Help, leaking Hot Water Tank

[Colin]

Hi,

Immersion heater RCD tripped yesterday. Inspecting the heater today I discovered that the hot water tank is leaking from around where the thermostat enters the tank on the immersion heater plate.. Slow leak, but enough to earth-trip the electrics.

The thermostat is tightish in it's hole but it is possible to twist it. Is this correct?

Is there supposed to be a seal to stop the water leaking out?

Anybody else experienced this problem? Any remedy suggestions? Pretty-please...

TIA, Colin

[Grunff]

The thermostat sits in a copper tube. It should be easy to twist/pull out. The tube should not contain water. If it does, the it has failed.

The tube is part of the immersion heater assembly. You should be able to remove this once you've drained down the tank. Sometimes they are difficult to remove.

[Christian McArdle]

No, it is a fully enclosed tube. Clearly it has corroded all the way through.

Sounds like you need a new immersion. It isn't always possible to remove them without destroying the cylinder.

The best approach to loosening them is:

1. Loads of pentrating oil round the thread. Leave for a few hours. Apply more.
2. Attach hose to drain c*ck.
3. Tie up ballcock in loft tank.
4. Drain down cylinder until the cold tank and pipework is empty, but leave the cylinder mostly full.
5. Apply longest immersion spanner you can find.
6. Hit spanner handle with hammer. The shocks will be less damaging to the cylinder than attempting to apply steady torque, whilst encouraging the heater to spin.

7a. Say "Oh Shit!" and drain down tank as quickly as possible through hose whilst using old towels to save plasterboard ceiling below. Fit new cylinder. 7b. Once loose, hand tighten again, drain cylinder, breathe sigh of relief and replace immersion.

Only one of 7a or 7b applies.

Christian.

[Colin]

Thanks Grunff and Christian,

Sounds like a job to start in the morning. I'll stick the pentrating fluid on tonight to get it started.

Regards, Colin

[Ed Sirett]

If a modest pressure does not get results, try a full drain down and apply heat to the cylinder near the immersion heater (older non-foam insulated tanks only), or to the dead immersion heater plate.

Whilst still empty apply modest pressure. If necessary fill with water (this is where shutting off the feed using a valve on the cylinder feed might have been the better idea), this will take a very short while if the cold tank is not drained. Redo 6. The purpose of the heat is to soften any rock hard boss white used to seal the 2" BSP immersion heater hole.

Sounds like you have one with the immersion at the bottom of the cylinder.

[Dave Liquorice]

Rumour has it that box type immersion spanners are better than the ring type. I have never had to perform this operation so have no 1st hand experince though.

[Grunff]

Gotta say I've not had good results with either type. My first immersion heater led me to purchase 2' long pump pliers, which I've used on all subsequent immersion heaters (and lots of other things). Highly recommended.