Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to keep
the heating going. I'd like to have the electrics for the heating system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.

Thanks in advance!

Harry

In article , Harry Davis
writes
Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

It should all be fed from the same point, it is a safety requirement so
that anyone working on the installation can go to a single location and
isolate the system without the risk of electrocution from some other
source of power back feeding into the control wiring.

The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to keep
the heating going. I'd like to have the electrics for the heating system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.

Which ever way you go, make sure you have enough headroom in your genny
or inverter to feed the motor and magnetic loads that make up most of
the c/h system. Others may be able to offer hands on advice but my guess
would be that 100% headroom would be required at least.
--
fred
it's a ba-na-na . . . .

On Sunday, November 4, 2012 2:52:44 PM UTC, fred wrote:
In article , Harry Davis
writes

Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

It should all be fed from the same point, it is a safety requirement so
that anyone working on the installation can go to a single location and
isolate the system without the risk of electrocution from some other
source of power back feeding into the control wiring.

Better to find out how yours is fed. And quicker. It should all be of one point, but of course shoulds aren't always followed.


The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to keep
the heating going. I'd like to have the electrics for the heating system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.

Which ever way you go, make sure you have enough headroom in your genny
or inverter to feed the motor and magnetic loads that make up most of
the c/h system. Others may be able to offer hands on advice but my guess
would be that 100% headroom would be required at least.

Motors draw many times run current during startup, and are the main load on a modern CH system.


NT

On Sun, 4 Nov 2012 14:11:05 +0000 (UTC), Harry Davis wrote:

Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or
all on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

The entire heating system should be fed from a single fused supply, be
that from a ring or direct from the CU. There are so many things
switching things on/off based on time or temperature that to have things
fed from multiple supplies would be down right dangerous. You might think
you've isolated something and test it, but time passes or the temp
changes and your "dead" circuit becomes live...

I'd like to have the electrics for the heating system on their own
plug, which could be plugged either into a mains socket or a socket
powered by another supply.

That's what I've had here for quite a while, unswitched socket and 3A
fuse in plug top. Absolute isolation of all heating related stuff when
unplugged (the plug is next to the board with all the stat receivers,
time switches, solar controller etc). Enables it to be plugged into
extension lead from generator when the mains fails.

--
Cheers
Dave.

On 04/11/12 14:11, Harry Davis wrote:
Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

hey should be all of one fused spur.

Whether its a dedicated ring or not is up to whoever cabled the thing
up. Normally its on another ring as the power draw is small.

Or is it common for one of the appliances to be on one ring, another on
another, etc.?


Never unless its been bodged.

The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to keep
the heating going. I'd like to have the electrics for the heating system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.


Do the job properly and use a changeover on the spur and a properly
wired in generator.

Thanks in advance!

Harry



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On Sun, 4 Nov 2012 06:57:27 -0800 (PST), wrote:

Motors draw many times run current during startup, and are the main
load on a modern CH system.

'tis true but they are small motors. Circulation pump 100W similar for
the pump/blower in an oil boiler. Even a little stinky 750W two stroke
generator can cope. Not even sure that the motors in circulation pumps
have a particulary large switch on surge as I think they are sychronous
(or at least brushless) rather than universal or induction.

--
Cheers
Dave.

On Sun, 04 Nov 2012 15:04:22 +0000, The Natural Philosopher wrote:

Do the job properly and use a changeover on the spur and a properly
wired in generator.

Opens a whole new can of worms regarding earthing. You have to be
absolutely sure that the bonding of generator chassis and "neutral" and
generator chassis and your supplied true earth connection are all low
enough to enable any fault protect to still operate within the prescribed
times. Not to mention that a small genset probably won't be able to
supply enough current under fault conditions either.

Personally I go for a floating L and N supply from the genset and ignore
the lack of true earth. I only connect some appliances to the genset via
extension cables. Those are heating, fridges/freezers and the fish tank.

--
Cheers
Dave.

On 04/11/2012 14:52, fred wrote:
In article , Harry Davis
writes
Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

It should all be fed from the same point, it is a safety requirement so
that anyone working on the installation can go to a single location and
isolate the system without the risk of electrocution from some other
source of power back feeding into the control wiring.

Indeed. Although it is *all too common* to find that some DIY idiot has
bridged either a ring main or in my house a *lighting* circuit to allow
the CH pump to be switched on manually from the living room. Back boiler
on the main room fire (now a wood burning stove).

Fortunately we spotted the problem before it killed the boiler service
engineer. I always test supposedly isolated mains circuits with a neon
screwdriver but until then I had never seen one fail.

The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to
keep
the heating going. I'd like to have the electrics for the heating
system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.

Which ever way you go, make sure you have enough headroom in your genny
or inverter to feed the motor and magnetic loads that make up most of
the c/h system. Others may be able to offer hands on advice but my guess
would be that 100% headroom would be required at least.

The total electrical load for my CH is relatively modest. I'd guess a
1kW generator or inverter would do it at a pinch. I have a 2kW unit.

The really difficult loads are the fridge and freezer. The compressor
motor is an absolutely evil high current load as it starts up.

--
Regards,
Martin Brown

On 04/11/2012 16:05, Dave Liquorice wrote:
On Sun, 04 Nov 2012 15:04:22 +0000, The Natural Philosopher wrote:

Do the job properly and use a changeover on the spur and a properly
wired in generator.

Opens a whole new can of worms regarding earthing. You have to be
absolutely sure that the bonding of generator chassis and "neutral" and
generator chassis and your supplied true earth connection are all low
enough to enable any fault protect to still operate within the prescribed
times. Not to mention that a small genset probably won't be able to
supply enough current under fault conditions either.

Personally I go for a floating L and N supply from the genset and ignore
the lack of true earth. I only connect some appliances to the genset via
extension cables. Those are heating, fridges/freezers and the fish tank.

Not a problem with all of them, but IIUC, some boilers won't flame sense
correctly without an earth reference.

Changeover switches are easy enough on TT properties, but get a bit more
complex on TN ones.




--
Cheers,

John.

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On Mon, 05 Nov 2012 00:37:37 +0000, John Rumm wrote:

Not a problem with all of them, but IIUC, some boilers won't flame
sense correctly without an earth reference.

Not a problem in the context of this thread. Oil boiler, flame sense is
optical, ignition a BFO spark. B-)

--
Cheers
Dave.

On Nov 4, 2:11*pm, Harry Davis wrote:
Are all the electrics for an oil central heating and hot water system
(pump, timer, stats, etc.) usually all off a dedicated mains fuse? Or all
on the same fused spur from one of the rings?

Or is it common for one of the appliances to be on one ring, another on
another, etc.?

The reason I ask is that we suffer from constant power cuts, and I'm
considering giving myself the option of another supply, either from a
standalone diesel generator or from batteries, thereby enabling us to keep
the heating going. I'd like to have the electrics for the heating system on
their own plug, which could be plugged either into a mains socket or a
socket powered by another supply.

Thanks in advance!

Harry

I have a small wood burning stove with a hot plate. Needs no gas,
electricity and I can store wood.
You can run out of oil too.