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Bosch Greenstar 100 boiler questions

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KenJ
KenJ Member Posts: 8
edited January 2019 in THE MAIN WALL
I have a heating only boiler with an indirect tank that was installed in my new home a couple years ago. I had the plumbing contractor run the primary/secondary piping and he left me a couple stub outs to hook up radiant floor zones. The boiler is set up with the power for the DHW pump coming from the red plug on the boiler and using the supplied DHW temperature sensor in the indirect tank. Radiant zone pumps wired to non-bosch relay and relay connected to pins 2 and 4 on the boiler Heatronics panel. Boiler is in Comfort mode. While radiant zones are calling for heat, the DHW should have priority and turn off the heat zones when calling for DHW. This doesn't happen. DHW pump and heating pumps will run and the boiler will increase supply temperature for hot water. Service Function 1F is set to 03, for the DHW pump. I have tried setting Service Function 1E to 00 and 04 and both do the same thing. What else could affect this?
Second question, the service function 2B for maximum supply temperature I had set at a lower temperature than the default 187 but when DHW zone is running it will exceed my set temperature. Is that the way it is supposed to work? Thanks in advance for any insight.

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  • GW
    GW Member Posts: 4,726
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    Doesn’t sound like the heat pump is wired directly to the BOSCH; I’ve never seen what you’re describing. Pull the cover off of the circulator control you mentioned and post a pic of the general wiring. If you are a little unsure with tools, please don’t, there’s live power in there
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • KenJ
    KenJ Member Posts: 8
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    The heat zone pumps are powered through the relay. I attached a picture from the Bosch Application Manual. My system is done just like this.
  • GW
    GW Member Posts: 4,726
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    I think I lost track of the original question, you’re wondering why the water heater circulator and the heating circulators are running simultaneously? That diagram you posted does not indicate anything regarding wiring. You need to take the heating pump circuit from the Bosch and wire it to the ZC terminal on the relay, and drop the jumper. That is my best guess without seeing what you actually have going on
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • fenkel
    fenkel Member Posts: 162
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    Your are correct...the boiler needs to have the zone pumps wired to boiler .and the indirect wired to boiler as well.heres the reason the zones will run at the same time as boiler..
    The zone controller only sends a signal to boiler to turn off and on.
    You cannot use a zone or pump controller and expect it to control the boiler functions...
    The boiler has the brains..
    zone controller only turns pumps or opens valves up or closes them...
    If you want the boiler to shut down and have the indirect run youll need to:
    Use only one thermostat and hook all the pumps to boiler...then the.bpiler will controll both functions..
    To solve your other problem, youll need the fw 200 controller..
  • markthepadrone
    markthepadrone Member Posts: 1
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    I'm new here so. . .
    I just saw this old post and am setting up a similar configuration.

    I have a Bosch Greenstar 151 with a Tekmar 306V zone controller.

    As posted above by others, the boiler needs to take control of the zone pumps during DHW mode. I'll try this by connecting a relay to the red connector on the boiler along with the tank pump and using the relay to interrupt power going to the zone pumps during DHW mode.

    Or, if I feel fancy I might try to drive the relay with the black connector and set SF 5.E to 03.