In article ,
PoP wrote:
I view my small genny as being able to power my CH system and not much
else if the supply company hit difficulties - I'd have to jury-rig the
genny into the CH system so this is very much on the "ideas" charter
rather than a genny sitting waiting to power up. I'm old enough to
remember the electricity strikes of the 70's, and I don't want to go
thru that again if I can help it.

I've just finished doing something similar to mine, although I've used a
car battery and invertor as the standby source. But the method is similar
from the safety point of view, and I'd be happy with comments from others
on any improvements.

Like most systems, my CH is all fed via an FCU. After the FCU I've fitted
a DPDT rocker switch marked normal and emergency. In the normal position,
it simply routes the output of the FCU direct to the CH in the normal way.
In emergency position, it routes the output of a mains coil relay - I've
used a triple pole CO type with 10 amp contacts which is readily available
from the likes of TLC or RS etc for about 20 quid including base. With
mains still working the coil is energised and simply routes the mains
through in the normal way. If the mains fails, the relay drops out and
routes the output of my invertor -(or generator) to the CH spur. The
reason for the relay is that the output lead from the generator or
invertor has to be a plug, and this eliminates any chance of mains flowing
back up the lead and making the plug live - or indeed damaging the standby
source. The third pole on the relay is used to switch the invertor on.
Note it actually just switches the electronics, not the battery feed,
which would require a much larger relay due to the current involved. This
extra pole could also be used to control the starter on a self start genny
set.

I've mounted the rocker switch in a matching blank panel to the FCU, and
incorporated the LEDs from the invertor which show working and low battery
volts. The relay is fitted in a steel adaptable box behind it - I'm
fortunate that the CH controls are mounted in the oven housing unit in the
kitched so there's plenty of space behind. The invertor and battery simply
sit in an adjacent kitchen unit - I don't intend it as a permanent
installation.

On tests, I've had the system running for about 6 hours on a fully
charged 50 Ah battery, and it showed no signs of failing. But of course it
will depend on the weather and how hard the pump etc is running. A test
with a 100 watt bulb showed a life of again about 6 hours before the
battery died.

The next thing is whether to fit a battery charger to the system.

--
*If I worked as much as others, I would do as little as they *

Dave Plowman London SW 12
RIP Acorn