Tuning a Variable Speed Circulator?

[velvetfoot]

So, I installed a couple of variable speed pumps (EcoCirc Vario) yesterday on my 2 heat zones, one circ each, baseboard system. They have a stepless control of motor speed. I set the first floor to "2" and the second to, say, 2.5. It was still cool enough for heat this morning, so when I went downstairs to look at the supply and return temperatures, I noticed that the return wasn't getting warm at all (only upstairs zone running). I bumped the speed up until the return temps started rising, maybe 3.4 or so. I guess that got it over the hump, as in, and is the absolute minimum speed. The question is, how much above this is optimum and how do I find this?



According to my crappy calculation, there is 12' of head on the second floor zone. Looking at the pump curve, the setting I should be at to give a minimum 12' of head and minimum flow is about a "5". A 3.4 pump setting would be more like 7 feet of head. Baseboards generally recommend 1gpm.

I guess I need help interpreting the diagram.

 

[maple1]

Do you know how many GPM you need to give you the heat you want?

I think I'd just play with the speeds until I got to where I was getting enough heat - but not so fast that my return temps were more than I wanted. Even though I use math most every day in my real work - sometimes I find it's overated & trumped by good old trial & error.

 

[heaterman]

Check your supply to return temp differential from each zone. Shoot for 20* difference between them and that should be your sweet spot between pumping power and heat output from the baseboard.