I am preparing to look at 4 zone valves and a grundflos variable spped circulator for that Buderus boiler. Anyone out there have opinions on (1 )which zone valves will give me the least trouble and (2) will be compatible with what relay box and the bolier (3) do we need end switches or no end switches on the ZV's (4) yes the DHW is built in control with the boiler.
When you say "relay box", are you referring to something like a Taco ZVC panel? See the attachment.
Zoning with a mod/con can cause issues due to its low mass which will result in short cycling. You'll most likely need a buffer tank if you go that route.
Also, the GB142 will remain off for 10 minutes to prevent short cycling which could result in insufficient heat in some zones.
You'll be much better off eliminating or minimizing zoning and getting the reset curve set up properly to match the load. TRV's and constant circulation is a much better approach and is what that boiler's designed for.
Taco's latest version of the ZVC is not in that literature. They are calling it Enhanced ZVC. It is almost the same, but gives you the "common" connection for each thermostat.Which is needed for some thermostats.Anyway....if you go with a ZVC, get the "enhanced". You may decide to upgrade a thermostat in the future.
I second the advice not to chop the home up into zones. Look around the "Wall" and you'll find it's the biggest problem that mod/con owners have.