Hot Water Woes

We are adding a new bath onto our house and today finished the water supply feeds into the new addition. These tie in to the existing supply lines just before the existing bathroom ( which will be removed later ). Tonight I found that the hot water in the old bathroom is not near as hot as it normally has been. Could the location of the new supply tie in be the culprit or is it a more likely obstructions in the faucet and shower valves? Kitchen is hot as always - but the shower downstream of the new tie in is way off.
We added about 30' of 3/4" supply to the new bath - tied into 3/4" before it reduced to 1/2".

The longer the 3/4" the more time it may take to clear the hot lines of tempered water.
Also you may have obstructions at the valves that should be cleared out.

I thought the same about it may take a little longer, but it doesn't get any better no matter how long you run it. I don't think now that it is strainer or obstruction issues, the flow seems good and it has affected both showers and sinks downstream.

Thanks

I'm not a plumber, hopefully a pro will pop in, the only other thing I can think about, if everything is installed correctly is maybe a bad shower valve/cartridge letting the cold side mix prematurely with the hot.

hot waert

YOu probably installed a Delta shower valve body, but did not insert the anti crossover plug inside it, and do not have the cartridge inserted either. If that is the case you have to do one or the other to eliminate your problem.

You probably installed a Delta shower valve body, but did not insert the anti crossover plug inside it, and do not have the cartridge inserted either. If that is the case you have to do one or the other to eliminate your problem. hj

Click to expand...

That's my guess too.
If the plumber left the rough-in cap on a Delta valve, the hot or cold would cross over at the tub.
Removing the plug and inserting the cartridge fixes that.

Thanks guys - after talking it over and considering what had changed, I kinda came to the same conclusion - bleed over throught the rough in valve. I'll insert the cartridges this afternoon. Thanks again.

I will take a very long time and waste alot of water to purge the cold water from that much 3/4" pipe. This would be a good time to install a recirculation system.

Once you get the problem fixed, would this also be a good time to put insulation on all the hot water lines that can be reached? (And perhaps the cold too for when you want cold water from the tap.) This should speed the warm up time to fixtures, slow the cool down of the hot lines, and increase the hot water temp at the tap a few degrees. The pipe insulation is really inexpensive.

It seems to have helped in my house. I only regret that I can't reach the 40 feet or so of line running to the kitchen, it's all behind drywall.