John Molyneux
Member
My system is piped primary/secondary. There's a 3-speed pump inside the boiler that I have on its lowest setting. I have a Grundfos Alpha that supplies water to the zones that I've been running in 'auto-adapt' mode.
When the system is stable at near-design outdoor temps the Alpha indicates it's pushing about 3 gal/minute with 13 Watt energy use to the primary zone (the second zone is much, much smaller). Under those conditions it appears the boiler pump is running at a slightly higher speed than the Alpha. In other words, I can detect some (but not much) 'backflow' across the primary/secondary header meaning that some of the hot water coming out of the boiler is being recycled back into the boiler and is therefore diluting (slightly increasing the temp of) the return water from the radiators before it enters the boiler.
Is it correct to assume that the flow through the pri/sec header should be neutral, or at least mildly positive toward the radiators, such that the boiler is seeing the lowest return water temps it can? Should I manually bump up the speed of the Alpha?
Thanks!
When the system is stable at near-design outdoor temps the Alpha indicates it's pushing about 3 gal/minute with 13 Watt energy use to the primary zone (the second zone is much, much smaller). Under those conditions it appears the boiler pump is running at a slightly higher speed than the Alpha. In other words, I can detect some (but not much) 'backflow' across the primary/secondary header meaning that some of the hot water coming out of the boiler is being recycled back into the boiler and is therefore diluting (slightly increasing the temp of) the return water from the radiators before it enters the boiler.
Is it correct to assume that the flow through the pri/sec header should be neutral, or at least mildly positive toward the radiators, such that the boiler is seeing the lowest return water temps it can? Should I manually bump up the speed of the Alpha?
Thanks!