Top Reasons for Slow Hot Water Recovery and Quick Fixes

One of the common complaints homeowners in North America have is the slow hot water recovery or reduced hot water supply. With slow recovery, even simple tasks like dishwashing and showering require much longer waits for hot water to heat up.

This can be frustrating, especially with a busy lifestyle and impatient teenagers waiting.

If your water heater isn’t performing as it should, troubleshooting is essential to avoid wasting energy and water or dealing with potential bacteria development.

Sometimes, fixing a water heater is straightforward, especially for DIY enthusiasts with the right skills and tools.

But what if the problem is too complex to fix, or you don’t have the time and need hot water quickly?

7 Reasons for Slow Hot Water Recovery and Repair Tips

Insufficient Air or Flue Blockage

Proper ventilation is essential for gas water heaters, especially when dealing with slow hot water recovery. An adequate supply of fresh combustion air is mandatory for safe and effective gas combustion. Without sufficient air, the performance of your heating device can be significantly impacted, potentially exposing your home to contamination or carbon monoxide poisoning, which is hazardous.

To avoid these risks, it’s recommended to provide sufficient openings as specified by the manufacturer, which are often detailed in the manufacturer’s manual. Manufacturers typically require a minimum indoor air volume of 50 cubic feet per 1,000 BTU/hour. Ventilation air can be supplied directly from the outdoors or an adjoining room.

A lack of combustion air can lead to slow hot water recovery, causing a low-quality flame, reduced heating power, decreased performance, and lower efficiency.

To address this, check the flue way, flue baffle, and burner for potential blockages. A water heater must exhaust combustion gases outdoors via approved venting, without any obstructions. The venting system should comply with local or state codes to ensure safe and efficient operation. A correctly installed vent system will be free of cracks, sagging, misalignments, or changes in diameter.

Symptoms of insufficient air delivery, such as a yellow, glowing burner flame and soot buildup in the gas combustion chamber, burners, or flue tubes, indicate poor performance.

Tip: Hire a qualified professional to install a vent system to ensure proper performance and safety, helping to prevent slow hot water recovery.

Low Gas Pressure

If there is a gas delivery problem and your water heater is not heating water or experiencing slow recovery, contact your gas utility company for updates on the current gas pressure. If the issue is on their side, they will address it.

You can also check for gas leaks at home by using a leak detector or applying a mixture of soap and water to gas connections. If bubbles form, there is a leak.

Important: For gas-related issues, always call a licensed gas technician.

Low gas pressure can lead to an improper air-gas mixture, poor combustion, reduced water heater efficiency, and prolonged water heating.

Orifice Too Small

Refer to the manufacturer’s manual or rating plate to verify the correct orifice type and size.

If the orifice is clogged or too small, clean or replace it with the correct one. If you are converting from natural gas to propane (or vice versa), you must replace the burner orifices due to size differences.

This issue can occur if the water heater has been modified or converted from one fuel type to another.

Thermostat Set Too Low

A thermostat set too low can result in uncomfortable showers, insufficient hot water, slow recovery, and bacterial growth.

To adjust the temperature:

• For gas models: Turn the temperature dial on the gas valve assembly clockwise or counterclockwise.
• For electric models: Remove the access panel and adjust the temperature with a flat screwdriver or control panel buttons.

The recommended thermostat setting is between 120°F and 125°F. Avoid setting it too high to prevent scalding or injury.

Tip: For tank-type water heaters, changes may take hours to reflect. If the temperature doesn’t increase after adjustment, the thermostat may need replacement.

The Water Heater is Too Small

If you installed a water heater when there were only two people in the household, but your family has since grown, or you have guests, or your habits have changed, you might find that the unit can no longer handle the increased demand. It may now be too small.

Alternatively, your gas model may not have enough BTUs to heat water quickly enough.

The solution to these problems is to install a larger unit that provides sufficient power or recovery rate.

When sizing a water heater, use the following guidelines, which show the relationship between the number of people in the household and the required capacity (in gallons):

• 1-2 people – 30-40 gallons
• 2-3 people – 40-50 gallons
• 3-4 people – 50-60 gallons
• 5+ people – 60-80 gallons (or more)

You can also opt for a tankless water heater with a high GPM (gallons per minute) rate to enjoy on-demand and endless hot water.

Piping Connection and Dip Tube

During installation, ensure that the cold water supply pipe is connected to the cold water inlet (blue ring), and the hot water pipe is linked to the hot water outlet (red ring).

Plumbing crossover is another issue that can occur with faulty single-handle faucets, mixing valves, or checking valves. It allows hot water to cross over to the cold side and vice versa, reducing the water temperature.

Verify that the dip tube, which extends from the cold water inlet, is not broken. Dip tubes are designed to direct cold water to the bottom of the tank. If the dip tube is broken, cold water will exit near the top of the heater, mixing with the heated water and lowering the temperature to lukewarm.

Sediment Buildup

If you have a gas unit installed and live in an area with hard water, your device may be prone to sediment buildup. Dissolved minerals in water and higher temperatures can cause increased accumulation at the bottom of the tank. Over time, this sediment layer grows, reducing heat transfer between the burner flame and the water, or between the heating elements and surrounding water (for electric models).

As a result, it takes longer to heat the water, or the device may struggle to produce hot water as quickly as it once did.

While sedimentation is difficult to avoid in areas with hard water, you can take steps to prevent it.

One way to reduce sediment buildup is to regularly flush your heating device or use a water softener.

Note: There are two recovery rates to consider: the manufacturer-rated recovery rate and the actual recovery rate. The manufacturer-rated recovery rate is found on the EnergyGuide label or in the model’s specifications. It tells you how much hot water a heater can generate in one hour after being completely drained. The actual recovery rate is what you are actually getting while using the water heater.

How to Improve Hot Water Recovery Rate

If you have a growing family, your water heater may need to be large enough to meet the increased hot water demand. If not, there are several ways to improve the delivery rate and prevent slow hot water recovery.

One solution is to install a point-of-use water heater (POU) with a few gallons of capacity. Hot water will always be ready for use, making it ideal for small tasks while waiting for the large heater.

Another option is to install a recirculation pump, which delivers hot water instantly.

You can also invest in a tankless unit, with or without a recirculation system, to enjoy on-demand and endless hot water delivery.

If you prefer to avoid adding new appliances, try flushing your water heater to remove sediment that may be blocking heat transfer. For those living in colder areas, consider insulating the tank and all exposed pipes.

Did You Know?

• Did you know that you can buy a smaller water heater with a high recovery rate?
• It takes longer for larger water tanks to recover.
• A gas model can heat water up to two times faster than electric models.
• Water heaters with the higher first-hour rating – FHR, can recover in less time.
• The temperature of incoming cold water has a significant impact on how fast water can reheat. If the temperature rise (the difference between the set temperature and incoming water temperature) is higher, the longer the recovery time.