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BOSCH T9800SE 160K BTU having Heating Problem Water Flow Rate shows 0.3gpm No Heating



  • tester22
    tester22 Member Posts: 48
    This FLOW CONTROL reduce Water Flow and release up to 1.5gpm, according to RED ZINE DVS 600, that is why on Flow Control it is written 1.5gpm.
    Here it is Part List from Manufacturer.
  • SuperTech
    SuperTech Member Posts: 2,126
    Yeah that's not a flow sensor.  That's in your air handler not the BOSCH machine. You need to determine if the sensor in your BOSCH machine is correctly reading the flow or not. A pressure reading while the BOSCH machine is calling for heat would need to be measured on the inlet and outlet of your BOSCH machine. If you have a pressure drop then your flow sensor in the BOSCH may be OK. If you have no pressure drop then the flow sensor in your BOSCH MACHINE may be faulty.  
  • tester22
    tester22 Member Posts: 48
    edited April 2023
    Hope some BOSCH exports look my 1st Post to identify the FLOW SENSOR, where it is sitting.

    And I have only one Gauge for Water Pressure Test & one Gauge for Expansion Tank Air Pressure.

    Is there any special tool do I need to measure flow inside the BOSCH Machine (or i just need Multimeter), and out side the Machine can I use my Water pressure Gauge.

    Please let me know, what Tools do I need to measure INLET & OUTLET water flow.

    If any thing I write in my big posts any upset, please forgive me your all members, I am still trying to fix this problem.

  • dko
    dko Member Posts: 562
    edited April 2023

    You can manually test a flow sensor as well.

    Shut off the HWR and HWS ball valves at the air handler.

    If you weren't calling for heat, it should be reading 0gpm anyway. But for the test keep the valves closed.

    Bosch should read 0 gpm. Now open the hot water on one faucet. Go check GPM. Now open another one, check GPM again. Now open the hot water at your shower/tub spout, check GPM. Is the GPM going up incrementally from the moment you open another faucet to the next? Let us know the GPMs at each interval.

    But this is it. It is a combination flow sensor and motor stepper to control max water flow.

    The flow sensor is probably ok it read the 1.6gpm just fine when it made hot water through the open loop AH test. But still do the above test. If that's all dandy..

    Grab another garden hose pressure gauge and put one on HWR drain and HWS drain at the same time while the pump is running.

    While you're at it, take a picture of how the pump is wired. And since you have a multimeter, make sure it's getting the 115V during call for heat.

  • tester22
    tester22 Member Posts: 48
    edited April 2023
    -HWS & HWR - Off --------------------- 0.0gpm
    -1 Faucet - Open ---------------------- 0.8gpm
    -2 Faucet - Open ---------------------- 1.0gpm
    -3 Faucet - Open ---------------------- 1,5gpm
    -3 Faucet & 1 Shower - Open ------------ 2.4gpm

    RED (L) ------- power Line
    WHITE (N) ----- Neutral
    GREEN (G) ----- Ground
    When Heat Pump is Running, Multimeter I set to 200 AVC on Meter & which probe where I have to touch to see 115V.
    And my Control Board Wirings Photos also attached.

    And currently I have only one Water Pressure Gauge, I have to order another Gauge to get pressure from HWS & HWR.

    And I want to know, how to do Heat pump wiring 115V measurement towards Control Boar wiring connection side, because there is no way I can remove top black cover from the Heat Pump with out pulling out complete Heat Pump. So is there any way I can do this 115V test on Control Board wiring side.
  • fenkel
    fenkel Member Posts: 162
    question, does the system make good hot water for DHW ? Has it ever worked correctly? Was this a new install? or new boiler ? what in system is old?
    i think your air to air coil is pluged.
  • fenkel
    fenkel Member Posts: 162
    i would pull out the check valves and inspect them, you would be amazed at how easily they can plug, soldering joints can leave small amounts of solder in system, once you fill with water it will plug these check valves... It doesnt take much.