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Grundfos 15-55FC pump question/problem
in Gas Heating
Last January I had a Viessman WB2B 9-26 gas boiler installed in my house converting from an oil baseboard system . Performs wonderfully since heating bills have decreased dramatically. I decided to go with the Grundfos 15-55FC variable speed pump to supply flow for 3 zones. (two of which are operational one for future addition) . I've had 3 instances where the zone valve or valves are calling for heat but the LED displays on the pump remain in a what seems like a OFF condition. Since the pump has no reset button I have had to power off the boiler an power it back on to reset the pump. Any idea what would cause this problem? Grundfos tech support are closed through the holiday so couldn't contact them. Anybody encounter this problem before?
That circ must remain powered all the time.
That circulator must remain powered all the time. When the variable speed circs first hit the market, we wired them like we always did, providing power by using the Zone Valve end switch to activate a Circ Relay. However, those must have constant power.
I wire them off the boiler power now. If no zone valve opens then they are in standby.
Unless you are a heating tech or an electrician, you probably shouldn't try to change this yourself.
Call a professional.0
Grundfos Alpha Plug-in
The Grundfos Alpha was installed using the plug-in option which required no special wiring. It is using the same box as the Viessman boiler. Being the homeowner I'm quite comfortable doing the research necessary but I will have any work done by a licensed contractor. Any other thoughts?0
You say that resetting the boiler will power-cycle the pump. Where did you reset the boiler? At the boiler? Or at the service switch/breaker?
If you're plugged into the wall and the boiler is not controlling the pump, there's no way that the pump should get power-cycled when the boiler is reset.
Also: which mode are you using? AutoAdapt or one of the constant-pressure modes?0
The alpha is plugged into the same junction box as the boiler and is running in autoadpt mode. This has happened once more since last post. It seems to take a very long time for the pump to come out of standby mode. The Viessmann readout shows temps ranging from 150 to 167 for about 3 to 5 minutes before the alpha kicks on. Any thoughts as to why the lag time or for that reason why I need to reset the pump by unplugging it??? Tried Grundfoss but was on hold for a extremely long time before giving up. Will try local (Hartford Ct ) rep.0
But try this: rather than running in AutoAdapt, pick one of the fixed differential pressure modes. Start with the middle one, I guess. See whether you run into the same problem. When you power-cycle the pump, it forgets what it learned, so that would explain why it's kicking in. I don't know what's causing it to respond so slowly in AutoAdapt, but chances are that you could run happily in one of the fixed dP modes anyway.
For what it's worth, I got the hard-wire type Alpha, and have it wired as the boiler pump (boiler turns it on/off.) I will not be using AutoAdapt.0
Wait a minute.
Are you wired into the 20 plug on the Pump Power module?
If so then this only is energized when the boiler is ready for it to be. That explains your lag time. Put the circ on a grounded whip and plug it into the outlet that the Pump Power module is plugged into. This will leave the circ powered all the time. It will work in Auto Adapt mode then. I do it all the time.
The 20 plug is energized through the control on the Vitodens. It is de-energized during a call for DHW, warm weather shutdown and a whole host of other reasons.
Try plugging it into the outlet and see if it works. I bet it will.0
Just wanted to say THANKS for the input and feedback . Switching outlets seems to have resolved the problem. You guys are amazing! Your ability to remotely diagnosis and remedy problems is why this site is a true resource!! Thanks again!!0
MEPlumber Quick Question
If your utlizing the LLH Sensor and zoning with VZ's why do you need to use the 20A plug? We simply wire the system pump to the zone valve control. If a valve opens the pump runs. When you use a LLH sensor the boiler supply sensor in the boiler becomes disengaged. As soon as the LLH sensor senses flow/temp change the boiler will fire if need be. The only time we use the 20A plug is if we are running constant circulation and utilizing a Vitorol. The boiler pump a 15-58 is wired to the 20 plug. If he used an Alpha as a boiler pump he cannot use the autoadapt feature. He has to use the setpoint feature and keep a constant gpm across the boiler. If not the boiler flow sensor won't allow the boiler to fire if he cannot keep the minumum 1.7gpm flowing through the heat exchanger . The 15-58 spec for the boiler is based on keeping a 40 degree delta-t across it."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."0
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