[RE-wrenches] tankless hot water and pumping question

[robert ellison]

My understanding of the Bosch Hydro units is that there is just a hydro
generator in the water line, no other gear, water runs, it sparks and
lights.
the service manuals I have do not have that model in them.  I plumbed one
last summer and don't remember any controls, they are as simple as can be.
The lower pressure is 15 PSI, and 1/2 GMP or it will not heat.

Bob

On Fri, Nov 14, 2008 at 8:00 AM, Bill Loesch <solar1online at charter.net>wrote:

>
> Hi Todd,
>
> Congrats on the off-grid solar application to improve quality of life.
>
> I will defer to my more learned colleagues re the optimum water pressure
> pump.
>
> If you don't want to use any electricity to create the hot water, then you
> want to use a *natural draft* tankless. (Like a conventional tank, no
> electricity required.) Please be aware of the minimum flow requirements to
> turn on the tankless - something on the order of a half gallon per minute.
> Less flow than that and the tankless will not fire. If you can find any, the
> (out of production) piloted Paloma PH series (some folks have said it
> resembles R2D2) would work on much lower water pressure than the Bosch
> series which work reliably only with a minimum of 30 psi (e.g. the lower
> limit of your pump switch would be set to 31 psi or more).
>
> The hydro generated Bosch model sounds great in principle and were able to
> provide you a tax credit in the previous tax credit program . What is
> required for the hydro generated models to work (in addition to the hydro
> generator) is an expensive electronics box and a multitude of
> connectors which IMHO are not up to the rigors that the piloted models
> offer, especially in less than pristine environments. The piloted models
> utilize a thermocouple which most everyone is familiar with and has many
> fewer connectors. Most all the natural draft piloted tankless machines
> incorporate a piezo igniter like on your BBQ grill, so turning off the pilot
> manually and relighting as required is nowhere near the contortionist effort
> experienced with a tank and provides the savings of no pilot gas usage when
> not working.
>
> Good luck,
>
> Bill Loesch
> Solar 1 - Saint Louis Solar
>
>  ----- Original Message -----
> *From:* Todd Cory <toddcory at finestplanet.com>
>  *To:* re-wrenches at lists.re-wrenches.org
> *Sent:* Thursday, November 13, 2008 7:58 PM
> *Subject:* [RE-wrenches] tankless hot water and pumping question
>
> I am working on a semi-volunteer job for a local non-profit. It is off grid
> with water being trucked in and stored in a ground level polyethylene tank.
>
> I need recommendations for:
>
> 1) A 24 volt DC pressure pump. This is a single residence so can be
> relatively low volume as it will only feed a shower or sink... no
> irrigation.
>
> as well as
>
> 2) Which tankless (propane) hot water heater would be best? I think there
> is one that uses the water flow to spin a tiny generator that ignites the
> burner. Being off grid it is important to not have a unit that draws power
> 24/7.
>
> Thanks,
>
> Todd
> --
>  Todd Cory KE6SXS
>
> *toddcory at finestplanet.com*
> Mt. Shasta Energy Services License C-10  #811428 P.O. Box 689 Mt. Shasta,
> CA. 96067
>
> *(530) 926-1079*
>
> *<!--[if !supportEmptyParas]--> <!--[endif]-->*
>
> "I'd put my money on solar energy...I hope we don't have to wait till oil and coal run out before we tackle that."
>
> ∞ Thomas Edison, in conversation with Henry Ford and Harvey Firestone,
> March 1931**
>
> <!--[if !supportEmptyParas]--> <!--[endif]-->
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