Wiring to new Boiler

starlored · Jun 20, 2016

I'm having a new Boiler fitted and moving position in my wisdom I've decided to do the wiring myself I've also decided to upgrade my consumer unit at the same time.

Anyway the Boiler being fitted is a Baxi EcoBlue (Heat only) in the instructions and all my research state that all it needs is a Switch Live, Neutral and Earth, I'm guessing this is correct the thing is in my experience of Boiler install/wiring they have had a Pump overun. I'm more Industrial based, my last major domestic work was over 15 years ago has anyone wired one of these and can tell me.

One other thing is I need a condensate pump I was going to wire this in a radial with the FCU to the heating controls. I:E 16AMP MCB to heating control FCU to Condensate FCU

TJ Anderson · Jun 20, 2016

The boiler must have internal pump then if there is no connections for external one and it must have overrun.

The 16A radial feeding two FCU's is fine. Although the new circuit is notifiable work.

Although as a spark you can physically replace your fuse board no problem, again it is notifiable work though.

Leesparkykent · Jun 20, 2016

If its the heat only boiler it only needs switched live, neutral and earth.

davesparks · Jun 20, 2016

Read the manual for the boiler, it I'll will you everything you need to know.

Gas boilers without pump overrun are very rare these days, but they do exist. The last new gas boiler without overrun which I wired was a Baxi, can't remember the model name/number but it was forever breaking down and caused the water-clown no end of trouble.

Sent from my iPad using Tapatalk

davesparks · Jun 20, 2016

TJ Anderson said:
The boiler must have internal pump then if there is no connections for external one and it must have overrun.

A boiler described as being 'heat only' won't have any internal pump or diverted valves etc. If it has an internal pump it will be described as a system boiler.

There is nothing to say a boiler must have overrun, it is obviously very rare for a new gas boiler to not have it these days but it is possible.

Of course we are assuming it is gas, if it is in fact oil then it would be very rare for it to have a pump overrun.

Sent from my iPad using Tapatalk

TJ Anderson · Jun 20, 2016

davesparks said:
A boiler described as being 'heat only' won't have any internal pump or diverted valves etc. If it has an internal pump it will be described as a system boiler.

There is nothing to say a boiler must have overrun, it is obviously very rare for a new gas boiler to not have it these days but it is possible.

Of course we are assuming it is gas, if it is in fact oil then it would be very rare for it to have a pump overrun.

Sent from my iPad using Tapatalk

The heat only boiler would still have external pump overrun terminals, that was what I meant. I was not a aware that any gas boilers that did not have it now, so that was news to me. I was just thinking of the last boiler I did without overrun. It was oil. I really can't remember the last gas one that did not have it to be honest.

starlored · Jun 20, 2016

No worries, like I said everything I've read and searched appears to show no pump overrun.
Still seems odd, but not a problem.
I just hope it doesn't keep breaking down as it's replacing an old Baxi fitted in 1994 still workingish.

Leesparkykent · Jun 20, 2016

If you take the feed from the load side of the SFCU in to the wiring centre then the condensate pump can be fed from there and the switch live to boiler taken through the normally closed float switch. No need for the extra SFCU just for the condensate pump.

Leesparkykent · Jun 20, 2016

starlored said:
No worries, like I said everything I've read and searched appears to show no pump overrun.
Still seems odd, but not a problem.
I just hope it doesn't keep breaking down as it's replacing an old Baxi fitted in 1994 still workingish.

As long as its installed properly and serviced every year you get a 7 year warranty with the boiler. If you shopped around a bit you could get a boiler with 10 year warranty for the same sort of money.

davesparks · Jun 20, 2016

TJ Anderson said:
The heat only boiler would still have external pump overrun terminals, that was what I meant. I was not a aware that any gas boilers that did not have it now, so that was news to me. I was just thinking of the last boiler I did without overrun. It was oil. I really can't remember the last gas one that did not have it to be honest.

I just looked up the boiler in question and it indeed a standard heat-only boiler. So it has no pump overrun or any internal pumps or diverters etc.
This suggests to me that it's going to weigh a ton! Pump overrun was introduced to counteract the problem of lightweight aluminium heat exchangers 'kettleing' when connected in a standard configuration. The older cast iron heat exchangers didn't have that problem so I would guess that this boiler has a cast iron heat exchanger.

Sent from my iPad using Tapatalk

Skelly · Jun 21, 2016

Hi there, Have a look at this, It should help and stop all the ques work.
http://www.baxi.co.uk/documents/EcoBlue_Heat_Installation_Guide.pdf

Spark1979 · Jun 22, 2016

Baxi are one of the only companies left which produce a heat only boiler with no pump overrun needed. This is one of their selling points, most others need a pump over run

Tof99 · Jun 24, 2016

Hi,

They normally require a permanent L-N-E supply and the SL becomes live when the room thermostat calls for heat, causing the boiler to ignite/fire up.

If no room stat is to be fitted you may have to provide a permenant live to the SL pin.

The boiler will then rely on the return water temp to work out whether it needs to fire up; not a particularly efficient way of doing things.

Have you considered a Smart thermostat,as you're re-doing the wiring, such as a Nest/Hive/Netatmo etc? Should save you money.

TJ Anderson · Jun 24, 2016

Tof99 said:
Hi,

They normally require a permanent L-N-E supply and the SL becomes live when the room thermostat calls for heat, causing the boiler to ignite/fire up.

If no room stat is to be fitted you may have to provide a permenant live to the SL pin.

The boiler will then rely on the return water temp to work out whether it needs to fire up; not a particularly efficient way of doing things.

Have you considered a Smart thermostat,as you're re-doing the wiring, such as a Nest/Hive/Netatmo etc? Should save you money.

Retro fit "on/off" so say smart thermostats like nest, aren't that smart. They are like regular stats but with tighter control windows and you can work it from your phone. A modulating boiler like those from Valiant and Worcester with compensating controls are genuinely smart and can ramp up and down to maintain heat with the minimum required gas being consumed .

Tof99 · Jun 24, 2016

I disagree TJ-independent studies have shown that most Smart stats save at least 30% energy use in the first year.

The Nest is am intelligent system that learns the behaviours and patterns of the home user and will adjust accordingly. Don't forget they replace the programmer as well as the R/Stat and if combined with a highly efficiency boiler they will save energy.

BTW, I'm not a salesman of any of these systems!!