Poor hot water Worcester Bosch 24i

[pellow]

My daughter has recently moved in to a small 2 bedroom house with a four year old central heating system. The boiler is a Worcester Bosch 24i and all the radiators were replaced as well. I have just removed disabled wet room equipment and re-instated a bath connecting up to the original capped 15mm pipework. I left the Mira electric shower in place. She tells me that when running a bath the hot water isn't hot enough for "a nice relaxing soak" The basin and kitchen sink water is adequate. The handbook says the water temperature is fixed at 55 degrees C and cannot be changed.
Has anyone got any ideas about increasing the temperature of the water? 55 degrees seems a little bit low to me. Is this now the norm with modern condensing boilers? Surely, a modern boiler should be able to supply hot water for a bath or has the "green brigade" taken over!

I welcome any replies

 

[picasso]

The mains water coming in is a lot colder this time of year and 24kw boilers struggle to fill a bath, even if it wasnt capped at 55c you would not get a lot more out of it.

 

[easyflow]

Also the outlet on bath taps are larger 22mm so the flow will be greater, turn the tap down a bit this may help.

 

[muggles]

It's a 24kW boiler, the performance isn't going to be very special especially with a cold main. 55°C is hotter than any normal person would be able to lie down in without squealing like a lobster. If it's not getting that hot, she needs to reduce the flow rate coming out of the tap (IE don't turn it on as much). The boiler will give you a 40ºC rise in temperature above the cold main's temperature at a flow rate of about 8.5 litres per minute, run the tap faster than that and the boiler just won't keep up

The only way to get better hot water performance is to change the boiler for a more powerful one

 

[pellow]

Thanks for your prompt replies. My daughter has now tried reducing the flow at the tap and now has hot water with steam! Would it be best to reduce the flow going in to the boiler (I think there's an isolating valve) or is it best to leave things as they are. I can't see the point of manufacturers producing a boiler that just about copes with filling a bath. I'm used to a 30yr old Vulcan Continental with a hot water cylinder. I hope it goes on for ever!
Once again, thanks for your help.

 

[Dan Robinson]

You can buy flow limiting valves. Probably easier just to bang one on the bath.

 

[Agile]

Easier still to just not turn the tap on to more than the boiler can manage of about 8 litres per minute.

Tony

 

[picasso]

I can't see the point of manufacturers producing a boiler that just about copes with filling a bath.

Its not the manufacturers fault that someone has installed a small combi in an unsuitable place, blame the installer (if he specced it) or homeowner that was on a "budget".

 

[Agile]

To be fair 90% of combis that I see are only 24 kW.

The users just have to learn how to manage adequately with them.

Tony

 

[muggles]

Glad you've worked it out. 24kW combi boilers are great if they're used as they're designed, but in much the same way as you wouldn't enter a Nissan Micra into a race with a load of Ferraris because it wouldn't stand a chance, you also wouldn't expect a 24kW combi to be used to fill a bath

 

[pellow]

I can't blame the installer or the previous elderly owner because I think the wet room was installed before the change of boiler so there wouldn't have been a bath. The 24kw would have been fine for a sink, washbasin and 5 radiators.
Again, thanks for the replies.