Buying tankless water heater...

by Daniel

OK. I have few questions about using tankless water heaters in home. I like the idea to heat water on demand and their small size.

But, are the tankless heaters more or less efficient than tank type water heaters? Does it cost less to heat water with the tankless technology and the last question is can any size of these on demand heaters provide hot water enough for the whole house, or they are just for the point of use service.

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Aug 04, 2010
why tankless water heater is the best
by: Mark

On demand or tankless water heaters are more efficient than tank type units; they use less energy and their energy factor, EF, is on most of the brands from 0.78 up, while tank type energy factor is ranging from 0.53 to 0.63.

When you look at the Energy Star requirements for high efficiency, you will see that water heaters are qualified if their EF is 0.82 or higher for tankless, and 0.62 or higher for tank type water heaters. EF factor shows how water heater efficiently heats the water.

There are condensing water heater, tank type, whose EF is usually above 0.9.

Higher energy factor means also actual savings on fuel bills.

When looking to buy a new tankless water heater, or replace the old tank type with the tankless type, keep in mind that initial cost for these small units and the installation is much higher (tankless units can cost more than $2000, the average price is around $1000).

When switching from tank type to tankless option, be aware than the material and labor cost more; larger venting is required and special vent pipes has to be purchased from the water heater manufacturer (recommended); larger gas pipe is needed due to the high gas inputs also.

Tankless water heater can heat water at the point of service; called point-of-use water heater and they are mainly for one application, like sink use; and there are whole house water heaters that serve several applications simultaneously.

This is what you should take into account when looking to buy a tankless unit:

- The minimum and max. BTU gas input, per hour.
- Hot water demand (how much hot water do you need per day and what is the usage pattern of your family members)
- What is the water flow of the tankless water heater, in gallons per minute.
- Temperature rise and temperature of the incoming water.

You can find water heaters with over 300,000 BTUs and maximum of 13 gpm water flow on todays market. These is more than enough for large homes. Standard size homes with families of 4 to 6 are using much smaller tankless units. If looking for Energy Star models, keep in mind that they have maximum of 199,000 BTU/hr gas input.

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