Water not coming out hot in shower - OK everywhere else

Sumarokov

I have just moved into a new flat. It has an Ideal gas boiler (see image) and, on the advice of the previous tenant, who showed me how everything works, I have kept the settings. The flat is quite small, so I just turn on the central heating when it gets cold and the flat gets heated quickly. Water comes out of the kitchen and bathroom sink taps very hot and very quickly... except in the shower. I have tried every combination below I can think of, but it only ever starts getting even "warm" (not hot) when it is time to get out the shower!

Can anyone suggest what I might be doing wrong and what combination is needed? There is nothing wrong with the shower settings, because when I turn on "cold" it goes real cold, but the heat settings (up to 45) are just "lukewarm" (at best) and then, after a long time, "warmish"... Could there be something else at play?

sevenhills

Can you post a photo of your shower?

My shower is fed by the boiler, but most have electric showers. My central heating goes cold when the shower is used.

Perhaps your boiler lacks the power to heat both?

ThisIsWeird

Sumarokov said:

I have just moved into a new flat. It has an Ideal gas boiler (see image) and, on the advice of the previous tenant, who showed me how everything works, I have kept the settings. The flat is quite small, so I just turn on the central heating when it gets cold and the flat gets heated quickly. Water comes out of the kitchen and bathroom sink taps very hot and very quickly... except in the shower. I have tried every combination below I can think of, but it only ever starts getting even "warm" (not hot) when it is time to get out the shower!

Can anyone suggest what I might be doing wrong and what combination is needed? There is nothing wrong with the shower settings, because when I turn on "cold" it goes real cold, but the heat settings (up to 45) are just "lukewarm" (at best) and then, after a long time, "warmish"... Could there be something else at play?

That's a combi boiler, so will divert to providing DHW whenever a hot tap (or shower) is opened. Yes, the CH will turn off for that duration, but that's not usually a problem unless you run a tap for a half hour or more...

All your controls are 'fine', although turned up high, both DHW and CH. If you can manage with lower output settings, you should place less strain on your boiler, and also improve its efficiency, assuming it's a condensing type - which it almost certainly is.

You say your flat heats up quickly from cold, so I would be looking to turn the rad control down by a third and see how that goes. Do your rads currently go 'ouch' hot? Do they need to?

Ditto with the DHW control - that is also high. If you are ok with this - not concerned about any risk of scalding (do you have kids in the flat?) - then you can keep it where it is, or - again - you can try turning it down a bit as long as it's still hot enough for you.

Then there's the 'preheat' control, which is currently off - good. With it being 'off', the boiler doesn't run unless there's a tap opened or the CH calling. With this control 'on', the boiler will fire up, often every few minutes or so, in order to keep the DHW side 'hot' and ready to deliver. So, with it 'on', you will get hot water coming out of your tap probably 10-odd seconds faster, but you'll pay the price by having the boiler firing up far more often than it needs to - extra wear - and it consumes gas each time just to preheat the boiler. So, 'off' - as it is - if you can.

Oookkaay - why the not-hot shower? Almost certainly 'cos it's faulty

As 7hills asks, a photo and ideally make and model, please.

Do you know if the shower has isolating valves fitted to shut off its flow for repairs and stuff? Is there a cupboard in the room next to where the shower is located? Can you trace the shower pipes at all?

amanda1024

Sometimes it can take longer to heat up because the hot water is having to go further -there’s more cold water in the pipe to push out before the hot can run through, plus if the pipes go outside at all the pipes themselves suck out some of the heat. But if it never gets hot, that does suggest a problem with the shower itself and whatever mixer/thermostatic control it uses.

Swasterix

If it’s a thermostatic mixer shower, the cartridge which controls the temperature may be knackered. Try putting the shower on then open the cold tap fully to the bathroom sink. Does the shower get hot? 

Sumarokov

Swasterix said:

If it’s a thermostatic mixer shower, the cartridge which controls the temperature may be knackered. Try putting the shower on then open the cold tap fully to the bathroom sink. Does the shower get hot? 

That is a clever suggestion, thanks. But when I tried it... bizarrely, the water in the shower also came out ice cold. So the complete opposite effect!

ThisIsWeird

Sumarokov said:

Swasterix said:

If it’s a thermostatic mixer shower, the cartridge which controls the temperature may be knackered. Try putting the shower on then open the cold tap fully to the bathroom sink. Does the shower get hot? 

That is a clever suggestion, thanks. But when I tried it... bizarrely, the water in the shower also came out ice cold. So the complete opposite effect!

A few possible reasons for that result - eg the cold tap deprived the combi boiler of water to the point it shut down, or perhaps the thermo cartridge is still operating to the effect that it shuts off the hot supply fully when it perceives a risk of scalding. Who knows.

PICTURE OF SHOWER!!!

and

CAN YOU LOCATE THE PIPES GOING TO IT?!!

Ganga

Could the shower be piped up the wrong way round? that is the hot pipe to the cold side of the shower.

ThisIsWeird

Ganga said:

Could the shower be piped up the wrong way round? that is the hot pipe to the cold side of the shower.

I've seen that before on here!

Sumarokov

ThisIsWeird said:

Sumarokov said:

Swasterix said:

If it’s a thermostatic mixer shower, the cartridge which controls the temperature may be knackered. Try putting the shower on then open the cold tap fully to the bathroom sink. Does the shower get hot? 

That is a clever suggestion, thanks. But when I tried it... bizarrely, the water in the shower also came out ice cold. So the complete opposite effect!

A few possible reasons for that result - eg the cold tap deprived the combi boiler of water to the point it shut down, or perhaps the thermo cartridge is still operating to the effect that it shuts off the hot supply fully when it perceives a risk of scalding. Who knows.

PICTURE OF SHOWER!!!

and

CAN YOU LOCATE THE PIPES GOING TO IT?!!

Apologies that the picture is a bit blurry, but I hope it does the purpose.

I cannot see the pipes, but the bathroom is right next to the kitchen (through the wall), where the gas boiler hangs, so very short route from the boiler and water supply to the shower itself.

There is no question of the hot and cold being mixed up. The cold does as it should, but the hot just comes out lukewarm and only becomes something approaching "pleasantly warm" when I am ready to finish my shower and jump out!

Miser1964

95% certain that the shower thermostat is the culprit. Had the same issue with a Triton mixer shower, hot water in all the taps but the shower temp never got above tepid. The cartridges can be quite expensive, plus the fitting of course.