Old radiant with a new Alpha

Ron Jr._3

We replaced an original Low York boiler in a Levitt house yesterday . The 60+ year old , 3/8 copper radiant is still up and running . Tried a Grundfos Alpha . For some reason the display told us it was moving 0 gpm , no matter what setting we had it at . On high speed it would ramp up to 15 watts max . On AutoAdapt it stayed a steady 5 watts . We pulled the motor off with the power still connected and the impeller spun but it seemed kinda slow even on the high setting . But since this is the first time I've seen one open I'm not sure . Kenny had to flip the orientation of the motor .



Anyone else have this happen with an Alpha ? The boiler temp didn't drop like a stone like I thought it would with radiant that was off for 6 or 7 hours . Even with the bypass temporarily closed . We changed the circ out with a 007 temporarily till we can come back with another Alpha .



Also , how low can you go with boiler pressure if the heating zone is lower than the boiler ? The homeowner wanted us to keep it as low as possible to help prevent the radiant from leaking in the future . There's no heat above the boiler . I set it at 10 psi , but I know on steam boilers with zones off the bottom there's no pressure on them except the weight of the water .



Thanks in advance .  

SWEI

Help prevent the radiant from leaking in the future

I'd take a serious look at the water chemistry.  Test, drain/clean/flush, then treat & monitor on a regular schedule.

Mark Eatherton

Nice install... Bad widget...

Hi Ron, Nice install as usual.





As for the Alpha, I think you got a bad one, because if you set it on the 3rd speed, manual setting, it should run at maximum speed, maximum wattage. Me thinks you got the one in a million defect.



As for minimum pressure in a low/no rise system, other than keeping entrained air in suspension, the only other requirement is maintaining minimum net positive suction head. (NPSH) to the pump.



Not sure what it is for the Alpha, but am certain its listed in their literature.



ME

Ron Jr._3

Water is fine

The system has been in operation 6 decades and is holding pressure . All these Levitt homes had radiant originally . Most of them have been converted to baseboard due to slab leaks . Some say it was the reaction of the copper to the concrete . Some say it was from the copper rubbing against the steel staples that held it in place on wood for the concrete pour . I've chopped enough floors and repaired enough leaks to honestly say they leak from the outside .



It's also a catch 22 . I could run a cleaner through the system but what if it causes a leak ? On these systems we try not to purge at all . Just add air cans to the supply and return and hope no air pockets form in the floor . Thanks SWEI .

Ron Jr._3

Thanks Mark !

A rare 1 zone boiler ! Sometimes we see 4 zones in these small homes .



I hope this is a rare issue with these circs , which I do like to use . This is probably only our 5th Alpha . Very weird looking impeller and I'm not sure what it's supposed to look like on high speed . I know what a 007 looks like and the Alpha on high wasn't nowhere near that  .



I'll take a look for minimum pressure in their lit . I'll guess we'll never see a job like this again , with one zone of radiant and no heat upstairs .

ChasMan

I had one..

I had one do it too. It worked ok for a couple of weeks but then it got flakey and finally ended up doing what yours did. I have another one in there now, it has started to go flakey as well but it is working. So I guess that is 3 in a million. I don;t like flakey things so the other Alpha will be coming out shortly. I may try a Wilo even though they cost double and don;t have IFC's. I think the IFC may be what breaks these things.

Steamhead

I had one that showed 0 GPM

turned out to be air in the volute. I loosened the motor bolts enough to get rid of the air and it worked after that. 

Robert O'Brien

Auto Adapt

I've had the same issues with 1/2" baseboard zones, put them on constant pressure and they work great