Odd immersion heater problem

[bainbridge]

Our immersion heater main heater has stopped heating. I changed both thermostats 3 months ago.

Is there an easy way to test the elements before replacing?

Thanks

 

[pp111]

Disconnect the mains supply and just pop resistance meter over it. They are low resistance, or should be, so it's very obvious if they have failed. Be advised that they often can't be removed without damaging the tank ( tanks are thin and over time those large fittings seize up. ). You should budget in time and money for a total replacement as the worst case.... just in case the worst happens!

 

[Semple]

When we were renting a flat it had quite an old immersion heater. The elements used to burn out all the time, the plumber did test the element before replacing them out. I think we went through about 3 in 4 months. The LL was getting pretty ****** off, so don't know if the plumbers were just reusing components they'd pulled from elsewhere.

 

[bainbridge]

Disconnect the mains supply and just pop resistance meter over it. They are low resistance, or should be, so it's very obvious if they have failed. Be advised that they often can't be removed without damaging the tank ( tanks are thin and over time those large fittings seize up. ). You should budget in time and money for a total replacement as the worst case.... just in case the worst happens!

Thanks. I had another quick look this morning and it turns out that the top "booster" element which we normally leave off is working, so it's logical that the lower one which we leave switched on would have failed first.

Shame about the thin tank walls, I thought it was simply a bolt off/bolt on job after draining the tank with one of those massive spanners.

I'll test for resistance first and go from there.

 

[bainbridge]

When we were renting a flat it had quite an old immersion heater. The elements used to burn out all the time, the plumber did test the element before replacing them out. I think we went through about 3 in 4 months. The LL was getting pretty ****** off, so don't know if the plumbers were just reusing components they'd pulled from elsewhere.

We had a similar experience in a flat we rented. In this house, which we've purchased, our solicitor raised the fact that there wasn't a current electrical certificate but we agreed to complete anyway because we'd been waiting so long during lockdown.

 

[LuckyBenski]

If you're keen to calculate it, resistance can be worked out using the rule power = voltage squared divided by resistance.

P = V²/R

So assuming your mains is 240V, expect your element to measure 57600 divided by the heater's wattage.

 

[pp111]

Thanks. I had another quick look this morning and it turns out that the top "booster" element which we normally leave off is working, so it's logical that the lower one which we leave switched on would have failed first.

Shame about the thin tank walls, I thought it was simply a bolt off/bolt on job after draining the tank with one of those massive spanners.

I'll test for resistance first and go from there.

The general theory is to put the large spanner on and give it a short sharp whack with a hammer. If it doesn't go then be prepared to replace the entire tank before you hit it again, because if it is very tight it may well damage the tank.

 

[bainbridge]

The general theory is to put the large spanner on and give it a short sharp whack with a hammer. If it doesn't go then be prepared to replace the entire tank before you hit it again, because if it is very tight it may well damage the tank.

A plumber on YouTube recommended spannering the element to move slightly while the tank was still full, because this stabilised the walls of the tank. Sounds feasible.

 

[pp111]

A plumber on YouTube recommended spannering the element to move slightly while the tank was still full, because this stabilised the walls of the tank. Sounds feasible.

I agree with that. The tanks ( unless full of lime ) are really light. You don't want to hit it empty or you are in real danger of it moving and a pipe joint leaking. What I usually do is hit it few times, get it ready to drain and then try a last "put some serious torque in to it" and if that fails, drain it and replace it all. I might add that the tanks do rot anyway. Usually the seams give way first. Even one as young as 20 years can be leaking in to the insulation ( which will go undetected ).
Incoloy or titanium elements last a lot longer.

 

[pp111]

Oops

 

[bainbridge]

Turns out it was the thermostat that failed. I tested continuity on the element and it was fine, the thermostat was clicking when I moved the temperature dial but had no continuity. Must've been a bad one, I'll get it replaced at screwfix.