[RE-wrenches] tankless hot water and pumping question

[Conrad Geyser]

Hey Ian,
The key is that you want "temperature modulated", not "flow modulated".
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.  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!
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
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