Plumber reversed the hot and cold lines during installation

I am not familiar with that valve, but I hope I can offer some help. It may be that you installed the valve upside down. Every shower valve I have ever installed has writing on the back that says; UP. If you still have access to the rough-in valve, you may want to check that. Also, if it is installed upside down, you can try to pull the cartridge, flip it and reinstall it. That does not work with all cartridges, but it is worth trying if the rough-in is installed upside down.

You may have installed the cartridge incorrectly. That is reverse flow direction. Please check. Please provide model number of the mixer you have used. It might be on this site. http://www.symmons.com/Bathroom-Products/Product-Categories/Tub-Shower-Systems.aspx

typically hot is on the left and cold is on the right at the house faucets but in some cases they are reversed so if filling with a cold setting and the right side supply is hot the plumber reversed the lines when the house was built which while its semi rare has been seen numberous times

Hot on left.
Cold on right.
Some single handle faucets have bleed-over where both hot and cold enter mixing valve each time handle is turned on, even when faucet calls for just cold or just hot.
Otherwise maybe a do-it-yourself plumber got pipes backwards... or maybe the tub used to be on other side of wall, and tub was moved during remodeling but pipes were not changed.

To fix problem:
First of all, turn off shower faucet. Turn on Hot at sink and put ear against shower faucet listening for sound of water flowing through the mixing valve.
If mixing valve is working fine, you need to open wall and investigate more.
For example if you have access door, reach in and feel which pipe is hot.
Pipes might need to be reversed if problem comes up in home inspection, otherwise the problem will not harm anything.

I can think of a few possibilities. 1) Something is blocking the hot water in to the mixing valve. Fixing this would probably mean cutting out the valve (then redoing the water lines with a new valve (possible option)).

2) The hot water line is losing too much heat going to this second faucet. (If the two tubs are on different floors this is more common. Many places are plumbed with one line with Ts to all fixtures.) Insulating the water lines might help; alternatively an point of use water heater would help.

3) The hot water and the cold water in are reversed. (Test by leaving the water on full cold and full hot for a few minutes each.) If you get full hot when it should be cold, valves with a cartridge are easy to fix. Open the valve assembly, remove the cartridge and reinsert it after turning it around (side closest to you when you removed it goes in first). Otherwise, the incoming plumbing needs to be redone at the point where the cold and hot lines come into the shower.

I hope this helps.

Cindy Wells

Behind the handle check to see if it has a dail to take out and replace at a different postion this will change the hot and cold. It a anti scald protection device. Don't remove cartridge just adjust dail.

Mark where you start and take out and move a 1/8-1/4 turn at a time and replace til temp desired. It has teeth like a gear you move to adjust temp.

If this is a new installation and has always beenj this way, then I would suspect that there may be an obstruction in the cold water line leading to the valve. Or something stuck in the valve at the point where the cold water is connected. If someone has worked on thius valve recently , then I would suspect that they got the valve cartridge in backwards, If the catridge is not placed in the valve correctly the opperation is messed up.

Hi,

If the hot and cold are fitted the wrong way round then the thermostat on the shower unit cannot operate properly!

Most thermostatic mixer showers have a 'bi-metallic' thermostat, if you supply the hot to the cold and vice versa IT WILL NOT WORK.

It is like wearing the left shoe on the right foot and the right on the left! It doesn't work.

Re-install the hot and cold to the correct supply, and this will sort it.

I hope this helps.

Mixing valves usually have a diaphragm inside that keeps the hot and cold separate. If the diaphragm is old it may be allowing the hot and cold to mix improperly at the back of the valve. This is similar to a cross connection (a hot water line tied into a cold line) in your plumbing. Cross connections interfere with the performance of Combination Boilers and Tankless Water heaters due to their having no water storage or a very small buffer tank. The brand of the valve will help as each one is different in their mechanical design. If this is the problem you or a licensed plumber can replace the cartridge in the valve. Refer to your valve's owner's manual for part numbers.

The valve stem has been turned 180 degrees allowing the ports to be on the side opposite the display on the chrome trim. This is a simple solution. Cut the water supply off to the valve, and bleed the pressure off the valve, remove the handle,remove the chrome extension tube behind the handle, pull the brass clip out of it's slot, spint the valve 180 degrees and reassemble. If you have an issue gaing access to the valve cartridge to turn it 180 degrees put the handle back on and carefully pull the cartridge out and turn it 180 and reinsert. This will resove your issue so that the hot is on the left and the cold is on the right. There is one other possibility and that is that the supply lines were reversed when the shower was roughed in. Either way the 180 tiurn will fix the issue. Thanks fo using Fix Ya.