Wiring an old immersion - can anything go wrong?

surreygirl

My house was built in 2004 and had a system boiler installed with a hot water tank. Recently the gas boiler stopped working, so I turned on the immersion heater switch as a back up - but the water remained cold. The gas engineer said that although the illuminated immersion switch was on, it was not actually wired into the hot water tank - hence no hot water. It now seems that I'll need a new boiler installed. The wiring panel for the immersion is in the bottom 1/4 of the tank. 

Is there any risk from getting this wired in? Is 19 years old heating element likely to have issues? I supposedly live in a moderately hard water area yet when we use water from the tap to make tea we never get a scummy layer on it, and soap foams easily. Any thoughts?

Miser1964

The worst that can happen is a fuse will blow

Gerry1

Sounds odd that it was never wired up; perhaps the gas technician was mistaken?

It could be something as simple as the reset button on the immerson heater needing to be pressed (or even just its thermostat being turned up).

It's a very simple job if you're confident that you can switch everything off at the consumer unit and have basic knowledge of electrical safety precautions, otherwise it's a quick job for an electrician to check.

mmmmikey

As @Gerry1 says it's a simple enough job but unless you're very confident in your own ability I'd suggest trusting the job to an electrician. If you don't know the history of how it was installed in then it's possible that it was a DIY job without the correct fusing or cabling, which can create a fire hazard. Also, it may have been disconnected because of an earth leakage or other fault which is not uncommon. So unless you're skilled enough to check this yourself it really is best to get an electrician in to check things properly. I don't want to go overboard on this and in reality the fire and/or shock risks are probably quite low, but IMHO this is a case of better safe than sorry.

Gerry1

mmmmikey said:

As @Gerry1 says it's a simple enough job but unless you're very confident in your own ability I'd suggest trusting the job to an electrician.

Agreed, electricity is a good friend but a bad foe.

Gerry1

Miser1964 said:

The worst that can happen is a fuse will blow

No, if it's bodged you could be electrocuted or cremated if the property burns down.  ⚰️

QrizB

surreygirl said:

Is there any risk from getting this wired in? Is 19 years old heating element likely to have issues? I supposedly live in a moderately hard water area yet when we use water from the tap to make tea we never get a scummy layer on it, and soap foams easily. Any thoughts?

My house was built in the 50s but refurb'd in the early 2000s, so the electrical etc. installations are a similar age to yours. My hot water tank had an immersion heater but it wasn't wired in (there was no cable connecting it to the wall point.)

I wired it up a couple of years ago and it worked fine. It seems the builders who did the refurb didn't bother to connect it, since we had (and still gave ) gas CH. (I connected it to give redundancy, and also to take advantage of surplus electricity from my solar PV.)

surreygirl

Gerry1 said:

Miser1964 said:

The worst that can happen is a fuse will blow

No, if it's bodged you could be electrocuted or cremated if the property burns down.  ⚰️

very keen to avoid that scenario! LOL

Qyburn

surreygirl said:

The gas engineer said that although the illuminated immersion switch was on, it was not actually wired into the hot water tank - hence no hot water. It now seems that I'll need a new boiler installed. The wiring panel for the immersion is in the bottom 1/4 of the tank. 

Is there any risk from getting this wired in?

Can you post a couple of pictures? The immersion heater where the cable should go, and the switch. If you go ahead, remember to use heat resistant flex, should be available by the meter from EBay, you will need 3 core 1.5sq.mm.

EssexHebridean

Another thing to ensure gets checked when the immersion is wired in is that there is a working thermostat - as that is what will act to stop the immersion just continuing to try to heat water past the desired temperature. When you first use it to heat water, do so at times while you are awake, and ensure that the heater does work properly and cut out at the point where it gets to the stage of heating the water to the correct temperature. 

Grizzlebeard

Question: Was it never wired up or was it once wired but then disconnected?

The most common failure in immersion heaters is for it to corrode so the live element leaks current to.the water. This trips the RCD everytime it's switched on at the fusebox.

Someone may have disconnected the element at some time as a cheap "fix" to stop it tripping the whole house.

But if the element has never been turned on it's likely to be in good shape. Nearly all corrosion and limescale build up happens when it's powered on and making heat.