Steam pressure gauge and pressure control switch on a WeilMcLain Model 68 steam boiler (C) Daniel FriedmanSteam Boiler Gauges
Guide to types, location, uses & how to read the pressure gauge on a steam boiler

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Steam heating boiler gauges: this article describes the pressure or sometimes combination & temperature gauges found on most steam heating systems. The steam oiler gauge gives helpful pressure readings that tell us if the boiler is operating normally.

The steam boiler pressure readings at a boiler can help diagnose problems abnormally high pressure levels that often mean problems with the steam heat distribution system or its piping. We give normal low-pressure steam heating boiler pressure numbers and we explain what variations from these data signify.

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Steam Boiler Pressure Gauge and Normal Pressure Ranges

Steam pressure gauge on a steam boiler

Pressure and Temperature gauge on steam heating boilers: Residential steam heating systems are almost always designed to operate at very low pressures, perhaps around .5 psi - that' s 1/2 of one psi.

You can see these pressures in our page top photo - both on the gauge and on the pressure controller.

You should see similar settings on the pressure gauge (at left in our photograph) and on the steam pressure control switch (the gray box at right in our photo) on your boiler.

The controls in this photo are discussed in detail



What Are the Normal Hot and Cold Operating Pressures of Residential Steam Heating Boilers?

Steam pressure gauge and pressure control switch on a WeilMcLain Model 68 steam boiler (C) Daniel FriedmanResidential steam heating systems are almost always designed to operate at very low pressures, perhaps around .5 psi - that' s 1/2 of one psi.

[Click to enlarge any image]

At left if you enlarge the image you'll see that the steam pressure gauge on this Weil McLain Model 68 steam boiler reads about 0.5 psi - a setting consistent with the pressure set and shown on the scale on the steam pressure control to the right of the gauge.

If your residential steam boiler is operating at higher pressures (take a look at the dial setting on
your PRESSURE CONTROL, STEAM BOILERS) , that may be an indication that a service technician or owner was having trouble getting heat distributed through the building. Rather than finding and fixing the problem, someone is trying to "force" the steam around the system.

An experienced steam heat service technician will look at the operating pressure of your steam heating boiler and if it is not set to a normal level, the technician will look for the reason. Examples of problems that can affect the flow of steam heat through the system, leading to attempts to over pressurized the system include

  • Blocked condensate returns at individual steam radiators
  • Steam radiators tipped the wrong way
  • Improperly relocated steam piping that has the incorrect slope
  • Radiator valves that are not operating,
  • Radiator steam vents that are not operating properly - STEAM VENTS

For details about radiator problems see RADIATORS



More about steam boiler gauges is at STEAM PRESSURE GAUGE.

Steam Pressure Gauges on Condensate Recivers

Condensate return sysem on steam heat (C) D Friedman

At the right side of our photo of a remote building steam condensate receiver and pump system we see a steam pressure gauge that is used by the service technician to monitor pressure in the steam heating systerm.

This added information can be helpful when a central steam plant is feeding steam to multiple buildings.

In this case the photo shows a condensate receiver and pump in a Poughkeepsie New York building that is across a major street and several thousand feet from a central steam plant.

The steam gauge shown in the photo at left is installed with an isolating valve - that blue handle below the gauge itself. The handle is in the "open" position - allowing steam pressure to be read as you can see that the handle is parallel to the connecting piping.

Watch out: some technicians leave the isolating valve or handle for remote gauges in the closed position when the gauge is not in use. This is a "safe" position that protects from pressure, steam, or condensate loss should the gauge become damaged.

See CONDENSATE RETURN PIPES, PUMPS, STEAM for details about steam condensate return systems & controls.

Steam Boiler Sight Glass Gauge: When & How Much Water to Add to the Steam Boiler

Steam boiler sight glass

If your steam boiler has an automatic water feeder you should see the water level always close to the fill-mark and the automatic water makeup valve will normally do this job for you.

When to add water to the steam boiler

If your steam boiler has only a manual valve for adding water, until you know the system's rate of water usage, you should check the water level at least once a week during the heating season.

You'll want to add water whenever the sight glass shows that the water level has dropped to the "add" mark and you should always see some water in the sight glass.

How much water to add to the steam boiler

The sight glass on a steam boiler, combined with a mark or gauge usually placed on the sight glass or on the boiler body behind the glass, will show the proper level to which the steam boiler should be re-filled when it's low on water.

See SIGHT GLASS, STEAM BOILER for details of this component.


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