We recently experienced a problem with insufficient hot water from our gas water heater. We discovered that the problem was caused by a shower valve that had just been installed as part of a bathroom remodel project. The mixing valve body was installed without the internal cartridge, which allowed hot and cold water to mix, resulting in only lukewarm or variable water temps at different faucets throughout the house. The contractor who did the installation said that leaving out the cartridge until other work is completed is standard procedure, and should not have resulted in the problem. The cartridge was installed which immediately corrected the problem.

Has anyone ever heard of this practice?

Yes. Done when the valve body is roughed in and the remaining components - cartridges, trim etc are not on site yet. Even if the components are on site, the plumber might not want to install them till the end of the job to prevent damage.

well the contractor is half right and half wrong.
it is standard procedure to leave the cartridge out but that will always result in hot/cold crossover unless certain steps are done.

thanks for the reply. What prevents this problem from occurring?

thanks for the reply. What should have been done?

what he SHOULD have done is install the "anti bypass plug" that came with the valve to prevent it.



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or if it had integral stops then simply shut them.

Around here very few installations have integral stops.

thanks. It is a Delta brand valve and included the cartridge. It also came with a "reusable test plug" that is designed to "... prevent cross flow... before the cartridge is installed." Needless to say it was not installed. Should have read the installation instructions myself and micro-managed the contractor.

unfortunately 'many' projects/contractors (in today's world) require micro-management



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

two weeks ago I drove miles out of may and spent another hour purchasing and installing the Delta plug so this very situation would not happen.

your installer was either unaware or too lazy to do the right thing.

It would be nice if Delta would provide this part with their rough in valves.
Normally I carry a few these but was unable to locate when needed. Poor planning on my part.

best to wait to install the mixing cartridge after tile guy is done to ensure no accidental damage.

They DO, unless it is an entire valve with the cartridge, in which case they expect it to be installed during the rough in and protected by the plastic cover.