[Greenbuilding] old question revisited-tankless heater

[RT]

On Tue, 21 Feb 2012 10:33:38 -0500, Sacie Lambertson  
<sacie.lambertson at gmail.com> wrote:


> hot water system in a cabin that will have one occupant.

> --ie it would fit in the shed in which the tankless now resides.
>

I don't know anything about tankless HWHs but the question does arise in  
my mind :

Why is the tankless HWH out in a shed ?  (ie probably making for  
longer-than-necessary plumbing runs and accompanying heat loss  
inefficiencies and if the lines from the shed to the house are only  
minimally insulated, further exacerbating the problem)

I thought that one of the selling points of tankless heaters was their  
compact size and as such one would think that locating it central to and  
close by the points of use would be simpler (as compared to a full size 40  
or 60 gallon "standard" HWH.)

And if the water on the inlet side is extremely cold, tempering the water  
(ie either by just letting it sit around in tempering pipes suspended in  
an unused ceiling joist cavity (ie over a hallway if there is no basement)  
or in a batch preheating tank placed in a sun-exposed location) before it  
goes to the inlet of the tankless would make its task a lot easier. ie If  
the inlet water is at room temp (ie 21 degC) instead of groundwater  
temperature
(say 5 - 7 degC) then the temperature rise that the HWH would have to  
provide would only be ~39 degC instead of 55 degC).


-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada

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