How to Fix Common Temperature Control Problems with a Tankless Hot Water Heater

What You'll Need
Large Pump
Owners Manual

A tankless hot water heater can sometimes lead to temperature control problems. Tankless hot water heater systems avoid heating water until it is needed. Rather than keeping water warm in a tank, it runs the water through a heater and then delivers it directly to the faucet. Some of the problems may arise from the process of running hot water through the heater, while others are caused by features of the water heater itself, such as a lock-out system. Often, you can alleviate these situations yourself by following some simple steps.

Step 1 - If Water Is Too Cool

The most common problem experienced by people using tankless hot water heaters is that the water cools down too quickly. This can mean that instead of a lovely warm shower you receive an ice storm instead. This problem is caused by poor insulation of the pipes, so that the water gets the opportunity to cool down on its way to you. There are two ways to solve this problem. The first is to add more insulation around the pipes going to and from the heater, ensuring that no heat is lost on the journey. This will only keep so much of the water warm, however, as it will loose some through movement. In order to keep your hot water truly hot you need to add a tank to your system. This seems to defeat the objective, but a small tank could create a gentle buffer between the hot water heater and the faucet.

Step 2 - If Hot Water Takes Too Long

Another common problem experienced by people using a tankless hot water heater is that the temperature of the water takes too long to increase. Since the heater only warms up water as you demand it, it may take around 5 minutes to heat up enough water for a shower, and if there is another appliance, such as a washing machine, using hot water at the same time, you could be waiting a while. The answer to this is to add a pump with a reciprocating loop to your heater. The pump pushes the water around at an increased pressure, keeping it going to all places quickly, while the reciprocating loop ensures that hot water never stops travelling around the home, so you can call on it when you need to.

Step 3 - If Temperature Doesn't Elevate

If you find that the temperature of your tankless hot water heater is consistently too cool, and the machine won't increase the heat above 100 degrees or so, you need to perform a manual override. Many heaters have a computer chip with a programmed temperature that they cannot exceed. Read the owner's manual to find out a way to bypass the heat. Beware of adding too much temperature to your thermostat, as this will increase pressure on the heater.