• How much will an installation cost?

A simple installation should take less than three hours. Tankless water heaters require 1/2 inch or 3/4 inch gas lines (depending on size) or larger, so if a larger gas supply line is required, the time (hence, cost) will be more.
Venting work can also cause the installation cost to increase. The AquaStar 1600 Series requires a minimun of a 5 inch vent. These units can also be power vented through 4-inch vents, making retrofits into existing exhaust systems less costly. Check out the power vent AQ4 accessory on the AquaStar 1600 lineup page. The Bosch 2400ES and 2700ES use CAT III Stainless Steel Venting and can be vented through the roof or out a side wall.


• Can tankless water heaters be installed anywhere?

Tankless water heaters cannot be installed inside of bathrooms or bedrooms or in mobile homes, recreational vehicles or boats. Closets are fine as long as adequate air supply is present. Direct Vent units like the 2400ES and 2700ES can be installed in smaller locations since they pull air from outside and not from inside your house - check your local code.


• Who would install the unit?

A licensed plumber or a licensed gas technician would be able to install an Bosch AquaStar Tankless Water Heater. The connections at the heater are standard 1/2 inch (AquaStar) and 3/4 inch (2400ES / 2700ES) for water and gas lines or larger.


• What are the venting and combustion air requirements?

Venting and combustion air requirements for each unit are located on the Tech Support pages on the AquaStar 1600 Series page. Direct Vent units like the 2400ES and 2700ES can be installed in smaller locations since they pull air from outside and not from inside your house - check your local code.


• How much hot water can I get at any one time?

Tankless water heaters are rated by gallons per minute (gpm) at specific degree rises. Check the specifications for any given model. For example, the AquaStar 1600P and 1600H will produce 3.5 gallons per minute (gpm) at a 50 degree rise. This means you would have 105°F water at 3.5 gpm (50-degree rise to inlet water temperature of 55°F). This is plenty for a good shower and simultaneous hand washing at a sink. The flow rate is the same as 210 gallons per hour at a shower temperature. The 2400ES and 2700ES will produce up to 7.15 gpm.


• How many gallons per minute (gpm) are used by a shower, a sink, a bathtub, etc...?

As stated by the Department of Energy: shower = 2.5 gpm; sink = .5 to 1.5 gpm; washing machine = 2 gpm; dishwasher = 2 gpm. A bathtub that holds 30 gallons of water will take about 10 minutes to fill.


• What water temperatures are common in a home?

Hand washing is comfortable at 110°F. Showers and baths are safe around 104°F.


• What happens when I increase or decrease the flow rate?

Bosch AquaStars have a modulating gas valve, so accordingly the burner flames will increase and decrease in order to keep the temperature steady. AquaStar Tankless Water Heaters modulate by flow, so that the gas burners activate according to the volume of water flowing through the heater. Therefore, the temperatures will not vary when flow is increased or decreased at the faucet.


• Are there limits to the flow rates?

Yes. When the AquaStar Tankless Water Heater 1600 Series are set to activate at 0.5 gpm, the maximum flow rate is 4.2 gpm. At this setting, the temperature rise will be 90°F (giving 140°F water). Adding cold water produces higher flow rates. The AquaStar can easily be set to activate at a higher flow rate, and then it will produce up to 3.5 gpm at shower temperatures. The 2400ES and 2700ES will produce up to 7.15 gpm.


• What happens if two big draws (for example shower + washing machine) are running at the same time using an AquaStar?

The temperature will remain constant but the flow will decrease. The decrease in flow will be equal if the outlets are the same distance from the Bosch AquaStar and if the outlets have the same flow rate. If one outlet is further than the other from the AquaStar, the decrease will be most noticeable at the further outlet. If one outlet has a greater flow (bathtub compared to a sink, for example), the flow at the bathtub will not experience as much decrease as the faucet since water runs the path of least resistance and the tub's spigot is larger than the sink's.


• What do you mean by endless hot water?

The hot water at any faucet or outlet will never run out as long as you are calling for hot water. The Bosch AquaStar Tankless Water Heater will allow one major flow of hot water at a time. You could run shower after shower, then when finished, run loads of laundry, and then do the dishes, and so on. It is generally fine to run hot water at a sink while someone is taking a shower.


• What is the average ground water temperature and why does it matter?
The average ground water temperature is 50-55° F (ground water temperatures vary as little as two to three degrees from summer to winter). Because tankless water heaters operate by increasing the incoming water temperature by a fixed number of degrees (called degree rise), knowledge of the ground water temperature allows you to know what water temperature a tankless water heater will produce.


• How can the tankless water heater heat water instantly?

There are very powerful burners located beneath the copper heat exchanger that heat the water as it flows through the numerous feet of copper coils. Copper transfers heat instantly to the water in the coils.

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• How long will the unit last?

With nominal service, the average life span is twenty years. This means the payback for an AquaStar tankless water heater is in about 2-3 years.


• How will hard water affect my AquaStar?

Since there is no storage of water in the unit it is difficult for mineral buildup to occur. If need be, the heat exchanger can be removed and descaled in a vinegar solution in the bathtub.


• What is the warranty?

Ten years on the heat exchanger and two years on the parts.

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• If these units are superior to tanks, why haven't I heard about them before?

This is the way the Europeans and Asians have heated water for over seventy-five years, and the engineering technology has evolved over this time. However, since fuel costs in the U.S. have been quite low, we've never had to think much about the waste of keeping a tank of water hot 24 hours a day.


• Does HouseNeeds.Com sell a tankless electric hot water heater?

Yes! We offer several electric tankless water heaters that can supply hot water for one sink (point-of-use) or for an entire home (one major flow at a time). The units can be installed in such a way as to eliminate a long water run (plumbed independently of the main hot water heating system). Ask for Powerstream (point of use models) or PowerStar (for the whole house) and Ariston point-of-use mini tank.