Electric tap/shower

[IanD]

12 minutes ago, rusty69 said:

......or fit your calorfiier with a thermostatic valve that controls the temperature to all taps and shower.

That's usually recommended to be set around 55C, much too hot for a shower (around 40C).

[LadyG]

2 hours ago, IanD said:

Why not fit your shower with a thermostatic mixer fitting to take in hot water from the calorifier and cold from the tank and provide a shower at the right (and adjustable) temperature?

I dare not change anything, i don't know how the shower is fitted, it does not seem to be accessible, it's not a problem really, as it is usually warm, if it is hot, say after a few engine hours, i just draw off a bucket full of hot and all is well.

The first rule of boating on a muddy ditch is "if it ain't broke, don't fix it"

Edited February 11 by LadyG

[cuthound]

On 11/02/2024 at 17:51, IanD said:

That's usually recommended to be set around 55C, much too hot for a shower (around 40C).

 

I think you are talking at cross purposes to @rusty69.

 

Most domestic calorifiers are thermostatically controlled to 65 degrees to save enregy and avoid legionella problems, not an issue with boats where the calorifier is heated by the engine coolant (typically 80 degrees or a diesel boiler such as a Webasto). Fitting a thermostatic mixer valve set to around 40 degrees to the outlet of a boat's calorifier ensures that no one can get accidentally scalded AND effectively increases the useable capacity of the calorifier.

Edited February 15 by cuthound
Clarification

[IanD]

Just now, cuthound said:

 

I think you are talking at cross purposes to @rusty69.

 

Most domestic calorifiers are thermostatically controlled to 65 degrees to avoid legionella problems. Fitting a thermostatic mixer valve set to around 40 degrees to the outlet of a boat's calorifier ensures that no one can get accidentally scalded AND effectively increases the useable capacity of the calorifier.

 

It's usually recommended to use something around 50C for hot water to the taps to avoid scalding but keep it as hot as safe, many boiler/heating sites quote this figure (or 120F in the USA).

 

https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/8.1/domestic-hot-water-temp-at-kitchen-sink.pdf

 

If you're going to mix it with cold afterwards then it doesn't make any difference to energy use or water capacity whether this is done at the calorifier output or elsewhere e.g. in the sink, or at a thermostatic shower valve.

 

So the recommended setup -- at least that's what Ricky told me! -- is to have the calorifier at 65C or above to avoid legionella (can go hotter than this when being heated by engine or boiler if you want to maximise usable hot water capacity, certainly up to 85C or even higher -- but mustn't boil, for obvious reasons!), have a thermostatic mixer at its output to drop down to 50C for distribution, and then a thermostatic shower valve because 50C is too hot for this -- and also this keeps shower temperature stable if there are any water pressure changes, especially in the cold pipes.

 

You could use a 40C mixer at the calorifier output, but this would give water at the taps a bit cool for some purposes (especially after flowing down long cold pipes...) which is why 50C is recommended.

[Tracy D'arth]

Safe maximum shower temperature for elderly and children is suggested to be 43 C. We always set thermostatic shower valve to this temperature limit when installing for Grohe and Mira.

[IanD]

Just now, Tracy D'arth said:

Safe maximum shower temperature for elderly and children is suggested to be 43 C. We always set thermostatic shower valve to this temperature limit when installing for Grohe and Mira.

 

It's also safer to rely on this to set discharge temperature at the shower, not a remote one in the calorifier -- which can also end up with water at the shower being too cool for some, especially in winter.

[Tracy D'arth]

21 minutes ago, IanD said:

 

It's also safer to rely on this to set discharge temperature at the shower, not a remote one in the calorifier -- which can also end up with water at the shower being too cool for some, especially in winter.

It was always set with a flow cup in the shower stream so that temperature and flow rate could be equated to the valve characteristics.