Hot water problem in shower

I recently purchased a home that was built in the 1950s. The house is supplied with city water, has a gas water heater, and most of the supply lines have been converted to CPVC.
Within the past week, the shower valve was putting out "very little" hot water. The shower is equipped with a single handle American Standard faucet/valve. I removed the handle and checked the anti-scald setting to ensure that it was set on the hottest possible setting. Next, I checked all the other faucets in the house to ensure they were getting hot water, which they all were. Finally, I checked the shut- off valve on the shower hot water supply line to ensure that it was completely open, which it was. At this point I was stumped, so I called a plumber.
The plumber came to the house and performed all the same checks that I did. He then informed me that the supply risers going from the basement to the 2nd floor shower were galvanized pipes and could have corroded, causing water deposits to clog in the valve or somewhere else in the pipe. To remedy this, he tried to flush out the pipe by turning the hot water shut-off off and on. Some debris did come out of the pipe. After that, he put everything back together and still no hot water from the faucet. He then made the determination that since the risers were galvanized and the rest of the supply lines were CPVC, the water pressure entering the shower valve must not be correct. Apparently, plumbing code requires that shower valves be equipped with a pressure balancing mechanism, and if the pressure is too low/high then hot water will not come out of the faucet. To completely fix the problem, he said that the galvanized risers would have to be removed and be replaced with CPVC risers.
Does everyone agree that the only way to completely fix the problem is to replace the galvanized risers? For the time being, we turned the cold water shut-off valve to about 3/4, but this causes the water to be fairly hot, even when the valve is turned all the way on cold.
Please help!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On May 17, 4:54?pm, snipped-for-privacy@gmail.com wrote:

yeah replace all the galavanied in your home, although I would use PEX its easier to work with
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Have you tried taking apart the shower valve to check for debris? It should be a fairly simple process.
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@gmail.com wrote: For the time being, we turned the

try 7/8
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd certainly do that. I'd use PEX instead of CPVC because it is more flexible and will be easier to get up the wall. Just a guess, but that is maybe why they did not replace the risers when the rest of hte conversion was done.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.