Cold showers aren’t for everyone. When a homeowner decided to do something about her distinct lack of hot water, she called upon the Ask This Old House team for help. Richard Trethewey, our resident plumbing and heating expert, answered the call and took us on a road trip to stop an undersized water heater from ruining the homeowner’s showers.
Troubleshooting Hot Water Problems
If you’re running out of hot water during your showers, the first thing to determine is whether the water heater works appropriately. Here’s the test:
- Inspect your water heater and determine what the total gallonage is.
- Turn the shower faucet to the hot water setting, and place a bucket with a 1-gallon mark under the shower head.
- Time how many seconds it takes before the bucket has been filled to the 1-gallon mark. Divide the number 60 by the total seconds to determine the GPM.
- Let the water heater refill and reheat the tank.
- Set the shower to normal showering temperature and time how long it takes to start getting cold.
Multiply the GPM by the minutes it takes to get cold. The number should be 65 to 70 of the water heater’s total size. If that is the case, the water heater is working properly—it’s just too small. If that’s not the case, the water heater might need to be replaced.
Pro Tip: Richard Trethewey, This Old House plumbing and heating expert, advises homeowners to think ahead: “Many people wait for the water heater to fail and all of a sudden they panic and have to get hot water that night.” Instead of waiting for a crisis, he recommends evaluating your hot water needs proactively—especially if your household is growing or you’re adding a bathroom.
A Hybrid Water Heater May Be the Best Solution
Upgrading to a larger water heater doesn’t necessarily mean more energy consumption. Hybrid water heaters exist, combining the age-old technology of electrical elements and built-in heat pumps that remove and resume the heat energy from the space. This allows them to run for a fraction of the cost of a traditional water heater while providing more hot water.
Here’s how the heat pump side works: The unit draws warm air from the room into a compressor on top of the tank. As Richard Trethewey, This Old House plumbing and heating expert, explains, the refrigerant cycle moves heat “down into a heat exchanger at the very bottom, and that heat exchanger wraps around the tank and gives up its heat to the tank water, so now that cold water becomes hotter. By the time it gets to the bottom, that refrigerant is cooled again. Now it comes back, and the cycle repeats and just does it all day.” Because the unit also extracts humidity from the air, a condensate drain is required for the moisture that collects on the cold coils.
Are They Expensive?
Hybrid water heaters are more expensive to purchase than traditional water heaters. However, they’re less expensive to operate. There are also many rebates from states and the federal government to move to more efficient, more economically-friendly appliances. There are potentially thousands of dollars in rebates available, making these water heaters affordable.
Pro Tip: Don’t overlook utility company incentives. As This Old House plumbing and heating expert John noted, “the local utilities are often your partners, they want to help you with rebates.” In many cases, the monthly payment for new high-efficiency equipment can actually be less than the savings you’ll see in operating costs — making the upgrade pay for itself from day one.
Resources
Be sure that the water heater has a T-valve and that it is correctly installed. (May require an expansion valve or expansion tank.)
The new hybrid hot water heater was manufactured by Ruud ®.
