Water Heater wiring query

[Welsh_sparky_21]

Just wondering if someone with more experience can enlighten me, called out to a bar today. Plumber was in to replace immersion element but FCU was faulty and wouldn’t switch off . Noticed that both the top and bottom elements were being supplied from the local ring circuit and were constantly on. Now A, is this normal? My understanding was you normally had a an off peak and a 24 hour supply? I’m normally working in houses were this is normally the case, and B, should there not be a timer of some sort on the circuit so these aren’t constantly heating

 

[timhoward]

I think you are asking good questions. I would add some more:

Is one 13A FCU supplying the two approx. 3000W elements? You said it wouldn't turn off so I'm naturally suspicious it's been overloaded.
Do both the immersion heaters have thermal cut-outs? (If not this is disaster waiting to happen)

To try and answer your questions - no it isn't normal; there would normally be a stat on the cylinder to regulate the water temperature and a time clock to control demand for the main heater and the boost.

From what you've said I'd have concerns about that setup. Any other high current drawing devices on the same RFC like dishwashers maybe?

 

[littlespark]

A. No its not normal.
B. Ideally, yes. but the thermostat in the immersion will cut the heater on and off.

A pub may still have an off peak supply bringing on one of the immersions... but not if they're both off the rfc... which also isnt right.
They really should be on individual, dedicated circuits

The prices for a pint in there must be astronomical to pay for the electric

 

[Welsh_sparky_21]

I think you are asking good questions. I would add some more:

Is one 13A FCU supplying the two approx. 3000W elements? You said it wouldn't turn off so I'm naturally suspicious it's been overloaded.
Do both the immersion heaters have thermal cut-outs? (If not this is disaster waiting to happen)

To try and answer your questions - no it isn't normal; there would normally be a stat on the cylinder to regulate the water temperature and a time clock to control demand for the main heater and the boost.

From what you've said I'd have concerns about that setup. Any other high current drawing devices on the same RFC like

I think you are asking good questions. I would add some more:

Is one 13A FCU supplying the two approx. 3000W elements? You said it wouldn't turn off so I'm naturally suspicious it's been overloaded.
Do both the immersion heaters have thermal cut-outs? (If not this is disaster waiting to happen)

To try and answer your questions - no it isn't normal; there would normally be a stat on the cylinder to regulate the water temperature and a time clock to control demand for the main heater and the boost.

From what you've said I'd have concerns about that setup. Any other high current drawing devices on the same RFC like dishwashers maybe?

Yeah there’s stats on the immersors with thermal cut outs. I replaced the faulty FCU but made them aware that the current set up isn’t safe as it is

 

[Welsh_sparky_21]

A. No its not normal.
B. Ideally, yes. but the thermostat in the immersion will cut the heater on and off.

A pub may still have an off peak supply bringing on one of the immersions... but not if they're both off the rfc... which also isnt right.
They really should be on individual, dedicated circuits

The prices for a pint in there must be astronomical to pay for the electric

There was another cable connected into the load side of the DP switch which I’m not sure where it was going. Whole set up was a joke

 

[mainline]

There was another cable connected into the load side of the DP switch which I’m not sure where it was going. Whole set up was a joke

Immersion heater shouldn't be fed from a FCU it should be a dedicated circuit on a switch.