Heating the House: Steam Boilers


Steam heating systems are very rare in new homes, but we do find them in older homes. The function of a steam boiler is the same as any other central heating system. The goal is to heat the house, making it comfortable in a safe and economic fashion.

Steam heating has some advantages.  The basics of residential steam heating systems are simple and there are few moving parts.  After the guys that designed and installed these old systems died, it became complicated. Old two-pipe hot water systems with standing iron radiators are considered among the most efficient, most comfortable, longest-lasting, and most extravagant heating systems ever made. They are no more archaic than slate roofs, copper gutters, clear old-growth weather-resistant wood, or any of the other fine traditional materials that are so expensive today.

There are also disadvantages to steam as well. The working environment of a steam boiler is harsh because of the high temperatures and the changes of state that take place. The interior components are variously exposed to air, water, and steam.

Because steam heating systems are not used in new construction, many service people are not well qualified to work on steam systems. There are very few people left at the residential service level who have designed steam heating systems from the ground up. Modern commercial steam systems are very different from older residential systems. This poses another challenge to service people who may not be used to working on house steam systems. Additionally, because steam heating systems are not manufactured in large quantity anymore, parts can be difficult to obtain.

Inspecting these units poses challenges as well. Due to the age of the units, many of them are not in their original state. Vents and traps may have been added, abandoned, or removed. Gravity return systems may have been converted to pumped return systems. Dry returns may have become wet returns, by design or by accident.  You get the idea. In many homes with steam systems, agents will prepare the owner that it may be difficult to find a buyer to purchase a home with a steam boiler. Often, we find that negotiations include a cost for a heating system upgrade.

Although boilers are well designed, and when maintained, steam heating systems should be as quiet as hot water systems. The reality is that many are not in good working order and these systems can be noisy. The noise can be very disturbing if water hammer is a feature of the system. Additionally, because we are dealing with a change of state and higher temperatures than with hot water boilers, steam boilers can be more dangerous. However, both steam boilers and hot water boilers are safe as long as the proper safety controls are in place.

When we come across steam systems, which are rare in the Piedmont Triad area, we recommend the buyer call for help from a specialist. We are particularly cautious because steam heating systems may appear to be working fine during the middle of the day, however, at night or during a startup phase, there can be considerable water hammer, noise, or even leaks that are not apparent at other times.  While we are informed and experienced inspectors, one of the major components of our job is to guide you in the right direction. It is important to us that you have all the necessary information to make an informed decision during your due diligence period. The current owner can be a good source of information if possible. It is important to ask if they have service records on hand. Additionally, you can find out who they have been using to work on the system. The lack of available service people may require you continue to use the company already servicing the boiler. Finding a great technician is worth the effort because they can help you keep your system functioning for many years to come.

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