[2manyfbods]

Yeah, it's a little off the usual topic content but, My Hot water heater is starting to go. I would prefer to change it before it quits completely.

I've done some research on tankless water heaters but, I would like to here feedback on those of you that have them. I live in the phoenix area so, ground water rarely gets below 45-50 degrees and I have a 200amp service panel. I only have electric

Thanks !


<F body content - I take a shower before going to the race track with my Firebird :lol >

[cccbock]

Yeah, it's a little off the usual topic content but, My Hot water heater is starting to go. I would prefer to change it before it quits completely.

I've done some research on tankless water heaters but, I would like to here feedback on those of you that have them. I live in the phoenix area so, ground water rarely gets below 45-50 degrees and I have a 200amp service panel. I only have electric

Thanks !


<F body content - I take a shower before going to the race track with my Firebird :lol >

two main concerns.

Do you have electric capacity? a typical unit might require three 40 amp circuits on a 240V system. Unless your home is practically new, and the electric service was way oversized to begin with, you probably don't have this capacity.

Second, the unit needs to be sized to supply enough hot water to meet the flow requirements of the users. For example, if the unit supplies 3 gallons per minute at a 40 degree rise (and your incoming is 50), it will never be capable of filling a 50 gallon tub with 100 degree water since the max temp here would be 90. If you reset the system to supply a higher temp, then the available flow will be less. for example, if you get 2gpm with a 50 degree rise, in this example, you will need 25 minutes to fill a 50 gallon tub with 100 degree water. Not too good.

This type of system makes more sense in an application where space is at a premium, where there may be extremely long plumbing runs, where there is plenty of electric capacity, and where long periods of time pass (measured in many days or weeks) where hot water is not required.

I suspect your local electric utility company would greatly frown on this as well...since they need to have more capacity (about 27kw) to serve your tankless unit than your old fashioned tank (about 5kw). Just round numbers.

I'd stick with old school.

bock

[Eskimo]

This type of system makes more sense in an application where space is at a premium, where there may be extremely long plumbing runs, where there is plenty of electric capacity, and where long periods of time pass (measured in many days or weeks) where hot water is not required.

Interesting, and the first negaitve I've read about them. However, most of what I'm read was from vendors.. and come to think of it, the electric ones were only mentioned for an under-sink install out in a shop (f-body content - which is where I fix my f-body), or something similar. All the whole-house units are always shown as gas.. now I know why!

Bock - Does your opinion hold true for gas units as well? Our HW heater is nowhere near dead, but: we have a gigantic jacuzzi tub (drains our 80 gal. HW heater in order to almost fill it), and there's only the 2 of us in the house, so the usage is very much 2x a day. We're also on well water, so we'd need a very good amount of temp rise.

I'd also have to think that it would take even longer to get hot water at the tap with a tankless, since the unit itself would have to heat up?

[cccbock]

This type of system makes more sense in an application where space is at a premium, where there may be extremely long plumbing runs, where there is plenty of electric capacity, and where long periods of time pass (measured in many days or weeks) where hot water is not required.

Interesting, and the first negaitve I've read about them. However, most of what I'm read was from vendors.. and come to think of it, the electric ones were only mentioned for an under-sink install out in a shop (f-body content - which is where I fix my f-body), or something similar. All the whole-house units are always shown as gas.. now I know why!

Bock - Does your opinion hold true for gas units as well? Our HW heater is nowhere near dead, but: we have a gigantic jacuzzi tub (drains our 80 gal. HW heater in order to almost fill it), and there's only the 2 of us in the house, so the usage is very much 2x a day. We're also on well water, so we'd need a very good amount of temp rise.

I'd also have to think that it would take even longer to get hot water at the tap with a tankless, since the unit itself would have to heat up?

The typical instantaneous water heater (gas or electric) is placed as near the point of use as possible with the cold water piped to it and the hot supply coming out would be very near to the point of use. The under the sink application is actually a very good one for this type of unit, especially in a shop.

The gas versus electric question relates mainly to the availability and price of gas (natural gas typically, LP gas costs too much) relative to electric. For example, in the northwest where they have a lot of cheap hydroelectric, it is usually way cheaper to run an electric unit. I can do some calculations if given the parameters (cost of each fuel, install costs, maintenance, etc.) but generally speaking in most parts of the country, the gas unit will cost more to install, but less to operate over a long period of time which would yield some sort of rate of return relative to the electric.

Where I live (Florida) well water is about 70F year round so we don't have the same temp rise problems as other parts of the country. Although the point of use water heater sellers would like you to believe that you are wasting tons of energy with the old style storage tank type heater, the truth is there are real significant cost tradeoffs. If you are actually using your hot water twice a day (bathing, dish washing, jacuzziing, or whatever) then the old style tank (gas or electric) is very probably your best bang for the buck, even though it sits there much of the time not being used.

bock

[pknowles]

Where I live (Florida) well water is about 70F year round so we don't have the same temp rise problems as other parts of the country. Although the point of use water heater sellers would like you to believe that you are wasting tons of energy with the old style storage tank type heater, the truth is there are real significant cost tradeoffs. If you are actually using your hot water twice a day (bathing, dish washing, jacuzziing, or whatever) then the old style tank (gas or electric) is very probably your best bang for the buck, even though it sits there much of the time not being used.

bock

I just moved from a 3 BR house that had an old style NG water heater and furnace. In the summer when I was not using the furnace, my NG bills were like $26/month for 2 people.

Edit: added "old style"

This post has been edited by pknowles: Mar 12 2009, 07:50 PM