[Greenbuilding] Opinions on electric tankless HW heaters?

[Nick Pyner]

Rewiring the water heater would surely have to be a pretty pointless
exercise. The only way that that could make a savings is by giving you
colder water and, if that was the goal, you could have achieved it by less
stressful means, like using a lower thermostat. Or indeed, install a
secondary control timer thereby allowing less time for proper recovery,
which may possibly be what you are doing now.  I say "may possibly" because
I suspect that putting the timer on the water heater was a complete waste of
(ahem!) time, and the real savings from that execise are all down to the
fridge. If that is the case, the same result could have been achieved by by
putting the fridge on the water heater circuit. I haven't heard of anybody
doing that but I imagine it would be kosher.

Seeing that you are now used to a bit of wiring, and presumably know you way
around the HWS connections, and if your timer is a mechanical one, you might
find it useful to wire it in parrallel with the element. By doing that, the
water heater controls the timer rather than the timer, ostensibly,
controlling the water heater. You may then be able to work out how long the
water heater is on and, more importantly, when it is on. The last, of
course, may be answered by you local electrician, or even the supply
authority.

Even in the unlikely event that you have done what you set out to do, your
timer pattern doesn't simulate 375 continuous watts it simply does what it
it is set it to do, which is allow the element to run at 750 watts at less
times that it did before. It is not the same thing but may be (minimally)
advantageous.

Nobody seems to want to answer my " are you checking about legionella?"
questions ad nauseam but, if you are running colder water, I feel I should
raise this matter once (sigh) again.

After all that, I have just realised that our HWS timer is pretty close to
the fridge power point  . I will look at having it control our fridge too.



Nick Pyner

Dee Why   NSW

  -----Original Message-----
  From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of Richard
Garbary




  Biggest consumption is the water heater which I rewired from 240/3000 watt
to 120/750 watt. This was simple to do (but took a lot of nerve!). By
connecting 120 volt to existing 240 volt water heater the elements output
1/4 the wattage. A timer switches on and off as follows: 21:30on - 22:30off,
23:30on - 24:30off, 1:30on - 2:30off, 3:30on - 4:30off, 5:30on - 6:30off.
This simulates 375 watt continuous on for the water heater as per the graph.
Fridge is on a timer also that simulates this pattern. Fridge does not come
on at all during the peak (red) periods; only green and yellow. This creates
a very flat consumption pattern over 24 hour period.


-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1209 / Virus Database: 1500/3591 - Release Date: 04/22/11
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20110423/180d2a1b/attachment.html>