Hot water temperatures at the basin

[blueplanet]

Hello

I recently had a new cylinder install. The temperature at the basin sinks is between 56-58C and is far too hot to use.

Is there a legal maximum that is applicable for domestic properties? What should the temperature be for basin sinks? Thanks.

 

[ShaunCorbs]

60 unless blended down to 40-45 at source

 

[Timmy D]

Regs state max temp delivered to a bath should be 48c. From memory it only states bath, not bathroom. This is to reduce the risk of scalding, especially by children.

I assume it doesn’t specifically mention bathrooms/basins/sinks as the risk of scalding is lower as you would immediately remove your hand. With a bath, a child may jump straight in with out testing.

As Shaun mentioned, the water in the tank should be stored at 60c (legionnaires prevention). I’d put a mixing valve on the cylinder output.

 

[ShaunCorbs]

Regs state max temp delivered to a bath should be 48c. From memory it only states bath, not bathroom. This is to reduce the risk of scalding, especially by children.

I assume it doesn’t specifically mention bathrooms/basins/sinks as the risk of scalding is lower as you would immediately remove your hand. With a bath, a child may jump straight in with out testing.

As Shaun mentioned, the water in the tank should be stored at 60c (legionnaires prevention). I’d put a mixing valve on the cylinder output.

distance to the outlet is an issue then also legionellas is a big issue

 

[Aquarius]

50 degrees to tap within 30 seconds is what I seem to remember. The regulations (Building regulations G3) for the 48 degrees max, iirc, only apply to new built properties and not replacement cylinders or baths. As stated, if you want lower temperatures at the basin/other outlets then a thermostatic mixing valve (TMV) will do the job. Bearing in mind, these should be checked annually, although not 100% if this applies to domestic properties.

 

[Last Plumber]

I would install a thermostatic mixer and set it to 43 degree's Celsius.
It should installed in line with current standards and regulations.

 

[Ric2013]

As others have hinted above, there are two sets of rules for hot water from storage that conflict.

One is that the water should be stored above 60° and should reach the tap at 50°C within 30 seconds. The other is that water should reach a bath at x degrees, and I'm sure I read somewhere that there are recommendations for a washbasin also.

The issue here is that the regulations for maximum temperatures apply to new bathrooms, not to existing ones. Your plumber has fitted a new cylinder and presumably set the storage temperature to around 60°C, which is correct. He has also not fitted a blending valve on the cylinder outlet, and was right not to do so as the water running through the pipes needs to be hot enough to keep them hygienic.

If you want to upgrade your bathroom to current standards regarding maximum temperatures, the right way to do it would be to have thermostatic mixing valves fitted directly under the taps to temper the water while allowing the hot water in the pipes to be hot enough to prevent biofilms forming. Personally, my feeling is it's just something else to go wrong, but if you want the water blended down, I do understand.

 

[blueplanet]

As others have hinted above, there are two sets of rules for hot water from storage that conflict.

One is that the water should be stored above 60° and should reach the tap at 50°C within 30 seconds. The other is that water should reach a bath at x degrees, and I'm sure I read somewhere that there are recommendations for a washbasin also.

The issue here is that the regulations for maximum temperatures apply to new bathrooms, not to existing ones. Your plumber has fitted a new cylinder and presumably set the storage temperature to around 60°C, which is correct. He has also not fitted a blending valve on the cylinder outlet, and was right not to do so as the water running through the pipes needs to be hot enough to keep them hygienic.

If you want to upgrade your bathroom to current standards regarding maximum temperatures, the right way to do it would be to have thermostatic mixing valves fitted directly under the taps to temper the water while allowing the hot water in the pipes to be hot enough to prevent biofilms forming. Personally, my feeling is it's just something else to go wrong, but if you want the water blended down, I do understand.

 

[blueplanet]

Thanks for the replies. The TMV is the way to go. One on the cylinder should do the trick. If I have one installed it will invalid the warranty on the system as the installers would claim that I changed the system.

Given that I paid over £5K as far as I am concerned they should have installed one or at the very least discussed/asked if I wanted one installed. I have gone back to them so hopefully they will sort it out.

 

[Last Plumber]

Thanks for the replies. The TMV is the way to go. One on the cylinder should do the trick. If I have one installed it will invalid the warranty on the system as the installers would claim that I changed the system.

Given that I paid over £5K as far as I am concerned they should have installed one or at the very least discussed/asked if I wanted one installed. I have gone back to them so hopefully they will sort it out.

You really need to have the shortest possible run from the TMV to the outlet. You should also be able to achieve 50 (55 in health care premises) degree C at the hot inlet to the TMV. within a minute of turning on the tap. That's the way I would want it to operate for safety.
Is this an unvented or open vented cylinder?

 

[Ric2013]

Thanks for the replies. The TMV is the way to go. One on the cylinder should do the trick. If I have one installed it will invalid the warranty on the system as the installers would claim that I changed the system.

Given that I paid over £5K as far as I am concerned they should have installed one or at the very least discussed/asked if I wanted one installed. I have gone back to them so hopefully they will sort it out.

The fact that you paid £5,000 is interesting as it sounds to be a lot for a cylinder installation, but still would not be a reason to expect TMVs to be fitted in your bathroom. Had your installers installed a TMV on the cylinder outlet to bring the temperature down to a nice level, that would be illegal for reasons outlined above and would put you at (hypothetical) risk from bacteria forming in the pipework. It's not something I would do even if the customer specifically requested it.

Out of interest, what was your previous hot water system? If it was already a cylinder then it should already have been storing water at 60°C, so I'm interested to know why there is obviously a change in temperature.

 

[blueplanet]

The fact that you paid £5,000 is interesting as it sounds to be a lot for a cylinder installation, but still would not be a reason to expect TMVs to be fitted in your bathroom. Had your installers installed a TMV on the cylinder outlet to bring the temperature down to a nice level, that would be illegal for reasons outlined above and would put you at (hypothetical) risk from bacteria forming in the pipework. It's not something I would do even if the customer specifically requested it.

Out of interest, what was your previous hot water system? If it was already a cylinder then it should already have been storing water at 60°C, so I'm interested to know why there is obviously a change in temperature.

You really need to have the shortest possible run from the TMV to the outlet. You should also be able to achieve 50 (55 in health care premises) degree C at the hot inlet to the TMV. within a minute of turning on the tap. That's the way I would want it to operate for safety.
Is this an unvented or open vented cylinder?

The previous system was an unvented cylinder and the water temperature was normal. I could lower or increase the temperature. The new cylinder is unvented and connected with a solar panel and under MCS procedures they are meant to consider TMV's and carry out a scalding risk survey.

 

[ShaunCorbs]

How could you lower the temperature?

 

[Knappers]

Scalding and outlet temps are something I dealt with commercially as part of risk assessments for legionella and duty of care for public access areas.
Domestically I don't look at these issues and just fit packages offered by manufacturers.
If the installation literature said something 'should' be done it has a very different meaning than it would in consumer literature, in technical literature 'should' is simply suggesting something while making it clear that it's not a requirement.

 

[blueplanet]

How could you lower the temperature?

Prior to the solar the temperature was controlled by the boiler setting and how long you ran it for. With the solar it is constantly heating.

 

[ShaunCorbs]

Prior to the solar the temperature was controlled by the boiler setting and how long you ran it for. With the solar it is constantly heating.

that’s bad as your not fully heating the store and bacteria could grow

 

[Ric2013]

I can see where the OP is coming from in that he or she used to be able to control how long the boiler was run for, like my grandmother who used to turn her immersion heater on for just half an hour. As ShaunCorbs has said, this method would result in the cylinder not being fully heated through and is bad practice. It's a bit like leaving the gas oven door open to warm the kitchen - effective, but you do it at your own risk and in breach of the manufacturer's instructions.

I can see why the OP is disappointed - he or she never presumably had formal instructions for the old system and so would not have realised that being able to control the temperature in this way is actually not a good idea. The correct way to use a stored hot water system is to heat the cylinder till it is hot through (and even if you don't maintain that temperature constantly at least you will have reached it for long enough to pasteurise the water), but if no-one tells you, you won't know.

On a more sceptical note, can anyone explain to me why water from a cylinder and that from a combi boiler are treated differently by the regulations? While I understand the combi boiler does not store water and thus bacterial growth in storage is not possible, I can't really see the technical difference between storing water at 60°C and blending it down at the cylinder outlet (which most of us will probably agree is not compliant) and water leaving a combi boiler at 40°C and running through the pipework at that temperature (which most of us will probably agree the Water Regulations seem to begrudgingly accept).