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Thread: Heater Bypass Data

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    Heater Bypass Data

    There have been several posts questioning whether or not to install a heater bypass in the pool plumbing to divert water prior to entering the heater. I conducted a little study on my own pool equipment to see if there were any gains from using a heater bypass when there was no need to heat the pool.

    Bypass Open

    RPM___________Watts __________GPM
    3250...........................2666......................... .....117
    3300...........................2794......................... .....119
    1250...........................208.......................... ......40
    1200...........................192.......................... ......38

    Bypass Closed

    RPM_________Watts __________GPM
    3250...........................2545......................... .....107
    3300...........................2665......................... .....109
    1250............................154......................... ......13
    1200............................148......................... ......12


    From what I've gathered, for those with single speed pumps that operate at higher RPM's, there is little to be gained from a heater bypass since I only saw a difference of 10 GPM. For those that have variable speed pumps and run them at lower speeds, then there is a definite gain from using a bypass. This of course, assumes that the pump time is reduced to compensate for the higher GPM since a higher flow rate at the same RPM draws more watts.

    IMG_20160104_154831_397.jpg

    The bypass valve is in the middle of the top right corner (in the bypass open position). All plumbing to the heater is 2.5" with a 2.5" Pentair FullFlo check valve (spring removed). The remainder of the plumbing is 3".

    This information was gathered from the use of Mark's (Mas985) spreadsheet. It is possible that there are discrepancies at the lower RPMs/Watts, but there is a very notable difference in water velocity from the return jets at the lower RPMs with the bypass open.

    To avoid having stagnant water sitting in the heater for long periods of time, I programmed a schedule to allow water to circulate through the heater 15 mins a couple times per week.

    I hope this clears up any confusion as to the benefits of a heater bypass.
    -Brian-
    33K Pool/Spa, Pentair Equipment
    POOL BUILD
    Davis Custom Construction - Home Page

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    JoyfulNoise's Avatar
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    Re: Heater Bypass Data

    Great post, Brian!!

    I do not have a bypass on my heater but it's nice to know it does show a difference.


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Heater Bypass Data

    Why is there more flow with the bypass closed?

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    Re: Heater Bypass Data

    I saw the error of my ways...its fixed now
    -Brian-
    33K Pool/Spa, Pentair Equipment
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    Davis Custom Construction - Home Page

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    Re: Heater Bypass Data

    Awesome info Brian!
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
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    Re: Heater Bypass Data

    My heater creates a Delta P increase for sure. I don't know the specifics, but I can check. It's significant I do know that. I lose a little flow, but I can't remember a number. I can check though...

    I know it's not a need, but I wanted a bypass, and I'm very glad I put one in. This reminds me of another question regarding heaters though, and I'll post it up soon.
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    Re: Heater Bypass Data

    The pool equipment manufacturers all seem very focused on reducing energy expenses, but no one has made much progress in plumbing efficiency (Jandy's Versaplumb is perhaps the closest but still leaves much desired). Variable speed pumps have significantly cut the costs but only by reducing the power required.

    Its been said multiple times that the heaters are not very restrictive, but with the numbers I saw, it seems that it is much the opposite. My filter pressure rises by 5-7 PSI with the bypass closed. It was only slightly higher before I removed the spring from the check valve, so that wasn't much of a factor. Even more can be said of the multi-port backwash valves (including Pentair's high flow version) being extremely restrictive; up to 10 PSI loss from them alone!

    Jandy and Pentair make three port and check valves to accept 2.5" and 3" pipe, but the heaters, filters and SWGs all max out at 2" (the SWGs seem especially restrictive). There are only a few residential pumps that accept larger piping. While 2" pipe is certainly fine, if we are truly looking for efficiency, then why not accommodate larger piping, sweep elbows, and high flow heaters and filters. Higher efficiency leads to shorter run times and ultimately lower expenses.

    Its another topic, but I also wish the SWGs were around 4x the size that they are now. Its crazy to have to run the thing 12+ hours a day to produce the chlorine needed (well beyond filtration requirements).
    -Brian-
    33K Pool/Spa, Pentair Equipment
    POOL BUILD
    Davis Custom Construction - Home Page

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    Re: Heater Bypass Data

    I use my heater bypass valve to control the water temperature leaving the heater. My raypak manual says to feel both pipes, the exit pipe should feel warmer than the intake pipe (but not hot). With my old single speed 1HP pump, I would open the valve about half way. With the valve compleatly closed (all the water circulated through heater) the water did not seem to warm up. Also, with the valve full open the exit pipe would feel kinda hot. I tried to get temperature readings at the return eyeball but not very reliable mixing with colder pool water. I'm not sure how I will adjust the valve with my new variable speed pump until spring. I wish there was a beter way to determine what the best position to keep it at, like with thermocouples in the PVC pipes near the heater?
    15x54 swim & play vinyl metal wall AG
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    Heater Bypass Data

    Shouldn't the internal bypass and thermostat valves be the ones to optimize the mix and flow? I thought people only installed external bypasses for on/off purposes (maintenance, chemical treatments, etc)?


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Heater Bypass Data

    Older heaters didn't have an internal bypass and required the installer to put an external one in place. Most newer heaters have an internal one but exterior ones are still installed due to old habit/lack of knowledge of newer systems. There is a pool builder in my area that I can always tell that they were responsible for the build by the way that they plumb a heater bypass (more of a flow diverter than an actual bypass since there is no way to open or close it) and the configuration of the spa make up valve.
    -Brian-
    33K Pool/Spa, Pentair Equipment
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    Davis Custom Construction - Home Page

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    Re: Heater Bypass Data

    My heater is only a bit over 3 years old. I have a sloppy setup but the valve is between the intake and return pipes like my manual suggest.
    Rheem 130 Pool and Spa Gas Heater

    From my experience it makes a big difference in temperature how much water flows through the heater. I just don't know what is the most efficient setting. It is too cold now but I now am re plumbing. Sorry If I'm hijacked this thread.
    15x54 swim & play vinyl metal wall AG
    Hayward S210T sand filter 1.5 HP Pentair Superflo vs
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    Re: Heater Bypass Data

    image.jpgIt is a ball valve between the two pipes, but maybe I will need it with my vs pump? Thanks
    15x54 swim & play vinyl metal wall AG
    Hayward S210T sand filter 1.5 HP Pentair Superflo vs
    Rheem raypak 130,000 BTU mv ng
    Jacuzzi 345 whirlpool bath
    TF-100 test kit, HM digital com100 Wanda the Whale

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    Re: Heater Bypass Data

    Being that its already installed, why remove it?

    If you are going to replumb your set up, I would include another bypass. Its a little bit of pipe and one valve, no big deal...and its a whole lot more work to do it after the fact.
    -Brian-
    33K Pool/Spa, Pentair Equipment
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    Davis Custom Construction - Home Page

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    Re: Heater Bypass Data

    Thanks. I just got some unions and Jandy shut offs. I miss counted and need a couple more unions.
    15x54 swim & play vinyl metal wall AG
    Hayward S210T sand filter 1.5 HP Pentair Superflo vs
    Rheem raypak 130,000 BTU mv ng
    Jacuzzi 345 whirlpool bath
    TF-100 test kit, HM digital com100 Wanda the Whale

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    Re: Heater Bypass Data

    No plumbing job would be complete without at least two more trips for fittings or supplies once you think you have everything.
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