ASCO Series 159/158 Gas Valve & Motorized Actuator: A Complete Guide for Combustion Systems

A practical guide to the ASCO 158 gas valve and 159 motorized actuator — what they do, where they fit, and how to choose the right configuration for your burner or combustion application.

What the Series 158/159 is

The ASCO Series 158 gas valve and Series 159 motorized actuator are a compact, modular safety shutoff solution built for gas burner and combustion equipment. The 158 is the valve body; the 159 is the motorized actuator that drives it. Together they deliver reliable on/off and modulating control with strong flow performance and high peak-pressure handling, which is what combustion systems demand when they need both safety and efficient heat output.

If you run package burners, thermal oxidizers, or industrial heating equipment, this is the platform worth understanding — because the right configuration can eliminate extra components, reduce installation labor, and improve the heat output of your application.

Where it fits: typical applications

The 158/159 platform is designed for demanding combustion duty, including:

• Package burners and boilers

• Metallurgy and heat treating

• Crop and grain drying

• Paint curing

• Baking and food-process ovens

• New and retrofit burner installations

• Regenerative Thermal Oxidizers (RTOs)

If your system is in one of these categories — especially anything 1.5" and larger, or any fuel-train application where flow and close-off pressure matter — this platform is built for it.

Why it's specified: the real advantages

Most combustion buyers care about four things: safety, flow, installation cost, and reliability in tough conditions. Here's where the 158/159 earns its place.

High flow factor

The 158/159 delivers a higher flow factor and operating-pressure tolerance than many comparable combustion valves. In practice that means high heat output with very low pressure drop — you get the flow you need, often with one size smaller body than you'd otherwise spec. Poor flow factor is a common cause of reduced heating output; this platform is built to avoid that.

High close-off pressure for genuine safety

The valve offers a close-off pressure of up to 75 psi (5 bar). That's the figure that matters in a fault: if an upstream regulator fails, the valve still seals. High close-off can eliminate the need for additional overpressure protection devices in many systems — fewer components, lower cost, same safety margin.

Built to simplify installation

A few design choices cut real labor and parts cost:

• Integrated end-connectors and double-valve design with integrated vent port — the double design doesn't require a separate vent kit, which is a common hidden cost on competing double-valve setups.

• Mountable in any position, including head down — fewer layout constraints in tight burner cabinets.

• Optional NPT/ISO threaded or ANSI/ISO flanged adapters — flexible connection without re-engineering your train.

• Backward actuator compatibility with the legacy V710B — useful on retrofits.

• Compact, modular body reduces footprint.

Reliability in tough conditions

• Wide temperature range: -40°F to +150°F (-40°C to +66°C) — including reliable cold-temperature operation that many actuators can't match without an electrical heater.

• Watertight Type 4 & IP65 enclosure — indoor or outdoor.

• Certified as a gas safety shutoff valve carrying FM, UL, CSA, and EN161 Class A approvals, supporting compliance with NFPA 85, NFPA 86, EN 676, and EN 746-2. Also RoHS compliant.

• Fast spring-return closure of less than one second.

• Visual position indication on both sides, with optional proof-of-closure and optional auxiliary switches for valve-position feedback.

 

Configuration options: matching the valve to the job

The platform is flexible, which is its strength — but it means you need to pick the right configuration. The main choices:

Single vs. double valve. Double-valve (block-and-bleed style) construction provides two shutoff points for higher safety integrity, and the integrated vent port keeps it from getting expensive on larger sizes. Single-valve works where one shutoff point meets code and risk requirements. Double designs are generally more suitable for fuel-train applications 1.5" and larger.

Actuator type (the 159 part). The 159 actuator comes in several control modes:

• On/Off — slow-opening or fast-opening

• High/Low/Off — for intermediate firing-position control on commercial/industrial burners

• Pressure-regulating — for applications needing modulated pressure control

Slow opening helps avoid blowing out the pilot flame on light-off; fast opening gets you to position quickly. High/Low/Off gives you an intermediate firing rate. Match the actuator mode to how your burner needs to fire.

Optional features worth knowing:

• High/Low/Off option for intermediate position control

• Optional damper shaft and arm for integration with traditional burner linkages

• Optional inline strainer for debris protection

• Optional auxiliary switches and proof of closure for position confirmation

How to choose: a quick decision framework

1. Size your flow first. Pick the body size off your required flow and acceptable pressure drop — the high flow factor often lets you go one size smaller, so don't oversize by habit.

2. Determine your safety requirement. Does code/risk call for single or double (block-and-bleed) shutoff? Larger trains (1.5"+) often want double.

3. Match the actuator to your firing sequence. On/off vs. high/low/off vs. pressure-regulating; slow vs. fast opening.

4. Confirm close-off pressure against your worst-case upstream pressure. Up to 75 psi (5 bar) available.

5. Add position feedback if your system needs it — proof of closure and/or auxiliary switches.

6. Check connection type and environment — threaded vs. flanged, indoor vs. outdoor (Type 4/IP65 covers both).

Not sure on a configuration? That's exactly the kind of question our technical team handles — sizing and configuration support is part of what you get buying through us, not an upsell.

 

Get the right 159/158 configuration

We stock and ship ASCO 158 gas valves and 159 actuators, and we'll help you spec the right configuration for your burner or combustion system — including sizing, single vs. double, and actuator selection.

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Need help selecting? Call us at 908-320-8240 or email orders@ecdistco.com. We serve NJ, Metro NY, and Greater Philadelphia for service, and ship parts nationwide.