[RE-wrenches] tankless hot water and pumping question

[Karl Schwingel]

the Takagi Jr apparently has an electric heater in it that will turn on 
when the outside temp drops below 5 F out.  this could add up to real 
kwh depending on it's final location.

Karl

Ian Woofenden wrote:
>
> Hi Conrad,
>
> At 12:35 PM -0500 11/14/08, Conrad Geyser wrote:
>> Hey Ian,
>> The key is that you want "temperature modulated", not "flow modulated".
>
> As a terminology guy, I really appreciate you bringing up this 
> distinction.
>
>> There are a number of temperature modulated units out there, the 
>> Rinnai and
>> Takagi probably being the most popular.  We have had one problem with a
>> solar preheat through one of these and that is if the solar water is 
>> pretty
>> close (around 115 or so) the unit doesn't come on.
>
> I have not experienced this with the Bosch 1600PS.
>
> In normal use in our system, it comes on for maybe 60 seconds and the 
> flame gradually diminishes until it goes out as the solar- or 
> wood-heated water hits it.
>
>> The factory settings
>> don't let you take the temperature higher than 125 to try to overcome 
>> this.
>> Both the Rinnai and Takagi have electric ignition, no pilot!
>
> Yes, but both use AC, and as I recall from a neighbor who has two, the 
> Rinnai uses a significant number of kWh. I would like to see numbers 
> on this for other units.
>
> Thanks,
>
> Ian
>
>> Cheers,
>> Conrad
>> Cotuit Solar
>>
>> -----Original Message-----
>> From: re-wrenches-bounces at lists.re-wrenches.org
>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ian
>> Woofenden
>> Sent: Friday, November 14, 2008 12:05 PM
>> To: RE-wrenches
>> Subject: Re: [RE-wrenches] tankless hot water and pumping question
>>
>>
>> Hi Todd and all,
>>
>> Since this is a renewable energy list, I think it's worth mentioning
>> that installing a modulating demand heater will make the installation
>> "solar ready".
>>
>> I'm only aware of one tankless heater that accepts pre-heated water
>> and has no electrical usage, and that's the Bosch 1600PS (which I
>> live with). I'd love to know if there are others, since this is a
>> common need in off-grid systems. Some of the other modulating heaters
>> on the market have significant electrical demand, which is a deal
>> breaker for us poor off-gridders.
>>
>> Ideally, we'd have such a unit that doesn't have a standing pilot,
>> but I've never heard of such a product, though there are
>> non-modulating heaters that run on piezo igniton and a couple of
>> D-cells. Bosch's hydro unit is a neat concept, but it's not
>> modulating.
>>
>> I hope others will share their knowledge and experience.
>>
>> Ian
>>
>>
>> -- 
>> Ian Woofenden <ian.woofenden at homepower.com>, Senior Editor, Home Power
>> magazine
>> Subscriptions: $24.95 per year PO Box 520, Ashland, OR 97520 USA
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-- 
Karl Schwingel
NABCEP Certified Solar Thermal Installer
NorthWind Renewable Energy LLC

PO Box 723 Stevens Point, WI 54481
Karl at Northwindre.com
Cell: 715 209 0446
Fax : 715 952 4501


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