My system:
3 Converted kegs HLT, MT, and Kettle. Bazooka screen in the bottom of the MT coming out to a walve and QDC (QDC centers all drilled out for better flow / less plugging). QDC to hose to intake of march pump mounted about 6" below valve on the MT (~2.5-3" below bottom of MT). Pump out to hose, pumps up ~36" to top/in of heatxer coil (B3 25' 3/8" Chiller) in HLT (typically ~200F, just below boiling). Top/out of coil runs back into top of MT. Pump is controlled off a digital TC with the thermocouple dangling in the MT because B3 hasn't shipped the #$%^ thermowell that it's going to be in (not their fault - manufacturer delays, etc.)
My problem:
Temp control works great. Precisely on time. Pumps running. Nothing comes out. Can hear it surging or sitting there spinning (yes, even though I like turtles, I did remember to open the valve). If I create a siphon (i.e. suck on the other end of the hose), fabulously hot runnings come out a good clip. This works for 2 or so minutes, then it starts slowing down until the flow stops - pump's still running. This process is repeated several times until, hopefully, it reaches temp and shuts off. Doppelbock last weekend never reached temp profile I wanted. However, in a previous batch everything worked the way it was supposed to (without the siphon subroutine). Weird.
My guess(es):
Am I exceeding the net pressure the pump can put out? If so, any idea what I should try? Lower the HLT? (
great. less gravity feed, more pumping) Reduce the length of the coil? ( great. hack up a perfectly good chiller coil or make a new one - either way less heat transfer) Am I doing something wrong with the pump? ( great. I'm an idiot - 'course that's probably true anyway) Is the pump old/worn out? Do I need a new pump? ( great. wifey's already not thrilled with the money-sink-on-wheels in the garage that I can't even drive to work)
Anybody have similar issues or can offer advice? Any help would be appreciated.
