How to know if Desuperheater pump is working

Discussion in 'General Discussions' started by Waukman, May 26, 2008.

  1. Waukman

    Waukman Member

    Geoexchange web site - where is it?

    I wanted to direct someone to the geoexchange web site but it no longer seems to be up. Does anyone know that status of the site? I see there is an annoucement regarding it but it is rather old. Is the site still being hit by dos attacks?
  2. The former GHPC website was hosted on a temporary windows server. The attacks stopped after we took the old site down.

    I planned on a smoother switch but the script vulnerabilities in the old site necessitated its prompt removal.

    Sorry for the inconvenience.

  3. Waukman

    Waukman Member

    Not a problem. I hope it is back soon. I have found it a very valuable resources over the last few years.
  4. brandtryan

    brandtryan Guest

    Ok, I'm a newbie, I admit it!

    Problem is, on my water furnace Spectra model, I've made sure the DHW pump is being commanded on, but there doesn't seem to be any circulation. All valves are open, and on the side of the unit where the DHW OUT line is, it is hot to the touch (right at the unit)--but six inches further away from the unit, and towards the water heater, it is ice cold.

    There are onboard diagnostics but only for the output signal to the pump--there's no way to get actual pump "status", as far as I can tell. I'm assuming it is not working since the line to the water heater is always cold!

    Plumbing is not an issue--I verified the setup according to the original installation guide (see figure 2 in attachment).

    Thanks for any replies!
  5. GeoXNE

    GeoXNE Guest


    1) The DSH loop may be airbound. Open vent as shown in piping diagram to purge air. Also try burping air from the wet rotor pump by backing off quarter sized slotted end cap only 1/2 to 1 turn CCW (you don't want to go far enough to blast the cap in your face) retighten when only water comes out.

    2) Verify voltage at the motor leads.

    3) Debris or excess solder could be jamming the impeller requiring the removal of the motor from the pump housing to clear.

    4)Verify flow, almost all sections of the DSH loop will "feel" about the same temp.

    !!! Make sure power is off and water is off and drained when opening anything up. If you are not qualified do not attempt!!!
  6. teetech

    teetech Member Forum Leader

    You can also turn off the DSH valve out for 2 min and then open and feel for shot of warm water on the DSH line out.

    That's an older unit you may have to clean the DSH circuit. They do need occasional maintenance.

    I suggest you have someone look at it.
  7. brandtryan

    brandtryan Guest

    Thanks for the help everyone!

    I did turn the cap 1/2 a turn CCW and there wasn't any noticable air coming out before a water dribble started. The water looked pretty bad--it was really gray looking and dirty :shock: . The geo unit was on, but I turned the dip switch to off for the DHW pump.

    I'm thinking this puppy needs to be completely flushed, as was advised above. Thanks again for the input everyone!
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    If you have or can borrow a clamp amp meter the dsh pump should draw 1/4 - 1/2 amp if it is running.

    Of course that measurement might not confirm or deny a locked rotor condition on the pump, another possibility.

    IMO if all is well the water out of the dsh ought to feel appreciably warmer than the water in, especially if the inlet water is fairly cool, 80 or less
  9. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    There should be a cap on the end of the shaft that can be removed. Take of the cap and stick a small screw driver in. If the shaft is turning, you will feel it vibrate the screw driver. I did this just today on a job.
  10. brandtryan

    brandtryan Guest


    where is the cap? The quarter sized screw I backed off a quarter of a turn--where is the cap in relation to it?

    Also fellas--if I want to take this pump and clean it, if there is a bunch of garbage in there preventing flow--I want to follow these steps, correct?
    Throw breaker for Geounit and Water Heater
    Open some hot faucets in house
    Drain Hot water heater
    Remove pump


    Can I just throw breaker for geo and water heater
    Shut geo isolation valves (one on DHW IN and one on DHW OUT) and drain the litter water that is in that line, and then remove pump?

    Finally--I'm pretty sure in the attached picture, that dip switch 2 is currently in the "OFF" position--but the sticker says one thing, and the actual switch another! I'm assuming the dip switch #2 needs to be in the "OFF" position (according to imprint on switch) to be "ON", correct?

    BTW--I'm not a complete newbie here--I worked at Johnson Controls for 4 years--as a validation engineer. More of a technical writer though--and only on large commercial AHU's, etc. :eek:
  11. brandtryan

    brandtryan Guest

    Mission Accomplished! I took the pump apart, it wasn't actually that dirty--the fly wheel, or whatever it's called--didn't have that much grime on it. The shaft spins very easily. Either there was air in the line, which I got rid of, and double checked after charging back up with water, or for some reason--controller had to reset, which happened when I turned the breaker back on. Now I'm getting the DHW green LED again, when diagnosing Outputs. The pump gets warm--and now there is only a 10 or 15 degree difference on the supply and return lines in the Geo. Also, I turned down the lower element setpoint on the water heater to 100 DEG F, and put the top element at 130 DEG F., per the instructions.

    Just one last thing I don't understand--the water heater setpoints. I know the hot water in the house comes from off the top of the tank, as that hot output stick going into the tank is short, and the supply/cold is a long tube going to the bottom. Couldn't I just turn off the lower element all together? The water going in to the tank (into the bottom via drain)is at least 100 DEG F--oops, think I just answered my own question. What if GEO unit isn't running and I'm running hot water in the house--that bottom element will have to help out again. Hmmm.

    Anyway--thanks for all the kind replies and information--it was fun solving this mystery.
  12. teetech

    teetech Member Forum Leader

    We are glad you fixed your problem!
    It can be fun to solve mysteries.
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    That last post explains EXACTLY why

    most pros like a separate buffer tank for desuperheater water!

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