TRV attached to storage cylinder?

[johnscales]

Hi all.
I'm going to drain down my system today to secure a new rad to the wall which I put up, thanks to the help of the form, on my own last week.
I was also thinking that with the system drained I would set about changing a couple of TRV's that haven't worked for some time and which no longer work with the gentle persuation technique (hammer, tapping and pin pulling )
My question is for another TRV which comes off of a pipe that exits the storage cylinder about half way up the cylinder. There is a thin silver wire coming from the TRV to a small silver block attached to the storage cylinder about a quarter of the way up from it's bottom. Also, above the TRV is what looks like a valve that I can close or open.
I know what this thermostat is for but i'm wondering if it is a simple matter of twisting shut the valve above and swapping the TRV out. If so, then what's with this silver wire? I just checked it again and to confirm, it's attached to a silver block a quarter of the way up the cylinder. The wire spirals up from there and disappears into the body of the TRV.

 

[Nige F]

It` a hollow "wire" with fluid in ( capillary tube) like a remote sensor ...No it IS a remote sensor

 

[johnscales]

Thanks Nige. How does that affect my wish to remove the TRV. Is it manually connected to the TRV if so how? or is there a type of TRV that comes with this wire as i've not seen it anywhere.

 

[JohnD]

it is not a TRV, it is a control to prevent more heat going to the cylinder once it is up to temp. Usually fitted where the cylinder is on Gravity Flow. Do you have some reason to suppose yours is faulty?

yours sounds like a Drayton Tapstat.

they are very expensive

It is vital that you do not cut or damage the thin silver tube or pull it out

If yours is faulty I have a New Old Stock one available.

 

[hobhead]

Commonly called a tapstat, controls the temperature of your stored hot water. Nothing to do with your radf circuit of course...

 

[hobhead]

Slow fingers..

 

[dextrous]

Slow fingers..

and yet a fast wrist

 

[johnscales]

Ok I feel like a doh! now. I was sure my mother used to use it to regulate the temp across the house. I turned it to it's coldest position last night obviously thinking that if the rads didn't get colder it would confirm that the TRV was faulty. Now that I have been educated what effect should I see? I ask because it's still at that setting and hasn't affected the hot water either.

Thanks again guys.

 

[JohnD]

test the hot water at the taps with a thermometer. You will have to use a bathfull of water out of the cylinder before it gets fully cold, only then will you see the effect of turning the tapstat down.

has the hot water ever seemed dangerously hot? if you have a gravity flow to the cylinder and the tapstat is jammed open, it will get hotter and hotter until it reaches the boiler temperature. This is wasteful of energy, and can be scalding, especially to small children and the elderly or infirm.

 

[johnscales]

Thanks JohnD. I don't want to waste all that hot water in one go so I'll do this. Leave the tapstat at the cold setting and by sometime this evening (I guess) my hot water supply should start to get colder.
I'll post back how it goes as I may end up asking about your "New Old Stock " one.

Cheers

 

[johnscales]

Checked the boiler tank earlier. The bottom was cold, top luke warm. Turned the tapstat back up and now the whole tank is very hot.
All ok.
Thanks for your help guys I know I can leave that one alone.