Condensation on underside of Ariston Contract STI 150 Indirect Protect

[BrianCox]

Hi guys - I have recently noticed that when the hot water is switched on I'm getting a little moisture on the underside of my Ariston Contract STI 150 Indirect Protect (one or two drips on the carpet under the unit after the hot water has been on for 20-25mins). When the hot water is not switched on there is no presence of moisture, which makes me believe that maybe this is condensation which has been formed during the heating process? I haven't noticed this before (mind you I haven't been looking) and we've lived in this house for years. After the hot water has been switched off the drops just get evaporated away from the carpet after about 20 minutes. Is this normal?

 

[Chuck]

It's an unvented (i.e. sealed) system so it should be impossible for water vapour to escape and cause condensation in the manner you seem to be envisaging. Lots of possible explanations but the root cause is most likely a small leak somewhere that needs tracking down.

Your photo appears, for example, to show a water stain leading down from the 'anti-corrosion' cover. How long has that been there?

Don't attempt to DIY this one. You need a plumber with a 'G3 / unvented' qualification and/or the cylinder manufacturer's approved engineers. Check the warranty for the cylinder, you may be lucky.

 

[BrianCox]

It's an unvented (i.e. sealed) system so it should be impossible for water vapour to escape and cause condensation in the manner you seem to be envisaging. Lots of possible explanations but the root cause is most likely a small leak somewhere that needs tracking down.

Your photo appears, for example, to show a water stain leading down from the 'anti-corrosion' cover. How long has that been there?

Don't attempt to DIY this one. You need a plumber with a 'G3 / unvented' qualification and/or the cylinder manufacturer's approved engineers. Check the warranty for the cylinder, you may be lucky.

Thanks for your reply. I've checked all the nuts and connections and there doesn't seem to be an obvious leak. Could the leak be coming from the bottom of the unit itself, or is the unit so sealed that this would be impossible?

 

[ShaunCorbs]

Have you checked behind the pro check cover ?

 

[BrianCox]

Have you checked behind the pro check cover ?

I have identified the source of the leak. It's not coming from the pro check cover. To the left of the pro check cover and down a bit is a pipe going into the unit - the same pipe which has the cable to the pro check hanging over it (see photo). The leak is coming from underneath the white plastic pipe collar. Any suggestions as to what may have happened/possible solutions?

 

[ShaunCorbs]

If it’s not coming from the nut of that pipe then sorry new cylinder as it’s a weld that’s gone or corrosion

 

[BrianCox]

If it’s not coming from the nut of that pipe then sorry new cylinder as it’s a weld that’s gone or corrosion

Are we looking at about £500 for a new cylinder and £200 fitting - £700-£750 job?

 

[ShaunCorbs]

Around 1k for a new cylinder and 500 ish to fit it approx