Hot Water Intermittently Cool

[BobD777]

We've been having our hot water intermittently get cool when taking showers. It can last anywhere from 30 seconds to a few minutes. It may have started around the time our geothermal heating/cooling was installed in 2017. Maybe.

In addition to the heating/cooling, I have desuperheaters coming from two of my six geothermal zones. The lines from the desuperheaters to the hot water system feed directly into the hot water outlet from the hot water tank. (The lines are the ones coming in on the right side of the first picture below.)

The geothermal units are about 10 feet from the hot water line. My understanding is that in the summer, when in AC mode, the desuperheaters pump out hot water. But in the winter they do not. There is a pump in the geothermal unit that circulates the water from the desuperheaters. It's a Taco Cartridge Circulator 006-BC8Y-1. (See second picture below.)

MY FIRST QUESTION IS: Could that cool water be coming from the lines that connect the desuperheaters to our hot water supply? And if so, could that pump allow water to circulate even when in heating mode? If so, then I guess the same thing could happen in the summer, even when the geothermal AC units are not putting out hot water. That would explain this being a year-round issue.

MY SECOND QUESTION IS: If this seems likely, any idea how this might be fixed? There is a valve right by the hot water line (see the 2nd pic), where the geothermal lines connect. I can turn that off, but obviously would not want to do that when the pump could possibly kick in.

Thanks for any insights here!

 

[Fitter30]

Normally with a desuperheater cold water enters it and the hot water enters where the drain valve is installed in the hw tank. Some use two tanks desuperheater feeds just the first tank (buffer)for preheating, from the hot outlet feeds the cold in the second tank (water heater). In heat mode when not running in house heating mode unit should run for hot water.
https://www.geoexchange.org/forum/attachments/geo_drawing-png.56/

 

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[BobD777]

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Normally with a desuperheater cold water enters it and the hot water enters where the drain valve is installed in the hw tank. Some use two tanks desuperheater feeds just the first tank (buffer)for preheating, from the hot outlet feeds the cold in the second tank (water heater). In heat mode when not running in house heating mode unit should run for hot water.

Hey Fitter- I checked the manual for my geo system, and like you said, the desuperheater lines are supposed to connect directly to the drain valve on the HWH (as in the manual below). My installer confirmed that it was done incorrectly.

I've been testing and I think this is the source of the cool water in our showers. Only took us 3 years to figure that one out.

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