Bell & Gossett and Taco circulators are the quiet backbone of hydronic heating — boiler loops, radiant floors, commercial HVAC. They run for months without stopping, in hot water, and their seals face a distinctive set of conditions.
What is different about hydronic duty
- Continuous running. Fewer starts than almost any other pump, which is good for seal life.
- Sustained heat. Working against it. Elevated temperature ages elastomers steadily — roughly a doubling of ageing rate per 18°F.
- Treated water chemistry. Glycol, inhibitors and pH treatment vary by system and interact with elastomers differently from plain water.
- Long service intervals. Circulators are ignored until they leak, by which point the leak has often been ongoing for a while.
Material matters here
In hot water service, EPDM outperforms nitrile substantially — EPDM is excellent with hot water and steam where Buna-N degrades. If your system runs glycol, check compatibility before ordering, because the right answer depends on the mix.
Our material guide covers the trade-offs.
Finding your seal
- Bell & Gossett pump shaft seals — over 100 listed
- Taco pump shaft seals — nearly 100 listed
Listed by original part number, so you can order from the pump tag rather than measuring anything.
A leak on a heating system is not just a leak
Make-up water carries oxygen and fresh minerals into a closed loop, which drives corrosion and scale far beyond the seal itself. A circulator seal that has been weeping for a season has been quietly ageing the whole system.
Before you reassemble
Seat every o-ring with a thin film of food-grade silicone. Dry rings pinch and take a set. Aqua Flex Food Grade Silicone Lubricant is what ships in our kits.
O-rings only. Never lubricate the polished faces of a mechanical shaft seal.
Beaver Island Parts Company is not affiliated with, endorsed by, or sponsored by any equipment manufacturer named on this page. All brand names, model numbers and part numbers are the property of their respective owners and are used solely to identify the equipment our replacement parts fit.