oversizing pumps

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You hear a lot about oversized boilers, but not so much about oversized pumps. I think that's because the pump operating cost appears on the electric bill, not the gas bill.

We had a series 100 on our gravity zone; it got replaced with a Grundfos 15-58, which moves much less water than the series 100 even on speed#3. But I've moved it back to speed#2 and even the attic room is still heating fine. (I understand that radiation output hardly changes at all when gpm changes, as long as some water is getting to the radiation.)

On another zone we had a B&G LR-20; that would correspond to speed#2 of a Grundfos 15-58. But it's running fine on speed#1.

Now of course the previous owner had bang-bang heating and so wasn't badly affected by the pump oversizing; we updated to a condensing boiler w/reset so our pumps are running much longer.

A 100 watt pump costs about 20 cents a day to run in our area. Over a 200-day heating season, that's $40, two pumps are $80. That isn't much, but it's over 5% of the heating bill. That's the same ballpark as what you might save by not oversizing the boiler.

Now I wish there were something I could do about the boiler loop pump on our Munchkin. All tht talk about Munchkin efficiency didn't mention that I would need to run one extra pump!

Weezbo

good thinking it out that way....

did you realize the long term advantages of operation and that depends on the size and configuration of the near boiler piping as well? i call these things "Features" now .the young Russian ladd that hangs with says thats what microsoft calls stuff nobody for saw they arent called mistakes or oversights any more they are called "Designe Features" ...