ECM Delta P Pumps - Seizing concern or no?

SpeyFitter

Many heating controls have an "excercising" function that periodically runs the pumps to ensure they do not seize. But due to the introduction of new ECM variable speed pumps that react to zone valves or actuators opening and closing, this is not an option unless there is somewhere for the pump to move water. So I'm curious if you guys see an issue that could be present here with these pumps in the future as they can't technically be excersized, unless of course there was a control that periodically triggers a zone valve or actuator to open.

Also, I know we're not into pricing here, but I won't mention any prices, but I priced out the cost of a Grundfos Alpha versus a Grundfos 15-58 with a differential bypass, 2 tees, and 2 male adapters and with 1/2 hour labour to instsall the differential it was roughly the same price. Makes it a no brainer to go with the Alpha. I priced the Alpha against a standard 15-58 on set speed in other applications as a fixed speed pump (i.e. main boiler circulator on a condensing set up) and with our current electricity rates where I live (fairly low compared to the rest of North America) based on the heating & indirect hours I anticipated it would be on for (conservatively) it would take around 14 years to pay back as far as efficiency versus price of electricty versus hours on is concerned. That is a ball park though for my area. In areas where electricity is higher, it may pay back sooner.  

Unknown

ECM Starting Torque

Scott, one of the cool things about ECM technology is the use of a permanent magnet rotor.  Driving a perm mag rotor with the magnetic field from the stator windings increases the starting torque by 3 to 4 times over s standard pump.



Our residential ECO has a "de-blocking" function where if the rotor does stick and the high starting torque doesn't work, it goes to max power.  If still stuck it goes into a vibration mode.  Don't know about the Grundfos Alpha but I assume it would have a similar feature.



There is an optional "External Off" interface module that can be used with the larger Stratos.  Break the Ext Off circuit and the motor is turned off.  The pump then automatically exercises itself once every 24 hours (and this exercise is recorded in the data logger).



Interesting cost analysis by the way...



Hope this helps...