Steam Boilers: The Basics

Steam boilers use heat from the burner to convert water in the boiler to steam. The steam moves from the top of the boiler through the distribution pipes to the radiators. The steam condenses at the radiators, releasing its heat. The condensate returns to the boiler as water.

Before the system starts, the top of the boiler, the distribution pipes, and the radiators are filled with air. As the steam moves through the system, it pushes the air out of the system. When the system shuts down, and the steam all condenses back to liquid, air is let back into the pipes and radiators, and into the top of the boiler.

When the thermostat calls for heat, the burner turns on. The water in the boiler heats up and boils. Steam comes off the top of the water in the boiler, just as it does in a pot on the stove. The burner is controlled by the thermostat and by the pressuretrol. The two devices are in series. The thermostat shuts off the burner when the house gets warm enough. The pressuretrol controls the steam pressure. When the steam pressure in the top of the boiler reaches the upper allowable limit, the burner will shut down, even though the thermostat is still calling for heat. When the steam pressure drops back into normal limits, the burner will come back on if the thermostat is still calling for heat.

As steam starts to form above the water in the boiler, it pushes up on the air above the water and pushes down on the water itself. Let’s assume that we have one psi of steam pressure. If we want to move the steam through the system, we have to get the air vents out of the way. Air vents in the system are open to the atmosphere. These allow the air to be pushed out of the piping and out of the radiators (depending on the type of system) to allow the steam to move into the piping and radiators. These vents remain open to the atmosphere until the steam hits them. The hot steam typically expands a bellows which pushes a valve closed. The air vents allow air to escape but don’t let the steam get out. The steam moves through the system, pushing the air out of the piping and radiators. The steam condenses as it hits the cold pipes and radiators, releasing its heat into the radiator.

The goal is to have the steam hit all of the radiators at about the same time. This allows for even heating of the building. Some air vents on radiators are adjustable. This means that they close at rates that can be adjusted by the homeowner or service technician so that all of the radiators fill with steam at about the same time.

In steam boilers, it is important to monitor how far the water rises in the return pipe. If the water gets pushed back into pipes that should contain steam, it will cause chaos. The steam won’t be able to move and we might have heating problems. The steam slamming into the water can cause water hammer. Boiler water levels may also drop to a point where the boiler shuts off on low water. A component known as the equalizer pipe is used to create equal pressure on the boiler water and the water in the return pipe, so we don’t have this problem.

When enough heat has been added to the house, the thermostat is satisfied. This causes the burner to shut off. No more steam is produced. The steam in the system condenses into water, which runs back into the boiler. As the system cools, the air vents which had been driven closed by the high temperature steam are cooled and the vents reopen. Air from the house comes back in through the vents to fill the pipes and radiators.

Ask the Home Inspector: Polybutylene Pipes

Can a home inspector predict the useful life of PB pipes in a home?

Unfortunately, inspectors cannot. Poly pipes may “look” fine, but most of the problems associated with poly systems are not visible. Inspectors can look for water leaking right now, we can look for evidence of repairs, and we can look for certain installation no-no’s (only where pipes are exposed), such as kinks in the piping. This helps a little, but many things contribute to a poly leak, most of which an inspector cannot see. When buying a house with PB piping, purchasers must be aware of the potential for leaks and damage and be comfortable moving forward with the purchase of the home, despite the risks.



Furnaces versus Boilers

The function of a boiler is the same as a furnace: to provide heat so that all parts of the home are comfortable. Boilers fulfill this function in a slightly different way than furnaces.

Hot water boilers, or what some people call hydronic heating systems, don’t really boil the water. They typically heat the water to a maximum of 200oF. Normal operating temperatures for many boilers are in the 120oF to 130oF range, depending on a number of factors, including outdoor temperature, design capacity, etc. There are boilers that do boil water into steam- but that is for a different blog.

Boilers work much like furnaces. Heat is generated by burning coal, oil, natural gas, or propane, for example. Heat can also be generated by electricity. There are electric boilers.

Furnaces use warm air to move heat from the source to various rooms of the house. Boilers use water instead of air to move heat through the house. Furnaces have heat exchanges, and so do boilers. The fire side of the heat exchangers for furnaces and boilers are virtually identical. In a furnace, however, the distribution medium is the house air, and that is what you find on the other side of the heat exchanger. Boilers have water on the other side of the heat exchanger.

Heat is transferred from the fire side of the heat exchanger, through the heat exchanger, into the water. This water is piped to the various rooms of the house, where it is released through radiators, baseboards, or convectors.

In some homes, radiant heating is used where the distribution pipes are embedded in floors or ceilings and heat is released along the entire length of these piping grids, buried in the finishes. In radiant systems, there are no radiators or convectors. There is also a lot less for the home inspector to look at!

Just as the air in a forced-air system is recirculated, so is the water in a boiler system. Cool water is brought to the boiler, heated, and sent to the radiators. The cool water is returned from the radiators through the piping system, to be warmed again by the heat exchanger.

Basic knowledge for better decisions: Plumbing System

Homeownership comes with maintenance and repairs. Great plumbers will make it easy for you to understand what is going on with your system, but if you are acquainted with the basics, you will be able to make a smart call when opting for repairs. Below you’ll find some common terms you may hear.

DWV System: Drain, Waste, Vent System. This system carries waste out of your home and into the city sewer lines (or septic system). The most important rule for this system is that every drain must have a trap, and every trap must have a vent. Traps, those U-shaped pipes you see under sinks, hold wastewater which prevents smelly sewer gas from flowing up into your home. Vents are simply pipes that lead outside through the roof. Without a vent, water flowing through a trap creates a vacuum and siphons the trap dry. By allowing air into the system, vents act as a vacuum breaker.

Water Supply System: Your water supply system taps into the city water main, runs through a meter that measures your water usage and then branches throughout your home. If you have a well, it taps into the pipes directly. Branch lines in a home may be made of a variety of materials (see below). The older the home, the more common it is to see a variety of pipe material types.

“Aggressive” water: Aggressive water is water that is prone to corrode pipes. When pipes corrode, leaks can develop and structural damage is possible. Certain pipe materials are affected more than others.

AAV: Air admittance valves. An air admittance valve lets air into (but not out of) the DWV system. Because of this, it can take the place of a vent pipe running up through the roof. On remodeling projects, utilizing air admittance valves can save the plumber a lot of work- and you a lot of money- if it is allowed by your local code. AAVs are not allowed in all situations.

Most common distribution pipe materials:

Galvanized Steel: Unlike other types of pipe, galvanized steel almost always has threaded, screw-together connections. Its life expectancy is about 70 years, but some century old galvanized pipes are still in service. If you have galvanized pipe and low flow at faucets, chances are the pipe is to blame. Galvanized pipe is prone to mineral buildup that eventually chokes off the water flow. Complete replacement is the best cure, but you can often improve flow just by replacing any exposed horizontal pipes.

Copper Pipe: Copper was the standard water supply pipe for decades until less costly materials became available. It can be connected in several ways, but most joints are sealed by melting metal solder into the joint. The lifespan of copper depends on the local water. In some areas, it lasts as little as 25years. In others, it lasts 2-3 times that long.

PEX: PEX is flexible, so it’s much easier to install than other types of pipe. That, plus low cost and immunity to aggressive water, make it the most common choice for newer waterlines. PEX is a latecomer to North America, but has been used for decades in Europe. PEX comes in a variety of colors.

CPVC: Unlike metals, this plastic pipe doesn’t corrode, so it’s been common in regions with “aggressive” water for the past 40 years. CPVC connections are usually made with a glue-like cement, but compression fittings and other methods can also be used.

PB: Polybutylene pipe. Polybutylene is a form of plastic resin that was used extensively in the manufacture of water supply piping from 1978 until 1995. Due to the low cost of the material and ease of installation, polybutylene piping systems were viewed as “the pipe of the future” and were used as a substitute for traditional copper piping. While scientific evidence is scarce, it is believed that oxidants in the public water supplies, such as chlorine, react with the polybutylene piping and acetal fittings causing them to scale and flake and become brittle. Micro-fractures result, and the basic structural integrity of the system is reduced. Thus, the system becomes weak and may fail without warning causing damage to the building structure and personal property. It is believed that other factors may also contribute to the failure of polybutylene systems, such as improper installation, but it is virtually impossible to detect installation problems throughout an entire system. Throughout the 1980’s lawsuits were filed complaining of allegedly defective manufacturing and defective installation causing hundreds of millions of dollars in damages. Although the manufacturers have never admitted that poly is defective, they have agreed to fund the Class Action settlement with an initial and minimum amount of $950 million. You’ll have to contact the appropriate settlement claim company to find out if you qualify under this settlement- but to our knowledge, payouts have ended.

Also check out a prior blog about pouring grease down the drain, located here, or another one on low water pressure, found here, for further practical tips and info related to your plumbing system.

2017 Operation Inasmuch Service Project

This year was a huge success. We helped a homeowner with limited mobility install railings for his front porch, repaired his shower and installed a new shower surround, landscaped to reroute water away from the foundation of his home, and stained a deck.

It was a long day, but as always a rewarding experience for an appreciative homeowner. Looking forward to next year!



3rd Annual Operation Inasmuch

We love our community and giving back. That is why we are participating in our 3rd Operation Inasmuch on Saturday, October 21st, 2017.

Evidence shows that when neighborhoods are full of rental properties, neighborhoods decline. In local areas where this trend is occurring, several service organizations are stepping up to encourage retention of owner occupied residences and assist owners with repairs to get their homes back on track.  Home ownership comes with expenses that can sometimes set an owner on a downward spiral financially.  Homes can become an eyesore in perpetual disrepair. When this happens, neighborhood pride goes down. By stepping up to relieve some of the burden, we create a positive impact and pride returns to the community.

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We have a great group ready to help make a positive impact for these homeowners, but as always, you are welcome to come out and lend a helping hand. If you are free and would like to help- please fill out the contact form below and we will be in touch with you about where to go on the 21st. Thank you for considering joining us for this rewarding day of community service.

2017 Tour de Emerywood

Please join us for the 2nd annual Tour De Emerywood presented by the Young Professionals Network and the High Point Regional Association of REALTORS.  We are a proud sponsor for the second year in a row. Proceeds from this event will go to the HPRAR Foundation. The Foundation is dedicated to helping REALTORS, their families, and the community in times of tragedy. A portion of the proceeds also go to Kisses for Kate, an organization that provides assistance, in many forms, to families with children battling cancer. This run also gives the community a look into one of the most popular neighborhoods in High Point. So come out and run with the your home inspectors!
  • Date: Saturday, September 30, 2017
  • Location: High Point, NC
  • Race Start Time: 9:00am
  • Race Distance: 5K, 1 mile
  • Registration Closes: Friday, September 29 at 9:00 am
  • Race Cap: 300
We look forward to seeing you running! Register here  or check out the event page here.

Other Foundation Types

Preserved wood foundations have become popular in some areas over the last few years. Wood in a below-grade, damp soil environment has historically not had a long life, particularly as a structural member. As a result, there are several design challenges with respect to wood foundations.

They are more likely to be successful in dry soils than in wet soils. For the most part, their modes of failure will be similar to what we will look at on most other foundation systems, with a couple of exceptions. Since wood is less brittle or more flexible than concrete, for example, cracking is likely to be less common and bowing may be prevalent. Rot and insect damage or obviously possibilities with wood foundations, while these are not issue with most other foundation and footing materials.

In most cases, the interiors of preserved wood foundations are finished as living space, and it may be difficult to identify the foundation system, let alone inspect it.

Some areas have expansive soils that make it risky to use conventional footings and foundations. A special reinforcement technique for concrete grade beams and floor slabs is sometimes used to resist the forces of the soil and to prevent differential movement of the structure.

Post-tensioned slabs and grade beams use steel cables or tendons that are laid in place before the concrete is poured. The cables are most often surrounded by a plastic sheathing. After the concrete is poured, jacks are used to pull the cables tight, strengthening the assembly. These post-tensioned cables sometimes snap, and in some cases, they shoot out from the foundation or come up through the floor slabs. Fortunately, this problem is rare, at least so far.