Thermostatic versus motorized 4-way valves for heating loop temp control. Which way do you go?

BigRob

I like that thermostatic valves are a simple solution. Have they been reliable for you? How long does the thermostatic element last with normal use?

I don't see much advantage of a motorized 4-way valve, except that you could modify the output temperature with the correct controller.

SWEI

Boiler protection comes for free with a motorized mixing valve.

Thermostatic valves work when the power is off, and some configurations will allow gravity circulation to protect (somewhat) a solid fuel boiler from runaway conditions.

As to longevity, ask me again in a decade or so. No failures yet, but it's only been a few years since we started using them.

hot_rod

if it is a condensing boiler then a thermostatic is a simple, affordable way to mix. If it is one zone a manual 3 way with the boiler on reset might work.

Motorized valves allow more user features but the cost of the valve, actuator, and control to drive it add up.

Really not much "under the hood' just a wax filled thermal pill to move the spool up and down.

If the fluid quality is good they last a long time, in DHW application hard water causes them to bind up, they need to be maintained, just like a tankless heater