Help interpreting gpm on Alpha pump

[hiker88]

Hi everyone,

I'm reluctant to ask this question because I will
a) look like a total noob
b) be asked for follow up information that I won't know how to provide that will make me look like a total noob

Anyway, here goes...

I mentioned in a previous post that I plumbed my system according to the square tank schematic at woodboilers.com. I went from my old taco pump which was mounted directly to the return port of my boiler to an alpha pump which is basically located right before my zone valves.

The Alpha pump is set in auto mode and as I understand it, it basically strives to maintain zero pressure differential - so when a valve opens it runs and will deliver what it takes to equalize things.

When only my first floor zone calls for heat, the read out displays about 2 gpm and about 9-10 watts. If the second floor of my house calls for heat, the wattage stays about the same, but it says 0 gpm. The upstairs seems to heat normally. The above happens whether I am running on oil or wood.

I can put the pump into high and move 4 gpm at about 45 watts through either floor.

Does it seem strange that it shows 0 gpm for the second floor? I just though it would take more, and of course I am concerned that maybe I did something like not get all the air out of the lines although there's nothing to make me think there is air in the lines other than my display question. I haven't done anything more than letting the air vents in the basement work the air out. I have baseboard and I don't think I have any kind of vents on either the first or second floor areas...

 

[711mhw]

I have one of those, it seems to act like yours. I just go around ignoring it as it is much smarter than me

Like you say,, reguardless of what the output is reading, everything seems to be heating normally, my radiant guy in Gardiner says that the reading (gpm) is more of a guideline while the wattage can be more accurate.

 

[hiker88]

Thanks. I obsess too much sometimes.

 

[maple1]

Wonder if it has anything to do with gravity flow helping things along on the higher level? When my system is up to temp and an upstairs zone valve opens, I don't really need the pump - things flow pretty good by themselves. Actually, one if not both of the end switches in the valves stopped working but I never bothered replacing them - the hot water goes up by itself and is helped along anyway when a downstairs zone also calls for heat which does start the circ.

 

[hiker88]

Wonder if it has anything to do with gravity flow helping things along on the higher level? When my system is up to temp and an upstairs zone valve opens, I don't really need the pump - things flow pretty good by themselves. Actually, one if not both of the end switches in the valves stopped working but I never bothered replacing them - the hot water goes up by itself and is helped along anyway when a downstairs zone also calls for heat which does start the circ.

That's kind of what I was wondering\hoping for. Almost like due to the gravity aspect the pressure on the return side of the pump is close to the supply side pressure due to the weight of the water.

I've had to drain and fill the system a few times due to a leak, or how I've added things in stages etc. After a fill, all my vents hiss and purge air for awhile and I can hear quite a bit of flow noise, but it gradually goes away.