Bosch Water Heaters What You Need to Know Before You Buy

What You Need to Know Before You Buy

Above all, anyone buying a tankless unit needs to think about how they use the water in their home -- during peak water usage times, how many faucets, shower heads, bath tubs, washing machines, dishwashers, and jacuzzis will you be running at once? Tankless water heaters provide endless hot water for up to two major applications at a time and up to 3-4 sinks at a time.

Our top models will handle up to two major applications at once, such as a dishwasher and washing machine or two showers running at the same time. The best tankless water heaters will pump out 5-6 gallons per minute, or over 300 gallons per hour - and you never run out. An extra-large capacity 80 gallon tank water heater runs dry in about 15 minutes by comparison.

The trouble with extra-large tank heaters is that whether or not you use the 80 gallons of water stored inside, you pay a high price to keep it hot 24 hours a day. Imagine leaving your car running 24 hours a day!

Once you've settled on a heater that will meet your hot water demands while saving you money, you'll need to carefully consider how it will work within your home.

Gas Tankless Water Heaters

Here are four things you'll need to consider before buying your tankless water heater:

The appropriate size for your household needs

To ensure your tankless water heater will deliver enough hot water, determine the flow rate and temperature rise you’ll need. Make sure the unit you purchase can deliver the most common temperature rise of 70 degrees Fahrenheit (39 degrees Celsius) at the desired flow rate. A trained professional can help you determine the right size for your home.

Minimum flow rate

Tankless water heaters require a minimum flow of water—typically around a half gallon per minute—through the heating system to heat water. To avoid problems associated with not meeting the minimum flow requirement, consult with a qualified plumber to make sure the flow rates at outlets you’ll connect to the heater exceed the unit’s minimum requirements.

Gas sizing information

Take a look at the installation manual of the product you'd like to purchase to see the gas sizing requirements. Tankless water heaters utilize three to four times the BTUs of a conventional tank water heater. Ask your plumber to verify that your current gas line, size, and length can provide sufficient gas flow to the unit. Consult with your gas company to determine if your gas meter is adequately to accommodate larger water heaters.

Compatibility with water supplies

Local water quality should be considered in areas where the potential for scaling may be increased. Scale control in water heaters requires disconnecting the unit, connecting deliming hoses and recirculating special deliming agents.

Combustion air

Tankless water heaters require combustion air. It's important to understand how combustion air will be delivered to your water heater and how much combustion air is needed. When placed in an unconfined area, combustion air can simply be the air within your home. Confined areas (such as a closet) may require air ducts or additional air inlets. Whenever possible, it is always better to pull combustion air in from outside the home - it is cleaner and will keep your tankless water heater operating at peak performance. Check the installation manual for more information about combustion air requirements.

Clearances

Tankless water heater placement is another important factor to consider. Each tankless water heater will have different distance requirements between the heater and other parts of your home, as seen in the example above.

Some of the clearances you'll need to consider are:

- Operable windows, doors and other fresh air openings
- Adjacent walls or tall bushes
- Below gutters, sanitary pipework, eaves or overhangs
- Distance above the ground
- From a gas meter, gas regulator, electrical box or another heater

Check the installation manual to see what your heater requires and whether it will work with your home layout.

Installation issues need to be considered

Special venting and/or the need for increased combustion air may require additional changes because of the unit’s higher input rates. You will also need 120 volt electric power, and in the event of an electrical power outage, the tankless water heater will not operate.

Venting

Tankless water heaters require gas exhaust venting to the outside. Some vent horizontally, others vent vertically. Check the installation manual for more information about venting options and for any accessories you'll need to buy for your chosen venting configuration.

All manufacturers of stainless steel products state that the installer cannot mix and match venting. It is a liability issue. If you start with one brand of stainless steel venting, you must complete the job with the same brand. You cannot mix and match venting. If you do all matters of warranty will be voided.

Electric Tankless Water Heaters

The size of your breaker box and how many amps you have available is the most important thing to consider when purchasing an electric water heater.

Depending on which electric tankless water heater best fits your home needs, the required amps will be 150 or 200 amps.

If you don't meet the amperage requirements stated in the installation manual, how do you plan to adapt? Some home owners choose to add an additional breaker box to their existing wiring while others will replace their existing breaker boxes with bigger ones. Talk to an electrician or installer before taking the next step in buying an electric water heater to be sure you'll be ready to put it to use in your home.

NOTE: CPO recommends that appliances be installed by a licensed professional.