All, I am a new geo operator and owner. I have been reading for hours on different setups of geo thermal desuper heater plumbing. I have a few diagrams and some questions and would really enjoy everyone's input. I have an engineering buddy I work with that has a strong opinion too. First, I am located in the Houston - College Station, TX area. I am on the far northwest side of Montgomery, TX about an 1:15 mintues northwest of Houston. Our climate is primarily a cooling with summer temps and humidity on the high sides. I do not have heat strips. I am running a Bosch SM60 5.0 ton system with (5) 200 plus feet loops... I am leaning towards reconfiguring the unit to pull cooler water from the bottom of the Marathon tank so that the heat exchanger works better in the summer... see attached...
The reconfigure looks like the better way make sure you get the coolest water flowing back to the desuperheater. Most will recommend a two tank setup, but your simple repipe will help.
Thanks. I do have a second tank, the Navien 240a condensing water heater plumbed off the Marathon 105 gallon tank.
Just for discussion... What I see with the reconfigure. During a hot water draw the cold water gets sent to the bottom of the tank, the DSH draws in that tepid water but can only raise it by a few degrees. Water is lazy so won't that not so hot water go directly into the Navien? At least the way it is now the hottest water goes to the Navien. Just my 2 cents. Chris
You are already drawing, through the dip tube, the coolest water from the Marathon. Re-injecting the water into the bottom is better than drawing from the bottom. Drawing from the bottom pulls sediment into the Desuperheater and circulator. Bergy
Correct, during recirculation I am drawing via the dip tube, but what I am most concerned about is where the water is being sent into the Marathon tank at the bottom... With the hot water from the DSH being sent into the bottom as well, is the dip tube picking up the hot water and sending it back to the DSH? see diagram...
It's a cost compromise. Were money no worry, a true buffer tank would be used. A buffer tank has more pipe openings to plumb the system. Drawing from close to the bottom is the best way, but not from the very bottom where sediments lurk. Bergy
How about this plumbing setup on multiple units? Came across this a few weeks back. Single tank setup as well. You are looking at both the in and out from the heat pump on that brass cross.
It's possible that crosstee is a homemade concentric fitting with the pipe stop removed on the adapter and the pipe slipped through into the tank. A decent deltaT could confirm without taking it apart. KJW I recommend you NOT reconfigure your piping. During a hot water draw the storage tank hot outlet would be tempered down by the cold inlet water filling the tank through the DSH loop.
