[RE-wrenches] On demand WH

[frenergy]

Thanks to all for the info and ideas for a direction on this.  I appreciate the help.

Bill

-

---- Original Message ----- 


From: "Bill Loesch" <solar1online at charter.net>
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Sent: Monday, September 30, 2013 4:59 AM
Subject: Re: [RE-wrenches] On demand WH


> 
> Hi Bill, et al,
> 
> There are two major categories of tankless water heaters-natural draft 
> (which work very similar in control aspect to a conventional tank i.e.. 
> no electric required, some form of pilot light) and power vented (all 
> power vented machines have need for at least a fan, most a computer with 
> some form of display included - if your own body is incapable of telling 
> you if the water is sufficiently hot).
> 
> Of the Big Five (major players in the tankless market) all manufacture 
> one or more models of power vented tankless. Today, only Bosch markets a 
> natural draft tankless. Bosch offers more than one model of natural 
> draft tankless, standing pilot and intermittent pilot. If you like 
> simple, trouble free, and low life cycle cost, you have but one choice.
> 
> 
> http://www.bosch-climate.us/files/201304181918370.520PN_English_06.2011.pdf
> 
> What must be properly addressed with _any_ tankless is intake and 
> exhaust venting, gas line sizing, and water quality. Since this isn't a 
> tank, the pilot flame does almost nothing in terms of freeze prevention.
> 
> Some manufacturers state flow rate for their heaters without also 
> providing temp rise. Flow rate without temp rise is meaningless. The 
> above is a 117,000 BTU/h machine. Sometimes winter ground water 
> temperatures are significantly colder than summertime temps. If you want 
> hot water in the winter, too, make sure you use the appropriate temp 
> rise. Hardness is the biggest issue with water quality, if you scale the 
> heat exchanger you won't get the performance advertised. If you have 
> hard water, a water softener or descaling _as required_ is necessary.
> 
> I am a big fan of tankless and have been since '89 when I was first 
> introduced to them as a user. Today, I install and troubleshoot all five 
> major manufacturers. Co-located with the load, tankless provides you not 
> only endless hot water but also instant hot water.
> 
> Good luck,
> 
> Bill Loesch
> Solar 1 - Saint Louis Solar
> 314 631 1094
> 
> 
> On Sat, Sep 28, 2013 at 10:19 PM, frenergy wrote:
> 
>> Off-grid Wrenches,
>>
>>         I'm working on a load sheet and am having a hard time finding 
>> standby and while firing electrical usage for a propane-fired on 
>> demand water heater.  Do they some/all have standing pilots, glow 
>> bars, something else?  I'm guessing the standby power needs are very 
>> low but we all know how even 10-15 watts adds up over 24 hrs when 
>> you're off-grid.
>>
>>         If any body has some actual numbers rather than just pdf.specs 
>> (though manus specs might help some), I would be most grateful. 
>> Thanks in advance.
>>
>> Bill
>> Feather River Solar Electric
>>
>>      ------------------------------
>>
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