Heat Ex Issue

[Mills]

I had the following problem occur the other day while knocking out a 15bbl batch. Here are the details: With 4bbls remaining in the kettle, I began experiencing temp spikes in my runoff. My heat ex is set up to run both with city water and glycol, but it is piped to run water on both sides. I control the temp of my runoff by varying the speed of my pump with a variable speed drive. Typically I turn up the speed of the pump during runoff to maintain a temp of 70 degrees. I do this by adjusting my vsd up in increments of .5 and this will give me a runoff temp increase of a few degrees. City water is still freely exiting both portions of the heat ex so there is no flow issue there. Any thoughts on why this is happening?

Thanks

[brewman21]

I would suggest, it might be a spike in incoming cold water supply, it happens to me occasionally. As your nearing the end of the transfer, you are pushing into a fuller tank with alot more resistance than in the beginning, so it moving thru H/X at a slower rate, unless your increasing speed on pump with VFD. A combination of the two, and dialing in a even transfer rate thru H/X may be the problem??
At our place, I increase flow rate near the end to maintain even transfer rate, by opening my butterfly(at ferm.) more as it nears end of knock-out. This is my only way to control flow rate, as I don't have a VFD drive on my pump.
I control pitch temp, by throttling the cold water supply ball valve, our water is so cold year round, I never have it more than 1/4 opened, maybe closer too 1/2 way in dead of hot summer months. It's so sensitive, that if you just bump it a C**t-hair in either direction, the temp can spike up or down 10F just like that!! I dont't even move it from it's sweet spot ever, I have another solenoid controlled valve before this one to turn the cold water supply on or off, so I never have too move it from that sweet spot.
Are you having issue's getting the wort cool enough?? Are you running cold water in at full pressure or slowing it down??

[rudge75]

Got caught by something like this a while back:
Check your supply pipe going from the kettle to the pump. It could be bunged up with protein deposits and or hops thereby causing a weak flow to the pump head. If it's a hard pipe, pull it, clean it and weigh it before reinstalling so you have a reference for next time.

[scmorgan]

Old plant i worked at had varying ambient water temps, in summer you had to hit it full tilt, and it would go up and down all throughout the run off.

Used to turn the tank temp on to help knock out any temps over expected.

[MPKill]

Cold Water

Do you have anything else going on in your brewery with the cold water? I found that I can't run my keg cleaner at the same time as my transfer to the FVs. During a cold water rinse cycle on the cleaner, my heat exchange temp would spike a little. About 5 degrees or so. Not a big deal, as I can wait 45 minutes to clean kegs.


Cheers,
Mike