Unvented cylinder - usage question

[ossocafe]

We have an unvented cylinder with a Horstmann Electronic 7 timer. The cylinder only serves a wet room which is very rarely used. The rest of the house is served by a Vaillant combi boiler.

The timer on the cylinder is set to heat up water 3 times per 24 hours, which I think it is the default. With energy costs spiralling, I would like (if possible) to reduce the time the water is heated, but also avoid creating problems with legionnaires due to lower water temperature or causing any short or long term damage to the cylinder.

Can anyone advise if there is a sensible 'minimum' setting I can use? I am happy to change the settings when we have people coming to stay (which is the only time the cylinder gets used these days).

Thanks for any advice.

 

[ShaunCorbs]

The tank has its own thermostat built into the immersions so if the tank is upto temp it won’t heat even if the programmer is on

 

[ossocafe]

The tank has its own thermostat built into the immersions so if the tank is upto temp it won’t heat even if the programmer is on

Thanks for replying. As we don't need any hot water from the tank 90% of the time I'm looking for a timer setting which would be the minimum necessary for safety/maintenance. For instance, would it be 'safe' to turn off the cylinder altogether and switch it on, say once a month, at high temperature to kill off any bacteria?

 

[ShaunCorbs]

Can I ask what it does in the wet room eg hot water wise ?

 

[ossocafe]

Just a shower in a small wet room

 

[ShaunCorbs]

Could this be changed for an electric version as you could get rid of the cylinder then

Or taken off the combi boiler ?

 

[ossocafe]

We deliberately wanted the wet room shower to be off a different system so we have a back up if anything goes wrong with the boiler. Also when we have guests it’s a second shower which can get hot water from a different source to the combi. However we find we only use it in those cases which is very rarely.

It was less of an issue when energy prices were normal but now they’re insane (and our new smart meter shows the spikes in use at 2am) it would be good if we could minimize the cost without taking it out completely.

 

[Roy_66]

Do you have the electric supply available to change it to an electric shower which would seem the sensible thing to do.

One other idea - could you use the wet room once per week? (That still leaves the legionaries questions)

Cheers,

Roy (amateur)

 

[ossocafe]

We don’t want to go to the expense of taking out the cylinder and adding an electric shower. Just to make the most economical use of what we have.

We could use the wet room more often but it still doesn’t answer the original dilemma of what’s the least time we can/should be setting the timer for ,,

 

[SJB060685]

In my property I have an ASHP as my energy source. These by their very nature run at lower flow temperatures. Sunday through to Friday the heat pump heats the cylinder to whatever the flow temperature is set to. On Fridays the immersion heater heats the stored water to 60°c. This once a week sterilisation day is what the system has been set to and so far works.
Legionella bacteria thrives in water at temperatures between 20°c and 45°c but can survive in colder water as well.
Even if you were to heat the cylinder to 60°c once or twice a week you would still have stagnant water in any runs of pipe out of the cylinder and at shower heads or tap spouts etc which will pose a risk.

 

[Roy_66]

We don’t want to go to the expense of taking out the cylinder and adding an electric shower. Just to make the most economical use of what we have.

We could use the wet room more often but it still doesn’t answer the original dilemma of what’s the least time we can/should be setting the timer for ,,

To be clear I've no expertise in Legionaries. The following GOV doc looks useful:

HSE - Legionnaires' disease - Hot and cold water systems - Things to consider

This page proveds a series of elements that must be considered in relation to water systems and legionella.

www.hse.gov.uk

Professional testing whatever the proposed solution would seem sensible.

In terms of costs think about through life costs not just the immediate cost. I appreciate that could be tricky if you don't have a clear picture how long the facility might be required for.

Kind regards,

Roy (amateur)