Leave immersion turned off in fuse box?

Deanicus · 07-01-2022 2:13pm #1

Our youngest lad likes turning the immersion switch on and it can be hours before we notice

I've turned the fuse off in the fuse box and just wondering if this is safe long term?

07-01-2022 4:19pm

It is fine to leave the MCB off for an extended period.

You could get a boost button installed, this would prevent it being turned on for more than 90 minutes. Also the stat can be turned down.

Deanicus · 07-01-2022 4:57pm

https://www.boards.ie/discussion/comment/118434045#Comment_118434045

Thanks! Was hoping to avoid replacing the switch or doing much work to be honest

We primarily use the gas boiler to heat the water so unfortunately can't turn the stat down. Just need him to lose interest in turning it on because the light doesn't come on anymore. Thinking of leaving it a couple of months, just to be sure. Is that ok do you think?

07-01-2022 5:37pm

You can turn the immersion stat down without impact the gas boiler stat. They are completely separate systems.

07-01-2022 5:39pm

Yes you can leave the MCB off for a few months. If the light is not working on the switch it may have developed a fault. It would be best not to use until this is resolved.

L1011 · 07-01-2022 5:39pm

https://www.boards.ie/discussion/comment/118434540#Comment_118434540

That's assuming the immersion actually has a stat, though.

07-01-2022 5:40pm

https://www.boards.ie/discussion/comment/118434557#Comment_118434557

I haven’t seen one thy doesn’t.

L1011 · 07-01-2022 5:42pm

https://www.boards.ie/discussion/comment/118434569#Comment_118434569

In terms of adjustable stats, rather than just overheat protection:

My own house, original install ca. 1972 - none. I assume but don't know if the 2017 replacement has one as it hasn't been used once - zoned gas went in at the same time!

Parents house, install ca. 1986 - none

Sisters house, install ca. 2004 - none (that, I suspect, is not standard but it was built by absolute cowboys)

GreeBo · 07-01-2022 5:47pm

https://www.boards.ie/discussion/comment/118434582#Comment_118434582

There is always an internal stat on teh immersion itself, they are adjustable, just not user friendly as you need to take the head off the element to expose the component, otherwise they would burn themselves out and boil the water --> kaboom.

CoBo55 · 07-01-2022 5:49pm

Mine has been off at the cu since 2000.

L1011 · 07-01-2022 5:51pm

https://www.boards.ie/discussion/comment/118434628#Comment_118434628

The only one of those I had the cap off was the 2004 one, and it didn't have any adjustment.

Even when there is one there, its not really something to guide a random punter to!

07-01-2022 7:04pm

I would think it unlikely that an immersion wouldn’t have one. It is under the metal cap at the top of the immersion where the cable connects. Generally a screwdriver is required to adjust.

John.G · 07-01-2022 9:56pm

Santon Immersion Nov 1972.jpg

I have a 1972 (Santon) 3 wire dual immersion, with the c/o switch "conveniently" mounted in the immersion cover, it hasn't the conventional "rod" type thermostat, but I think the stat is surface mounted on the immersion boss, it certainly has worked to perfection for the past 50 years and cuts out at 60/62C, I think the stat is a otterstat?.

08-01-2022 6:26pm

Even the oldest immersion heaters had a stat of some sort. It may not have been user adjustable or user-accessible, but it's there. Otherwise, your immersion cylinder would just heat until it boiled and keep on going.

As for leaving the immersion switched off the MCB. There's absolutely no reason why not. What I would not suggest doing though is using an MCB as a control switch.

They are protection devices, and not intended to be switched on and off regularly like a light switch or something similar. You would likely reduce their life span quite considerably.

You could have the controls moved out of reach, or you could have a second control switch installed, perhaps high up on the wall somewhere.

John.G · 09-01-2022 9:43am

Also, remember, leaving the immersion on all the time, doesn't mean that its using 2 or 3kwh continuously as long as hot water usage is normal, you will lose heat through the cylinder but most now are very well insulated so might lose 1.5/2 kwh (units) per day, not to be sneezed at, but someone switching the immersion on/off now and then will use the sq.root of nothing.

09-01-2022 7:51pm

The issue with the old ones is that they were so poorly insulated you might as well be just plugging in a 3kW oil radiator and leaving it on all day. The heat would just escape to the air, which is why hot presses were so toasty warm and good at airing clothes.

Modern, totally enclosed water cylinders are usually nearly like thermos flasks. You lose very little heat over the day. They're obviously not perfect, but the heat losses can be so low as to be negligible, especially if the pipework is properly lagged.

Deanicus · 10-01-2022 1:50pm

Thanks everyone

Can only see 1 stat on the exterior of the cylinder so assume the immersion stat is built in to the coil like the examples. Not something I want to mess around with to be honest

I realise the cost of the immersion is buttons really but I just see it as unnecessary expense. We often don't know how long it has been on and since we have the hw on a timer which suits us fine, it's just waste. I'm leaving it off in the consumer unit for a couple of months and hopefully by then my little fella would have lost interest in it. The light does work btw, it's turning on that light that has piqued his interest!

MuttonDagger · 11-01-2022 8:56am

https://www.boards.ie/discussion/comment/118434557#Comment_118434557

🙄 posting nonsense for the sake of it

Leave immersion turned off in fuse box?

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