Circuit to indicate failure of a heating element

[Baron]

amdx Inscribed thus:

Hmm! Here in the states with 240V, both sides are live. When wiring
a
standard water heater you connect 240V to the element and ground the
case. No neutral involved.
If you know how the UK system is wired could post a schematic on
ABSE,
photobucket or whatever site pleases you?
Sure would be nice for the original poster to chime in.
Mike

In the States a domestic supply is 110.0.110 where the 0 is the neutral
and I belive is also earthed or at earth potential. In the UK there is
only 230.0 where 0 is the neutral and at earth potential

 

[amdx]

An un-lit LED will do that.

But how do you know if it is un-lit because the thermostat has not
triggered current flow
or because the element is open.
Mike

 

[Jasen Betts]

Hmm! Here in the states with 240V, both sides are live. When wiring a
standard water heater you connect 240V to the element and ground the case.
No neutral involved.
If you know how the UK system is wired could post a schematic on ABSE,
photobucket or whatever site pleases you?
Sure would be nice for the original poster to chime in.
Mike

components involved in the domestic power circuit of a typical
2 element electric storage water heater on a 230V system.

I've drawn this according to what's done in NZ and AU.

UK uses a ring-main so the ordering of the switch and fuse might be
reversed.

to other equipment
|
|
+-------[p]-+-[f]----[t]-------.
| |
(phase) -------[E]-+-[L]---[P]---[F]----[T]---. |
230VAC | |
[R] [r]
| |
(neutral)----------+-----------------------------+---+--...
|
+-------------------------------- earth
_|_
///
ground peg


[E] entry fuse (where the electricity enters the dwelling)

[p] [P] power meters (connection to neutral not shown)

[L] load control (connection to neutral not shown)
you can think of it like a switch that's not under the
consumer's control.

[F] [f] fuses (or circuit breakers)

switch

[T] [t] thermostat

[R] [r] resistive heating element

The element on the load controlled circuit [R] will be mounted near
the base of the water cylinder and is only available while the load
controller is closed, electricity on this circuit is charged at a
cheaper rate.

the other element and its thermostat will be near the top
(maybe 2/3 the way up) the thermostat may be set to a
sligtly lower temperature, to only operate when most of
the hot water has been used up. (hot water is less dense
and floats on top of cold water)

in this way most (or all) of the hot water needed can be made using
cheap off-peak electricity (could be 1/3 the price) but the upper
element is available to provide hot water when all the cheap hot
water is used up.

Sometimes the load control and/or meters are combined into a single
unit.

Two element water heater example:
http://tinyurl.com/pucsqn
(http://waterheating.rheem.com/conte...s/Reference Material/Parts Breakdown/3000.pdf)

 

[Baron]

components involved in the domestic power circuit of a typical
2 element electric storage water heater on a 230V system.

I've drawn this according to what's done in NZ and AU.

UK uses a ring-main so the ordering of the switch and fuse might be
reversed.

Yes the fuse comes after the switch ! The logic being that there should
be no voltage on the fuse while being replaced. It protects from flash
burns if the circuit is live when the fuse is replaced.

to other equipment
|
|
+-------[p]-+-[f]----[t]-------.
| |
(phase) -------[E]-+-[L]---[P]---[F]----[T]---. |
230VAC | |
[R] [r]
| |
(neutral)----------+-----------------------------+---+--...
|
+-------------------------------- earth
_|_
///
ground peg


[E] entry fuse (where the electricity enters the dwelling)

[p] [P] power meters (connection to neutral not shown)

[L] load control (connection to neutral not shown)
you can think of it like a switch that's not under the
consumer's control.

[F] [f] fuses (or circuit breakers)

switch

[T] [t] thermostat

[R] [r] resistive heating element

The element on the load controlled circuit [R] will be mounted near
the base of the water cylinder and is only available while the load
controller is closed, electricity on this circuit is charged at a
cheaper rate.

Correct ! Often called "Economy 7" because for a 7 hour period
overnight the charge rate is reduced. Water heating and storage
heating is commonly run on a separate circuit that is timer controlled.

the other element and its thermostat will be near the top
(maybe 2/3 the way up) the thermostat may be set to a
sligtly lower temperature, to only operate when most of
the hot water has been used up. (hot water is less dense
and floats on top of cold water)

in this way most (or all) of the hot water needed can be made using
cheap off-peak electricity (could be 1/3 the price) but the upper
element is available to provide hot water when all the cheap hot
water is used up.

Sometimes the load control and/or meters are combined into a single
unit.

Ours is like that a single unit that provides metering and control.

Two element water heater example:
http://tinyurl.com/pucsqn

(http://waterheating.rheem.com/conte...s/Reference Material/Parts Breakdown/3000.pdf)