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26-11-2020, 15:23   #1
cargo
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T90SR thermostat (not TCO)

I have a T90sr that is tripping out the RCB after a few seconds of running. It started intermittently but got to the point of every time.

Changed the isolation switch in the bathroom for a start but the issue is still there so went under the cover. Found a badly corroded terminal on the temp sensor at the bottom of the heating tank and it had broken away from the sensor. One side of the sensor goes straight back to incoming Neutral and the other side is connected to one of the element connections at the top of the tank.

I can't find any parts listing that shows this sensor. All I get is the TCO but that's at the top of the tank. Anyone know what this is at the bottom?

I'm assuming the detached leg was causing my trips. I cant get anything soldered back onto it as there's f**k all to solder to. I even tried getting a very light wire onto it so i could attach to it to test but no good.

MM shows continuity across it (when i can get onto a bit of metal) and measuring around 1 ohm.

The part is a 36txe11 Thermostat so I assume giving some feedback to the temperature control or something. The shower ran again for a while with this wire disconnected completely and the sensor back in the outlet pipe but did trip out after about 2mins.
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File Type: jpg Clipboard04.jpg (1.86 MB, 19 views)

Last edited by cargo; 26-11-2020 at 15:50. Reason: Add thermostat model info
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26-11-2020, 16:06   #2
John.G
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I think its a TCO alright that just trips one element of the heating can and might be set at ~48C and self resets, the main TCO on the top trips at around 56C and does not reset but must be replaced. Its not a triton SR90 but might be a Triton T90SI.
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26-11-2020, 16:26   #3
Sleeper12
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Quote:
Originally Posted by cargo
I can't find any parts listing that shows this sensor. All I get is the TCO but that's at the top of the tank. Anyone know what this is at the bottom?

As John said definitely not a Triton t90sr. It's a Triton T90si & judging by the type of heating can I'd date it 17 to 20 years old. Looks like the heating can leaks. Triton stopped making the bottom TCO close 10 years ago.

Shower is dying of old age. I suggest replacing it with a Triton t90sr
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26-11-2020, 18:13   #4
cargo
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Quote:
Originally Posted by John.G View Post
I think its a TCO alright that just trips one element of the heating can and might be set at ~48C and self resets, the main TCO on the top trips at around 56C and does not reset but must be replaced. Its not a triton SR90 but might be a Triton T90SI.
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Originally Posted by Sleeper12 View Post
As John said definitely not a Triton t90sr. It's a Triton T90si & judging by the type of heating can I'd date it 17 to 20 years old. Looks like the heating can leaks. Triton stopped making the bottom TCO close 10 years ago.

Shower is dying of old age. I suggest replacing it with a Triton t90sr

Yep /facepalm it's a T90si... the one downstairs is the SR (non-priority unit installed)

@John.G The ~48C sounds about right as it's a L50-8 or something like that so operates around 50deg..

@Sleeper12 only moved in to look after some a few months ago so not sure when it went in but I'd say you are right on the age.

Yeah it wont owe anybody here anything and have asked plumber to sort out one when he's not flat out sorting boilers :-D but was just hoping there was a way to give it a bit of life until he gets a chance to come to me.

Thanks for the replies.
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26-11-2020, 23:34   #5
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I often wonder about the practical safety feature of those showers as (if its wired the way I think it is) then it would still operate on one element if the 48C TCO failed but now with the main TCO operating at 56C as protection from scalding so IMO not advisable.
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18-12-2020, 14:09   #6
John.G
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Yep /facepalm it's a T90si... the one downstairs is the SR (non-priority unit installed)

@John.G The ~48C sounds about right as it's a L50-8 or something like that so operates around 50deg..

@Sleeper12 only moved in to look after some a few months ago so not sure when it went in but I'd say you are right on the age.

Yeah it wont owe anybody here anything and have asked plumber to sort out one when he's not flat out sorting boilers :-D but was just hoping there was a way to give it a bit of life until he gets a chance to come to me.

Thanks for the replies.
I have that temperature regulator (and checked that it open circuits at 48/50C)
so if you are competent to install it the you can have it, the attachments look slightly different to yours so have a look.
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