Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Viessmann Vitodens 200-W WB2B circ pump runs constantly

arlmonter
arlmonter Member Posts: 2
Looking for suggestions on how to control the circ pump (Boiler pump [20 plug] p68 of Start-Up/Service instructions) so that it is only on when there is a call for heat from one of the 3 zones. As setup now the circ pump runs all the time when the outdoor temp is less than the Vitotrol 300 setpoint, wasting alot of energy. Have tried different settings but to no avail - circ pump is either always off or always on.

Best explanation I've seen is from an earlier post Bob in 2012 (included below). Is configuring for external demand the only way to do this? Can anyone expand and provide some additional detail? Currently setup as a LLH, 00:2 / DHW priority with a Vitotrol 300 on the main floor and 3 tstats to cover the 3 zones. Thanks.

"No No

The Vitodens 200 and Vitodens 100 are two different animals with different control and burner logic platforms.

In Viessman Bob's case, there is no RT on the boiler. No the 143 plug is not RT/TT Bob nor do we ever use the 20Aplug for the system pump unless I was running a constant circulation system like they do across the pond. Your system pump should be wired into the Taco Zone control so when a valve opens the pump runs. The boiler will fire if it needs to based on the feedback from the LLH sensor.

In the Vitodens 100 there is a TT (RT) to activate the boiler. Still waiting to see thos pics. Could you also draw and post how you have the boiler wired.

Bob in coding 2 you can get rid of the LLH sensor and then utilize the 143 plug if you want to run the boiler llike a traditional boiler with a TT. You then have to program the boiler via External Demand to tell it what you want it to do on that call."

Comments

  • arlmonter
    arlmonter Member Posts: 2
    So I can see why this is so challenging - configured the 143 plug (external demand) and no change. Disabled the LLH sensor (not sure why that matters) and no change - circ pump constantly on since the outside temp is less than the room setpoint on the 300.

    My current thinking is to get a TACO 1 zone off of the ZVC 403 end switch to control the circ pump instead of wiring it to 20 as it is now. Any reasons why that won't work?
  • Greeny1
    Greeny1 Member Posts: 9
    Coding 2, 51 controls the boiler pump.
  • Radman
    Radman Member Posts: 75
    You are correct in your thinking, you will need to control your system pump via a zone controller if you want it to be on/off as it relates to a heat call, and still have the boiler function on ODR. Using the external demand function will disable the outdoor reset function and the boiler will only target the programmed setpoint value, and modulate to that point. Viessmann boilers and Vitotronic controls operate on continuous circulation (save for the Vitodens 100) and they do not operate on a TT call. Your other option is to utilize a smart pump like a Wilo Stratos or Grundfos Alpha, and leave it connected to the 20A terminal. (Leave coding address 51 at 0, assuming you are using a hydraulic separator/low-loss header as noted (address 00:2) AND your DHW pump is connected up-stream of LLH, with coding A2:2)
    For the purpose of what you are asking then the solution is to run the pump from the zone controller. (You can use the output circuit from 20A to power the pump, switched via the zone relay if you so desire)
    "If it was easy, they would have called it PV."
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited January 2016
    Coding 2 change address 51:0 to 51:1. Boiler pump will only run on burner start. Have a nice day

    Is the Vitotrol for HC1 or do you have a mixing valve and HC2? If you do can give you the coding changes to stop HC2 pump once Vitotrol makes setpoint.

    You DO NOT have to disconnect the LLH sensor nor use the 143 external demand function. If zones are zoned with zone valves, wire the system pump to the Zone Control as a system pump. When any zone calls pump will operate. Boiler will fire when the LLH sensor sees the need based on your heating curve.

    I never use the 20A system pump output on the PPM to run a system circ. Use it to power the zone control. Have to remember once outdoor temp drops below WWSD 120Volts is sent to the 20A Plug until you come out of WWSD or are in DHW Priority. In essence you could use it to power anything 120volts. Its just an output labeled System Pump.

    The Vitotrol will not, I repeat will not, shut down a pump unless you are coded correctly in A5, B2,B5 in Coding 2 and will only de-energize the 20A plug (HC1) or 20 Plug on a Mixing Valve when using HC2.

    External Demand or 143 Plug is there for the boiler to do something based on the users input. 143 makes the boiler dumb, no brain, you have to tell it what you want it to do on that call. Generally only used when you want a setpoint temp for snow melt or heat exchanger.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."