New water heater and expansion tank - low pressure

Question

Replaced a 20+ year old natural gas 75 gallon water heater recently with an equivalent model. The plumber said an expansion tank was required per code. Two things I’m noticing now with the new set up:

1) Low hot water pressure: I used to turn hot and cold on full to fill a bathtub. Now, if I turn them both on full only cold water comes out. I have to turn the cold to half and hot to full to get a decent flow.

2) Two people took baths at the same time (one a whirlpool) and we ran out of hot water for the first time ever.

Is this because newer equipment (same specs on paper) isn’t as good as old equipment? Does the expansion tank explain any of this?

Answer 1

The new tank may have been piped wrong, and restriction may have been introduced. Did the plumber reduce the pipe sizes in and out of the tank. The new tank will supply the same amount of hot water as the tank you re[laced. The expansion tank is not the problem. Something has changed, you have to find out what.