Drip... Drip... Drip. I hear it somewhere, but cannot figure out where. Not in the kitchen, not in the bathroom. Where?

Dog? Nope, he is asleep.

Shoot, I hear it coming from the utility room. Venture in and I find water in front of the furnace. "That's not good at all" I think. Then it gets worse, the water isn't coming from the ac condensate line like I was expecting. Backtrace and it is coming from the top of my hot water heater and draining down the outside of the furnace/blower to the floor drain. DARN, so after 12 years and one month my Ruud 75 gallon unit is toast.

So now I have to replace it. I have a whirlpool tub, and the 50g tanks won't cover it. Do I want to get another 75 gallon tank OR do I want to get a tankless unit? If I get it installed before the end of the month there is a rebate available for high efficiency tankless. I'm thinking tankless, space savings and no longer using inside air for combusion since my gf and I are extremely allergy sensitive. Limiting drafts would help.

The condensing units are running around 1400-1600 unit cost, add in the service valves and PVC venting and it should be about 1800 total materials cost (sans copper and gas line of course).

That leads me to the real question. After calling a few places and getting price quotes from 3k to 6k for the install, the one thing that keeps popping up is the gas line. Mine is 1.3"OD (measured with calipers) which should equate to 1" ID from the meter into the house. Goes up about 6' in about 5, turns 90 for 5, turns 90 for 5 and hits a t. One end goes to my gas oven, the other end goes to the utility room about 10' either way.

In the utility room it goes from 1" to 3/4" at a t, one side to the furnace and the other to my existing HWH.

Is this enough information to say if the 1" pipe is enough? (199k BTU)

Otherwise the install is bone simple. I have power in there, the floor drain is easy to get to and the utility room has an exterior wall. Go up high enough and you can cut through the siding and have a simple exit. No features, windows, or anything else nearby. Gas line on the other hand is in the ceiling and the basement is finished. That would add thousands to the cost

(was thinking rinnai 98i condensing or rheem 95dvn condensing since that's what the vendor has. )

Gas appliances are furnace, range and oven and gas fireplace.

The help is MUCH appreciated.