Beer Forum

Okey dokey, need some help with my system. I'm trying to line out my recently put together HERMS and am having some issues with the pumping.

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.

I'll ask the short bus question:

Did you prime the pumps? I don't have pumps on my system but the sounds like a priming issue.

Sounds like you are slowly picking up air and loosing your prime. I'd check fittings and hoses. Hose clamps are famous for letting in air. How is the pump orientated? Do you have a pic?

Make sure your QD isn't sucking air. That will kill your prime.

bassetbeer wrote: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.

Dude, you said "suck on the other end of the hose"... That was like an underhanded softball toss by a sixth grader...

Well, it seems that as I am writing this, both Bad Rock and Jay have asked the same question... Looks like are getting air in there somewhere. Check your connections. Use some teflon tape on the threads. Also, your pump should be parallel to the ground, and the head should be rotated so that the intake is on the bottom, and the output is on top.


Mylo

I don't have a pic handy, but I'll see what I can do.

But priming the pump shouldn't be an issue if the pump is located below the liquid level. Maybe an issue there, but I don't think so.

I do have to QD sets between the pump and the MT:

MT->Valve->femQD->mQD->hose->mQD->femQD->pump->femQD->mQD->hose-coil

I could be pullin' in air through the QDs but (1) I shouldn't loose the prime if I've still got liquid gravity flowing into the pump and (2) if the QDs were leaking wouldn't it be leaking liquid at the QDs downstream of the pump?

Am I missing something?

If you are pulling any air into the pump body, it is possible to stop flow. Once air is entrapped in there you are going to need more than 1.5 psi to push it out. I would check into and correct any air leaks at the QD's and see if that helps.

bassetbeer wrote:MT->Valve->femQD->mQD->hose->mQD->femQD->pump->femQD->mQD->hose-coil

I could be pullin' in air through the QDs but (1) I shouldn't loose the prime if I've still got liquid gravity flowing into the pump and (2) if the QDs were leaking wouldn't it be leaking liquid at the QDs downstream of the pump?

Am I missing something?

Nah, we are saying that you might have a leak on the suction side, not the output side... So you are sucking air in before the pump and losing your prime. If you had a leak on the pressure side - yes, you would have a liquid leak...

Your problem is in here, somewhere : MT->Valve->femQD->mQD->hose->mQD->femQD->pump

Also, what are the specs on your march pump? Is it one of those tiny ones? I think that when they say that a particular pump can pump up to 10 feet - they are assuming that you haven't reduced the diameter to 3/8" - which you have. Let me ask you this - when you do work out all the suction issues - is it just dribbling out? If so, you need a bigger pump, or a larger diameter heat exchanger.

BTW - I see that you said that you also have your HLT up at 200 degrees. I don't have a HERMS, yet - but I would think that that is too hot. You will probably short cycle, create a thermocline in your MT, and really impact your efficiency by denaturing all those enzymes...


Mylo