On Feb 11, 8:10*pm, DerbyDad03 wrote:
On Feb 11, 2:48*pm, RBM wrote:

On 2/11/2012 2:39 PM, DerbyDad03 wrote:

True or False?

A hot water recirculating pump won't decrease the amount of time it
takes to get hot water to a fixture, it will only eliminate the waste
caused by the water running down the drain.

True, right?

(Another Ask This Old House inspired question)

It eliminates the waste by providing near instant hot water

How?

Here's the situation shown on Ask This Old House:

The homeowner had a tankless water heater installed. It was installed
at the opposite end of the house from the second floor bathroom and
the plumber used 3/4" pipe from the unit to the bathroom. The
homeowner used a stop watch to show that it took a full minute to
drain all of the cold water out of the pipe before there was hot water
at the fixture.

A recirculating pump with a push-button control (and a remote for a
second bathroom) was installed under the bathroom sink.

How would a recirculating pump speed up the emptying of the pipes? It
still has to pull all of the cold water out of the pipes before hot
water could reach the faucet. Does it move the water at a rate much
faster than the normal water pressure in the house can move it? If so,
wouldn't that faster flow rate be too fast for the tankless water
heater to heat it up?

It is not appropiate to tankless hot water systems, only to stored
systems.