DIYbanter - View Single Post - 40 gal just not enough: Replacing water heater for 2400 sq home. Family of 2 adults + 2 children

Paul M. Eldridge

On Wed, 9 Apr 2008 15:09:05 -0700 (PDT), wrote:

On Apr 9, 4:28*pm, Paul M. Eldridge
wrote:

Hi Mark,

I don't like misinformation either and I don't have a strong opinion
on this matter. *I don't doubt the operational performance of natural
gas tankless units is superior to that of their electric counterparts
and that the efficiency gains are more impressive. *I have no
first-hand experience with tankless gas, but I'm familiar with the
electric variant and that experience left me cold, literally! *

So your views are jaundiced. Taking experience from electric and
applying it to gas tankless is like comparing apples to oranges.

Let me say this again, but this time more slowly so perhaps you might
come to understand it. I said "I don't doubt the operational
performance of natural gas tankless units is superior to that of their
electric counterparts and that the efficiency gains are more
impressive." I also explicitly stated that "I have no first-hand
experience with tankless gas". I did not in any way knock gas
tankless; my criticism was in regards to *ELECTRIC* units, which
should have been obvious to even the most dim witted amongst us --
guess you proved me wrong.

It may
very well have been undersized (I don't honestly know), but the water
never got what you would call "hot" even though the shower was
equipped with a low-flow head and I was the only user at the time.
Based on this admittedly limited experience, I would be hard pressed
to recommend an electric unit, unless it was a high capacity model and
that, in itself, opens up another can of worms.

And that has what to do with gas which has far higher output
capability?

It has absolutely nothing to do with gas, just electric. Let me spell
it out for you again. *E-L-E-C-T-R-I-C*.

If someone could tell me that a conventional gas water heater with an
EF of 0.60 would use X cubic metres (or therms) of gas per year and
that a state-of-the-art tankless version would use Y, it would help me
to better compare these two technologies.

The EF is a measure of how much hot water the unit produces per unit
of energy. It isn't that hard to calculate. If you know the EF of
your current unit, what your bills are and the EF of the other unit,
the math is straightforward.

And if a homeowner uses natural gas for space heating, cooking,
clothes drying, etc., they can isolate the DHW component from their
bill how?

Cheers,
Paul