[Greenbuilding] old question revisited-tankless heater

[Corwyn]

On 2/20/2012 10:13 AM, Sacie Lambertson wrote:

> I've used tankless for years now but one aspect of the type I dislike is
> the fact a lot of water goes down the drain before the hot water finally
> reaches the faucet.  In this cabin the shower is within 10 feet, with
> the sinks not over 15'-18', but water loss nonetheless is a negative factor.

The extent to which you need to wait for hot water from any system is 
inversely related to its total efficiency.  The distance from the heater 
to the sink is (presumably) the same regardless of type.  The thermal 
mass of the pipes is the same.  The only differences are the thermal 
mass of the heating unit and power rating.  If a tank system provides 
quicker hot water, it is because it is pre-heating the pipes, which is 
potentially a heat loss.

Unless you have a faulty tankless (I saw one which didn't fire for 2 
full minutes after the water was turned on), it should be very close to 
the same wait time for two systems of equal efficiency.  Certainly the 
majority of the waiting will be due to the thermal mass and length of 
the pipes.

Thank You Kindly,

Corwyn

-- 
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
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topher at greenfret.com
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