Mixer shower not very hot

ck7ah

Hello. I have this shower in my bathroom but recently I have noticed that when you put the water control to full, the water isn't boiling hot. All other taps and showers in the house are fine.  Could there be an issue with it and if so, what could it be?

The shower is about 6 years old and was left by the previous owner.

nofoollikeold

1. There are likely to be filters and / or non-return valves fitted where the shower unit joins the pipes coming from the wall.  The hot ones may be scaled or stuck, particularly if you are in a hard water area.
2. The thermostatic valve in the water temperature control may be faulty.  
3. Isolate hot and cold supplies.  Take photos of the shower as is, particularly a close up of the body.
4. Undo the nuts securing the body of the shower to the pipes coming from the wall.
5. You may need to slacken the vertical square riser bar.  Don't if you don't have to.  They usually join the shower body as a push fit with O rings.
6. Check filters / non return valves.  If scaled up, descale with white vinegar of a proper descaling fluid like Kilrock. Reassemble and test.
7. If scale not the problem, take the control knob off and remove the thermostatic cartridge.  Photograph with control knob off and cartridge still in place.  Photograph the cartridge once removed.
8. If you know make and model of shower, order new cartridge.  Sit down while pricing!
9. If you don't know make or model, email photographs to showerdoc.com and see if they can help.
Other possibilities:
A. If you have a combi boiler, the shower doesn't cause enough flow to make it fire.
B. There is a thermostatic mixing valve fitted somewhere which is itself faulty.

neilmcl

The water shouldn't be "boiling hot" as you put it, 60 degrees is the max you should really have hot water coming from your boiler, a thermostatic mixer shower will not allow water to reach temps above the mid 40 degrees.

What sort of boiler do you have? I've always found that with a combi it's best to run a hot tap in the bathroom first until it comes up to full temperature, this could be seconds or longer dependant on what route the hot water takes to your bathroom, then start the shower.

ck7ah

neilmcl said:

The water shouldn't be "boiling hot" as you put it, 60 degrees is the max you should really have hot water coming from your boiler, a thermostatic mixer shower will not allow water to reach temps above the mid 40 degrees.

What sort of boiler do you have? I've always found that with a combi it's best to run a hot tap in the bathroom first until it comes up to full temperature, this could be seconds or longer dependant on what route the hot water takes to your bathroom, then start the shower.

Agree, i dont expect it to be "boiling" hot but more than luke warm.  The shower i have in my en-suite is set at 38c and its perfect, when i keep this at 38, its more on the cold side.
I have a system boiler with an unvented tank

ck7ah

nofoollikeold said:

1. There are likely to be filters and / or non-return valves fitted where the shower unit joins the pipes coming from the wall.  The hot ones may be scaled or stuck, particularly if you are in a hard water area.
2. The thermostatic valve in the water temperature control may be faulty.  
3. Isolate hot and cold supplies.  Take photos of the shower as is, particularly a close up of the body.
4. Undo the nuts securing the body of the shower to the pipes coming from the wall.
5. You may need to slacken the vertical square riser bar.  Don't if you don't have to.  They usually join the shower body as a push fit with O rings.
6. Check filters / non return valves.  If scaled up, descale with white vinegar of a proper descaling fluid like Kilrock. Reassemble and test.
7. If scale not the problem, take the control knob off and remove the thermostatic cartridge.  Photograph with control knob off and cartridge still in place.  Photograph the cartridge once removed.
8. If you know make and model of shower, order new cartridge.  Sit down while pricing!
9. If you don't know make or model, email photographs to showerdoc.com and see if they can help.
Other possibilities:
A. If you have a combi boiler, the shower doesn't cause enough flow to make it fire.
B. There is a thermostatic mixing valve fitted somewhere which is itself faulty.

Thank you for this, TBH, i am not a keen DIYer so not sure if i will be able to take it apart confidently, but will try.
I dont know the make as it was left by the previous owner and i have looked to see if i can see a brand name on it but cannot.
If it is a thermostatic cartridge, how much roughly do they cost?

Jeepers_Creepers

It's the same regardless of whether you use the handset or the rainhead? If so, the most likely cause is a failed thermostatic cartridge.

How much are these? Typically around £30+ I think.

Usually straight-forward to replace too, but you need to know how the handles and stuff come off.

Jeepers_Creepers

Has round handles instead of square, but might be similar enough?

https://www.youtube.com/watch?v=VV_9s5qGm_I&t=39s

Once you have the cartridge out, you should be able to match it to a suitable replacement - I'd imagine that most are similar.

ck7ah

Jeepers_Creepers said:

It's the same regardless of whether you use the handset or the rainhead? If so, the most likely cause is a failed thermostatic cartridge.

How much are these? Typically around £30+ I think.

Usually straight-forward to replace too, but you need to know how the handles and stuff come off.

Yes it's same with the rainhead.  I need to figure out how to remove it as there are no screws anywhere visible.

ck7ah

Jeepers_Creepers said:

Has round handles instead of square, but might be similar enough?

https://www.youtube.com/watch?v=VV_9s5qGm_I&t=39s

Once you have the cartridge out, you should be able to match it to a suitable replacement - I'd imagine that most are similar.

Looks fairly easy. I don't know where the isolation valves are for my shower. Probably behind the tiles

Jeepers_Creepers

Combi boiler? If so, turning off the mains stopcock will be all you'll need.

I wouldn't do this until you've got the handle off and are ready to unscrew the cartridge - correct spanner and everything. Then turn off the SC, open the shower valve (or a nearby tap) to release the stored pressure, and undo the cartridge.

Take a close-up photo of it and the primary dimensions, including the diameter of the splined shaft and the number of splines on it - so your tap head will still go on!

I guess you could try soaking the cartridge in limescale remover or similar, or else just replace it so's you can turn the water back on.

Once you get the new one, it'll be a 2 minute job to swap.

ck7ah

Jeepers_Creepers said:

Combi boiler? If so, turning off the mains stopcock will be all you'll need.

I wouldn't do this until you've got the handle off and are ready to unscrew the cartridge - correct spanner and everything. Then turn off the SC, open the shower valve (or a nearby tap) to release the stored pressure, and undo the cartridge.

Take a close-up photo of it and the primary dimensions, including the diameter of the splined shaft and the number of splines on it - so your tap head will still go on!

I guess you could try soaking the cartridge in limescale remover or similar, or else just replace it so's you can turn the water back on.

Once you get the new one, it'll be a 2 minute job to swap.

Thank you. 
I have a system boiler with an unvented tank (I think that's what they are called)
I guess the same process applies