Combi supplying a shower with hot water

[bernardgreen]

Running a shower on hot water from a combi.

When another hot water tap is turned the hot water supply to the shower is reduced in flow and/or temperature.

The reaction time of a thermostatically controlled shower mixer to this reduction in the hot water supply has to be fast enough to prevent a drastic drop in temperature of the water coming out of the shower head.

The sudden change from hot shower to colder shower is at best not comfortable, at worst it can result in a fall as the person tries to get away from the cold water..(*)

When the hot tap is turned off and the shower once again has hot water then the time taken for the shower thermostatic valve to react can be long enough for the un-expected hot water to scald the person in the shower before the thermostat adjusts the temperature to a safe level.

(*) The "cold shock" affects both heart rate and breathing, in extreme cases this can lead to a heart attack.

 

[bernardgreen]

I take it you know how a thermostatic shower gets over that problem

For some reason the thread was locked before I could reply to you

I know that some thermostatic shower mixers have a second line of defence in a "scald protector" but even that has a reaction time so a short duration of over temperature water is probably inevitable unless the increase in flow and/or temperature of the restored hot supply is gradual over a few seconds.

 

[Roger928]

Running a shower on hot water from a combi.

When another hot water tap is turned the hot water supply to the shower is reduced in flow and/or temperature.

The reaction time of a thermostatically controlled shower mixer to this reduction in the hot water supply has to be fast enough to prevent a drastic drop in temperature of the water coming out of the shower head.

The sudden change from hot shower to colder shower is at best not comfortable, at worst it can result in a fall as the person tries to get away from the cold water..(*)

When the hot tap is turned off and the shower once again has hot water then the time taken for the shower thermostatic valve to react can be long enough for the un-expected hot water to scald the person in the shower before the thermostat adjusts the temperature to a safe level.

(*) The "cold shock" affects both heart rate and breathing, in extreme cases this can lead to a heart attack.

And your solution is???

 

[bernardgreen]

And your solution is???

To avoid the use of a combi, heat only boiler and a hot water cylinder.

 

[Roger928]

But don't the majority of scalding incidents occur using a cylinder?
I assume you have researched this?
Keeping in the context of combi V cylinder!

 

[AGAS]

bernardgreen so what thermostatic shower do you recommend ???

 

[bernardgreen]

But don't the majority of scalding incidents occur using a cylinder?
I assume you have researched this?

Scalding can occur where ever there is hot water.

The water temperature at a tap or shower supplied from a cylinder will not change suddenly other than rapidly going from cold to hot when the tap is first turned on. Most people are aware of this and take care how they operate the tap to avoid being scalded. The person is in control of the situation, any accidents are due to their actions.

The water temperature at a tap or shower supplied directly from a combi boiler can change suddenly. The temperature can change due to the actions of a different person elsewhere in the house. The person in the shower can suffer accident or harm due to the actions of another person.

I have not formally "researched" the matter but others have and the results do show that cold shock is a significant factor in the accidents involving falls in showers supplied from a combi. Scalding in a shower supplied from a combi tends to be secondary after the person has already fallen and has been unable get away from the hot water when the hot water supply has been restored.

There is also my own experience when staying in houses with combi boilers.

so what thermostatic shower do you recommend

One that is not supplied by a combi boiler

 

[AGAS]

One that is not supplied by a combi boiler

well your pretty fooked then if you already have a combi . there are ways around it thou

 

[bernardgreen]

There is aparently a device which can be fitted in the pipe work to cut off the hot supply to taps if the shower is taking hot water. Probably means a lot of new pipe work.

Or more simple a water proof sign to hang on the kitchen sink taps "Shower in use , do not run hot water "

Or live alone......

well your pretty fooked then if you already have a combi

Add a hot water cylinder, even for just the shower,

 

[Dan Robinson]

To avoid the use of a combi, heat only boiler and a hot water cylinder.

Is that your alternative thinking on action?

There is also my own experience when staying in houses with combi boilers

Your experience has no bearing on the issue.

others have and the results do show that cold shock is a significant factor in the accidents involving falls in showers

Evidence?

Most people are aware of this and take care how they operate the tap to avoid being scalded.

So you can set up a preposition that suits your stance? How many people have been scolded in a combi fed thermostatic shower as opposed to a tank fed thermostatic shower?

 

[bernardgreen]

Your experience has no bearing on the issue.

Then by the same token your experience as an installer has no bearing on the issue.

How many people have been scolded in a combi fed thermostatic shower as opposed to a tank fed thermostatic shower?

As far as I know there is no collation of accident data for this in the public domain. And scalding is less likely than injury or aggrevated medical condition due to a cold shock incident in a combi fed shower.

 

[AGAS]

As far as I know there is no collation of accident data for this in the public domain. And scalding is less likely than injury or aggrevated medical condition due to a cold shock incident in a combi fed shower.

AND ??

 

[durhamplumber]

I think your point about possible cold water shock leading to cardiac arrest in the shower is way over the top,even if you are at deaths door.Its not the same effect as plunging into the artic ocean.You just move over a bit til the shower adjusts.happens to me regularly.Even if the water goes completely cold its still about 8C I would guess.That is very very unlikely to cause health problems even stood under it shivering for hours.

 

[dilalio]

I must remember not to venture outside my front door... just in case the thermal shock kills me!

Hey ho... didn't want to go back to work anyway

 

[dilalio]

A new profile pic for you Bernard...