Pressure relief valves (PRVs) are devices that are designed to open in case the water pressure inside of a water heater, boiler, or any other vessel that is designed to hold water under pressure. Water heaters heat water and are supposed to maintain that temperature. The process is simple. When the water is not hot enough, the fire turns on. When the water gets hot enough, the fire turns off. But with every mechanical device, things fail. The problem that the PRV is protecting is if the fire is on and the sensor/thermostat that says the water is hot enough malfunctions and the fire stays on. Water at atmospheric pressure boils at 212 degrees. When water boils, it turns into steam. In other words it changes from a liquid to a gas. Water changing state (from liquid to gas) creates a tremendous amount of pressure. Way back when, they used to have steam locomotives and steamboats. The boiling liquid was released to move the wheels of the locomotives and the paddles of the steamboats. It is possible to keep water in a liquid state above 212 degrees. We have to keep it in an enclosed vessel such as a water heater. Water heaters are designed by code to hold up to 150psi of pressure. In order to get water to 150psi of pressure I would have to heat it up to 300 degrees. When water turns to steam it wants to expand roughly 1000 times its size. If a 40 gallon water heater should explode due to overheating, it will want to fill a space of 40,000 gallons. The video of MythBusters below actually shows a water heater exploding from overheating.
There are three different codes that are followed in the Chicagoland area.
Depending on the location of the home, is which code is followed. To view which code is followed by community you can click here.
My home inspector friends are going to tell me (and you) that we don’t inspect to code. This is true. We don’t. But I do like to use codes to help base my opinion. The following excerpts are from the International Plumbing Code.
504.4 Relief Valve
Storage water heaters operating above atmospheric pressure shall be provided with an approved, self-closing (levered) pressure relief valve and temperature relief valve or combination thereof. The relief valve shall conform to ANSI Z21.22. The relief valve shall not be used as a means of controlling thermal expansion.
This means that any sealed container of water that has any pressure on it whatsoever needs to have a pressure relief valve designed for the container and purpose at hand. The only time it is not required would be in situations such as an open pot of water sitting on a stove. When a container is open, it cannot build pressure of any kind and no PRV is required.
Such valves shall be installed in the shell of the water heater tank. Temperature relief valves shall be so located in the tank as to be actuated by the water in the top 6 inches (152 mm) of the tank served. For installations with separate storage tanks, the approved, self-closing (levered) pressure relief valve and temperature relief valve or combination thereof conforming to ANSI Z21.22 valves shall be installed on both the storage water heater and storage tank. There shall not be a check valve or shutoff valve between a relief valve and the heater or tank served.
I have seen where these PRVs have been installed away from the tank. Along the piping. This section of pretty specific and the PRV needs to be attached directly to the tank, or within 6″ of the tank.
504.5 Relief Valve Approval
Temperature and pressure relief valves, or combinations thereof, and energy cutoff devices shall bear the label of an approved agency and shall have a temperature setting of not more than 210°F (99°C) and a pressure setting not exceeding the tank or water heater manufacturer’s rated working pressure or 150 psi (1035 kPa), whichever is less. The relieving capacity of each pressure relief valve and each temperature relief valve shall equal or exceed the heat input to the water heater or storage tank.
This section of the code is specific to water heaters. There are different types of systems that require different PRVs.
504.6 Requirements for Discharge Piping
The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:
1. Not be directly connected to the drainage system.
2. Discharge through an air gap located in the same room as the water heater.
3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.
4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
6. Discharge in a manner that does not cause personal injury or structural damage.
7. Discharge to a termination point that is readily observable by the building occupants.
8. Not be trapped.
9. Be installed so as to flow by gravity.
10. Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.
11. Not have a threaded connection at the end of such piping.
12. Not have valves or tee fittings.
13. Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
This last one is different for the Illinois Plumbing Code. It states that the discharge pipe needs to be metallic.
The above video shows a start up sequence of a condensing furnace, more commonly known as a high efficiency furnace. The video starts with the inducer fan already running. The computer in the furnace sends power to the inducer fan. It does not know if the fan is working or not. At the bottom of the video you will see two round disks. It is hard to tell that there are two of them because they are back-to-back and look like only one. There is a yellow wire leading to them. These are pressure differential sensors/switches. If the fan is spinning, it will create a positive pressure in the exhaust tube and a negative pressure inside the heat exchanger. These switches sense that difference in pressure and tells the computer that the inducer fan is spinning and a draft is induced. After the computer gets this signal, it will begin the next step of lighting the fire. Towards the top you will begin to see an orange glow. This is the igniter heating up and getting ready for the gas flow. After a few seconds, the computer will send gas to the burners. If the gas ignites, it will begin to make heat. There is a heat sensor by the burners. This is called the fan limit switch, aka high limit switch. If the heat is not sensed by this switch within a few seconds, the computer will shut off the gas and stop the unit from starting. After the switch proves to the computer that the fire is ignited, then the circulation fan will start. These furnaces are engineered to transfer the heat created by the fire into the home. The fire creates a specific amount of BTU’s (British Thermal Unit). The heat exchanger is designed to allow the heat to transfer to the circulation air without letting any of the byproducts such as Carbon Monoxide (CO) enter the air we breath. As long as the heat is being absorbed at the proper rate, the furnace will continue to run until the desired temperature at the thermostat is reached. The fan limit/high limit sensor measures this. The designed temperature rise will be written on the data plate of the furnace. On these furnaces, it is usually about 30 to 60 degrees. The high limit set on most furnaces is about 190 degrees. This is also stated on the data plate of the furnace. If the temperature of the furnace air flow reaches this number, the furnace shuts down. Heat this high and higher can cause a fire.
The first thing home inspectors check for is the proper operation, or sequence of operation, of the furnace. If the furnace can complete a startup cycle and reach the desired temperature of the thermostat, then the furnace computer thinks everything is okay. We also do temperature rise readings on the furnace to make sure it is within the range stated on the data plate.
If the temperature is too low, problems might include:
If the temperature is too high, problems might include:
We also use equipment to read how much CO the flame is producing. This helps us determine how well the furnace is tuned and can also tell us exactly how efficient the unit is operating.
When I started in this profession, every furnace was a natural draft furnace. We used mirrors and a flashlight to look for holes and cracks in the heat exchangers. Nowadays we cannot see inside the heat exchangers because of their designs. This is why we use the equipment that we use.
During an inspection of a home with a basement walkout, I noticed the exterior floor drain was covered with ice and there was not an additional drain on the interior side of the door. There are two schools of thought and depending on which suburb you are located in, this is what is required:
Additional photos were taken of the bottom left and right of the door that showed minor damage to the door frame from water entering the basement. This has happened and I advised my clients that this drain must be kept clear at all times.
I must admit that I do not know every code in the City of Chicago, nor do I know every code in every suburb. No home inspectors does. I assume that whichever method was installed, was installed to the local authority’s code. My job is to see if it is working properly and to warn my clients of possible issues.
The most important item with any exterior drain is to keep it clean. This includes window wells, bottoms of driveways, patios, and also the walkout basement stairs which we are talking about here.
Another construction gone bad. The opening was enlarged to fit this window in this photo. The studs that supported the head on the left side was removed. The header was not replaced. Heck it wasn’t even removed so it could be replace.
I removed some of the duct tape to expose above the window. As you can see the header and support studs are missing.
I have seen some fantastic remodels and some pretty poor work as well. This home; I honestly thought the contractors did a wonderful job. The utilities were professionally installed and new windows properly installed everywhere. Then I fired up the thermal imager and started getting some weird photos. Entire ceilings and stud channels were showing cold. I go up to the attic and there it is. Something got forgotten. With our recent snow and the colder temperatures, this home started ice damming and water was entering the attic.
I should lead off with a confession that I am not a big fan of wood burning fireplaces. During my tenure in the fireman business (1980 to 2018) I went on multiple house fires caused by fireplaces that were not in a safe condition. Two of those fires burned enough to make the houses uninhabitable for almost a year before they were able to be repaired. The only reason the rest of the fires didn’t completely damage the homes was because the occupants didn’t leave the fire. They were able to call the fire department early and we were able to extinguish the fire before holes were burning through the roof. Fire places require a few things to keep them safe:
I personally like sealed fireplaces with ceramic logs which burn gas. I am also fairly comfortable with non-vented fireplaces. They are much safer, require far less maintenance, and look extremely real.
Water spigots are also known by hose bibbs, faucets, nozzles valves, hydrants, spouts stopcocks, taps, and bibcocks. Their obvious purpose is to run water outside the building. In the last few days, the inspections that we have been doing we found frozen spigots. Frost free spigots have the handle outside of the house that is connected a valve about 10″ inside the walls. This way the water will be stopped in the heated part of the house and not close to the exterior where it can freeze. When the faucet is turned off, the water drains out and prevents it from freezing in the pipe. The hose attached to the spigot is our problem. The hose prevents the water from draining from the spigot. When the water is trapped in the spigot during our winters, it will freeze. When water freezes, it expands. If it expands enough, it will burst the pipe just inside the wall. This is more common than people think. After the thaw of the frozen water, the water will spray (inside the house) every time the spigot is turned on and it will not be visible from the outside.
This last one was a home inspection in Chicago. It was a frost free spigot that the hose wasn’t removed for the winter. This motivated me to write this blogpost. The garden hose needs to be disconnected every winter to allow water to drain properly from the spigot and prevent this freezing of the pipes..
Head flashing is sometimes referred to as Z flashing. The purpose of this type of flashing is to direct water away from the house. When windows are installed, part of the window protrudes from the siding. When water flows down the wall, it hits this protrusion and flashing is needed to keep water from flowing into the house. In the diagram to the left you can see how the flashing is behind the siding and goes over the top of the window. Although some windows have this built into them. most do not. The vinyl windows are the most common that have flashing installed. This is usually a J-channel the is built into a window. But this blogpost is about head flashing and not the J-channel.
Head flashing is not always required. If a window is not subject to having water flowing down from above, then this flashing not required. The rule is shown in the diagram to the right. If the distance from the bottom of the ceiling to the top of the window is less than 25% of the overhang then the head flashing is not required.
Very little of the flashing is visible from the finished window. There will be a small metal (sometimes plastic) strip that travels along the top of the window. On the gray house, there is only J-channel along the top of the door. Even though the top of the door is caulked very well, water still entered the door and rotted the bottom. The green house has the head flashing and water is kept from damaging the door and the structure.
There are two types of garage door springs. Expansion (extension) and torsion. All springs are under tremendous pressure and are considered dangerous. Only professionals should work on these springs.
First I will talk about the torsion springs and how we inspect them. Torsion springs come in many different sizes. They twist to help support the door to make it easier to open and close. Each one is designed to support certain weights and sizes of overhead garage doors. The first thing we have to do is determine if the springs are the correct size for the door they are helping to lift. If the springs are professionally installed, the installer will spray paint a line straight across the springs. The springs are supposed to be wound 7.5 times. So we should see 7.5 spaces between the lines if the springs are properly wound. Then we disconnect the door from the garage door opener. We move the door so that the bottom of the door is close the the middle of the opening. The door should stay in the middle, fully open, and the fully closed position. If the door falls or springs up, there is a problem.
Expansion springs are a bit different. They stretch to help support the door open and close. Their proper length and size will be unknown to home inspectors. They should be the same on both sides. The door should stay in the fully closed and open position without any help. Springs are ordered for the size of the door. Extension spring sizes use two numbers. The first number is the length of the spring when the spring is NOT extended. The second number is half the height of the garage door. So an Extension spring sized 25″X42″: would mean the not extended length is 25″ and the height of the door would be 7 feet. 42″ x 2 = 84″ or 7 feet
They are also color coded at the ends. The codes are as follows.
The most important thing to check when inspecting these doors is that a safety cable is installed. These springs break. When they break, they are violent. The cable secured at both ends will keep the spring from damaging property or harming people and animals should they be near when it does break. We will also check that both springs are the same on both sides. This includes length and color coding. And when we open the door; it should open equally on both sides.
We do many home inspections in Chicago. There are many times we run into poor installations. Heck, never have we found something perfect. Sometimes we find things that are appalling. This porch was built in such a way that is just out-right dangerous. I included a few photos of the porch and put some comments on the issues in the photos.
There are a lot of rules in the Porch Design & Construction Guidelines by the City of Chicago, Department of Buildings.