bath mixer: hot diverts in shower mode - cold does not

[devlin_weed]

Hi, i have just installed a moretti bath mixer from screwfix. the mixing works fine in bath mode but when you pull the plunger up on the spout the cold feed gets turned off somehow and only the hot water goes up into the shower. the cold water does not come out of the bath spout when this happens. when you just run the cold water and pull the plunger up it just pops back down immediately. thanks in advance for any help.

also, the cold water pressure is greater than the hot water feed. the bathroom also has a mixer tap on the sink, which mixes fine and there is another mixer tap on another sink in the toilet room next door to the bathroom, which also mixes fine. thanks.

 

[WHPES]

the cold water pressure is greater than the hot water feed.

There's your problem. Shower Mixers must be balanced. If you are from a gravity hot you need a cold feed to the mixer from the same tank the hot water originates from. If you are on unvented / combi you need 2 PRVs to balance the hot and cold supplies.

 

[devlin_weed]

brilliant, thanks very much. il do it as soon as. thanks