New boilers with permanent lives

[jackecole]

WHy do some boilers (most modern ones) have a permanent live feed as well as a switched live feed? What's the difference/benefits?

Most older boilers used to have a switched live, going to the wiring centre/junction box and being connection the the same terminal as the pump live and MV orange.

How do these new boilers wire? - Is it in the same way but with an additional L and N fed from the wiring centre L and N terminals or from a different feed?

 

[Jezclayton]

There are a few things that come to mind that you might find on a modern boiler, all of which require a permanent live:-

1) Fan Overrun
2) Pump Overrun
3) Inbuilt Frost Stat
4) 24 hourly pump run if boiler idle
5) Error logging on PCB

There should only be one double pole switch covering the whole central heating circuit. Manufacturer Instructions will give specific requirements for each boiler.

 

[gas4you]

When installing a boiler with a permanent live, it is always good practice to use a fan isolating switch next to the boiler, so both lives and neutral can be isolated for servicing and repairs etc.

 

[corgiman]

When installing a boiler with a permanent live, it is always good practice to use a fan isolating switch next to the boiler, so both lives and neutral can be isolated for servicing and repairs etc.

would that be luvverly if they did that dave

save me running up and down the stairs ahhhh bliss

 

[gas4you]

Thats why I get fatter when servicing my installations Matt

 

[corgiman]

Thats why I get fatter when servicing my installations Matt

lmao

good lad

 

[kevindgas]

We also fit 1 on each boiler install. we use the crabtree switch as it comes without the fan symbol on the switch

 

[BigBurner]

When installing a boiler with a permanent live, it is always good practice to use a fan isolating switch next to the boiler, so both lives and neutral can be isolated for servicing and repairs etc.

A 4 pole switch you mean. I always have that done where appropriate. Many W-B boilers need the power going through the boiler, which can complicate wiring.

 

[kevindgas]

A 4 pole switch you mean. I always have that done where appropriate. Many W-B boilers need the power going through the boiler, which can complicate wiring.

whats complicated about 4 wires

 

[corgiman]

A 4 pole switch you mean. I always have that done where appropriate. Many W-B boilers need the power going through the boiler, which can complicate wiring.

whats complicated about 4 wires

well theres four of em to start wif

 

[WDIK]

A 4 pole switch you mean. I always have that done where appropriate. Many W-B boilers need the power going through the boiler, which can complicate wiring.

whats complicated about 4 wires

well theres four of em to start wif

this would be the imaginary 3phs domestic boiler I suppose?
all switched lives are derived form the permanant live, you never interpolate supplies for obvious safety reasons, such as the IEEE regs.

use a 2 pole isolator.

 

[WDIK]

Thats why I get fatter when servicing my installations Matt

Dave that just so self depricating.

you are not fat, your stout

 

[kevindgas]

whats complicated about 4 wires

well theres four of em to start wif

this would be the imaginary 3phs domestic boiler I suppose?
all switched lives are derived form the permanant live, you never interpolate supplies for obvious safety reasons, such as the IEEE regs.

use a 2 pole isolator.

NO - domestic heat only boiler with perm & switched live from a wiring center with a switch as described alongside boiler so removing the need to run up and down flights of stairs! when undertaking work on said boiler isolation of Neutral, Switch live & Perm live at the flick of a switch. earth remains connected.

 

[gas4you]

A 4 pole switch you mean.

Why 4 pole? Fan isolator is 3 pole, all that is needed is to isolate, L, Sw/L & neutral

 

[HarrogateGas]

The Baxi Solo HE range of conventional boilers have no permanant live or pump live. Just Live neutral and earth, so will replace all boilers on a fully pump system with no additional wiring needed.

They were useless a few years back but are a decent boiler now that they have ironed the probs out. Ive installed quite a few and not been back to any faults.