Electric tankless water heater

[cordwood]

I believe the choice of tankless water heaters vs normal water heaters comes down to a few questions.

Do you care about water conservation? or are you worried about energy conservation?

tankless require the water to be run through them before they kick in, tanks require constant energy to keep the water warm.

I have come to the conclusion that a happy medium would be a small tank water heater. less energy to keep warm than the normal sized ones, and less water usage cause the water gets colder quicker.

But if you arent worried about either of the above questions then the questions are about money and space.

sorry if i ran off track on this topic.

Wildbil

I really like our little 2.6 gal under the kitchen sink for the fact that when we don't need it it is off, We only turn it on just before we want to use it and it takes a few minutes to heat up (it has a little red light that glows when its heating). I just wish it was a little bigger maybe another gallon or so. With it in the kitchen and a 40 gal elect. (30 y/o) in the laundry room that shares the back wall with the bathroom our hot water runs are very short and think in our new house I would like to go tankless for the bathroom & laundry with the short runs also. But I will still keep the little one in the kitchen just because everyone laughed at me when I bought it and now it is a sense of pride that I keep it .
I hear how the big electric tank heaters kill your electric bill but I haven't seen it here, With an 1100 sq.ft. draft hole P.O.S. all electric house save for the wood heat an average use of 550 KWH a month don't seem bad to me and we have fans everywhere and I weld quite a bit plus the wife needs her little space heater when she's on the putter.
Our elect. bill last month was $75 and our water bill was $48 with zero outside water use so I am torn with having to run more water to get hot water

[lobster]

I believe there is a bit of a balancing act between tankless heater temperature setting and low flow showers.

It is also possible to have the tankless set to too high a temperature for the flow. Picture an extremely low flow head (1.5 GPM), coupled to a heater set at a very high temperature. At the shower you set the temperature somewhat low, and that can cause the hot water flow rate to fall below that to actuate the burner/element.

in my 2 bedroom house (24' x 30') in maine (with external well) i have installed a seisco model ra-28 electric tankless, which i first saw at the "florida learning house" in sarasota.  it heats via 4 ordinary hot water heater elements inside, mounted in a serpentine pipe through which the water passes.  i have 200 amp service.  the seisco draws a maximum of 120 amps at 220 V when working. the rest of the house works off the remaining power.

the seisco does not have this problem of being "fooled" by a too low flow rate.  that's because there are no moving parts, the flow rate is sensed electronically.

the seisco does not necessarily work at full power under all circumstances.  it has microprocessor control, and uses thermistors to sense the temperature at the input, middle, and output portions of the unit, to determine the correct operating power to apply to the heating elements.

it uses 4 triacs (one for each element) to phase-control each of the 4 heating elements individually.  not all elements are necessarily turned on, and the elements that are on are not necessarily 100% on; rather there are several intermediate powers available for each of the four elements. so only enough power is applied to force the output temperature to the desired set point.

the seisco uses a PID (proportional-integral-differential) control loop to continually sense and react to the heating requirements.  it continuously calculates how much power should be applied to each element based on the flow rate, which it can ascertain by measuring the instantaneous difference of input vs. output temperature, and correlating that with the amount of power that it knows it is applying at that instant of time.  thus it can regulate the output temperature to keep it fairly constant no matter what the flow rate, or even if the flow rate changes - such as when another faucet is turned on.

even when not working (with no water flow) it keeps the internal water at a higher than ambient temperature.  it clicks on for a few seconds every so often, even if you are not using water, so when you do start to draw water after a long period of inactivity, you will not be surprised by a "slug" of cold water at first.

the level of smarts that went into its design is impressive.  there is a self-test built in, with a LED that flashes an error code, if any.  a beeper can be activated in parallel with the LED, to beep the error codes, thus allowing a factory service technician to diagnose any problem by listening on the telephone.  the triacs are cooled by being thermally mounted to the cold water inlet.  they are protected from high voltage surges on the power lines, such as lightning strikes, by being in series with mechanical relays, which are turned off when no power is being applied.  this implies one drawback - the unit is not 100% silent, but actually has slight clicks as the relays turn on prior to heating the water, and more clicks when they turn off after flow stops.

it has been working fine for me for 2 years, and i am using much less power than with my traditional water heater.

http://www.seisco.com

[CREATIVE1]

That's one I haven't heard of.  It's now bookmarked for future reference.  Thanks!

[MountainDon]

That sounds quite interesting. And I never heard of them before either. They've never come up on a Google.

[glenn kangiser]

to the forum, Lobster

Thanks for the info on that one.

[lobster]

thanks for the welcome to the forum :-)

All the tankless ones I have been around were gas and I was less than impressed with them as well. To just heat water enough to wash your hands and face in a work shop they worked good but anything like washing dishes where you want HOT water they were inadequate. JMHO

regarding dishwashing & tankless heaters, that may be true if you hand-wash the dishes (though such scalding hot water is uncomfortable, even with gloves), but surely, if you use a dishwasher, it is less costly in the long run to set the tankless to a humanly bearable temperature for showers, hand washing, etc.,  plus make sure you buy a dishwasher with "sani-clean" booster heater feature to super heat the internal dish washing water.

since all electric resistance water heating is 100% efficient, there is no difference in electric usage if the tankless heats the water vs. if the dishwasher heats the water.  but you do save overall because when the dishwasher does the heating it does so only for the actual water used, not the unused hot water in the pipe from the tankless to the dishwasher - not to mention all the uselessly heated hot water that must be diluted with cold in order to be comfortable for hand washing and bathing.

i understand that years ago people also used to boil their clothes in a big wash tub over a fire. but nowadays many use cold water detergent.

the need for super scalding hot water coming from the tap is nowadays diminished, and perhaps unjustifiable from a safety and economical viewpoint.  a tankless water heater is just the sufficient solution for hot water these days.

[glenn kangiser]

Keeping the tankless on lower heat reduces or stops scale build up also extending the life of the heater.

[cordwood]

thanks for the welcome to the forum :-)

All the tankless ones I have been around were gas and I was less than impressed with them as well. To just heat water enough to wash your hands and face in a work shop they worked good but anything like washing dishes where you want HOT water they were inadequate. JMHO

regarding dishwashing & tankless heaters, that may be true if you hand-wash the dishes (though such scalding hot water is uncomfortable, even with gloves), but surely, if you use a dishwasher, it is less costly in the long run to set the tankless to a humanly bearable temperature for showers, hand washing, etc.,  plus make sure you buy a dishwasher with "sani-clean" booster heater feature to super heat the internal dish washing water.

since all electric resistance water heating is 100% efficient, there is no difference in electric usage if the tankless heats the water vs. if the dishwasher heats the water.  but you do save overall because when the dishwasher does the heating it does so only for the actual water used, not the unused hot water in the pipe from the tankless to the dishwasher - not to mention all the uselessly heated hot water that must be diluted with cold in order to be comfortable for hand washing and bathing.

i understand that years ago people also used to boil their clothes in a big wash tub over a fire. but nowadays many use cold water detergent.

the need for super scalding hot water coming from the tap is nowadays diminished, and perhaps unjustifiable from a safety and economical viewpoint.  a tankless water heater is just the sufficient solution for hot water these days.

When your spouse is a commercial cook and she wants HOT water to wash dishes in it matters little that mere mortals hands would blister and peel and any argument would surely lead to my doing the dishes so "hot enough" ain't good enough for our house where I am the "King" and do as I'm told
Now as for the laundry I do most of that so cold or warm water works just fine.