Bell & Gossett Comfort-Trol Zone Valves

Bell & Gossett Comfort-Trol Zone Valve replacement parts are service components designed to restore failed or leaking Comfort-Trol zone valves on hydronic heating and cooling systems without replacing the entire valve assembly. The two core service parts carried here are the Heat Motor Assembly (SKU 189137) and the Seal Kit (SKU 189138), each targeting a specific failure mode in the CT-24, CTS-7524, and CTF-10024 Comfort-Trol valve family. For contractors managing aging multi-zone hydronic systems, stocking the right Bell & Gossett Comfort-Trol replacement parts means a valve that stops working in January doesn't require a pipe-cutting job to fix.

KEY SUBCATEGORIES / PRODUCT TYPES

SKU 189137 is the Heat Motor Assembly for Bell & Gossett Comfort-Trol Zone Valves, replacing the internal power pill and heater element inside the operator. It's compatible with the CT-24, CTS-7524 (SKU 109017), and CTF-10024 Comfort-Trol operators. The heat motor is the component to target when the power pill discolors from copper to gray or black, or when wax leakage appears around the piston. Replacing the Heat Motor Assembly instead of the full operator (SKU 109024) saves hardware cost and cuts repair time on a system that's already down for heat.

SKU 189138 is the Seal Kit for Bell & Gossett Comfort-Trol Zone Valves, sold as a pack of 6. The Seal Kit addresses leakage around the valve stem or the underside of the knurled head on the CT-24, CTS-7524, and CTF-10024 valve bodies. The Comfort-Trol is a backseating valve, so the seal can be replaced without draining the hydronic system, making SKU 189138 a practical mid-season repair. Only silicone grease should be used on the gland pin and O-ring seals during reassembly. Petroleum-based lubricants will cause swelling and failure of the U-rings.

BUYING GUIDE / HOW TO CHOOSE

Choosing between the Heat Motor Assembly (SKU 189137) and the Seal Kit (SKU 189138) starts with identifying where the Comfort-Trol zone valve has failed. The two failure modes don't overlap, so diagnosis is straightforward.

If the valve isn't opening when the thermostat calls, the heat motor is the likely cause. Pull the operator cover and inspect the power pill. A copper-colored pill is healthy. A pill that's turned gray or black, or shows signs of wax leakage around the piston, needs to be replaced. That's SKU 189137. If switches have also failed alongside the heat motor, the full CT-24 operator (SKU 109024) is the right move instead of the Heat Motor Assembly alone.

If the valve is cycling normally but water is showing up around the stem or the underside of the knurled head, the seal is the problem. That's SKU 189138. The Comfort-Trol's backseating design means the repair doesn't require draining the system or cutting pipe. Remove the operator, pull the old seal, and replace it carefully without disturbing the spring-loaded valve disc underneath. Use only silicone grease. Nothing petroleum-based goes near those O-rings.

For contractors running multi-zone residential systems, keeping both SKU 189137 and SKU 189138 on the truck covers the two most common Bell & Gossett Comfort-Trol Zone Valve service calls without carrying a full valve assembly. A pack of 6 seal kits (SKU 189138) is a smart investment on any property with multiple Comfort-Trol valves in service.

FAQs

What does the Bell & Gossett Heat Motor Assembly (SKU 189137) replace, and which valve models is it compatible with?

The Bell & Gossett Heat Motor Assembly (SKU 189137) replaces the internal power pill and heater element inside the Comfort-Trol operator. It's compatible with the CT-24, CTS-7524, and CTF-10024 Comfort-Trol zone valve operators and is the correct part when the power pill has discolored or shows wax leakage around the piston.

How do you know if a Comfort-Trol zone valve needs the Heat Motor Assembly (SKU 189137) versus the full CT-24 operator (SKU 109024)?

The Heat Motor Assembly (SKU 189137) is the right part when the power pill has failed but the operator housing and switches are still functional. The full CT-24 operator (SKU 109024) is the correct choice when switches have also failed or when the entire operator needs to be replaced. Inspecting the power pill color and the switch contacts before ordering determines which repair is needed.

Does replacing the Comfort-Trol Seal Kit (SKU 189138) require draining the hydronic system?

Replacing the Bell & Gossett Comfort-Trol Seal Kit (SKU 189138) does not require draining the system. The Comfort-Trol is a backseating valve, which allows the seal to be replaced with the system live. Care must be taken not to disturb the spring-loaded valve disc during seal removal and reinstallation.

What lubricant should be used when installing the Comfort-Trol Seal Kit (SKU 189138)?

Only silicone grease should be used on the gland pin and O-ring seals when installing the Bell & Gossett Comfort-Trol Seal Kit (SKU 189138). Petroleum-based lubricants will cause swelling and failure of the U-rings, per Bell & Gossett installation manual V01348H.

How many seal kits come in one order of SKU 189138, and when does it make sense to stock multiples?

SKU 189138 is sold as a pack of 6 seal kits for the Bell & Gossett Comfort-Trol Zone Valve. For contractors servicing multi-zone residential or light commercial hydronic systems with multiple Comfort-Trol valves in service, a pack of 6 covers several repairs from a single order and reduces callbacks caused by a repeat stem leak on adjacent zones.