N8N wrote:

Hi all,

i've got an older gas fired water heater in my house - came with the
house, I guess it's probably about 20 years old. It works fine, but I
do have one issue with it. If I am the *first* person to take a
shower in the morning, I leave the valve on full hot, and I have a
somewhat acceptably warm shower, but not quite as hot as I'd like. If
someone else showers first, they experience this same effect, but by
the time they've left the bathroom and I go in to take *my* shower, I
am rewarded with steamy hotness.

The gas control (thermostat) on water heaters
is purposely built with a wide "differential"
between on and off points.

Overnight, the tank temp drifts downward very
slowly and doesn't quite trip the control on again
until water is used.

There is no adjustment for this. A new control
*might* cure it, but not worth investing on an old tank.

BTW, when you get a new tank installed, ask about
a "thermal expansion tank". It's a small bladder
tank added to the piping and will help prevent "pop-off".

Jim