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Fig. 3 Delivered steam pressure is regulated in a similar manner as direct acting PRVs, however indirectly via a pilot valve. As the pilot valve is actuated, it provides the opening flow to the larger main valve which can supply significantly higher flow rates than the pilot itself. The pilot valve is then equalized by the secondary pressure, which correspondingly controls the opening flow to the main valve.

Fig. 2 Delivered steam pressure is regulated by balancing forces acting directly on the valve itself: the downward force caused by compression of the adjustment spring against the upward force from the secondary pressure acting against the underside of a bellows or diaphragm.

We covered the basics in this article, but if you are dealing with other types of systems (like with tankless water heaters) or more complicated setups (multiple hot water zones/loops) it can get more complicated. Designing and troubleshooting these setups can start to resemble designing a hydronic heating system – which is a science in and of itself. Fortunately, though, this isn’t common in your typical North Dallas residential application.

These pumps are typically installed right next to the water heaters on the return line so they are pushing water toward the water heater. Sometimes they are set to run all the time. Other times, they are set to run on a timer so that the homeowner can save a little electricity when quick hot water isn’t necessary.

A tankless water heater is no different, either. Tankless water heaters do not provide instant hot water to the faucets – this is a common misconception. A tankless water heater heats water instantaneously as it passes through the heater, but it can’t magically get that hot water instantly to the faucets on the other side of the house.

Now, when hot water is being pushed down the pipes by the pump, this valve allows the cooled-off water to cross over into the cold water system where it loops back to the water heater. Very ingenious! Furthermore, these valves have a mechanical wax thermostat inside them that closes when hot water reaches the fixture. That way it doesn’t put too much hot water into the cold water system.

Basically, this type of system creates a pure, simple loop in the hot water system. Hot water flows circuitously through this loop alone. The loop is designed in such a way that all of the hot water fixtures are very close to the path that it takes so there is never any substantial wait time across the whole system.

In pressure reducing valves, the mechanism that automatically adjusts the downstream pressure typically uses the balance of forces between the steam pressure and an adjustment spring. At present, this is a universal concept on almost all manufactured pressure reducing valves. However, there are two different ways in which this mechanism is implemented to control the amount of valve opening:

Every hot water faucet has a hot water pipe that travels from that faucet back to wherever your water heater is located in your home. In the North Dallas area where we work, the water heaters are mostly located in the garages and attics. (In older homes like those in parts of Carrollton, Richardson, southeast Plano, etc… water heaters can also frequently be found inside closets off of the main hallway in the house.)

For these purposes, these pumps are highly recommended. They also tend to be very reliable as well – as long as they are manufactured by one of the larger, reputable companies like Grundfos, Taco, Etc…

This is the essential concept of the hot water recirculation pump. It keeps the water moving through the hot water system like an invisible circular bucket brigade so there will be no more water wasted down the drain and instant hot water at your faucets!

This is the problem in a nutshell. Unless you have a mini water heater under every faucet, you can’t have instant hot water.

They can save money spent on water, but they do make the water heater work more. This is because the water heater is now keeping the entire hot system warm instead of just the water inside the tank. The larger the system is, the more heat loss occurs (which makes the water heater turn on more frequently to compensate). This decrease in efficiency and the small amount of electricity they use will offset some of the savings.

Because the downward force is amplified through the use of a piston or diaphragm, a small change in the opening on the pilot valve can result in a large change in flow and downstream pressure through the main valve. As a result, there is little change needed in adjustment spring force on the pilot to accomplish quick response over a wide range of steam flow rates. Quick response and tight delivered pressure control represent the main advantages of this type of valve over the direct-acting type.

This is where pumps come in. What if hot water never got a chance to just sit there in the pipes and cool off? What if water flowed through all of the hot water pipes in a big loop so that it was constantly being kept nice and hot by the water heater?

But wait a minute! Without a loop or some way to return the water, there would be no flow. That’s where the crossover tee comes in. Sometimes called a “bridge valve”, this ‘tee’ fitting is installed under the sink that is farthest away from the water heater. It is installed between the hot and cold pipes of the sink so that it “bridges” between the hot and cold water systems.

The pump itself is very similar. Instead of being mounted on a hot water return line, though, it is usually mounted on the hot water outlet of the water heater. That way, it’s pushing water out of the tank and down the normal hot water pipes to the fixtures.

Installing a retrofit pump or replacing a dedicated return line pump are usually pretty straightforward jobs for a plumber. The biggest variable is the soundness of the pipes that the new parts will attach to.

If it has been hours since the faucet was last used, it could take 3 – 5 minutes before you feel hot water. That wastes a lot of water and can be quite annoying sometimes. Gallons of water can easily be wasted every time this happens.

There is a less-common variation of the retrofit style pump called an “on-demand” recirculation pump. This pump is mounted at the faucet instead of at the water heater. It has either a button or a sensor that turns it on so that it runs only when someone enters the room.

If you want to get ‘instant’ hot water or want to save water usage in your home, a recirculation pump is a great way to do that!

There are two main categories of hot water recirculation pumps – dedicated return line pumps and retrofit crossover-style pumps.

Depending on the house floor plan, it may take more than one of the crossover valves to get hot water quickly to all of the faucets. Also, because of the way it works, there sometimes is lukewarm water that comes out of the cold side of the faucet for a few seconds when it is turned on.

In direct acting pressure reducing valves, the amount of valve opening is determined directly by the movement of the adjustment spring. If the spring is compressed, it creates an opening force on the valve which increases flow. As pressure builds downstream, equalizing occurs by feeding the downstream pressure to the underside of the adjustment spring (usually against a bellows or diaphragm) where its upward force counter-balances against the spring compression. Spring compressive force which opens the valve is limited to allow sufficient spring sensitivity to equalize with downstream pressure changes. The net result is simple pressure control through a valve orifice where high flow rates can cause pressure droop.

In a steam-using plant, steam is often generated at high pressures and reduced locally to provide heat for each steam user. This is usually done to minimize the diameter of steam distribution piping and enable more cost-efficient steam delivery.

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Did you know an estimated 76 million homes in the US have cast iron piping in various stages of disrepair?  If you live in a

Calculate and display steam property values using pressure-based saturated steam tables, temperature-based saturated steam tables, and heating steam tables.

From the above characteristics, it can be seen that the function and applications of non-piloted direct acting PRVs differ substantially from those of pilot-operated PRVs.

Have you ever turned on a hot water faucet only to have to wait FOREVER for the water to get warm? Read this article to learn how you can get instant hot water to your kitchen and bathroom faucets.

While it is possible to maintain a constant pressure by using the combination of an actuated control valve, a pressure sensor, and a controller, a pressure reducing valve offers the advantage of being able to control pressure through fully-automatic self-contained operation, requiring no type of external power source. It can offer the further advantage of extremely rapid response action by immediately sensing and adjusting based on the downstream pressure.

A common way of lowering pressure is by throttling down the size of the steam passageway. For the most basic pressure reduction, it is possible to simply use a conventional globe valve in a fixed partly-open position, or by inserting an orifice plate into the flow of steam. However, any fluctuation in flow rate would be accompanied by a corresponding fluctuation in pressure. To avoid such circumstances, pressure reducing valves (PRVs) can be used to provide precise control of downstream pressure. They automatically adjust the amount of valve opening to allow the pressure to remain unchanged even when the flow rate fluctuates.

What if your house wasn’t installed with a dedicated recirculation return line? It would be a big project to go back and install a new hot water plumbing line in a house after everything has been covered up in sheetrock and trim.

The dedicated return line pumps are installed on a special hot water return line that is plumbed to the farthest fixture. These are usually installed when the house is built. They are often required for larger square footage homes. Otherwise, the wait time would be ludicrous.

Feel free to reach out if you have any recirculation-related questions. We are an award-winning gas line plumber in the north DFW area, and our reputation for integrity, craftsmanship, and upfront pricing speaks for itself.

In pilot-operated pressure reducing valves, a pilot valve is used to load a piston or diaphragm that increases the downward force used to open a larger main valve. This enables larger flow capacity with a lower pressure offset (droop). The opening and closing of the pilot valve is controlled by the balance of force between the adjustment spring and the secondary pressure in the same manner that a direct-acting valve operates. However, in a pilot-operated PRV, this opening and closing of the pilot valve purposely delivers pressure to the main valve piston or diaphragm. This pilot flow pressure then causes a downward force that is amplified by the area of the piston or diaphragm to enable opening of a much larger main valve, which in turn provides the ability for very high flow rates.

Because of these factors, the initial investment of the pump/installation, and the added cost of maintenance, a recirculation pump isn’t high on the list as a way to save money. Convenience and comfort are the main motivations when choosing to add one of these pumps to your system.

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The length of this hot water pipe determines how long it will take for hot water to get to your faucet after it leaves the tank. When not in use, the hot water cools off in the water pipes and is the first to rush out when a faucet is turned on.

If the shut-off valves/supply lines/etc… are old and deteriorated, they may need to be addressed during the installation (new fixture shut-off valves, new water heater valve and supply lines, etc…).