I'm looking for a good fix for a hot water problem in a 30 year old 20' x 40' condo that is on a slab. The hot water heater is on one end of the unit and the copper pipe runs 40' under the slab to the other end where there is a shower/bathroom. It loops from there back to a second bathroom and on to the kitchen. The water heater works fine and is set at 135F. It takes 2 minutes running full flow to get any hot water from the kitchen sink. It's about 1 minute to the bathrooms from the tub. It's more than 2 minutes from the bathroom faucet. I'm suspecting that the pipe is not insulated under the slab. I think this because after about 20 minutes, we're back to a full 2 minutes to get hot water again. Because the copper lines are cooled so quickly, I fear that a recirculation pump would cost a bunch to keep running. That would just dump heat into the soil. My next thought would be to run new hot water lines through the attic and cap off the hot water under the slab. It's fairly accessible in the attic. I could put in a header run three 3/8" Pex lines to the bathroom, bathroom and kitchen, and insulate them. This is in North Carolina so freeze is not an issue. Is this a good path to take? Any other recommendations?

Thx.. .

You might want to explore this item or similar systems. Advanced Conservation Technologies: D'MAND Hot Water Systems Not that hard to install, easier than what you are planning. There are other systems that do not require power and simply push the first 5-10 gallons of cool water backwards down the cold supply, thus pulling the hot water faster.

That unit looks like this one Faster Hot Water For Tank Type and Tankless Water heaters. The Chili-Pepper is about half the cost. I wonder which one is more heavy duty. Sure would be less work.

Thanks.