Tankless Water Heaters Do Not Provide Instant Hot Water
Tankless water heaters heat water instantly. However unless you install one next to every sink, shower, washer and dishwasher you will not get hot water instantly at the tap.
No matter how you heat it, there is still cool water in the pipes between where you heated it and where you want to use it.
A plumber in Arizona recently told me that his company has installed over a thousand tankless heaters in the last 3 years. A great new extension to his already thriving business. But he estimates that 60% of his customers are somewhat dissatisfied even though their energy bills are lower because they do not get hot water any faster than they did with their old tank style heater.
Unless you have a recirculation line your pipes are a dead-end. There is no place for the water to go until you turn on a faucet. When you turn on a faucet the cool water must leave the system before you get what you want. That can take a lot of time.
The reality is that if you had to wait 15 seconds, 2 minutes or 5 minutes before you installed the new heater, you will still be waiting for 15 seconds, 2 minutes or 5 minutes afterwards.
Tankless heaters (also known as instantaneous or demand heaters) can provide you with an unlimited amount of hot water under the right conditions and if they are maintained properly. They take up less space, only run when you need them and qualify for energy rebates in many areas of the country. All very good things.
But the wait cannot be resolved with this new energy-efficient technology. The best solution is to install a recirculation pump at the water heater and a bridge valve underneath the furthest sink between the hot and cold lines so that the pump can push the cool water in your hot line back into the cold line.
The pump should be activated by turning on a faucet and it should be turned off when the faucet is turned off.
Leaving a pump running full-time or even part-time when there is no water usage is not good for the pipes or the pump and will increase your energy bill.
If you are interested in saving money on your energy costs, tankless heaters may be the way to go. But if you are trying to get hot water faster, you will need to do more than just heat it in a new way.