Stat on return pipe to buffer tank?

[frolingdual]

My buffer tank is plumbed such that flow is pumped (grunfos magna) from the top through the radiators and back to the bottom of the buffer tank. There is no mixing valve and I found that if the pump is set to a high speed the buffer tank is mixed and excessive boiler cycles are required.

I have pretty much solved this by setting the pump to its minimum speed and return temp is quite low. The downside of a low speed is that it can result in some rads being hard to balance and running cool.

My question is could I set the pump to a higher speed and wire a pipe mounted stat to stop the pump if a return temp rises too high?

 

[maple1]

What kind of rads? If it's the fin type did you try closing the enclosure shutters some on the first section of the zones?

I really like the way my Alpha slows the flow on all my zones as much as I want it to, but I got kinda lucky in that the first parts of my zones are where we need the most heat, and the ends of the zones are small rooms where we don't need a lot (bathrooms). I think my heating guys really knew what they were doing when they installed it 20 years ago - they oversized a bit also I think, overall.