Immersion heater-no hot water

[highspark]

Call out today no hot water. Not familiar with immersion heaters but tested cable to bottom of immersion heater and got 230v and could hear it fizzing. However still no hot water. There was a second cable supplying the top half of immersion heater got no voltage at all across live and neutral.. Did IR and cables tested fine. The IH is fed from 16A mcb then into a timer. Is the top half on a timer? When I switch timer on still nothing across top cable. Any ideas? Element gone? Timer nackered

 

[Dan the spark]

Split tanks, one will be genral use which heats up at night when cheaper and the other will be for it they run out of water and need to top it up

 

[telectrix]

on the element itself, do a continuity test. should read 20 ohms for a 3kw element. 1 element might be on E7 so you won't get a supply till midnight. and try the little reset button on the stat.

 

[Dan the spark]

Did u have voltage at the timer?

 

[GLENNSPARK]

R1 Rn on the circuit....

 

[highspark]

Yes had voltage at the timer but not on outgoing to top half. I could actually hear the bottom half fizzing. No I did not see a reset button. Not familiar with these at sll

 

[Darkwood]

You have 2 elements you say one gets power and you hear it fizzing.... did you clamp test or did you measure element resistance???
I know you say you dont do immersion heaters but these would be basics for even if it is your first time on them, use ohms law and you should be near the kw rating of the element.
The second element may be a boost element that is powered from a time clock and activated by the owner or it could be a backup element on an existing immersion heater switch seperate from the timer switch set-up.... their are quite a few variants it could be.

 

[Dan the spark]

Use your tester to see if the timer is switching on and off when u spin the clock

 

[J25GTi]

Is the over heat stat tripped?

Also if it is tripped has it activated a 2 port valve on the top of the cylinder that needs manually resetting?

 

[GLENNSPARK]

R1 Rn on the circuit....

sorry i meant R2 Rn.....

 

[highspark]

If there are separate elements why is there no hot water at all,coincidence if both have gone at the same time.Customer said she usually switchs the clock on herself. When she did it before there was nothing and that's how it's been. If she is on e7 that will support one element not working. But both?

 

[J25GTi]

If there are separate elements why is there no hot water at all,coincidence if both have gone at the same time.Customer said she usually switchs the clock on herself. When she did it before there was nothing and that's how it's been. If she is on e7 that will support one element not working. But both?

Which is what makes me think there might be an electronic/manual reset valve on the flow from the heater that might need resetting if the high limit stat has tripped?

This is mainly for commercial/industrial stuff but could apply.

 

[Edd]

Your bottom element is normally the Econ7 and the top is a boost. this allows the whole tank to heat up at off peak rate. and if they run out then they can top up using the boost.

A normal I/heater should read 20 Ohms across L and N and nothing to E.
some times a small pin hole can appear in the element and cause the element still to hiss, sounding like its heating up but its just the hole bubbling.

Diss the element and test across it for aprox 20 Ohms and also IR test to E at 500V which should be clear.

 

[rich.250]

Is there another system heating the tank also??
If so it is common in my experience for both thermal cut outs to trip as it gets to hot.

If the thermal cut outs are ok, As said use ohms law and test elements.

 

[Top Cat]

The "fizzing" could be the element split and open circuit but not enough to blow fuse. Do as above^^^^^^^^^