was disconnected and the flow switch was connected instead.

You can actually run the pressure switch in series with the flow switch so that you have both as safeties.

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Regarding the 3.5 lb. check valve bypass, I believe that it will work as described, however, on the Pentair Ultratemp (Heat Pump), they use a 12 lb. check valve bypass, which I think is incorrect, but maybe I am missing something.

I would recommend that you confirm with Pentair that a 3.5 lb. bypass would be correct for the MasterTemp before you use it.

I would also verify that the flow gets to 40 GPM, or higher, in the heater before the 3.5 lb check valve begins to bypass flow around the heater.

In any case, using the 3.5 lb check valve is at your discretion and risk.

The flow switch can help ensure that the flow is adequate.
 
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JamesW said:
Regarding the 3.5 lb. check valve bypass, I believe that it will work as described, however, on the Pentair Ultratemp (Heat Pump), they use a 12 lb. check valve bypass, which I think is incorrect, but maybe I am missing something.

I would recommend that you confirm with Pentair that a 3.5 lb. bypass would be correct for the MasterTemp before you use it.

I would also verify that the flow gets to 40 GPM, or higher, in the heater before the 3.5 lb check valve begins to bypass flow around the heater.

In any case, using the 3.5 lb check valve is at your discretion and risk.
Click to expand...
Understood, thanks.
 
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JamesW said:
The water feature pump should have its own set of main drains or an unblockable drain like a channel drain and a 4" suction.
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JamesW said:
Are you also going to have an infinity edge?

If yes, you need a separate suction for that as well at 4" line
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@JamesW I don't know whether it matters as it pertains to possibly using 3" piping in lieu of 4" but these are the lengths for the two drain lines:
Infinity Edge Drain - 75'
Water Feature Suction (secondary port on the main drain) - 50'

I will use 4" if necessary, but the PB feels 3" will be sufficient. When it all boils down, I will default to the calcs/science.
 
For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.

Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138............184 gpm
4.0"........238.............317 gpm

This is a best practice and it might be in your local code.

The Infinity edge and the water feature will be in excess of 138 GPM, which means that the pipe should be 4" as a best practice.
 
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For the infinity edge pump, the head loss at 200 GPM will be about 10 feet for 3" PVC pipe and the velocity will be about 9 feet per second.

The suction head loss also has to include the height of the pump above the basin water surface.

So, the suction head loss will probably be at least 15 feet.

If your code does not specify the maximum velocity, 3” will work.

In my opinion, 4” is better if you want to get near the full flow capability of the pump.

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JamesW said:
For the infinity edge pump, the head loss at 200 GPM will be about 10 feet for 3" PVC pipe and the velocity will be about 9 feet per second.

The suction head loss also has to include the height of the pump above the basin water surface.

So, the suction head loss will probably be at least 15 feet.

If your code does not specify the maximum velocity, 3” will work.

In my opinion, 4” is better if you want to get near the full flow capability of the pump.

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Understood, thanks. What about the water feature suction line?
 

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