On Fri, 10 Jul 2015 11:23:16 -0700 (PDT), DerbyDad03
wrote:

On Friday, July 10, 2015 at 1:24:11 PM UTC-4, wrote:
On Fri, 10 Jul 2015 05:36:55 +0000 (UTC), 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. 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.

If the water is too hot at low flow, there are two likely causes:

1. The water heater is set at too high of a temperature.

2. The pressure balance valve in the shower faucet is defective.

Both are easy fixes.

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?

I have no idea, but a standard tank model doesn't do this either. You set
a maximum temperature and the heater heats the water to that level
(typically 120 degrees). A tankless heater isn't really all that different.
It's just heating the water as it comes in instead of preheating it in a
big tank. Either way the water should always be 120 degrees when it leaves
the heater.

As I mentioned earlier, the original poster should check the water
temperature at a valve near the water heater. If the temperature remains
fairly constant at high and low flow, the heater is probably fine. The
problem is probably a defective faucet.

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

Space savings, potential energy savings, endless hot water, gadget wow
factor. How important any of these are depends on the situation and the
individual.

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com
A better answer is more money than brains.
In normal use a tankless will NEVER pay for itself in energy savings -
not even close.

While you may very well be right in regards to your second comment, your first comment doesn't hold water. (pun intended)

"More money than brains"

The fact that someone can afford to pay for the pleasure of "endless hot water" doesn't mean they suffer from diminished brain capacity.

If someone offered you free endless hot water, would you pass it up?

Move to iceland - hot water there truly IS endless - AND free.
I know I wouldn't. So, if my resources were such that I could absorb the initial and incremental cost differences of tanked vs. tankless hot water without feeling any pain, I'd do it in a second.
If I needed endless hot water, perhaps - but I've NEVER run out of hot
water - in a household with 2 daughters, and a standard 40 gallon gas
water heater. Growing up with 7 siblings and a 30 gallon electric
water heater it took some strategic planning.


We all do things like that quite often. We could sit on wooden boxes instead of couches. We could cook over an open fire instead of on a gas range. The fact that we spend more than we actually *need* to on things that make our lives more enjoyable doesn't (always) make us idiots.

Granted, when we make decisions based on unsubstantiated data and/or spend more than we can comfortably afford, then the "brain power" argument is valid.