Best layout of basement zones in renovation?

Jim R.

I have a 15 yr old conventional Buderus boiler (74,000 btu). Currently 2 zones each with their own circulator:
zone 1 - indirect DHW priority
zone 2 - baseboard heat

A full basement reno is in progress. 3 new zones are being added driven by one circulator with zone valves:
zone 3 - slab radiant bedrooms
zone 4 - slab radiant bathroom
zone 5 - baseboard

I realize there is no one right way to do it but what are some things I should check for / insist on when this is being connected? The tech gave me a confused look when I asked how the radiant slab temp would be lowered, now I feel I need to be more involved. He asked "do you want a mixing valve?" I don't know but I don't want a 180 degree floor.

Also, could a system like this with different types of emitters benefit from an outdoor reset? Of course tech said no, not worth it. I think they work primarily on forced hot air and are a little out of their element, but otherwise easy going and want to keep me happy. I watched their plumbing work and radiant install all of which is good.

To be fair, the owner of the company is coming to do the boiler hookup and he's an older guy who's been around the block. I just want to speak to him intelligently and make sure all bases are covered. Unless I request otherwise, I think his hookup will be very basic with minimal controls.

Any advice appreciated! Thanks.

Location: Philly, PA.
House is a 1600sqft ranch, newly insulated. Basement level is also 1600sqft, about 50% dyalight and 50% basement. Renovation was designed by an architect and is fully permitted.

HVACNUT

What model Buderus and what's the operating control? If it's the 2107 I'm sure you would have mentioned it.
Why not take zone 2 and change it to a zone valve as well. Use the existing circ. Connect all to a Taco ZVC406 zone valve control.
Not ever having piped or wired one with radiant, pros need to chime in on whether a relay, bypass, buffer tank is needed.
I assume the boiler circ would have to be on the return so its not pumping into the mixing valve.
Or repipe using primary/secondary. Secondary circuit in series with the 2 high temp BB zones being first and second in line. The main zone baseboard probably has a higher heat loss so that would be first.
Outdoor reset is definitely doable.

Jim R.

No logamatic 2107, I regret not getting that.

Currently it's setup with a 4-zone taco switching relay of which two zones are used. Both circulators are on the hot side of the boiler (not the return).

The existing baseboard zone is the whole first floor of the house. The new baseboard in the basement will be a smaller loop, 3-4 rooms. It's not totally decided if we'll use all baseboard or 1 room baseboard and 3 rooms radiant panels. I need to decide on that. I was going to go with runtal but it's a pricey.