Why is my boiler on?

[diy_fun_uk]

My heating and hot water system is pretty old, original to house that was built mid 80's. Separate boiler and hot water cylinder with immersion heater. Stating the obvious but I can put my heating on/off and my hot water on/off independently of each other or have both on. tbh I rarely use the hot water.

I've just noticed today (I've only lived here for a decade so give me a chance!) that when I put the hot water on, the boiler's running. I would have thought the water should be getting heated via the immersion, so why is the boiler coming on?

The rads aren't heating up.

 

[jj4091]

If you mean you are turning it on & off by a room stat or programmer for the boiler then that will not control the immersion heater

 

[CBW]

What are you using to put the hot water on? The programmer? If so, then yes boiler will run.

 

[diy_fun_uk]

What are you using to put the hot water on? The programmer? If so, then yes boiler will run.

Ah right, thanks, that explains it There's a hot water switch (behind my microwave) so it's that I should be using to ensure boiler doesn't run.

Thanks again.

 

[CBW]

so it's that I should be using to ensure boiler doesn't run.

Yes. Obviously boiler will run for heating. If your using the immersion heater as well it’s costing you twice.

 

[Harry Bloomfield]

I've just noticed today (I've only lived here for a decade so give me a chance!) that when I put the hot water on, the boiler's running. I would have thought the water should be getting heated via the immersion, so why is the boiler coming on?

Your immersion heater has probably been retained as back up for the boiler. Much cheaper to heat your water via the boiler, than via the immersion heater, but the controls for each system will be entirely separate.

 

[diy_fun_uk]

Yes. Obviously boiler will run for heating. If your using the immersion heater as well it’s costing you twice.

My stupid question of the day. If I am heating the water via the boiler (not immersion) then where is the hot water being stored. Still in the cylinder or in a tank elsewhere e.g. loft? In other words, does the water in the cylinder only get heated if I use the immersion?

My reason for asking is I've not used the immersion ever since I moved in (10+ years) so if the water in the cylinder has never been used, it'll be well and truly stagnant?

 

[CBW]

It’s not stupid at all. You’ll likely have an indirect cylinder, which has a coil attached to it to use the heating water circuit to heat the hot water indirectly, so yes the hot water is stored on the cylinder. If you’re using the available hot water, this will be getting replenished by a cold water storage cistern above, unless you have an unvented cylinder, which uses mains pressure water, but the water is rarely just sat there. Unless of course your not using hot water, in which case it would be stagnant.

This may help explain it better: https://www.diydoctor.org.uk/projects/domestic_hot_water_systems.htm

 

[Junglejames]

Crikey. Can't be many prefer the immersion heater over a gas boiler.
Still, they may (or may not) be doing their bit for global warming! Assuming heating isn't being used at the same time anyway!

But yes, your hot water cylinder will have two methods of heating it. Hot water, which is getting heated by your boiler, or the electric immersion heater.

The immersion heater is fine for a quick boost in temperature, but not a cheap way to heat your water.

 

[stem]

Your hot water taps will be supplied from the hot water cylinder. You have the option to heat the cylinder with the boiler, or as a back up using the electric immersion.

It's the same water that goes to the taps regardless of how it's heated.

 

[diy_fun_uk]

Thanks guys, you've put my mind at rest Whenever I do use the hot water, I'll just continue to heat it via the boiler.

 

[Harry Bloomfield]

Whenever I do use the hot water, I'll just continue to heat it via the boiler.

I'll ask the question - Why 'when you do'? What do you use for washing up, getting washed, having a bath etc.?

 

[Junglejames]

I'll ask the question - Why 'when you do'? What do you use for washing up, getting washed, having a bath etc.?

I have to admit a thousand questions ran through my mind when they said they rarely used the hot water.

Saying that, in the place my brother has moved into, it was noticed that the waste from the bath wasn't connected correctly. You'd have flooded the place every time you emptied the bath. So how were the previous family washing?

 

[stem]

I once had a house with an instantaneous electric shower, the dishwasher and washing machine were cold fill, meaning I only needed hot water to wash the dishes, so I used a kettle for that. [I was single back then so that didn't happen as often as it should ] Might have heated the water in the cylinder twice in 4 years.

 

[Harry Bloomfield]

Saying that, in the place my brother has moved into, it was noticed that the waste from the bath wasn't connected correctly. You'd have flooded the place every time you emptied the bath. So how were the previous family washing?

They maybe kept their coal in the bath