Unable to increase hot water temperature above 60

[Littlemoney]

I had a Worcester Bosch Greenstar 4000 installed in November 2024.

I wanted to increase the hot water temperature above 60 so I can fill my bath more quickly with hot water for my occasional soak in the bath.

On the boiler display the maximum hot water temperature is 60 yet on the Comfort + 2 RF control unit the hot water maximum can be set up to 70 degrees.

How do I increase the hot water temperature on the boiler above 60. I don't use the control unit for hot water as I use the Eco mode.

Any suggestions would be appreciated. I am new to the world of combination boilers and still learning. Thank you.

 

[Harry Bloomfield]

I wanted to increase the hot water temperature above 60

60C is maybe the limit, hotter comes with a risk of scalding, besides - increasing the flow temperature of a combi, means they have to reduce the flow to achieve it.

 

[terryplumb]

Surely you can't bathe in water above 60⁰ c ??

 

[MNW67]

They probably want to avoid scalding:

 

[MNW67]

on the Comfort + 2 RF control unit the hot water maximum can be set up to 70 degrees.

That might only apply to systems with a hot water cylinder.

 

[Johntheo5]

I had a Worcester Bosch Greenstar 4000 installed in November 2024.

I wanted to increase the hot water temperature above 60 so I can fill my bath more quickly with hot water for my occasional soak in the bath.

On the boiler display the maximum hot water temperature is 60 yet on the Comfort + 2 RF control unit the hot water maximum can be set up to 70 degrees.

How do I increase the hot water temperature on the boiler above 60. I don't use the control unit for hot water as I use the Eco mode.

Any suggestions would be appreciated. I am new to the world of combination boilers and still learning. Thank you.

Your 24kW? combi will give a flowrate, at 60C, of, 24*860/60/(60-10), 6.88LPM, from a (my) present mains temp of 10C, if you require a bath temperature of say 50C, then you mix the mains cold water at a rate of 1.72LPM with the 6.88LPM at 60C to give a flowrate of 8.6LPM at 50C.
If you set the combi HW temp to 50C then a 24kW combi will give a flowrate of, 24*860/60/(50-10), 8.6LPM, no different to the above, bath will take same time to fill.

 

[dilalio]

I had a Worcester Bosch Greenstar 4000 installed in November 2024.

I wanted to increase the hot water temperature above 60 so I can fill my bath more quickly with hot water for my occasional soak in the bath.

On the boiler display the maximum hot water temperature is 60 yet on the Comfort + 2 RF control unit the hot water maximum can be set up to 70 degrees.

How do I increase the hot water temperature on the boiler above 60. I don't use the control unit for hot water as I use the Eco mode.

Any suggestions would be appreciated. I am new to the world of combination boilers and still learning. Thank you.

Welcome to bathing with a combi.

 

[Littlemoney]

Your 24kW? combi will give a flowrate, at 60C, of, 24*860/60/(60-10), 6.88LPM, from a (my) present mains temp of 10C, if you require a bath temperature of say 50C, then you mix the mains cold water at a rate of 1.72LPM with the 6.88LPM at 60C to give a flowrate of 8.6LPM at 50C.
If you set the combi HW temp to 50C then a 24kW combi will give a flowrate of, 24*860/60/(50-10), 8.6LPM, no different to the above, bath will take same time to fill.

It's the 30kw model or so I was told as they were aware I bath rather than shower but there isn't a label on the outside of the boiler. Don't know what is behind the cover.

That might only apply to systems with a hot water cylinder.

This temperature shows on the hot water menu on the controller

I have an old cast iron bath which also lowers the water temperature.

 

[Madrab]

You 4000 combi is factory set where it has @ a max of 60Deg



The DHW function on the controller will do nothing on a combi, it is more for a system/reg boiler with the additional controls kit that would manage a DHW cylinder with diverter valve and cylinder stat.

 

[grantmac]

Sounds like you’re maxed out due to the safety settings on the boiler. Might wanna check if there’s an adjustment for the ECF (Economy Comfort mode) settings, but usually, they won't let temps go past 60 to avoid scalding.

 

[MNW67]

I wanted to increase the hot water temperature above 60 so I can fill my bath more quickly with hot water for my occasional soak in the bath.

As johntheo5 said, even if you could increase the temperature (which you can't) the bath wouldn't fill any faster. It's a bit like the old joke "must write faster because my pen's running out".

 

[Johntheo5]

It's the 30kw model or so I was told as they were aware I bath rather than shower but there isn't a label on the outside of the boiler. Don't know what is behind the cover.


This temperature shows on the hot water menu on the controller

I have an old cast iron bath which also lowers the water temperature.

Well then:
Your 30 combi will give a flowrate, at 60C, of, 30*860/60/(60-10), 8.6LPM, from a (my) present mains temp of 10C, if you require a bath temperature of say 50C, then you mix the mains cold water at a rate of 2.15LPM with the 8.6LPM at 60C to give a flowrate of 10.75LPM at 50C.
If you set the combi HW temp to 50C then a 30kW combi will give a flowrate of, 30*860/60/(50-10),10.75 LPM, no different to the above, bath will take same time to fill.

It would take huge power to give the same flowrate from a combi as from a HW cylinder, a 200L HW cylinder can be heated to 60C (from 10C) overnight in less than 4 hrs with only a 3kW heating coil or immersion element and can fill your bath at say 18LPM or greater to fill it rapidly but to get this (instant) waterflow rate of 18LPM at 60C from a combi would require a power rating of almost 63kW.

 

[Littlemoney]

Previously I had a 40 year old boiler with hot water tank which was also sited very near the bath. Just didn't understand what I was giving up when I lost my hot water tank plus modern health and safety where people are unable to use common sense when using hot water.

 

[ChrisJP]

Yup...in my opinion combi boilers that only heat water as you call for it have serious drawbacks which are often not made clear by boiler fitters who present them as the "modern" replacement for systems with HW cylinders. It's true of course that a HW cylinder continuously loses some heat which you've paid to provide, but this can be reduced to an insignificant amount by good lagging of the cylinder.

 

[Madrab]

You could always look to re-instate the HW cylinder, your combi will happily heat that alongside the radiators and the pipework for the old cylinder will probably still be in or around it's old location. Could even look to go unvented if the cold mains supply is adequate.