Not positemp or moentrol?


  #1  
Old 04-08-18, 11:08 AM
Z
Member
Thread Starter
Join Date: Jan 2018
Posts: 518
Received 0 Votes on 0 Posts
Not positemp or moentrol?

Hello,

Have a moen shower head and valve.

Seems like it operates as a moentrol. Push/pull to operate. Temperature memory feature. Moen website says the moentrol valve also provides pressure balancing to avoid scalding when a toilet is flushed.

Mine definelty doesn’t have temperature balancing since every time the toilet is flushed, I get scalding hot water in the shower. Is my valve defective or could I have an older moen system that doesn’t provide scalding protection?
 
  #2  
Old 04-08-18, 11:35 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 10,209
Received 374 Votes on 339 Posts
If I recall correctly, that temp balancing mechanism can be defeated or removed.
 
  #3  
Old 04-10-18, 01:30 AM
steve_gro's Avatar
Member
Join Date: Jan 2004
Location: San Francisco
Posts: 1,092
Received 1 Vote on 1 Post
There are many things that could cause scalding hot water in the shower when the toilet is flushed. Under-sized water piping for one. Old galvanized water piping for another. A main valve that isn't full open, a failing PRV... the list goes on. It doesn't sound like you have a pressure-balanced shower valve.

What material is your water piping & how old is your house?
 
  #4  
Old 04-10-18, 05:24 AM
Z
Member
Thread Starter
Join Date: Jan 2018
Posts: 518
Received 0 Votes on 0 Posts
40 years old with copper piping.
 
  #5  
Old 04-10-18, 12:13 PM
steve_gro's Avatar
Member
Join Date: Jan 2004
Location: San Francisco
Posts: 1,092
Received 1 Vote on 1 Post
It wouldn't hurt to know the incoming water pressure. You can get a pressure gauge that screws onto a hose bib for about $8. If there's a pressure reducing valve, check the pressure somewhere past it. And it wouldn't hurt to check that the main valve is full open (don't force it, just check that it is open).

https://www.amazon.com/Rain-Bird-P2A.../dp/B00004RACK
 
  #6  
Old 04-10-18, 03:15 PM
Z
Member
Thread Starter
Join Date: Jan 2018
Posts: 518
Received 0 Votes on 0 Posts
Is it possible the moen cartridge is to blame?
 
  #7  
Old 04-10-18, 03:18 PM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 10,209
Received 374 Votes on 339 Posts
Is it possible the moen cartridge is to blame?
Very possible.____________________________________________
 
  #8  
Old 04-11-18, 10:59 PM
steve_gro's Avatar
Member
Join Date: Jan 2004
Location: San Francisco
Posts: 1,092
Received 1 Vote on 1 Post
You need an adequate volume of water at an adequate pressure to supply two fixtures at the same time. If you don't have both you'll find yourself getting scalded in the shower when another fixture calls for water.

A Moen cartridge is easy to change, but it can be hard to get the old one out (there's a tool for that) and no harm in trying that first.
 
  #9  
Old 04-14-18, 11:23 AM
Z
Member
Thread Starter
Join Date: Jan 2018
Posts: 518
Received 0 Votes on 0 Posts
Is it the valve design or the cartridge itself which creates the pressure balancing which prevents scalding?
 
  #10  
Old 04-14-18, 12:31 PM
steve_gro's Avatar
Member
Join Date: Jan 2004
Location: San Francisco
Posts: 1,092
Received 1 Vote on 1 Post
Here's a link to a diagram of a Moen shower valve with a pressure balancing spool in it:

https://terrylove.com/forums/index.p...l-valve.57646/
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: