All Temperature Regulators
508 products
About Temperature Regulators
A temperature regulator is a self-contained control valve that holds a process at a set temperature without any external power. A liquid-filled sensing bulb sits in the tank or line you want to control; as the temperature rises, the fill expands, and that expansion travels up an armoured capillary to an actuator that strokes the valve. No electricity, no instrument air, no controller and no control loop to tune.
That is the whole appeal. On a hot-water storage tank, a lubricating-oil cooler or a jacketed vessel, a temperature regulator does one job reliably and keeps working through a power failure. Every regulator listed on this page is a Watson McDaniel W94 series unit; the non-indicating W91 version of each is available on request.
Which regulator do you need?
Pick by what the valve has to do when the process gets too hot:
- Heating with steam — direct-acting, normally open. The actuator drives the stem in-to-close as temperature rises, throttling the steam back. This is the classic tank-heating and heat-exchanger regulator.
- Cooling — the reverse action. The valve opens as temperature rises, admitting more cooling water or glycol. Used on oil coolers, jacket cooling and condenser water.
- Mixing & diverting (3-way) — a three-port body that blends a hot and a cold stream to a constant blended temperature, or splits one stream between two paths. Common on tempered-water skids and heat-recovery loops.
W91 or W94 — indicating or not
The two series are the same regulator with different actuator tops:
- W94 carries a 3-1/2" temperature indicating dial. The operator can read the actual process temperature at the valve and set the adjustment against it. Specify W94 when anyone will need to verify or tune the setpoint without a separate thermometer.
- W91 is non-indicating and has a noticeably lower profile. Specify W91 where headroom above the valve is tight — not listed on this page; call 888-825-8800 to order.
Sensing bulb and capillary
The bulb and capillary are available in copper or stainless steel. Copper transfers heat better and gives faster, tighter temperature control, so it is the default choice — use stainless steel when the medium around the bulb is corrosive. Longer capillary runs require a longer sensing bulb to develop enough fill volume to stroke the valve, so bulb length and capillary length are specified together.
The bulb installs through a union hub threaded into the tank or pipe. The bulb slides through the hub and a union nut spins freely around the armoured capillary and threads into the hub, so the bulb seals metal-to-metal and can be withdrawn later without cutting the capillary.
Getting the range right
Each regulator is supplied for a nominal temperature range. The recommended working span sits in the upper third of that nominal range for single-seat in-to-close valves, all double-seat valves and all 3-way valves. Selecting so your setpoint falls in that upper third gives the system a faster temperature response. Choosing a range where the setpoint sits near the bottom is the most common cause of sluggish control.
Construction
- Heavy-duty die-cast aluminum actuator housing with a fully enclosed bellows assembly.
- An internal over-range protection spring that protects the thermal system if the process overshoots the regulator's range.
- Valve sizes 1/2" through 4", in NPT-threaded and flanged bodies.
- Self-operating — no external power source of any kind.
Not sure which one to specify?
Temperature regulators are one of the easier products to get wrong on paper — the action, the range and the bulb material all have to match the application. Our team in Exton, Pennsylvania has been specifying valves since 1965. Call 888-825-8800 with your medium, your setpoint, your line size and where the bulb is going, and we will work through the selection with you. Expedited shipping on request.
Frequently Asked Questions
A temperature regulator is a self-operating control valve that holds a process at a set temperature without external power. A liquid-filled sensing bulb is installed in the tank or line being controlled. As the temperature rises the fill expands, and that expansion is carried through a capillary tube to an actuator that strokes the valve. There is no electricity, no instrument air, no controller and no control loop to tune — which is why these valves keep working through a power failure.
They are built the same way but sense different things. A pressure regulator senses the pressure of the fluid itself and modulates to hold a pressure setpoint. A temperature regulator senses temperature at a remote bulb — often in a tank several feet away from the valve — and modulates to hold a temperature setpoint. A temperature regulator is not a pressure-reducing valve and will not control downstream pressure.
They are the same regulator with different actuator tops. The W94 has a 3-1/2" temperature indicating dial, so an operator can read the actual process temperature at the valve and adjust against it. The W91 is non-indicating and has a lower profile, which matters when headroom above the valve is limited. Specify W94 if anyone will need to verify or tune the setpoint without a separate thermometer.
Copper unless the service is corrosive. Copper has better heat-transfer properties than stainless steel, so it responds faster and gives tighter temperature control. Choose a stainless steel bulb and capillary when the medium surrounding the bulb would attack copper. Note that longer capillary lengths require a longer sensing bulb to operate the regulator, so the two are specified together.
Select so that your setpoint falls in the upper third of the regulator's nominal range. That is the recommended working span for single-seat in-to-close valves, all double-seat valves and all 3-way valves, and it gives the system a faster temperature response. Sizing so the setpoint sits near the bottom of the nominal range is the most common cause of sluggish control.
Decide by what the valve must do when the process gets too hot. For heating with steam, you need a direct-acting, normally open valve that closes as temperature rises (in-to-close) to throttle the steam back. For cooling, you need the reverse action — the valve opens as temperature rises to admit more cooling water or glycol. A 3-way mixing and diverting valve blends a hot and a cold stream to a constant blended temperature, or splits one stream between two paths.
No. These are self-operating regulators — the energy to move the valve comes from thermal expansion of the fill in the sensing bulb. No electrical supply, no instrument air and no positioner is required. That makes them a common choice where running power to the valve is impractical, and it means the valve continues to control during a power outage.
Valve bodies run from 1/2" through 4", in NPT-threaded and flanged configurations. The actuator uses a heavy-duty die-cast aluminum housing with a fully enclosed bellows and an internal over-range protection spring that protects the thermal system if the process overshoots the regulator's range. For help matching a body size, connection and range to your application, call 888-825-8800.