[RE-wrenches] tankless hot water and pumping question

[Ian Woofenden]

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
>800-707-6585 (US), 541-512-0220
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-- 
Ian Woofenden <ian.woofenden at homepower.com>, Senior Editor, Home Power magazine
Subscriptions: $24.95 per year PO Box 520, Ashland, OR 97520 USA 
800-707-6585 (US), 541-512-0220
or download free sample issue at <http://www.homepower.com>