LEGACY R0453701 BYPASS ASSEMBLY, is this an important part?

poolH2O

Member
May 8, 2020
14
New Jersey
Hello,
I got Jandy LRZ gas heater and I noticed water gushing out of Bypass Assembly so I opened it and found there is just plastic stick inside which I aligned it back to the opening and water leak stopped. Now I am checking parts diagram online and it seems I am missing a spring and some kind of conical disk. Google image "LEGACY R0453701 BYPASS ASSEMBLY" What is the purpose of this part, Should I worry about replacing it right away? My pool filtration is working great, water is crystal clear. I haven't used my Gas heater this season, I suspend my gas meter every winter so I still need to request my gas company to reactivate my account and turn on the gas. Though I did notice rusty water coming out when I de-winterized my pool this season which now makes me think that it could be rusted missing spring.
Any thoughts?
Thanks in advance!
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
25,659
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The heater will not work properly with a broken bypass. You will not have the correct water flow through the heater.

See section 7.8 on page 29 in https://www.jandy.com/-/media/zodiac/global/downloads/h/h0299500.pdf

The Legacy pool and spa heaters have an internal
bypass which accommodates a wide range of water
flow. The bypass is easily adjustable to change the
temperature rise for optimum performance and length of
heater life. The bypass assures constant heat exchanger
flow even though flow through the filter system will
vary depending on how dirty the filter is.
For most installations, an external bypass valve
is not needed in the heater water piping. This is due to
the large size of the heater's internal bypass valve. If
the pump flow rate is known to exceed 125 gpm (7.9
lps), an external bypass may be needed to assure proper
heater operation.
Water flow should be confirmed upon start-up of
the heater and in most servicing situations. If the flow
is not normal, corrections must be made to the pool
system. Flow is evaluated by determining the water
temperature rise through the heat exchanger.
 

poolH2O

Member
May 8, 2020
14
New Jersey
Thanks for the reply. I did read this section in the manual before posting to find out part number and it's purpose. Today I put request to the utility company to turn on my gas meter as well, apparently 2 week wait time. Once the gas is turned ON I'll test to find out how badly I need this part in the heater. Also, it seems I will need the temperature rise measurement kit if I have to adjust the bypass assembly. Well...either I should hire someone to do this to avoid temperature rise measurement kit or perhaps start calling tomorrow local pool stores to find parts and DIY. It would be nice to hear from someone who has gone through the same issue/repair. Let's see if others have any thoughts.
 

poolH2O

Member
May 8, 2020
14
New Jersey
The heater will not work properly with a broken bypass. You will not have the correct water flow through the heater.

See section 7.8 on page 29 in https://www.jandy.com/-/media/zodiac/global/downloads/h/h0299500.pdf

The Legacy pool and spa heaters have an internal
bypass which accommodates a wide range of water
flow. The bypass is easily adjustable to change the
temperature rise for optimum performance and length of
heater life. The bypass assures constant heat exchanger
flow even though flow through the filter system will
vary depending on how dirty the filter is.
For most installations, an external bypass valve
is not needed in the heater water piping. This is due to
the large size of the heater's internal bypass valve. If
the pump flow rate is known to exceed 125 gpm (7.9
lps), an external bypass may be needed to assure proper
heater operation.
Water flow should be confirmed upon start-up of
the heater and in most servicing situations. If the flow
is not normal, corrections must be made to the pool
system. Flow is evaluated by determining the water
temperature rise through the heat exchanger.

So I replaced the bypass assembly, now waiting for the utility company to turn ON gas and temperature rise measurement kit should arrive over the weekend also. I'll find out if it was a necessary part or not for my system. Though the outflow of water must be so intense that I doubt the tension provided by such a small spring is of any use to regulate the flow. I should be able to find out by late next week.
 
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