[jeffmb]

I have a 2007 55 gal 60K btu water heater that may be nearing its end of life. I replaced the burner assembly but still have trouble with the pilot staying lit.

we really like the quick return on the heater, however with the efficiency of the newer models can I go to a lower BTU and still have a decent return rate?
5bedroom 1.5 baths but only two if use living here right now

 

[VTP99]

Look at the recovery rate

 

[Calgary.hvac]

Issues with the pilot staying lit are usually due to flame sensing.

Thermocouple or thermopile.

If it’s an atmospheric and you like where you are at, moving to a smaller size may be disappointing

 

[kdean1]

By “return” do you mean delivery of hot water? A pump or a plumbing loop can accomplish nearly instant delivery no matter what size water heater is there.

You should probably size the unit for the house in case it is fully occupied at some point. If you ever sell the house, a sharp-eyed inspector is likely to tag it as a problem.