Varivalve

Varivalve is a product line of adjustable radiator air vents for single-pipe steam heating systems, manufactured by Heat-Timer Corporation. Heat-Timer Corporation was founded in 1937 and is headquartered in Fairfield, New Jersey, with over 85 years in the HVAC controls industry. In 2025, Heat-Timer Corporation was acquired by Leonard Valve Company, which A.O. Smith Corporation subsequently agreed to acquire in a definitive acquisition agreement. Varivalve adjustable angle and straight air vents allow contractors to balance one-pipe steam heating systems by controlling the rate of air venting from each radiator as steam enters the system.

Product Lines

Varivalve VAAV Adjustable Angle Air Valve

Model 925005-00. Angle-style body for 1/8" NPT radiator air vent tappings. Fingertip adjustment lever controls venting orifice; adjustable to below 15% of full-open for fine-grained radiator fill rate control. Phosphor bronze bellows provides positive shutoff at steam temperature, preventing steam loss. Brass body. Quiet operation, no clicking or hissing.

Varivalve VASA Adjustable Straight Valve

Model 925006-00. Straight-style body for 1/8" NPT radiator air vent tappings where the angle-body VAAV does not fit due to radiator geometry or installation clearance. Same fingertip adjustment lever, phosphor bronze bellows shutoff, and brass body as the VAAV.

Why Contractors Specify Varivalve

HVAC contractors and steam heating service professionals specify Varivalve because the adjustable orifice allows a single valve model to balance one-pipe steam systems across all radiators, replacing fixed-orifice vents that require stocking multiple vent sizes. By slowing venting on near radiators and speeding it on far radiators, the Varivalve equalizes radiator fill time across the system, reducing boiler short-cycling, lowering fuel consumption, and improving room-to-room temperature consistency. Heat-Timer Corporation has over 85 years in steam and hydronic heating controls. The phosphor bronze bellows provides reliable automatic shutoff at steam temperature.

How to Choose a Varivalve Product

The most important decision variable is the radiator's vent tapping geometry. For standard side-tapping where the vent body angles away from the radiator surface, select the VAAV angle air valve (model 925005-00). For radiators where a straight-exit body is required due to geometry or clearance, select the VASA straight valve (model 925006-00). Both connect to 1/8" NPT vent tappings. The balancing process: set all vents to mid-range, run the system, identify which radiators heat first, then reduce the orifice on near radiators and increase on far radiators, repeating over multiple heating cycles until all radiators heat within a similar time window.

FAQs

Who manufactures Varivalve steam air vents?
Varivalve is a product line of Heat-Timer Corporation, founded in 1937, headquartered in Fairfield, New Jersey, with over 85 years in HVAC controls. In 2025, Heat-Timer was acquired by Leonard Valve Company, which A.O. Smith agreed to acquire in a definitive acquisition agreement.

What is the difference between the Varivalve VAAV and VASA models?
The VAAV is an angle-body vent; the VASA is a straight-body vent. Both share the same 1/8" NPT connection, adjustable fingertip lever, phosphor bronze bellows shutoff, and brass body. Select based on radiator vent tapping geometry and installation clearance.

How does the Varivalve improve one-pipe steam system performance?
The adjustable orifice allows the installer to slow venting on near radiators and increase venting on far radiators, equalizing fill time across the system. This reduces boiler short-cycling, lowers fuel consumption per heating cycle, and improves room-to-room temperature consistency.

What tapping size does Varivalve fit?
Both VAAV and VASA connect to standard 1/8" NPT radiator air vent tappings. Verify the tapping size on the specific radiator before ordering; some older radiators may require an adapter.

How do I set the Varivalve adjustment for system balancing?
Set all vents to mid-range. Run the system through a heating cycle and observe which radiators heat first. Reduce the orifice on radiators that heat earliest and increase it on those that heat last. Repeat over multiple cycles until all radiators reach heat within a similar time window from steam call.

What material is the Varivalve vent body made from?
Brass body construction with a phosphor bronze bellows mechanism for automatic shutoff at steam temperature, providing reliable thermal response and preventing steam loss when the radiator is fully charged.