A recirculation pump can operate 24/7. But the energy savings would be nonexistent if the external circulator were always on and continuously recirculating hot water.

One type of recirculation system — and the focus of this blog — is a closed-loop, pump-assisted, hot-water recirculation system.

So why does the water coming from your “hot”-water faucet or shower run cold at first before finally turning hot? When that outlet was last turned on, hot water flowed through the pipes, right?

Australian plumbing regulations state that all hot water systems in new homes must be fitted with a tempering valve to control the hot water supply to the bathrooms. Our plumbers recommend installing a valve on all storage hot water systems, new and old.

Hot waterrecirculating system cost

It’s safe to say we’ve all experienced the inconvenience of having to wait for hot water to arrive at the faucet or shower — most of us every morning. You’ve probably grown accustomed to waiting several seconds or even a minute or two, depending on the distance to your bathroom or kitchen from your water heater in your basement, garage or utility closet on the opposite side of the house. The longer that distance, the longer the wait, the bigger the annoyance.

The most efficient “traditional” recirculation method would use a combination of both a temperature sensor and a timer to activate the system.

The large volume of water which spends most of the day just sitting in your hot water tank (unless you have instant) is a perfect breeding ground for all sorts of nasty bacteria. One of which is the Legionella bacteria that can cause a serious pneumonia-like bacterial infection Legionnaires disease, which in some cases leads to death.

Hot waterrecirculating pump installation diagram

It’s especially important to fit a solar hot water system with a tempering valve because of the higher temperatures the water can be heated to on hot sunny days.

TMVs are often more expensive to install, however, can be repaired and maintained lasting longer on average than a tempering valve. The Australian Standard states that tempering valve testing should be carried out every 12 months with thermostats and o-rings replaced every 5 years.

The problem with keeping your storage hot water at this temperature is that at 60℃ hot water can cause severe scalding in only a few seconds. Small children, the elderly, and the infirm are some of the groups at most risk of burns.

Whether you choose to install an external recirculation pump or go with a fully integrated system, the benefits for both are clear. A hot-water recirculation pump eliminates the need to wait for hot water by recirculating the water through your plumbing system, keeping hot water flowing and ready for the moment someone turns on the faucet or shower.

Hot waterrecirculation valve

Instead of wasting energy by having hot water flow through the system continuously, some water heaters have an integral display on the front of the unit that allows homeowners to program the recirculation system to operate at specified times.

Not sure which one is right for your hot water system? Contact our Sutherland Shire plumbers for professional advice and tempering valve installation services.

Solution - install a tempering valve or TMV to the hot water pipe supplying personal hygiene areas (bathrooms), in some situations the whole house, which reduces the water to a much safer 50℃ (122℉), or in some cases 45℃ (113℉), to safeguard residents.

Another option is to purchase a “crossover kit” that is sold with the water heater and acts as a substitute for a return line.

Recirculatinghot watersystem diagram

Hot-water recirculation dramatically reduces water waste. With time and temperature sensors, hot-water recirculation pumps can control when the recirculation kicks on, ensuring that energy is not constantly being wasted.

A tempering valve is accurate to around 3℃ +/-, while a thermostatic mixing valve can keep the water to 1℃ +/- and responds faster than a tempering valve to changes in incoming water temperature.

Prohibiting the growth of bacteria in your hot water system is achieved by maintaining the thermostat at 60℃ (140℉) or above. However, increasing the temperate significantly above this will just result in higher power bills, not added protection.

Hot waterrecirculating system with dedicated return line

Some recirculation pumps can serve as a separate, add-on component that uses a dedicated pipe loop for hot-water recirculation.

A large tourist attraction in Melbourne was totally shut down due to a Legionnaires disease outbreak caused by bacteria breeding in the building’s air conditioner cooling tower system. This is just one example of many and is why we should take the risk seriously in our homes.

Some hot-water recirculation pumps are built into the water heater itself. An integrated recirculation pump is ideal if your home lacks a dedicated return line, and you want to avoid the cost of adding one.

Tempering valves are usually installed in standard home water heating situations. A thermostatic mixing valve would be fitted if there was a requirement for more exacting control of the water temperature, as well as in larger applications.

Hot waterrecirculating pump without return line

Not only is this inconvenient (and downright uncomfortable if you’re standing in the shower), but a typical American home annually wastes thousands of gallons of perfectly usable potable water down the drain, thanks to lengthy wait times at hot-water outlets in the bath and kitchen.

Not sure if you need to install a tempering valve or a thermostatic mixing valve? Your local plumber can provide you with advice specific to your water heating requirements but here’s the low down to get you started.

Both valves contain a temperature-sensitive element which expands or contracts in response to temperature changes in the incoming water. This expansion and contraction control a slide valve which allows more or less hot or cold water into the mix to consistently maintain the desired temperature.

So what’s the solution? Is it possible to get truly “instantaneous” hot water? Yes, with a hot-water recirculation system that delivers hot water with virtually no wait time.

Often tempering valves and TMVs can also restrict the supply of hot water totally if for some reason the cold water stops, further safeguarding against burns.

But once the outlet was shut off, the remaining warm water in the pipes did not return to the water heater for reheating. Instead, it stayed in the pipes and eventually turned cold. When the outlet was next turned on, this resting cold water exited the pipes first, ahead of the incoming hot water from the water heater.

A hot-water recirculation system delivers hot water to a faucet, shower or appliance in seconds, eliminating the usual water-wasting wait. The system does so by recirculating the water that remained in the pipes and eventually turned cold, back to the water heater, through either the cold-water line or a dedicated return line.