Why Does Hot Water Take So Long to Reach the Tap?

You turn on the shower and wait.

For several seconds, sometimes much longer, the water stays cold before the hot water finally arrives.

It is easy to assume the hot water system is slow, undersized or starting to fail.

But in many homes, the hot water system is not actually the problem.

The delay often comes down to something much simpler: the amount of cold water sitting in the pipe between the hot water system and the tap.

Before hot water can reach the shower, basin or kitchen sink, that water has to be pushed out first.

The Hot Water May Already Be Ready

Whether you have a storage or continuous flow hot water system, there can still be a delay before hot water reaches a fixture.

A storage system may already have a tank full of heated water.

A continuous flow system may begin heating almost immediately after detecting water flow.

Neither of those things changes the fact that there may be several metres of plumbing between the hot water system and the tap.

The water already sitting inside that pipe is usually cold.

When you open the hot tap, the cold water in the pipe has to leave before freshly heated water reaches you.

This is why installing a larger or more powerful hot water system does not necessarily make hot water reach the tap faster.

Distance From the Hot Water System Matters

The further a fixture is from the hot water system, the more pipework the water has to travel through.

A bathroom located close to the hot water unit may receive hot water quickly, while an ensuite on the opposite side of the house may take considerably longer.

This can be particularly noticeable in:

• Large homes.
• Two-storey homes.
• Homes that have been extended.
• Properties where the hot water system is located at one end of the building.
• Renovated homes where new bathrooms have been added further from the original plumbing.

The layout of the plumbing system can therefore have a significant effect on how quickly hot water reaches different parts of the home.

Pipe Size Also Makes a Difference

The diameter of the pipe affects how much water is sitting between the hot water system and the fixture.

A larger pipe can hold more water.

That means more cold water may need to be displaced before hot water arrives.

This does not mean larger pipework is automatically bad. Pipe sizing also needs to account for flow rates, pressure and how many fixtures the plumbing system needs to supply.

The important point is that hot water delivery time is affected by the whole plumbing design, not just the appliance heating the water.

Why Does One Tap Get Hot Faster Than Another?

If your kitchen tap becomes hot quickly but your shower takes much longer, the difference may simply be the distance and pipework between each fixture and the hot water system.

Each hot water outlet effectively has its own path back to the heater.

A nearby fixture may only have a short run of pipe to clear.

A distant bathroom may have a much longer run.

This is also why the delay can seem worse first thing in the morning or after the hot water has not been used for a while.

The water sitting inside the pipes has had time to cool completely.

Heat Loss Through the Pipework Can Add to the Problem

Hot water begins losing heat as soon as it leaves the hot water system.

Insulated hot water pipework helps reduce that heat loss.

If pipework is poorly insulated, particularly through colder areas of the building, the water travelling to the fixture can lose more heat along the way.

This may not necessarily create the entire delay, but it can affect how quickly the water at the tap reaches a comfortable temperature.

Pipe insulation is therefore an important part of an efficient hot water installation.

Does Continuous Flow Hot Water Fix the Delay?

Not necessarily.

Continuous flow systems are sometimes described as providing instant hot water, but there is an important distinction.

The unit can begin producing hot water when required, but it cannot instantly transport that water through several metres of pipework.

If the continuous flow system is mounted a long distance from the bathroom, you may still need to wait for the cold water in the pipe to clear.

This is why continuous flow does not automatically mean instant hot water at the tap.

Could Moving the Hot Water System Help?

In some situations, system location can make a noticeable difference.

If a hot water system is being replaced, it may be worth considering whether the existing location is still the best place for it.

Moving a hot water system closer to the fixtures that use the most hot water can sometimes reduce pipe runs and improve delivery time.

However, relocating a system also involves other considerations including plumbing, gas supply, electrical requirements, drainage, ventilation and installation regulations.

It is therefore something that needs to be assessed as part of the overall hot water installation.

What About Hot Water Recirculation?

For larger homes, another option can be a hot water recirculation system.

Instead of allowing hot water in the pipework to cool completely between uses, a recirculation system moves hot water through a dedicated plumbing loop so that hot water can be available closer to the fixtures.

This can significantly reduce the amount of time spent waiting for hot water.

However, recirculation systems are not suitable or necessary for every property.

The plumbing layout, energy use, installation cost and way the household uses hot water all need to be considered.

How Much Water Is Wasted While You Wait?

The delay is not only inconvenient.

Every time you stand at the shower waiting for the water to warm up, the water flowing down the drain is still being paid for.

If several people in the household do the same thing every day, that wasted water can add up over time.

Long hot water delivery times can therefore be both a comfort issue and an efficiency issue.

When Could a Long Delay Indicate a Problem?

If the hot water has always taken roughly the same amount of time to arrive, the delay may simply be a result of the plumbing layout.

But if the system suddenly takes much longer than it used to, something may have changed.

Possible issues can include:

• Reduced water flow.
• A restriction in the hot water pipework.
• A problem with the hot water system itself.
• A fault affecting continuous flow operation.
• Changes to valves or plumbing within the property.

A noticeable change in performance is worth investigating rather than assuming it is normal.

Hot Water Performance Is About More Than the Heater

A good hot water system is only one part of the equation.

The position of the system, length of the pipework, pipe sizing, insulation and overall plumbing design all affect how hot water reaches the fixtures throughout your home.

This is why replacing a hot water system should not always be treated as simply swapping one appliance for another.

A properly planned installation looks at how the entire system will perform.

Need Help With Your Hot Water System?

If your hot water takes a long time to reach the shower, your system is not performing the way it used to or you are considering replacing your existing hot water unit, RJT Plumbing & Gas can help.

We can assess the hot water system along with the plumbing supporting it to determine what is causing the delay and whether there is a practical way to improve performance.

Contact RJT Plumbing & Gas for hot water repairs, replacements and installation advice across North Lakes and surrounding areas.