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Gas Regulators 101: How They Work and Why Your Project Might Need One

In the HVAC market, there is a near-constant use of gas fired appliances, ranging from small unit heaters to large scale condensing boilers. In both small and large appliances, the concept is the same: A gas supply line (for this article we will assume natural gas) is routed from the city or municipality to the pressure reducing station on the job site.

The engineer of record will typically size the gas line to the appliances for what gas pressure is available onsite. The question is now: What if the appliance cannot accept the gas pressure coming from the gas supply?


The answer is in the name. Gas regulators are devices that “regulate” incoming gas pressure. Regulators are used to reduce the gas pressure from a high pressure to a lower pressure usually before a gas appliance is used. Each appliance has a factory recommended gas pressure range that is required to ensure the proper performance of the appliance.

It is typical for gas pressure to be measured in inches of water column, or X" WC. This quite literally means the gas pressure could lift a 1”x1” column of water X inches. It is common for a main gas supply line to deliver 10, 5, or 2 PSI into the building and for a regulator to be installed upstream of the appliance.

An example of a typical incoming gas pressure range for a condensing boiler would be 6-10” WC. This means for proper function of the condensing boiler, the incoming gas supply should be anywhere from 6" WC to 10” WC. This allows each appliance to get the correct gas pressure by means of the gas regulator “knocking down” the incoming gas supply. So, how is a gas regulator constructed?


Most gas regulators are constructed similarly. The inlet side of the regulator is where the gas supply enters and there is typically a valve that opens and closes by the force of a spring pushing on a diaphragm at the top of the regulator.

In some regulators, such as the Pietro Fiorentini models, there is a balanced valve design. This design helps to control the outlet pressure by a balancing piston creating an equal force to the inlet pressure. The outlet gas pressure is now reduced to the spring setpoint per the appliance.

As the gas pressure is reduced, the gas will exit the outlet side and be delivered to the appliance.

A diagram of a Petro Fioentini gas regulator
Image courtesy of Pietro Fiorentini

At this point, you're probably thinking 'I think I need a gas regulator — but where can I get one?'


Hoffman Hydronics has Pietro Fiorentini gas regulators in stock at our warehouse in Greensboro, NC. Feel free to reach out to the Hoffman Hydronics sales team to help you size and select gas regulators for your next project!

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