Immersion thermostat keeps needing reset

VidaLoca

Hi,

My immersion boiler thermostat keeps needing the reset button pressed.

I got a new boiler, it has 3-terminals

B & S & T

One end of the thermostat is connected the T terminal and the other to the neutral connection of the wall switch, the NOUT connection.

The B terminal is connected to the L1 of the wall switch
The S terminal is connected to the L2 of the wall switch

The common L is connected to the LOUT of the wall switch.

I suppose my main question is if I have the thermostat connected correctly by connecting it to NEUTRAL ?

Thanks.

brightspark

Is the immersion heated by another source (oil or gas central heating?)

Is the immersion heater cap being covered with clothing etc?

VidaLoca

brightspark wrote: »

Is the immersion heated by another source (oil or gas central heating?)

Is the immersion heater cap being covered with clothing etc?

At the moment its only being heated by the electric. Nothing in the press at all.

brightspark

What reset button needs to be pressed?

VidaLoca

brightspark wrote: »

What reset button needs to be pressed?

The little one on the thermostat, it works great for about 4 hours and then needs to be reset to start again.

brightspark

How hot is the water?

What is the temperature control stat set to?

VidaLoca

brightspark wrote: »

How hot is the water?

What is the temperature control stat set to?

65'C

VidaLoca

brightspark wrote: »

How hot is the water?

What is the temperature control stat set to?

65'C

You think it all sounds correct with the Neutral connected to the thermostat ?

Could it be just faulty ?

2011

There are a few possibilities:
1) The high temperature cut out may be faulty
2) The stat may be faulty allowing the water to overheat (you could try turning it down)
3) the immersion heating element may be on the way out. I have seen this cause the water temperature to rise rapidly before the stat turns it off.

VidaLoca

2011 wrote: »

There are a few possibilities:
1) The high temperature cut out may be faulty
2) The stat may be faulty allowing the water to overheat (you could try turning it down)
3) the immersion heating element may be on the way out. I have seen this cause the water temperature to rise rapidly before the stat turns it off.

Nice one , Ill try lowering the temperature on it.

Its all new out of the box only 2 weeks.

2011

If the water never gets to what would appear to be too hot then #1 above is the most likley IMHO.

meercat

Any chance of a pic.
I'm a bit confused by your original post

VidaLoca

meercat wrote: »

Any chance of a pic.
I'm a bit confused by your original post

can't, I'm only new

VidaLoca

Hi,

A quick update.

I left the cap (the round metal) off the boiler over the weekend and the thermostat didn't need resetting once.

jsd1004

Dodgy thermostat. Get one without the reset button. Had the same problem.. replaced mine with a blue one without the reset button and all good.

brightspark

jsd1004 wrote: »

Dodgy thermostat. Get one without the reset button. Had the same problem.. replaced mine with a blue one without the reset button and all good.

Dangerous advice! :eek:

The cut-off stats are there for safety, so not "all good" :rolleyes:

Bruthal

There is also the slight possibility of being incorrectly connected at the switch, which can have the immersion stat bypassed. Unusual though, but possible.

VidaLoca

Bruthal wrote: »

There is also the slight possibility of being incorrectly connected at the switch, which can have the immersion stat bypassed. Unusual though, but possible.

How would that happen ?

It was all good the last few days but neded to be reset again today. Im thinking it my be a faulty one.

I might replace it and see how that goes.

Bruthal

VidaLoca wrote: »

How would that happen ?

It was all good the last few days but neded to be reset again today. Im thinking it my be a faulty one.

I might replace it and see how that goes.

Neutral mixed up with bath or sink wires which then leaves the immersion temperature control stat out of the circuit depending on selector switch position.

Very unlikely the cause here though. Probably the overheat stat cutting out too early.

VidaLoca

Bruthal wrote: »

Neutral mixed up with bath or sink wires which then leaves the immersion temperature control stat out of the circuit depending on selector switch position.

Very unlikely the cause here though. Probably the overheat stat cutting out too early.

I only have the single Neutral going into one side of the thermostat . The live for bath goes to the "B" post on the boiler and the other live for the sink goes to the "S" post on the boiler.

Bruthal

VidaLoca wrote: »

I only have the single Neutral going into one side of the thermostat . The live for bath goes to the "B" post on the boiler and the other live for the sink goes to the "S" post on the boiler.

Like I was saying, its unliky to be wrong. It's at the switch the mistake is possible. But very unliky.

The overheat cutout is likely operating too early.

Other causes are air trapped at top of immersion element, again very unlikely. Or a limescale covered element if its in a decent amount of time.

jsd1004

Bruthal wrote: »

Like I was saying, its unliky to be wrong. It's at the switch the mistake is possible. But very unliky.

The overheat cutout is likely operating too early.

Other causes are air trapped at top of immersion element, again very unlikely. Or a limescale covered element if its in a decent amount of time.

My house has still not burnt down. I still think the dodgy thermostat caused the problem! Water nice and warm..No resetting required

jsd1004

brightspark wrote: »

Dangerous advice! :eek:

The cut-off stats are there for safety, so not "all good" :rolleyes:

I certify european CE equipment so if you regard it as unsafe maybe you might explain to me why? I am a real engineer by the way!

2011

jsd1004 wrote: »

I certify european CE equipment so if you regard it as unsafe maybe you might explain to me why? I am a real engineer by the way!

The high temperature cut out stats are safety devices. If fitted with a reset then operation of the device has to be investigated (rather than automatically resetting) which mitigates the risk of the underlying problem developing into something more serious.

By the way this was CE marked by an engineer:

brightspark

jsd1004 wrote: »

I certify european CE equipment so if you regard it as unsafe maybe you might explain to me why? I am a real engineer by the way!

If you are a real engineer I shouldn't have to explain why modifying equipment and bypassing safety devices is unsafe.

And do you really think that it's ok for unqualified people to modify equipment?

jsd1004

brightspark wrote: »

If you are a real engineer I shouldn't have to explain why modifying equipment and bypassing safety devices is unsafe.

And do you really think that it's ok for unqualified people to modify equipment?

But I never advocated modifying or bypassing anything. The alternative thermostat has a built in high temp cut out it just does not have a reset option..

jsd1004

2011 wrote: »

The high temperature cut out stats are safety devices. If fitted with a reset then operation of the device has to be investigated (rather than automatically resetting) which mitigates the risk of the underlying problem developing into something more serious.

By the way this was CE marked by an engineer:

[/quote

Yes. But the problem is 90% caused by a dodgy thermostat that is activating the high temp cut out unnecessarily. The easy solution is to change the stat to one with an integrated high end cut out and see if it solves the problem. A cheap and easy option.

brightspark

jsd1004 wrote: »

But I never advocated modifying or bypassing anything. The alternative thermostat has a built in high temp cut out it just does not have a reset option..

What alternative did you suggest?

jsd1004 Dodgy thermostat. Get one without the reset button. Had the same problem.. replaced mine with a blue one without the reset button and all good.

You do know that not all blue ones have a high temp cut out?

E.g. The ones linked below

https://www.tlc-direct.co.uk/Main_Index/Wiring_Accessories_Menu_Index/Therostats_All/Immersion_Heaters_2/index.html

And a high temp cut off that doesn't need to be reset? How would that be safe?

meercat

Point 3 in link below.

I believe some fatalities may have been prevented if an overheat trip were in place.

As others have pointed out earlier
It's never a good idea to bypass a safety device.

http://www.hse.gov.uk/services/localgovernment/hotwatersystems.htm