Altherma Direct to Radiant Floor

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Altherma Direct to Radiant Floor

Goals of Experiment

  • Determine to what extent the Altherma is able to heat the Historical building directly.
  • Analyze data to extrapolate what results would be on a 0 degree day.
  • Check for leaks in radiant floor loops.
  • Collect more data on energy impact of 3-way mixing valve being limited to 70%.

Decisions to be made from Experiment

  • What should our minimum storage tank temperature be before the Altherma comes on when solar is lacking?
  • Reconcile temperatures between our DDC loop supply and return sensors and the manifold gauges.
  • Do we have any leaks?
  • Do our DDC loop temp sensors need to be re-calibrated?
  • Is 3-way valve limit okay as permanent solution to limit flow through heat exchanger, or is there some benefit from reconfiguring this part of the distribution system?

Expected Outcomes

  • Strategy for operation of the Altherma in heating season.
  • Knowledge on Altherma's capabilities as emergency heating backup.
  • Confidence in our DDC temperature sensors.
  • Recommendation on keeping 3-way mixing valve limited or revising piping.



  • Update flow system diagram with measured flows for each zone/pump; impact of taking Annex off loop.
  • Re-calibrate T-6, T-7, and manifold temperature gauges.
  • Thermal image floor for leaks or inactive sections during heating test.
  • Open up manifold and see temperature of zone in and out, temperature of floor, determine how much heat is going to floor.
  • Run heating with Altherma only direct to loop.
  • Take temperatures throughout process until "steady state" is reached.
  • Periodically repeat test at various points in season vs. OA temperature to understand heat loss of building better in relation to outside air temperatures.
  • Extrapolate results to 0-degree F outside day.
  • Determine/confirm impact of 3-way mixing valve being limited on temperatures and operation.

Process Measurements

  • Check calibration of T-6, T-7, selected manifold gauges using handheld meters.
  • Install thermocouples with data loggers in selected locations; loops in and out, manifolds in and out, around 3-way valve, on selected floor(s).
  • Read and record system temps, outside air temp, thermal image floor temps.
  • Record flows in each loop available to read.

Resources Required

  • Flow Test Kit (tackle box) - currently not working
  • Fluke w/thermocouple sensor, heat tape, insulation
  • Thermal imaging camera
  • Data Loggers with thermocouple sensors
  • Data Logger with current sensors on Altherma



  • Labs


  • Expert/Cochrane to get sensors re-calibrated and for trending histories

Help Wanted

  • Temperature readers to watch gauges and record manually at manifolds

Scheduling & Sequencing

  • Need cold outside air temperature

Results and Analysis

Observations & Data



  • If 3-way valve was not limited, storage tank and Altherma could produce lower temperature supply water to meet space loads because it would not have to blend with return water.


Decisions to be Made From Lab

Expected Outcomes Met




  • Plan / Do / Study / Act / Repeat
  • Look up how temp required from Altherma impacts efficiency due to 3-way valve being limited
  • Document discussion and conclusions; publish results