Temperature Controllers, Valves, Aquastats, Humidistats

A sometimes overwhelming aspect of HVAC and glycol chiller systems is deciding how much control is required, and finding just the right solution get the job done with out blowing the budget! While customers are welcome and encouraged to bring their own controllers to their configurations, we're sometimes limited in the level of support we can provide for those one-off installations, though we're always happy to try! In order to make basic controller decisions a little easier on our customers we provide a few options for the most frequently used controllers with which we have experience. What follows is a short list of aquastats, thermostats, humidistats, and flow control devices which should make your installation and usability as easy and efficient as possible.

Penn - A421 Temperature Controller Single-stage SPDT

The A421 Series controls are single stage, electronic temperature controls with a single-pole, double-throw (SPDT) output relay. The controls feature an adjustable backlit LCD for viewing the temperature and status of other functions, and a three-button touchpad for setup and adjustment. An LED indicates the On/Off status of the output relay.

The A421 controls are available in low voltage 24 VAC and high voltge 120 or 240 VAC models, which provide options for most refrigeration and HVAC applications.

Johnson Controls - High Pressure Cut-off Switch SPST (475/600) (P100CP-165C)

The P100 series are encapsulated, non-adjustable, direct mount pressure controls typically used for low and high-pressure cut-outs for OEM applications. The P100 series are produced according to switchpoint requirements of customers. The small dimensions, weight and protection class makes the P100 series applicable for use without the need of additional mounting brackets. The P100 series can be used for all non-corrosive refrigerants.

Hydro Innovations - Resistat Water Temperature Controller (Installed With Valve)

The Hydro Innovations Resistat is a simple, set-it and forget-it device intended to maintain temperature in reservoirs. The stainless steel temperature probe offers protection against corrosion due to long term exposure to water and harsh chemical nutrients. Simple place the probe in the reservoir you wish to control the temperature of, set the dial to the desired temperature, then plug in your electronically actuated valve to control chilled water flow through your heat exchanger device.

Rheostat Fan Speed Controller

These Rheostat fan speed controllers are an easy and inexpensive way to provide variability to the output of your unit heater, as well as modulate fan noise. They're compact, light weight, and can be used with just about any kind of fan or high velocity blower.


  • Three Settings: Off / Full Speed / Variable Speed (High-Low).
  • Heavy duty HDPE construction for durability.
  • Easy to install and use!
  • Built-in and easily replaced 15A fuse.
Hygge - Aquastat Probe Well

These probe wells are intended to protect aquastat probes from the corrosive harshness of most hydronic/water/glycol systems. These very simple devices will add many years to your aquastat probes vs. directly immersing probe ends into your reservoir or manifold system. Made primarily of copper, these wells are safe for potable water, easy to clean and care for, and provide great thermally conductivity for quick and accurate measurement of your system's water temps.

Johnson Controls - Networked Thermostats & Humidistats

The TEC3000 Series Thermostat Controllers are stand-alone and field-selectable BACnet® Master-Slave/Token-Passing (MS/TP) or N2 networked devices that provide on/off, floating, and proportional control of:

Ranco - Aquastat / Electronic Temperature Controllers

The Ranco ETC is a microprocessor-based family of temperature controls designed to provide on/off control for commercial heating, cooling, air conditioning and refrigeration applications. With its wide temperature range, one and two stage capability, selectable heating/cooling modes and multi-voltage input, the ETC is one of the most versatile temperature controls available.

Honeywell - Valve Actuators (Actuator Only)

The VU844 Valve Actuators, and VU52, VU53 and VU54 Valve Bodies, will control hot or chilled water in commercial HVAC equipment such as fan coil units, terminal reheat coils and convectors. These valves are humidity resistant and are suitable for use in condensing, non-corrosive environments.

Port-All Manifolds - Brass Manifolds For PEX

Our Port-All Manifolds provide an amazing value that's hard to beat! These manifolds are come standard with generously large Supply & Return ports, 1/2" PEX quick connect circuit ports, gauges to monitor temp and pressure, both circuit level and system level valves for maximum control and ease of maintenance, air vent, and fill/drain ports. It's never been easier to multi-task your water chiller to provide cooling to multiple heat exchangers and achieve climate control in multiple spaces!