cold loop temps

Discussion in 'Maintenance and Troubleshooting' started by 597, Jan 24, 2013.

  1. 597

    597 New Member

    I went to a new building with 38 heat pumps. every time the outdoor temp gets to zero or below, rooms can't keep up. The ewt at 1 unit was at 36 degrees. the manufacturer says at 35 degrees the unit will have only a 20 degree temp rise. This is not enough to heat outer rooms. I am waiting for info on the loops, but wondering why ewt is so cold. i think the loops are vertical, but don't know all info yet. Is this normal temps in cold climates?
     
  2. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Most loops get down to 30° when under heavy load. Where is the project? What kind of heat pumps?
     
  3. 597

    597 New Member

    it is in chicago. trane 1 ton to 5 ton units m# gete01211a02a0t1c01000 I have since found out the VALUE engineer changed the system from 2 pipes to a 1 pipe loop. It's a 3 story building, and each hp supply and return are off the main 12 inches or so apart. Giving the last hp's "used" water! There is no back up heat at all. No electric strips or gas heat anywhere. The project manager says. at least' there should be a loop re-heat water to water hp to help. I don't know what will happen when we have a real chicago winter of many below day's below zero!!??
     
  4. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    sounds like problems ahead. What is your involvement ?
     
  5. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    That is a tough setup to rectify. I'm sensing some plumbing in the future.

    One could potentially "overpump" the building loop to minimize the delta T from start to finish.
     
  6. 597

    597 New Member

    I'm just the service tech for the mechanical contractor who installed the sheet metal. Our sub did the piping. At least it looks like the job was installed per plans, so the engineer will have to get involved. Has anyone ever heard of re-heating the water ?
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    We are currently doing a similar set with 29 heatpumps. 5 story building with 24 apartments and 5 shops.

    36F EWT is not bad, the question is what the leaving water temperature is. Are you saying that return line from each heatpump goes back into the same pipe as the supply is coming from?
     

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