closed loop cooling entering temp

[geonewbee]

I just had a new 6 ton geo unit installed in southeastern PA a few weeks ago. Entering temp from the closed loop system is 68F. Well driller says that's great, but it sounds high to me. Am I off base? I have three 300ft wells for this system.

[Bergy]

is great!! There is no need to worry unless the entering water temp gets higher than 90~95*.

Bergy

[crash11]

That is really good. I'm in Michigan slightly north of you, and my EWT is about 70 F. I have a horizontal closed loop about 7 feet underground which is why my temps are warmer than yours.

[geonewbee]

I used certified contractors for the wells and the geo unit (FHP Aquarius II). It's good to know they did the job well. I was just concerned because my electricity consumption has been in the 45-55kwhr/day range since installing the new system and that seemed high to me. Of course it has been in the high 80's and low 90's with high humidity during this period, so I probably started off in a worst case scenario. This weekend I put a timer on my electric water heater so that the elements would only come on for a few hours a day if the desuperheater isn't keeping the water hot enough.

[Bergy]

water heaters do you have? You should have two electric tanks piped in SERIES. The first tank should be piped to the desuperheater as a buffer tank.

Bergy

[geonewbee]

I have one 80 gal water heater. It is connected as shown in the FHP installation instructions. That is, the drain valve is removed and a pipe within a pipe is connected in its place. This draws water out of the tank and into the desuperheater, returning the water through the same port in the tank. The desuperheater controls are totally separate from the electric heating elements which are simple thermostats. I turned down the temperature on the electric elements so I'm not trying to keep the water hotter than the 120F that the desuperheater is designed to provide.

[Bergy]

Having just one tank is not a effective method of using the desuperheater. The tanks elements and the desuperheater are competing to make hot water. You need two electric water heaters piped as shown in the drawing. As shown, the first tank becomes a "buffer" tank for the desuperheater. Whenever the Geo is running the desuperheater can produce hot water for you. All day, or night, the buffer tank is being recharged by the desuperheater.

Think of it this way...After your family takes their morning showers and leaves for the day, the electric elements are trying to heat the tank up. If the Geo kicks in it is also trying to heat the tank up. In effect they are fighting one another. With twin tanks, the buffer's water temp gets drawn down as it feeds the main tank. The elements energize in the main tank and the cooler buffer sits there until the stat calls for heating or cooling.

The concentric fitting at the bottom of your tank is prone to fowling. The calcium that forms in your tank falls to the bottom and can get sucked into the fitting. over time this can clog the narrow spaces of the concentric pipe. When pipe as shown, water is drawn UP through the dip tube and re-injected into the bottom of the tank. This is why the backflow preventer MUST be removed. The two 1/2" ball valve make servicing the desuperheater circ easy AND are used to limit flow to acheive the desired delta T for the desuperheater. The ball valve BELOW the desuperheater branch makes flushing the lines a snap.

Bergy

[geonewbee]

Bergy,
Thanks for the advice. Still being new to the site I haven't figured out how to view your attachment. When I try I get a message saying I don't have that privilege. I guess that's reserved for pro members. I just might call the installer and see if I can get my old propane water heater back from them or have them install it (or another used tank) as a buffer as you suggest.

[Bergy]

why you can't open the attachment. I'm not a pro member either.

Bergy

[geonewbee]

Changed my user editing settings and can now see the attachment. Meanwhile I found another thread saying to not use a gas heat tank for the buffer since it has a vent pipe down the middle making it less efficient. Plan to talk to the installer tomorrow. Makes total sense that the electric elements will respond immediately to hot water use whether or not the desuperheater is running. My first reaction was that using a buffer tank just meant I would be heating twice as much water and heating it twice while not running the hot water. Thanks for your help.

[Bergy]

tank does not need to be wired. Use it just as a buffer.

Bergy

[hvacguy55]

To expand on what Bergy said, an important reason to use a buffer tank is that when you use hot water, the element will rapidly re-heat the tank to your set point. Thus, even if the geo unit runs six hours that day, you will get NO benefit from the de-superheater. By having a buffer tank, that water will be pre-heated when the geo unit operates, even if the main tank is fully hot. On a moderate day, you may not get the buffer tank up to 120, but any increase in the entering water temperature is work that the main tank does not have to do.

Gas and propane water heaters lose a tremendous amount of energy when connected to a flue (stand-by loss). A buffer tank is simply a holding vessel. If you want, remove the flue baffle, and stuff the 4" tube with insulation. Be sure to retain the T/P valve.

[Carnak]

definitely want a tank preheated by the desuperheater that feeds the second tank