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Thread: Plumbing Question - Heater Bypass

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    Plumbing Question - Heater Bypass

    Hi Guys, I was re-plumbing my heater. As I was curious , I shut off the valve labeled Heater Bypass. I turned on the pump and water still flowed through the plumbing at the heater. I got a gusher right in the chest.

    Am I missing something. What is the valve supposed to do...

    Thanks


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    mas985's Avatar
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    Re: Plumbing Question - Heater Bypass

    The bypass may not prevent water going through the heater but just bypass some around it. But where did the gusher occur? That should not happen.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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    Re: Plumbing Question - Heater Bypass

    Hi Mark, while I had the "out" plumbing off the heater, I ran the pump with the heater bypass valve closed and water still gushed out of the "out" pipe at heater. Also, I don't understand, at the filter, there is a union so water coming out of the filter travels in two directions.

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    mas985's Avatar
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    Re: Plumbing Question - Heater Bypass

    Quote Originally Posted by garywi View Post
    Hi Mark, while I had the "out" plumbing off the heater, I ran the pump with the heater bypass valve closed and water still gushed out of the "out" pipe at heater.
    Ok, that makes sense. I think it is operating as intended. It is not for heater isolation but simply to reduce head loss.

    Quote Originally Posted by garywi View Post
    Also, I don't understand, at the filter, there is a union so water coming out of the filter travels in two directions.
    Again, that is for the heater bypass. One direction goes into the heater and the other ties in past the heater.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Plumbing Question - Heater Bypass

    Thanks Mark! Ok, still, what is the purpose of this valve, heater bypass.

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    Re: Plumbing Question - Heater Bypass

    I ask because I am still learning about flow and hydraulics. My heater is currently hitting the high limit temp and shutting off. Wondering if this valve setting has anything to do with it...

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    Re: Plumbing Question - Heater Bypass

    Solved heater high limit error. Turning heater bypass valve half way closed, which I assume directly more water through the heater. I fixed my flow problem. Yea!

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    Re: Plumbing Question - Heater Bypass

    Quote Originally Posted by garywi View Post
    Thanks Mark! Ok, still, what is the purpose of this valve, heater bypass.
    Some heaters require a bypass if flow rates are too high because they don't have a built in bypass. But most modern heaters have built-in bypasses.

    If the filter pressure does not change much, you might just leave that valve closed. Too little water through the heater could stress the heat exchanger over time. But check the heater manual to see if it requires a bypass.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Plumbing Question - Heater Bypass

    Thanks Mark. I checked and my Laars has an internal bypass, but I never understood the external manual bypass valve until today. I am thrilled to understand now, why my heater was overheating and thrilled I don't need any repairs. I wish the manual had this simple step in the troubleshooting guide.

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    Re: Plumbing Question - Heater Bypass

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