Gas and Oil Home Heating Furnaces - lennox pulse

I helped my neighbor take out his hot water heater and replaced with a power vent heater. At the same time we changed the gas pipe arrangement in order to be able to install a ceiling in the basement. There was about 15 feet of 1 inch pipe that wasnt needed,and we went to 1/2 inch(from 1 inch) about 5 feet from the pulse.Now he thinks the furnace is louder than before when firing.I am wondering if changing the diameter 5 feet makes a difference.My pulse has a 1/2 inch line that is a lot longer,along with a gas hot water heater.Any thoughts are appreciated.Thanks.

Just to understand a little better.

Was it 1" across the ceiling to maybe a tee. Then 1" to the furnace and 1" to the water heater. And you changed the 1" to the water heater to 1/2".

Doesn't the furnace have 1/2" gas line also.

Thanks for the reply.Sorry it took so long to get back.Yes,it is 1 inch along the cieling,then from the tee reduced it to 1/2"to the furnace about 5 feet.Do you think it made a difference to shorten the supply lenghth and the diameter?Thanks

how many btu's is the furnace?

I am pretty sure it is a 60000 btu unit.I am at work so I cant check to make sure.

5 ft off of a 1 inch line to a 60kbtu furnace does sound ok. may want to check gas pressure

appreciate the response.I will see if I can borrow a manometer from a couple of friends in the business and check the pressure.