tankless water heaters [RE-wrenches]

[jay peltz]

Hi Travis,

Heres some more info.

Many new hi effic boilers are so efficient that they use PVC vent piping. They
truly are 95%+ effic.  Most use some sort of built in storage as well.  Granted
most are not used for domestic HW only, but space heating as well.

I've use a Takagi and it sure works well.  Modulates really well, and doesn't
have the flow issues that the Aquastars have.

I agree that people do need education about the on demand and most plumbers
won't touch them, ( they don't think they work!)

thanks,

jay
Peltz Power

"Travis Creswell, Ozark Solar" wrote:

> Hi Jay,
>
> First let me say I have very little experience with standard heating
> boilers.  I have played with a lot of steam engine and installed of couple
> of Skip Goebles steam fired generators.   I haven't seen any home boilers
> much over 90% eff  and the common ones are just over 80%.  From what I have
> heard, if you use them to heat water in your residence they can be terribly
> inefficient because the efficiency is the peak, not when they are modulated
> down to 50% or so as they could be when they are heating water in the
> summer.   If you are using a boiler to send water to a "indirect water
> heater" the heat exchanger in the indirect tank typically cannot get all the
> heat out of the hot water which means you are running a 100,000 BTU boiler
> for a 20,000 BTU water heater.  That's fine in the winter but in the summer
> when you aren't heating your house your running the boiler just for hot
> water that can be bad.
>
> Your typical gas water heater is less than 50% efficient before you figure
> any standby losses and of course an electric is 100% efficient before you
> figure the stand by losses.
>
> The tankless model from Japan you mention look very promising.  I believe
> you are speaking about the Takagi.  It is comparable to the Aquastar 170 in
> output but the same size as a 125.  It has no standing pilot and is
> electronically modulated unlike the troublesome mechanical system of the
> AquaStars.  Powervent is standard as is a freeze protection system  (75 watt
> draw, I think?).  Of course it would not be wise to install them outside in
> any other place than FL or southern TX as even though the Takagi could
> survive the light freeze the rest of your outdoor plumbing would be in
> danger unless you heat taped all of it.
>
> Travis
>
> ----- Original Message -----
> From: "jay peltz" <jay at asis.com>
> To: <RE-wrenches at topica.com>
> Sent: Monday, March 26, 2001 8:41 AM
> Subject: Re: tankless water heaters [RE-wrenches]
>
> > Hi Bob,
> >
> > Not really a fair comparison as you using electric vs natural gas.
> >
> > If someone outthere has info on efficiencys then I would love to see it.
> All
> > the data I have seen points the other way.  Boilers on the other hand are
> > getting more effieicent at 95%+, but now you are talking thousands of $$.
> >
> > There are new models from Japan that are really nice.  They install
> outside on
> > the wall, ( they have freeze protection built in) so take up no inside
> space,
> > need no vent ( direct vent) cost about the same as a Aquastar.
> >
> >
> > jay
> > Peltz Power
> >
> > > -
> >
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