shower mixer valve

[quickfit]

hi all, still having problems with this shower mixer valve, the valve is a meynell V8/3 thermostatic shower valve, the combi boiler is a worcester 350 combi, the hot water coming out of the shower is cold, when the shower is running i`ve check the boiler for demand and there isn`t any not until i turn a sink tap on then the demand runs, i`ve replaced countless cartridges in the mixer still no joy, can somebody tell me what to remove out of the cartridge so that i will get hot water i.e which bits exactly , this will also do away with the question that there is a blockage in the lines because there won`t be anything left in the cartridge to stop the flow, my gut feeling is the boiler at fault but the british gas engineer says the boiler is ok, so if i can prove the mixer is ok and there is no blockage then i will have to get a plumbing in and if he says the boiler is at fault then british gas can sort it

 

[seco services]

, when the shower is running i`ve check the boiler for demand and there isn`t any not until i turn a sink tap on then the demand runs,

so you proved it.
the boiler is not running when demand for the shower is required.
i'd be looking at the boiler

 

[quickfit]

thanks for the speedy reply seco services, excuse if i seem thick on this but does the hot water come from the same outlet on the combi for the shower as well as the sink taps, the reason i ask is that when the british gas engineer came he turned the hot sink tap on and he said the pressure was ok and hot enough coming out of the tap thats when he said it must be the shower valve, that is why i`m a little confused, cheers, mick

 

[seco services]

yep same pipe.
its probably teed off the bath hot tap.

 

[quickfit]

hi seco services, so if it is coming from a hot tap pipe in the bathroom can you tell me what to remove out of the shower cartridge so that there are no restriction in the mixer, so that in theory the hot water will run out of the shower head because it won`t have a thermostate to regulate it then at least i will be able to know if there is a blockage in the hot pipe that feeds the shower mixer valve, cheers mick

 

[seco services]

if you start taking the thermostatic cartridge apet the shower won't work at all.
have you tried it without the shower head on ?
you said you get water through but the boiler won't fire up so its not blocked.

is the flow from shower hot slower than it was when working ?
if so have you cleaned any filters in the shower ?

what happens if you run a tap get the boiler firing then turn shower on does it come through hot ?

 

[quickfit]

hi seco services, it is a new exactly the same shower head and flexi pipe, if i run the hot sink tap which is next to the shower cubical then the shower does get hot , but as soon as i turn the sink tap off the shower goes cold again, that is why i`m also asking about taking bits out of the cartridge just in case there isn`t enough water pressure to move the valves inside the cartridge, if the mixer works with the bits removed from the cartridge i will then know one way or another that there is or is not a restriction from the hot feed pipe to the mixer, cheers mick

 

[seco services]

their is a restrictor in the inlets you could remove.

 

[quickfit]

hi seco services, the restrictiors you mention do you mean the little mesh on the cartridge valve or a restrictor in the feed line upto the mixer, cheers mick

 

[seco services]

restrictor on the inlet feeds.

http://showerdoc.co.uk/shower-spares/meynell/safemixV8.htm

 

[quickfit]

hi seco services, i have brand new recessed and external shower mixer bodies which i removed the cartridges from and there isn`t any filters or restrictions on the inlet ports, cheers mick

 

[seco services]

thats that out the window then.
have you checked to see how many litres/m its giving out on the hot/cold feeds. as to why the boiler not kicking in.

 

[quickfit]

hi seco services, no i haven`t, it does take a couple of minutes when the hot taps are turned on because the boiler is at the back of my garage about 30ft, i find it all very confusing why i`m getting hot water at my taps and not at the shower especially when they come from the same outlet on the boiler, cheers mick

 

[seco services]

its useally theirs not enough flow to get the boiler to kick in.
which can sometimes be a diverter valve diaphragm going and the shower is the first to pick it up.

 

[quickfit]

hi seco services, thanks for your patience and help, i will either get a plumber in or british gas (of who i have a mainternance contract with) to try and sort it, once again thanks for your help and advise, cheers mick