I have been experimenting with the settings on the hot water cylinder heated by a old gas boiler.

Earlier this year I replaced the hot water cylinder insulation jacket and I have bought an indoor/outdoor thermometer with a wireless remote temperature sensor that can measure up to 60 degrees that I have pushed under the cylinder jacket near the top of the cylinder.

The thermometer cost me just over a tenner through EBay, it now shows the temperature of the hot water cylinder, also the temperature and humidity level on our coffee table along with the maximum and minimum readings.

Along with this I have the in home display for the Smart meters allowing me to easily monitor the gas used.

I have the hot water set to come on in the morning and evening, two people shower and wash plus some hot water is used in the kitchen but we do have a dishwasher.

On days we both shower in the morning I have cancelled the evening heating period, cost wise it makes no real difference to having the boiler coming on twice when one of us has showered in the morning and the other in the evening. Basically having replaced the the insulation jacket the boiler is topping up the hot water remaining in the cylinder when it comes on twice a day and any saving by cancelling a heating period is lost having to reheat from a lower temperature.

My conclusion is that it’s insulation that makes the savings not fiddling with the time clock settings.

Remember, thermostatic mixer showers have a maximum preset of 38 degrees that you have to manually override.

In the winter I shower at 38 degrees, cooler in the summer, so if the hot water cylinder is a 38 degrees or above the thermostatic mixer is blending hot and cold water to achieve the required temperature, so that 47.6 degrees at lunchtime after one person showered this morning indicates there will be enough hot water for someone to shower this evening without the boiler kicking in again.

So I could now cancel tonight’s heating period, but I’m finding the actual cost saving isn’t significant, the lost heat is in the boiler and pipework rather than the well insulated cylinder.

I have been experimenting with the settings on the hot water cylinder heated by a old gas boiler.

Earlier this year I replaced the hot water cylinder insulation jacket and I have bought an indoor/outdoor thermometer with a wireless remote temperature sensor that can measure up to 60 degrees that I have pushed under the cylinder jacket near the top of the cylinder.

The thermometer cost me just over a tenner through EBay, it now shows the temperature of the hot water cylinder, also the temperature and humidity level on our coffee table along with the maximum and minimum readings.

Along with this I have the in home display for the Smart meters allowing me to easily monitor the gas used.

I have the hot water set to come on in the morning and evening, two people shower and wash plus some hot water is used in the kitchen but we do have a dishwasher.

On days we both shower in the morning I have cancelled the evening heating period, cost wise it makes no real difference to having the boiler coming on twice when one of us has showered in the morning and the other in the evening. Basically having replaced the the insulation jacket the boiler is topping up the hot water remaining in the cylinder when it comes on twice a day and any saving by cancelling a heating period is lost having to reheat from a lower temperature.

My conclusion is that it’s insulation that makes the savings not fiddling with the time clock settings.

Remember, thermostatic mixer showers have a maximum preset of 38 degrees that you have to manually override.

In the winter I shower at 38 degrees, cooler in the summer, so if the hot water cylinder is a 38 degrees or above the thermostatic mixer is blending hot and cold water to achieve the required temperature, so that 47.6 degrees at lunchtime after one person showered this morning indicates there will be enough hot water for someone to shower this evening without the boiler kicking in again.

So I could now cancel tonight’s heating period, but I’m finding the actual cost saving isn’t significant, the lost heat is in the boiler and pipework rather than the well insulated cylinder.

Sparkingchip  I've recently cancelled my morning water heating period as I'm not always there during the day to use any of the hot water anyway. Mine comes on around 4pm so there's hot water for the evening wash up and shower etc. If I am working from home that day I just leave the washing up until later (I don't own a dishwasher or should I say I do have a dishwasher but it's called having a sink and using hands... ) 

I would love to replace my hot water cylinder with something similar to what we have installed in our French home. We find that we can turn off the element 3 days before we're due to return to the UK and the water is still plenty hot enough after those 3 days for us both to have showers and washing up etc. 

Unfortunately in the tank in my UK home, even though it is both foam insulated and has an additional jacket on it too, the water seems to cool off very quickly. 

I think when it comes to replacing the boiler, it may be Combi time... 

Effective insulation on any water storage which is 10° or more above ambient is essential (unless you just like burning gas to heat up the world). (Or you could install it in the living room without the insulation, but summers might become unbearable.) Also, swapping out that "old gas boiler" for an energy-efficient one may well save you half the cost or more of gas.

Only if it is < 50% efficient, which seems unlikely.

Peter Bernard Ladkin said:

Also, swapping out that "old gas boiler" for an energy-efficient one may well save you half the cost or more of gas.