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trader_4 trader_4 is offline
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Default Two Faucets in Shower? Still Legal?

On Thursday, July 9, 2015 at 3:24:23 PM UTC-4, sms wrote:
On 7/8/2015 9:30 PM, HerHusband wrote:

Tankless heaters are generally rated for a given temperature rise at a
given flow rate. If you draw water faster than it can heat it, you'll get
cooler water.


This isn't his problem.


That would seem to be exactly his problem. At a slower flow rate,
it's able to heat the water hotter. If he had a unit with a much
higher capacity, then he wouldn't be having the problem.

The problem is that tankless heater is not
heating to a specific temperature regardless of the flow rate so at low
flow the water is too hot.


It can't heat to the same temperature at 5 gal a minute as it can
at 1 gal a minute. It's very much an issue of the flow rate.

Changing the mix at the faucet for more cold
and less hot doesn't work because then the hot water, while lower in
volume, is much hotter.


That would indeed be the problem he stated.


Does any tankless hot water heater monitor the flow rate and output
temperature and then adjust the flame to keep the temperature constant
regardless of the flow? It would not be difficult to do this but a good
flow meter that works for hot water is not cheap.


I would certainly hope so. Otherwise when you were drawing .1 gal
a minute, you'd get steam, wouldn't you?


Why would anyone put in a tankless water heater in a residential
property?


If you had a big family and had experiences of running out of hot
water I can see it. Around here, they are putting in two tank type
to support large homes, with Jacuzzi type tubs, etc. I can see
putting one in there instead of two tank type.



Even for vacation homes it's easy to fit something that turns
the hot water heater off when not in use.


Not so easy unless you have a predictable schedule of when you're
going to be there. For vacation rentals it wouldn't work well
either.