I bought a house last year that has a Weil-McLain boiler/tankless
heater. I believe it was installed in 1992. It looks pretty beat
up---more rust and the like than I would expect on a boiler that's
about 15 years old---but I'm told that the water around here is pretty
hard and that it eats up boiler. (On the other hand, I have a water
softener system, so what's that all about?)

Anyway, the boiler simply doesn't provide enough hot water. We can't
fill up the bathtub, and showers get cool after a short period of
time. Even when the boiler kicks back on, the water only becomes
warm, not hot. I can deal with this in the shower, but I'm concerned
about the washing machine and dishwasher.

The heater part of the boiler has three controls as far as I can
tell. There are two thermostat controls that determine when the
boiler fires on and off, and a valve that blends the hot water from
the heater with cold water to deliver to hot water faucets.

If I want more hot water, how should I adjust these things to serve us
better?

Also, I read on the Weil-McLain web site about an indirect-fired water
heater. Is this something that adds onto a tankless system to provide
extra hot water? (I have no idea if this could physically fit into
our mechanicals closet, but it's somethng to look at if it would take
care of the problem we are having.)

Any suggestions appreciated!

Thanks,
-Ben