Moving circ pump to ZCM ES from 2107 control

architrex

I just purchased a house in New England and this is my first experience owning and running a radiant system (FHW baseboards). In general, the system works great and I've developed a pretty good understanding of the theory and configuration. The system is composed of:

• Buderus Logano G234X-45
  
• Logamatic 2107 (no BFU)
  
• Indirect DHW
  
• Grundfos pumps: 1 for the 4 baseboard loops, and 1 for the DHW
  
• 4 loop wirsbo manifold, only 3 have thermal actuators
  
• 4 zone wirsbo zone control module
  
• 3 thermal actuators (1 older wirsbo, 2 newer uponor)
  

The four baseboard loops are:

1. Basement (always open, no actuator)
   
2. First floor left
   
3. First floor right
   
4. Second floor
   

My first challenge was finding out why the first floor left zone wasn't getting heat even though the boiler temp, pumps, and zone actuator were fine. I "solved" that by figuring out the pin in the return manifold for that zone sticks (will try some WD40 or just replace the pin if necessary in the future).

My real question though is about the constant circulation happening in the basement. Currently, the way things are wired and configured results in the basement (a single heating element) getting constant circulation when the Logamatic 2107 has the heating system turned on. I want this to not be the case but I'm confused on how to fix this. I think I need to:

1. Buy a fourth thermal actuator and install it on the return manifold for the basement loop
   
2. Add a thermostat to the basement and connect it to zone 4 of the ZCM and connect the new actuator to that zone
   
3. Rewire the Grundfos pump from the 2107 to the ES on the ZCM (this is where I'm confused)
   

How does the ES on a ZCM work? Do I just put the hot lead from the pump in series across the two ES terminals so that when it's closed (when a zone is calling for heat) the circuit is complete and the pump switches on? Or do I need some other relay thats controlled by the ES and in turn controls the pump?

Also, is there any harm in moving the pump from being controlled by the 2107 to the ZCM? I've read that the Buderus 2107 theory is based on the German constant circulation paradigm, so I'm wanting to verify that it can actually be setup in a way where the circ pump is only run when a zone calls for heat (like in the American heating paradigm). If the circ pump and DHW pump are off (because no zone calls for heat) but the 2107 decides to fire the boiler, is that bad?

Here is a picture of the 2107 wiring and a view of the manifold with pumps. For the wiring, I'm fairly sure terminals 61 and 63 are powering the transformer for the ZCM and the baseboard pump.




Thank you, any help is greatly appreciated!

Big Ed_4

What is a ZCM ?

Big Ed_4

Yes ,add an actuator to the control the basement .

The off balance to the heating system is the piping of the manifold . To correct the problem reverse the order of the zone takeoffs on one manifold to balance the pressures and flow .

You want to have the 2107 control the heat and hot water circulator ...

architrex

Big Ed_4, thanks for your response!

ZCM = zone control module, the wirsbo board that is connected to the thermostats and actuators. I'm most likely calling it the wrong thing. In the current setup, the transformer that is powering this board is is getting its power from the 2107 when the heating system is on (WWSD is not triggered).

> You want to have the 2107 control the heat and hot water circulator ...

If I have 4 actuators controlled by four thermostats, but the circulator is still being controlled by the 2107 (which is oblivious to to the state of the actuators) won't I be wasting energy when the 2107 has the heating system turned on (when WWSD is not triggered) but all 4 thermostats are satisfied and the actuators are closed? Not only that, but where does the excess head pressure go if the circ pump can't push the water through all 4 closed loops? (I'm guessing the connection between the supply and return
red/blue shut-off valves is a pressure-regulated bypass valve, but I'm not sure).

For these reasons, I was thinking it made sense to have the 2107 control power to the ZCM only, and then move the circ pump to a new zone switching relay (like a SR501-4). The power to the SR501-4 would still come from from 2107 (the PH-HK1 block) but I'd us the ES on the zone control module to actually turn on the pump using the SR501-4.

Alternatively, can I just connect the power from the 2107 to the circ pump with the ZCM ES in series so that the circuit is only complete when the ES is closed? My naive guess would be that's unsafe and I need to isolate the ZCM from the pump current draw with a relay like a SR501-4 but maybe I'm wrong.

Thanks again!

Big Ed_4

There should be no benefit to shut off the actuators . They are slow to begin with . The 2107 shuts off the circulators until the boiler reaches 120* to help prevent condensing of combustion . It also shuts down the heat circulator to heat up the hot water quicker .

architrex

But what happens if the 4 actuators are shut but the circ pump is still on?

Big Ed_4

Your right ,it has been awhile since I last wired one .... Instal a relay powered from the 2107 to power up the heat circulator use the end switch to control the relay .