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What Does a Hartford Loop Do? The Purpose of This Boiler Structure and Common Installation Errors

Invented in 1919, the Hartford loop was a game-changer in the boiler industry; the component, together with modern low-water shutoffs, prevents the unsafe and unstable operation of steam boilers. Before the invention of the loop, cracked and exploding boilers plagued the industry. One insurer, the Hartford Steam Boiler and Inspection Company, founded in 1866, grew tired of the dangerous issues and created the design, putting immediate mandates into effect. Consequently, the design became an industry staple, but what does a Hartford loop do exactly?

What Does a Hartford Loop Do, and Why Is It Necessary?

Understanding the Design

The Hartford Loop may not seem particularly groundbreaking. On the surface, it is a series of interconnected pipes that extends between the header of a steam boiler and the gravity return. The loop helps maintain the pressure balance between the steam feed to radiators and the return feed of condensation to the boiler. Condensed steam or water returns to the unit below the operating water level, lower than the lowest level by at least 2 inches. While the additional piping of the design may seem redundant, it serves a significant purpose: safety.

Acknowledging the Necessity of the Design

At first look, one might believe that the Hartford loop design is a case of over-engineering. After all, can’t an installer connect a return line directly to the boiler below the required 2-inch mark? Technically, an installer can do this, and prior to the invention of the Hartford loop, it was standard practice.

The problem with this installation method is that it fails to consider the pressure within the boiler. With a return line directly connected, any pressure within the boiler pushes all the water from the system into the line. So, what does a Hartford loop do to address this? It prevents dry-firing by balancing the system.

Before the Hartford loop, installers used check valves to eliminate backflow issues, but the valves often failed in the open position. Failures meant water still escaped the system, resulting in cracks and explosions. Old steam boilers relied on coal to fire and heat. Without water in the system, the boilers super-heated. The addition of water caused volatile reactions and presented significant safety risks to operators.

The Hartford loop is a piping configuration that came out of frustration and necessity. The Hartford Steam Boiler Insurance Company, tired of paying out on policies and frustrated with the level of hazards, created the pressure-equalizing design and made installation a requirement of coverage beginning in 1919.

Recognizing a Pervasive Flaw

Despite the ingenuity of the Hartford loop design, it was not a cure-all. The configuration works as intended; it maintains balanced pressure in the system to keep water in the boiler. Also, if a condensate return line fails, the loop only allows water to escape to the connection point level. Unfortunately, the design still allows water to escape the system.

A Hartford loop is still essential to steam boiler operation, even if a leak occurs in the return. The loop slows the leak and will not let the boiler empty its water completely. By maintaining a specific water level, the configuration gives boiler operators time to save the system and prevent catastrophic failure.

Still, without quick intervention, even low water levels can cause damage to a steam boiler. While the Hartford loop solved one massive issue, it could not resolve the other. It wasn’t until 1923 and the creation of the low-water cutoff that both problems had solutions, establishing a new standard for boiler safety.

Addressing Installation Errors

Most installation errors occur because an installer puts the return line in the wrong position. An incorrect installation can affect the pressure within the system. Also, some installers use the wrong nipple type. A Hartford loop requires a close nipple.

The close nipple reduces the noise within the equalizer. A long nipple acts like a gun barrel, producing violent water hammer reactions.

Incorrect installations can cause excessive wear on pipes and connections, increasing the risk of pipe or seal failures. While auto-shutoffs are built into most modern systems, it is still best to avoid common errors.

A steam boiler is a unique piece of machinery requiring skilled technicians for upkeep. For properties that still maintain steam systems, contact Calray Boilers to discuss annual service contracts and limit system risks.

What Does a Hartford Loop Do, and Why is Professional Maintenance Necessary?

Importance of Safe Operation and Regular Maintenance

What does a Hartford loop do? The piping configuration helps balance the return within a steam boiler system and prevents it from emptying water. While it is not the only safety feature that matters to steam boiler installation, the loop is a critical design. If your commercial or residential steam boiler is giving you problems, contact Calray Boilers at 212-722-5506 to schedule an inspection and discuss our annual service contracts.