Shower not staying hot

[John Gayewski]

Yes, I have a recirculating system. What should I be checking for to identify and correct the cross-connection?

This can be hard to find. I did a hotel and parts of it complained about no hot water. It took three days and two different plumbers to find what was going on. There were some valves left on in some uncompleted rooms where the shower valves hadn't had the cartridges put in yet. The mop sink was also contributing as they had a chemical mixing station hooked up to it.

It's usually laundry, mop sink (or similar), the water heater itself where there lines tie in, or showers. These can have the hot and cold tied together and constantly on.

 

[Jadnashua]

The water will take the path of least resistance, so if there's a cross-connection to the cold line somewhere, it can draw water from the cold line into the hot one. Depending on how far away it is will determine how long you have hot water in the shower.

Some cartridges of single handle faucets can allow a cross-connection when they wear. If you have any, try turning the cold inlet to that faucet off and see if it the shower works. If it does, buy a new cartridge for that faucet...if not, try another one.

 

[Sponsor]

 

[Mpkadz]

I'm officially stumped. I can not identify any crossovers. I swapped in a spare cartridge I have and this morning things were actually worse, if you can believe that. The water got cooler much quicker to where it was uncomfortably cool. I was able to adjust it warmer, although it had to be constantly adjusted up until it actually got hot. Once it was too hot, I backed it off a little to where it seemed to stabilize for the last minute or so of my shower. Does this indicate some sort of pressure drop issue on either the hot or cold side?

 

[Jadnashua]

Just to clarify, when a valve is open, unless it has internal check valves, it is a cross-over, since you have both hot and cold coming out. But, when using say your shower, if another valve somewhere is allowing cross-over, the shower valve may see a less restrictive path of the cold from that other valve rather than pulling it from the hot line you want it to.

So, to test that out, you'd first shut the cold supply valve off to say the sinks near by. That only applies to single-handle valves.

Some people use a Y connection at the washing machine to mix the hot and cold...that's a cross-over, too.

SO, start shutting off the cold supply lines to various fixtures and see if any one of them results in a working shower for you. Then, change the cartridge to that valve (not the shower!).

Now, if you have a thermostatically controlled shower valve, it could just be that cartridge is bad.

 

[John Gayewski]

To add to what jadnashua just said. Some faucet kits are starting to come with 3/8" compression check valves for this exact reason. Lots if recirculating lines with mixing valves nowadays.

 

[Jadnashua]

The reason why I ended replacing my recirculation system is its internal check valve died. It was like 20-years old, and had a proprietary check internally, and parts weren't available. I probably could have cobbled something up, but it didn't owe me anything after that time, and the pump would likely have just decided to go after I fixed the assembly. The indication that had happened was my shower wouldn't get as hot as it used to.

 

[Mpkadz]

So, there are four single-handled faucets in the house. The kitchen faucet (Kohler Fairfax) is the farthest away from the water heater, so I replaced the valve and spacer assembly with parts direct from Kohler. Things got better temp wise, but still not like it used to be. One of the other three is in the same bathroom as the shower and is the newest, so for now I am not thinking I'll start there. The other two bathrooms have the same Moen single-handle faucets so I think I'll look for new cartridges for them, starting with the farthest away from the water heater.

Thanks to all who have taken the time to guide me through this issue.

 

[Jadnashua]

At each single-handle valve, shut the cold water supply off one at a time, then see if the shower works as you expect. IF it does, you've identified (at least one of) the bad faucet. If it doesn't change, it's probably fine, and move to the next one.