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Posted by BobK207 on April 3, 2008, 11:57 pm
>
>
>
>
> > > Since there's been some discussion about these critters here lately, I
> > > thought I'd add my take on them. I have three customers who actually
> > > have them, so I speak from some experience.
>
> > > First of all, the answer to questions like "should I install one?", "are
> > > they more efficient/cheaper/better than a tank heater?" is definitely
> > > "it depends". It depends on (in no particular order):
>
> > > o where the heater is installed (how far it is from the farthest faucet)
> > > o how big the heater is
> > > o the water usage pattern
>
> > > The last probably being the most important.
>
> > > Two of my customers have the same type of older-generation tankless
> > > heaters (Aquastar, a French-made unit, now handled by Bosch for spares).
> > > Two of them are installed in the attic crawlspaces of a
> > > commercial/residential building, probably because the remodeling
> > > contractor didn't want to sacrifice any more space in the living units
> > > than necessary (and also simplified venting, since they're right under
> > > the roof). This makes these two a pain in the ass to service; I've
> > > overhauled both of them (replacing water valves and thermostats). Still,
> > > they operate pretty well.
>
> > > One of these had an odd setup, which it took me a while to figure out.
> > > Someone had written "OPEN 3/4 TURN" on the inlet valve, and it turned
> > > out that sure enough, the heater would simply not function correctly if
> > > it was opened any further. Not enough hot water in the shower, though
> > > the kitchen sink was OK. The culprit was the shower valve, which was a
> > > strange one that was full-on with temperature control; there was simply
> > > no way to have anything less than full flow in the shower. This shows
> > > that there's a definite limitation to how much flow these heaters will
> > > handle.
>
> > > Another customer has this same heater in their fairly large house.
> > > They're very happy with it; they have plenty of hot water and their gas
> > > bills are lower.
>
> > > My other customer just installed a Tagaki heater outside her house. This
> > > unit is remarkably small, requires no venting, and supposedly has a much
> > > higher capacity (and is more efficient). (Having electronic ignition
> > > doesn't hurt, either.) I'm told that this is pretty much the state of
> > > the art today. Too early to tell how it'll affect her gas bill.
>
> > > One thing that ought to be considered is insulating hot water pipes to
> > > further avoid heat loss.
>
> > > --
> > > The best argument against democracy is a five-minute
> > > conversation with the average voter.
>
> > > - Attributed to Winston Churchill
>
> > If you're listing issues.......
>
> > It depends on (in no particular order):
> > o where the heater is installed (how far it is from the farthest
> > faucet)
> > o how big the heater is
> > o the water usage pattern
>
> > better consider as well
>
> > o temperature of incoming water
> > o elevation (above sea level) of installation
>
> > if the incoming water is really cold (like sub 45) and / or
> > installation is in the higher elevations (like the mountains) forget
> > about a tankless
>
> > cheers
> > Bob- Hide quoted text -
>
> > - Show quoted text -
>
> Yea , What BS, my incomming can be 35, and if you only had a brain
> enough to not post BS, or did simple spec research. you would see the
> Cheapest Bosch has a 90f rise, If you cant take a shower in 105f you
> are anemic or sick! I only need 103f thats a 70f+ rise, and figure in
> pipe loss of 15f and you still get a real hot shower, well over "
> Comfort level" You just made another Bull Shit, unsubstansiated ,
> wrong post. at 45f incomming 135f output is what you get on "Cheap
> models" NOBODY can shower at 110f or you BURN. So STFU Bob , your
> post is total ,,BS,,crap.
Dear R-
No need to be rude or insulting, I can assure you that I know how to
do the calcs.
I was merely mentioning that one needs to also consider incoming water
temp & elevation of installation as well as usage patterns.
As a mechanical engineer I do in fact like the tankless
concept...depending on the particular installtion & usage patterns.
I actually looked into getting a tankless for my mountain home. This
was a few years ago but all the mfrs' sales reps with whom I spoke
suggested that I NOT go tankless.
Their comments were, more or less, "with the derating due to altitude
(8000+, their spec..the house is actually at 8300 ft) plus the very
cold water incoming water in the winter, you'll be disappointed with
the performance."
I should have been more precise in my comment
>>if the incoming water is really cold (like sub 45) and / or installation is in
the higher elevations (like the mountains) forget about a tankless. <<<
being able to service a high instantaneous demand at over 8000 ft.
I have researched the temp rise at the flow I need & tankless won't
work for my particular installation.
When people come back from skiing and there are three showers running
(even with low flow heads that's 7.5 gpm) tankless won't do the job
but a quick recovery 75 gallon tank that was cranked up before we left
in the morning does the job.
I done the calculus problem, a tank pencils Plus based on actual
usage it works (empirical data) . A single tank less won't & I'm not
about to rework the plumbing to install two units.
It's a demand thing, in my particular case.
Tankless can work but not in every situation.
Sorry if I pissed you off but really was your reply warranted?
cheers
Bob
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