My heater-bypass that we installed

[jesse-99]

So we added a heater bypass this last Spring before opening. It's just 2 manual Jandy valves that I close/open basically when I was to enable/disable the bypass. I thought it'd be nice to NOT send water through the heater if I'm not using it for long periods of time (especially as one of my two SWCG's is before the heater, which I know isn't ideal, but ugh, replumbing that one is going to be such a PITA). So, I have had the heater bypass enabled occasionally, but recently started wondering if it's a problem bypassing the heater and having that stagnant water sitting IN the heater?

What's the standard operating procedure when using a heater bypass? Should I also be draining the water in the heater? Or just leaving it there, or doesn't it really matter if my water chemistry is on spec? Thoughts one way or the other?

 

[PoolGate]

You should crack open flow to the heater a bit so that the water does not get stagnant. Jandy sells a bypass for some of their heaters and that is what they do.

 

[jesse-99]

Playing devil's advocate... What's the harm in the water sitting there stagnant if the chemicals are good? Thanks.!

 

[PoolGate]

You could - but test that theory first and see just how stagnant it gets. I mean if you are flushing it weekly it is probably ok. If it was me, I would just set my bypass to always allow a little water to flow through the heater. It doesn't hurt the heater with a properly balanced pool.

 

[jesse-99]

Ah yeah I am doing that, if I have the heater bypassed for more than a week, I do open the valves for an hour, or sometimes for an entire day, and then after that hour or entire day, I re-enable the bypass. So the water hasn't been sitting in the heater for more than a week basically, even if I'm bypassing the heater for 2-3 weeks at a time.

 

[flynwill]

The main reason for adding a heater by pass is to reduce the restriction when the heater is not in use, thereby reducing the amount of work the pump has to do to move a given volume of water.
Given that as the reason there is no particular reason to cutoff the flow through the heater, just open a pathway around it, (Which is what the Jandy bypass accessory does.)

 

[1poolman1]

Playing devil's advocate... What's the harm in the water sitting there stagnant if the chemicals are good? Thanks.!

Its not so much that they are stagnant as that the water will evaporate and leave deposits inside the heat exchanger. Every heater school I attended encouraged allowing just a small amount through the heater if a bypass was installed.