Boiler or shower?

R

Russell

Well-known member
Our shower has gone a bit cool. I'm trying to work out if it's the shower mixer valve or boiler.
The temperature on the boiler hot water is maximum (I'll check in a bit) but the bath hot tap is 48c. Does that sound right? I don't want to change the mixer valve if it's the boiler because it's otherwise working fine and £300+. We recently had the boiler serviced but I'm reluctant to get them back as they charged £300 to replace the fan, supply and fit.
Edit:
I've just seen mixer valve on eBay for £230 (Mira element) so not as bad. Has anyone replaced the valve cartridge or thermostat successfully?
 
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S

Stroppymonkey

Well-known member
Bath Tap could have TMV (mixing valve on it) giving you a false reading. What boiler do you have? Which model of shower?. If its exposed I usually swap complete shower for a new one as I can warranty the work then. If built in/BIV/Concealed then cartridge change needed. Sometimes identifying the correct cartridge is the a challenge. What is temp at kitchen tap? What are you using to measure temp?
 
R

Russell

Well-known member
Bath tap is separate hot and cold. Kitchen tap is 55c. Shower is surface mounted Mira element.
I'll look at boiler In a bit.
 
S

Stroppymonkey

Well-known member
Russell said:
Bath tap is separate hot and cold. Kitchen tap is 55c. Shower is surface mounted Mira element.
I'll look at boiler In a bit.
Click to expand...
Mira element - we go to a lot of those causing problems. From Memory there is the MK1 and MK2 and now also one with a lever option. We pay about £56+vat for a cartridge on the MK2 and its easy to fit, can of spray silicone lube usually helps. If its exposed you can feel the pipes right and left. If the LH one is hotter than the outlet, and the RH is cold and condensation drops on it and its turned to max then its most likely the cartridge failing. Hot water 55C at tap sounds about right.. if the bath is 48 then you might have a mixer valve under the bath, likely if a newish house.
 
R

Russell

Well-known member
Thanks I'll check that out. Can you recommend where to get the cartridge?
Edit:
 

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TiltyShaun

TiltyShaun

Well-known member
We have changed our shower cartridge several times after issues. Last time I found a stuck valve in the thermal hot water system was feeding cold water to the shower.
 
S

Stroppymonkey

Well-known member
TiltyShaun said:
We have changed our shower cartridge several times after issues. Last time I found a stuck valve in the thermal hot water system was feeding cold water to the shower.
Click to expand...
OP has a combi boiler. If its an exposed mixer shower then try and get an accurate temp reading from the LH feed pipe.
 
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