Immersion heater thermostat

SeanMacEoin

Hi All, Just visiting my parents house over the weekend and noticed the hot water is way too hot. My parents heat water using an immersion heater so I automatically thought I could turn down thermostat. On opening the top of the immersion I can't see an obvious thermostat, it's a Stanford dual star K71 .... best part of 20 years old fitted to top of standard copper cylinder. Is it likely this immersion predates ones which have thermostat fitted or am I missing something.
Thanks for your advice
Sean

MOD NOTE. I am moving this thread to Electrical.

Wearb

Has this recently changed? Or has it been like this for 20 years?


This is one with a thermostat.

You could always fit a pipe/cylinder stat to control it.

NOTE: The wiring on the image above is incorrect.

seamus

Sorry OP, piggybacking on your thread to see the answers. My immersion is the same; probably the same element in the tank for at least 20 year if not 30. When I moved in, the water was scalding so I adjusted the thermostat on the "sink" element and it's bearable now. But the "bath" one is still scalding, and I've been wondering if I should just adjust it or if it's an indication of the heater element being on the way out.

Wearb

seamus wrote: »

Sorry OP, piggybacking on your thread to see the answers. My immersion is the same; probably the same element in the tank for at least 20 year if not 30. When I moved in, the water was scalding so I adjusted the thermostat on the "sink" element and it's bearable now. But the "bath" one is still scalding, and I've been wondering if I should just adjust it or if it's an indication of the heater element being on the way out.

Usually one thermostat controls both elements, unless wired incorrectly.

SeanMacEoin

Wearb wrote: »

Has this recently changed? Or has it been like this for 20 years?


This is one with a thermostat.

You could always fit a pipe/cylinder stat to control it.

NOTE: The wiring on the image above is incorrect.

I don't believe much has changed apart from in the past they used oil heating to heat water rather than immersion. From the image you posted I can clearly see the thermostat. Please see photo of my parents immersion.
Thanks

Wearb

SeanMacEoin wrote: »

I don't believe much has changed apart from in the past they used oil heating to heat water rather than immersion. From the image you posted I can clearly see the thermostat. Please see photo of my parents immersion.
Thanks

That’s a new one on me.
I might move this post to electrical later if you haven’t gotten answers here.

SeanMacEoin

Wearb wrote: »

That’s a new one on me.
I might move this post to electrical later if you haven’t gotten answers here.

Anyone else willing to comment??
Thanks

Wearb

SeanMacEoin wrote: »

Anyone else willing to comment??
Thanks

I will move it tomorrow or later tonight if no answer here.

The Red Ace

If the water in the cylinder is also heated by a range or back boiler that stat wont have any control over the heat of the water

SeanMacEoin

The Red Ace wrote: »

If the water in the cylinder is also heated by a range or back boiler that stat wont have any control over the heat of the water

From what I know the water is heated all throughout summer / autumn months by immersion only. Seems a waste to overheat the water everyday plus it's dangerously hot. On this basis I'd prefer if the immersion was controlled by thermostat. Granted other heat sources will come into effect other times of the year but all these have pipestats fitted.

meercat

Think you will struggle to find a suitable thermostat
Best bet is to replace the immersion with a dual immersion (sink/bath) and new switch(wiring on existing setup looks like they used earth as a neutral)
Might be tricky getting existing one out after 20 years so I would advise getting a plumber to do so for you

brightspark

SeanMacEoin wrote: »

Hi All, Just visiting my parents house over the weekend and noticed the hot water is way too hot. My parents heat water using an immersion heater so I automatically thought I could turn down thermostat. On opening the top of the immersion I can't see an obvious thermostat, it's a Stanford dual star K71 .... best part of 20 years old fitted to top of standard copper cylinder. Is it likely this immersion predates ones which have thermostat fitted or am I missing something.
Thanks for your advice
Sean

MOD NOTE. I am moving this thread to Electrical.

Read it again, what you were looking at is the stat "Dualstat" However it may have been wired incorrectly or else has failed on.

Testing with a multimeter would quickly decide if it had failed or just wired wrong.
Doesn't appear to be any information online about the stat, but Otter are still trading so perhaps you could email them.

http://www.ottercontrols.co.uk/index.html

As others have suggested the easiest option may be to consider replacing the immersion completely.

Wearb

brightspark wrote: »

Read it again, what you were looking at is the stat "Dualstat" However it may have been wired incorrectly or else has failed on.

Testing with a multimeter would quickly decide if it had failed or just wired wrong.
Doesn't appear to be any information online about the stat, but Otter are still trading so perhaps you could email them.

http://www.ottercontrols.co.uk/index.html

As others have suggested the easiest option may be to consider replacing the immersion completely.

What do you think about putting a cylindar/pipe stat on it?
Might save destroying the cylinder trying to remove it.

SeanMacEoin

Wearb wrote: »

What do you think about putting a cylindar/pipe stat on it?
Might save destroying the cylinder trying to remove it.

I think I'll check out the stat with a multimeter, failing this a pipestat seems the most sensible option. As you suggest there is a high risk of damage to the cylinder trying to remove the existing immersion. Thanks

brightspark

Wearb wrote: »

What do you think about putting a cylindar/pipe stat on it?
Might save destroying the cylinder trying to remove it.

Most pipe stats are not rated for the currents involved. (I'd worry about what happens if the stat falls of the pipe too)

OP how hot is the water getting? Remember it does have to be hot enough to prevent legionaries etc.

Perhaps the stat is removable and can be replaced?

2011

As above pipe stats would not normally be rated to switch loads as large as an immersion (generally 2 or 3 kW). If it was mine I would install a dual immersion. Not only will this have a suitable stat but it offers the choice between heating a small amount of water and a larger amount. Be aware heating water electrically is the most expensive way to heat water!

On another note, plenty of people still use oil field boilers to heat water!

Wearb

2011 wrote: »

As above pipe stats would not normally be rated to switch loads as large as an immersion (generally 2 or 3 kW). If it was mine I would install a dual immersion. Not only will this have a suitable stat but it offers the choice between heating a small amount of water and a larger amount. Be aware heating water electrically is the most expensive way to heat water!

On another note, plenty of people still use oil field boilers to heat water!

Myself included. It works out even cheaper this time of year as there aren't the same standby losses that you get in the summer when the cylinder is the only requirement for heating.

On the pipe stat; I see lots of them rated 16A inductive which I think would fall within the required parameters.

2011

Wearb wrote: »

On the pipe stat; I see lots of them rated 16A inductive which I think would fall within the required parameters.

A 3kW immersion is not an inductive load, it is resistive. It will draw a current of around 13A.

If a suitably rated pipe stat was to be used the phase for the immersion would have to be broken through the stat before connecting to the immersion element. This would be possible but as pipe stats generally only have one cable entry this would probably mean that a junction box would be required. The stat would have to be mounted on the tank, which often requires removing insulation from the hot water tank. All of this is possible, but more hassle than it is worth in my opinion.

All of the "modern" immersion elements I have seen (over the last 25 years or so) have internal stats. Nice and simple

Wearb

2011 wrote: »

A 3kW immersion is not an inductive load, it is resistive. It will draw a current of around 13A.

If a suitably rated pipe stat was to be used the phase for the immersion would have to be broken through the stat before connecting to the immersion element. This would be possible but as pipe stats generally only have one cable entry this would probably mean that a junction box would be required. The stat would have to be mounted on the tank, which often requires removing insulation from the hot water tank. All of this is possible, but more hassle than it is worth in my opinion.

All of the "modern" immersion elements I have seen (over the last 25 years or so) have internal stats. Nice and simple

Slip of the “tongue” on inductive.

Thanks for for your thoughts on the stat. Was just considering if it would be a possible solution for op in the event of not being able to remove or repair.
Thanks

Bruthal

Wearb wrote: »

Slip of the “tongue” on inductive.

Thanks for for your thoughts on the stat. Was just considering if it would be a possible solution for op in the event of not being able to remove or repair.
Thanks

It is possible to do it that way, which I did before using a cylinder stat and contactor setup for a particular application, to allow easy altering of temperature.

Not really worth it for a standard domestic immersion setup though.

gctest50

You could run the pipe(tank) stat to a contactor

Use a momentary push-button to trigger it all and it will all switch itself off automatically

Mammies everywhere will be delighted

2011

gctest50 wrote: »

You could run the pipe(tank) stat to a contactor

Use a momentary push-button to trigger it all and it will all switch itself off automatically

Mammies everywhere will be delighted

I went for a simpler and better solution. Because I pay the electricity bill I disconnected the immersion. They can leave it on for as long as they like and I won't complain

To get additional hot water in my house they have to use the ½ hour boost button I have installed on the gas boiler, it is so much cheaper.

Bruthal

gctest50 wrote: »

You could run the pipe(tank) stat to a contactor

Use a momentary push-button to trigger it all and it will all switch itself off automatically

Mammies everywhere will be delighted

Yea, wire the stat in like a stop button, momentary as a start, contactor with H/O contact etc. It can be done with the immersions own stat also.

gctest50

2011

Here is a simple solution:

gctest50

That doesn't allow for colder ( incoming ) water in the winter though

2011

gctest50 wrote: »

That doesn't allow for colder ( incoming ) water in the winter though

What do you mean ??

Bruthal

2011 wrote: »

What do you mean ??

It means if you setup the momentary switch and contactor setup, the final temperature will always be the same regardless of the starting one.

SeanMacEoin

brightspark wrote: »

Most pipe stats are not rated for the currents involved. (I'd worry about what happens if the stat falls of the pipe too)

OP how hot is the water getting? Remember it does have to be hot enough to prevent legionaries etc.

Perhaps the stat is removable and can be replaced?

At a guess the water is >60, the hot tap fosset when I used it at the weekend instantly alarmed me for my kids sake.

gctest50

SeanMacEoin wrote: »

At a guess the water is >60, the hot tap fosset when I used it at the weekend instantly alarmed me for my kids sake.

You need a TMV ( anti scald valve )

have the water in the tank hot to kill disease, and nice regulated water temp at the taps


http://bit.ly/2jd28I6

http://www.hevac.ie/p/tmv3s/hdomwaterservtmv

2011

gctest50 wrote: »

You need a TMV ( anti scald valve )

have the water in the tank hot to kill disease, and nice regulated water temp at the taps

It would be much easier and more cost effective to install an immersion with a stat.

SeanMacEoin

2011 wrote: »

It would be much easier and more cost effective to install an immersion with a stat.

Truly appreciate the advice I've received over the past few days on this topic. Some great ideas to mull over. I think replacing the immersion with a new one is my preference but knowing the difficulty removing the old one may bring I will get a professional in. Thanks to all for input.
Sean.

Sleeper12

SeanMacEoin wrote:

Truly appreciate the advice I've received over the past few days on this topic. Some great ideas to mull over. I think replacing the immersion with a new one is my preference but knowing the difficulty removing the old one may bring I will get a professional in. Thanks to all for input. Sean.

Just be aware, an old cylinder with old immersion. Taking the immersion out may destroy the cylinder even with a professional. There is a chance you might end up having to replace the cylinder too.

gctest50

2011 wrote: »

It would be much easier and more cost effective to install an immersion with a stat.

You need a TMV anyway - what if the stat in the new immersion sticks ?


Cost effective ? Cost effective ?


Cost effective this :

Little girl who fell head-first into scalding bath water after having 321 operations

( Photo of burns etc in link )

http://www.dailymail.co.uk/health/article-2266381/Miracle-recovery-little-girl-scalded-bath-water--321st-operation.html

.

2011

gctest50 wrote: »

You need a TMV anyway - what if the stat in the new immersion sticks ?

Yes, it could stick but not likely.
If genuinely concerned about this it would be easier to install 2 in series.

Cost effective ?

Yes, heating water that is too hot to use is wasteful.
Installing an immersion with a stat is cheap and will prevent costly overheating of water.

No harm in installing a TMV too for extra safety, but the stat will pay for itself quite quickly.

gctest50

Hot water temperatures that do not cause scalding are ideal for the legionella bacteria to grow in a water system, but hot water temperatures that kill the legionella bacteria will cause scalding.

2011

gctest50 wrote: »

Hot water temperatures that do not cause scalding are ideal for the legionella bacteria to grow in a water system, but hot water temperatures that kill the legionella bacteria will cause scalding.

Unnecessary.
Deliberately heating water in the hot water cylinder to temperatures that can scald is not normal practice in Ireland as far as i know.

The Red Ace

you can buy a replacement stat like yours on ebay for less than 15 quid

SeanMacEoin

The Red Ace wrote: »

you can buy a replacement stat like yours on ebay for less than 15 quid

Hi Red Ace - I can't find an otter replacement stat on eBay but can find the more modern Backer stat. Is this what you found also?
I wonder Is it possible to fit backer stat to existing Otter fitting. Probably not?

The Red Ace

Ideally get the existing stat removed and measure its length and diameter and then email the supplier to see if the replacement measures up

Tommy Ferguson

Wearb wrote: »

Has this recently changed? Or has it been like this for 20 years?


This is one with a thermostat.

You could always fit a pipe/cylinder stat to control it.

NOTE: The wiring on the image above is incorrect.

Why have you posted this image?