Experiences With A Tankless Hot Water Heater
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- Another Takagi onwer on December 19, 2005:
- for most norht american plumbing pipe size is by i.d. (inside diameter )
not o.d. (outside diameter).This is the case for black iron pipe such as
you mention for the gas supply. So the correct size reference would be
3/4". Side wall thickness changes with application so the o.d. will
change for the same nominative pipe size.Typically iron pipe in gas is
spec'ed as schedule 40.High pressure apps would use sced 80 , and 160 .
Tubing however is specified by o.d. , so to know the equivalent capacity
to pipe you have to know the wall thickness.
Rigid copper pipe is i.d.
copper tubing is o.d.
It would help people if you correctly refered to the iron pipe in your
article as 3/4" ( which I believe you will find on the table Takagi
includes , and they refer to 3/4 pipe as the connection size ( i.d.
implied ).3/4" o.d. would be inadequate to supply the maximum output.
- Anonymous on January 6, 2006:
- Thank you for your information on this. It was very helpful.
- Anonymous on April 17, 2006:
- thanl you for your info--godd to hear from someone not trying to sell
- Anonymous on June 7, 2006:
- The info on low flow rate shut off is great!
I have read a lot on tankless heaters and not come across that fact.
- Collecting Information on July 29, 2006:
- I've been replacing older appliances with more energy efficent ones
over time. Heat/AC, Washer/Dryer, Dishwasher, Refrigerator, ect. I've
been hearing a lot about Tankless Water heaters and I was curious
about ones experiance on such device. I have an older home that isn't
all that efficent and I've been doing what I can to help keep cost
down. Adding Insulation to the attic made a huge differance in comfort
and cost. Especially here in Texas. Thanks for sharing your experience
on this and look forword to seeing updates in the future.
- Anonymous on January 24, 2007:
- Wouldn't it work better if you had a tankless cold water heater? It
don't make a lot of sense to heat water that's already hot.
- jep on January 31, 2007:
- Jan, I have a general question.
I am researching water heaters with the idea that my elderly house has
an elderly water heater which will need replacement.
I've heard tankless water heaters can deliver unevenly heated water;
that is, if you are taking a shower and the washing machine (for
example) starts using water, your shower temperature can drop. Then
when the washing machine stops using water, your shower temperature can
rise sharply. Have you had any problems with that?
Also, Lowe's currently advertises on certain models, "This product may
qualify for a $300 tax credit". I don't know the details of that tax
credit but it may reduce the cost of a $1000 tankless water heater to
$700, which would be comparable to a standard water heater.
- Jan Wolter on April 25, 2007:
- All tankless hot water heaters have a limit on how much water they can
heat per minute. As long as you don't exceed that limit, I think the
water will be delivered at a consistent temperature. If you do exceed
that limit, then something is clearly going to happen.
What happens depends on the heater. Some will simply deliver water that
isn't entirely heated up to the desired temperature. Mine is a little
fancier. If it hits the limit, it will continue to deliver water at 120
degrees, but it just won't allow more to flow through the meter.
Not that that'll prevent temperature changes in your shower. Since you
control your shower temperature by mixing hot and cold, changes in the
flow rate of the hot water are going to feel like temperature changes.
I've never had this problem though. Basically, you need to get a big
enough heater for your needs.
- Steinebach in Portland, OR on July 22, 2007:
Thanks for the informative article. Your comprehensive article answered
a question that I had on the low volume shut off. I use minimum flow
when I shower and was worried that the system might shut down at some
minimum flow level. You answered that question - it does. Now I need to
know if a smaller system might work better. My plumbing contractor is
trying to sell me what I think is a whole house tankless water heater
and I only need it for one bathroom. Nothing else will be drawing hot
water from it. Time for more research.
- Jan Wolter on August 11, 2007:
- If you're worried about this, I'd do some experimenting and try to come
up with an estimate of how many gallons per minute of hot water you are
actually using when you shower. Maybe you could set the shower how you
like it, then measure the total water flow. (I used a gallon milk jug
and a stop watch to do this.) Figuring out what percentage of that
water is hot is probably trickier. Probably the best way would be
measure the water temperature you shower at, the hot water temperature
and the cold water temperature. This should give you a decent guess at
what percentage hot water you are using.
If the total hot water usage is in the neighborhood of the hot water
heater's shut off, then you may have a problem. I expect, however, that
most people won't have one. The shower I had a problem with was set to
use much less water than a normal low-flow shower head, and
even then we only occasionally had problems.
- meredith gossland on April 20, 2008:
Thanks for a great article, clearly written. I learned a lot! Just one
thing about the electric heaters. If you have solar energy as little as
50 watt panels you might be able to power your heater in the event of
power failure. Even when it is extreamly cold, if you have a battery
backup powered by solar you be ok.
Once again thanks so much for the info!