View Full Version : Hot Side Pump Seizing

08-28-2018, 09:39 AM
Hey All,

We have a Thomsen centrifugal pump that we use for hot a cold side. After boil, we'll hook our pump to the kettle, then to the heat ex. After knock out, if we shut the pump off, it will seize up, requiring it to be broken down to clean out and cool off. Our particular model did have a recall for the seal, but the replacement hasn't seemed to work in this situation. There is no visible damage to the plate or o-ring, and it never has trouble cold side.

Just wondering is anyone has dealt with this issue, it's never been a problem for me in other breweries. The pump head is held on by a clamp instead of bolts, is this a pressure issue?

08-28-2018, 10:30 AM
My brewhouse has two Thomsen pumps. The mash/lauder pump has an internal seal, the kettle has an external. The external is held in place with a spring so it can only take so much back pressure. The difference is the external is designed for high temps, the internal is for under 180f. When I first started working with this brewhouse the kettle seal would wear out every 6 months b/c it was replaced at some point with an internal seal backplate. I changed it and have not had a problem since. Mine never seized, just leaked. Are you sure this is not a wet seal? What exactly is causing the seizure is it dried up malt glue, the seal, bearings?

08-29-2018, 06:55 AM
I used to have a couple of Thomsens. If I recall, you had to have about a credit card's width of clearance between the impeller and the back plate. If the impeller is too close to the backplate, it may be rubbing once it gets hot. I can't remember how to adjust it - I think it had a set screw that locked it to the motor shaft.

08-29-2018, 09:44 AM
My brew house pump has an external seal and I added a small bit of tubing that sprays water on it while brewing. It keeps the seal cool and lubricated and also prevents the sugars from building up. I just turn the valve enough so there's a steady stream of water hitting it. Haven't had any squeaks or problems with it in two years.