Separate zones for radiant heat controlled by single T-stat: why weren't they just plumbed together?

MoreCowbell

I just purchased a house that uses a boiler for radiant heat in the floor. This house is configured with 10 zones, 10 zone valves, and 7 T-stats.

In my previous house also heated w/ radiant heat, there were 3 zones, 3 zone valves, and 3 T-stats - which seemed very logical.

In the new house, 3 pair of adjacent zones - each with its own zone valve - are controlled by 3 T-stats, respectively. I must wonder for each of these pairs, why wouldn't they have just been plumbed together to create a single zone and used a single zone valve? Put another way, what would be the mechanical advantage of having 2 adjacent zones controlled by a single T-stat?

Jamie Hall

Good question… maybe someone had the idea of separating them once upon a time. Your guess is as good as mine.

MoreCowbell

I appreciate your response Jamie, though I was hoping to get something more definitive. I bet there HAS to be a rationale.

My head scratch continues until someone smarter than me can please enlighten … 🤔

JUGHNE

Could be a couple of reasons, maybe…..

the flow together exceeds the capacity of one zone valve…..

OR

one zone is too small of a flow/load to prevent short cycling of the boiler.

Just a WAG.

EBEBRATT-Ed

You could eliminate 1 or 2 thermostats and wire two or three zone valves together to reduce the # of zones.