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Discussion Starter · #1 · (Edited)
Hi, it's me again;

I have been looking at all of the plumbing in the basement after having to replace a pretty good amount of old pipe after a leak last Saturday.

I am looking in the furnace room, where the water heater is also located.
It's a gas unit, 10yrs old. No problems with it yet, but I'm starting to think of ways I can improve the system when eventually it does need replacement.

One thing I am thinking of is removing all of the 1/2" pipe to the hot water heater, on both the cold and hot sides and replacing with 3/4".
Most of the major plumbing is already 3/4", but around the WH, it drops down to 1/2" copper. The fittings on the WH are 3/4".

How much of an improvement in hot water supply would I see by replaceing the 1/2" pipe with 3/4", including several 90 ells, and a couple of Tees.
There is approximately 4ft of 1/2" pipe in the cold supply to the WH, and about 3ft in the output side.

I'm thinking that perhaps there would be less of a decrease in hot water supply (shower suddenly turning cold) when the washing machine is using hot water for instance.
There seems to be less of a problem when cold water is used elsewhere in the house during a shower downstairs.

I'm also thinking of replacing the bath/shower faucet with a pressure regulating type.

Thanks for your advice/suggestions


Mold!! Let's kill it!
2,849 Posts
Think about this. 3/4" pipe holds 2-1/2 times more water than 1/2". If you run 3/4" out of the water heater, you'll have to run 2-1/2 times more water until it gets hot at the point of use. Afterwards, 2-1/2 times more water that you've paid to heat is laying in the 3/4" pipe getting cold. Run 3/4 cold supply, then branch of to individual fixtures with 1/2". Run a separate hot supply to the washing machine from as close to the water heater as possible. Run 3/4" supply TO the water heater.
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