Fixing electric immersion heater of hot water cylinder..

Jonboy_1984

ThisIsWeird said:

But what temps does it represent?

The markings are normally either (a nominal) 10 or 15 degrees per marking as the thermostats go 0-70ish or 0-80ish.

Based on the number of markings there, I would assume 10 personally and that it's set to around 70. 

sujsuj

Other thing I noticed is even if I switch ON electric heater for 30 minutes its not giving enough hot water to take a good shower! I haven't removed the immersion heater from the tank as it looks to be difficult task. It could be because the heater may be affected by hard water scaling..? Last time  may be repaired/ inspected   20 years ago when it installed. Is it worth attempting to inspect that and may be replacing it a longer more efficient heater?

Only worth if that makes significant difference in heating and if make shower toowork with electric heating..? But not sure if it worth trying that knowing the difficulty involved..? Thanks

Jonboy_1984

Possibly depends where you are. 

We lived in a very hard water area (water directly off chalk streams) and got through 2 replacements in 4 years. The first time it emerged the immersion element had rotted through and there were only two stubs left... 

On the second one I creased the tank (drain valve was mounted directly on the side unlike yours) and it contained around a quarter scale when the tank was emptied for replacement .

The tank was around 25 years old at that point. 

ThisIsWeird

sujsuj said:

Other thing I noticed is even if I switch ON electric heater for 30 minutes its not giving enough hot water to take a good shower! I haven't removed the immersion heater from the tank as it looks to be difficult task. It could be because the heater may be affected by hard water scaling..? Last time  may be repaired/ inspected   20 years ago when it installed. Is it worth attempting to inspect that and may be replacing it a longer more efficient heater?

Only worth if that makes significant difference in heating and if make shower toowork with electric heating..? But not sure if it worth trying that knowing the difficulty involved..? Thanks

This is a single-element immersion heater, so it either works or it doesn't. Yes, scale build-up could insulate it to some degree, but I can't see it being to an extent that really noticeable, but I don't know.

So, are you sure the thermostat isn't set too low, so a half-hour heating doesn't raise the temp very much because the 'stat keeps switching?

All your other tests - the audible 'sizzle' when it's on, the spark when the switch is turned off, etc, all suggest that the element is working fine.

When the immersion is on, at what position does the stat 'click'? Make sure it's turned up significantly above this point so it doesn't shut off again during the half-hour.

ThisIsWeird

Jonboy_1984 said:

ThisIsWeird said:

But what temps does it represent?

The markings are normally either (a nominal) 10 or 15 degrees per marking as the thermostats go 0-70ish or 0-80ish.

Based on the number of markings there, I would assume 10 personally and that it's set to around 70. 

Thanks. But if they are 10oC markings, you are suggesting it goes to 70oC maximum? That's not very high.

Why doesn't it have a labelled scale? It's one of these situations where you'd like to find the designer, and turn the 'stat into a rectal thermometer.

EDIT. I hadn't realised that the adjustment is likely to reduce the temp when turned clockwise. I now see that the '-' and '+' suggest this, but hey... :-(

It also looks as tho' SS has it set to 'max' temp, so if the 'stat is working ok, then it can't be that that's preventing the tank from being heated.

SS, the next time you heat the tank for hot water using the immersion, try turning the 'stat setting back and forth every 5 minutes, and note where it 'clicks' each time.

It should be 'clicking' at increasingly 'high' positions - ie anti-clock. When you note where it clicks, make sure it's then returned to a positioned 'higher' than the click, or else it'll turn offski.