Greetings,

I purchased a 40 gallon Whirlpool gas water heater (including
installation) from Lowe's in December of 2003 to replace a 30 gallon
water heater. Before, the 30 gallon water heater was sufficient to
fill our oversized bathtub, but we wanted to increase the size anyway.

In a nutshell, the new water heater is unable to fill our bathtub with
hot water as before, despite being 10 gallons larger. We now get
about 2-3 inches of hot water.

After careful measurement using a 2 gallon bucket, we found out that
we get approximately 22 gallons of water after a 12 hours of recovery
time. After 20 gallons, the water becomes worse than lukewarm. For
now, we are OK with showers (I like days, she likes nights), but we
would like to be able to take a bath sometime over the next few years.

Upon the plumber's recommendation, we had Whirlpool send us a new
thermostat. After installation, the performance is exactly the same.

Whirlpool said that we should be able to get 27 gallons (70%) of hot
water, and that we haven't done enough troubleshooting on the heater.
Whirlpool indicated that we would need to check the mixing valves (our
bathtub has separate valves!), implement low-flow shower heads (we
already have them, and care about the bathtub), or have them replace
the thermostat (a second time). They indicated that they would not
replace the water heater unless I could prove that it was damaged in
some way.

I'd like to check the dip tube, but I believe it requires the plumber
to come back. Is it possible for me to check the dip tube myself?
When I asked Whirlpool about it, they made it sound like it's as easy
as replacing an air filter...

Am I expecting too much from this 3 month old water heater? Any other
thoughts?