I think you need to sit down and draw out what you're proposing here
Bosch Greenstar wiring
- Thread starter RichardShelley
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I did the normal, googled the installation manual, I got this
which does not show 3 neutrals, what we need to remember a boiler can be simply plugged in, and although we have polarised plugs, many countries don't, and although we are not permitted to fuse neutral other countries do, so likely designed so safe in any EU country as well as UK.
Some of the things asked for in the installation instructions are it seems daft, I noted one Bosch boiler asked for type A RCD protection, but one boilers instructions asked for type B, really?
Also seen it say should be connected to the same supply, I am sure they mean circuit, as very few homes have more than one supply, but look at Nest Gen 3 thermostats and common for the controller to have a different supply to the heat link, OK the USB volt dropper is independent to the controller, not built in, but as long as volt free contacts there seems to be no good reason why you should not have two circuits.
However for it to be one circuit in the main the supply must come from the boiler, as the boilers often have a fuse, so forming another circuit.
There comes a point where we need to use common sense, but also we can't use common sense if we don't know what is inside the appliance. However if Bosch will not tell you, likely no one else knows either, and I may decide I can combine neutrals, but I would never tell some one else to do the same, as all too easy to have missed some thing.
To my mind having a common base plate for three versions of thermostat/programmer with one being volt free and the other two being internally connected to line is asking for problems. And having scheme membership and being gas safe one questions which was their selected profession?
This idea of allied trades is the reason why my working life ended, I was told to do a job I was not trained to do, without assess to the paperwork, and to do any risk assessment you first need to have a method agreed (statement) and some one removed my electricians lock (personal lock was on another isolator) and turned on the plant I was working on. It seems I should have insisted whole plant was stopped, not just the recycling bit I was working on. Result never worked again.
So either you are an electricians in which case should not need to ask question, or your not, in which case you should not be working on it.
Some of the things asked for in the installation instructions are it seems daft, I noted one Bosch boiler asked for type A RCD protection, but one boilers instructions asked for type B, really?
Also seen it say should be connected to the same supply, I am sure they mean circuit, as very few homes have more than one supply, but look at Nest Gen 3 thermostats and common for the controller to have a different supply to the heat link, OK the USB volt dropper is independent to the controller, not built in, but as long as volt free contacts there seems to be no good reason why you should not have two circuits.
However for it to be one circuit in the main the supply must come from the boiler, as the boilers often have a fuse, so forming another circuit.
There comes a point where we need to use common sense, but also we can't use common sense if we don't know what is inside the appliance. However if Bosch will not tell you, likely no one else knows either, and I may decide I can combine neutrals, but I would never tell some one else to do the same, as all too easy to have missed some thing.
To my mind having a common base plate for three versions of thermostat/programmer with one being volt free and the other two being internally connected to line is asking for problems. And having scheme membership and being gas safe one questions which was their selected profession?
This idea of allied trades is the reason why my working life ended, I was told to do a job I was not trained to do, without assess to the paperwork, and to do any risk assessment you first need to have a method agreed (statement) and some one removed my electricians lock (personal lock was on another isolator) and turned on the plant I was working on. It seems I should have insisted whole plant was stopped, not just the recycling bit I was working on. Result never worked again.
So either you are an electricians in which case should not need to ask question, or your not, in which case you should not be working on it.
I don't see the point of your last sentence. It seems you needed to Google to find some of this stuff out.
Anyway through my research (like yours) it seems as if in some of their boilers (not all) Bosch are catering for countries/situations where there is a need for the control circuitry to be volt-free. I have also read that having the control circuits "isolated" also can prevent a backfeed to the boiler from wrong wiring of the external circuitry such as a second 230 volt supply.
Anyway, as several people have said, I suspect it is OK to "common" neutrals in the wiring centre in the UK. However I imagine that like several other things there could be an impact on the Warranty with wiring not complying with Bosch's specification. Another example of this would be not having the 230 volt supply FCU alongside the Boiler for easy access by the Service Engineer.
My 5-core cable won't accommodate more than one neutral so I will choose a boiler that doesn't use this particular Bosch Greenstar wiring convention.
Anyway through my research (like yours) it seems as if in some of their boilers (not all) Bosch are catering for countries/situations where there is a need for the control circuitry to be volt-free. I have also read that having the control circuits "isolated" also can prevent a backfeed to the boiler from wrong wiring of the external circuitry such as a second 230 volt supply.
Anyway, as several people have said, I suspect it is OK to "common" neutrals in the wiring centre in the UK. However I imagine that like several other things there could be an impact on the Warranty with wiring not complying with Bosch's specification. Another example of this would be not having the 230 volt supply FCU alongside the Boiler for easy access by the Service Engineer.
My 5-core cable won't accommodate more than one neutral so I will choose a boiler that doesn't use this particular Bosch Greenstar wiring convention.
ericmarc.
In the Bosch Greenstar boiler in question there are 3 neutrals as follows:
N - Netral of incoming supply
Ns - Neutral of control circuits
Np - (sometimes Pn or Nz) - Pump Neutral for remote pump (switched from boiler).
Bosch seem to have a range of wiring conventions in their boilers some of them illogical.
In the Bosch Greenstar boiler in question there are 3 neutrals as follows:
N - Netral of incoming supply
Ns - Neutral of control circuits
Np - (sometimes Pn or Nz) - Pump Neutral for remote pump (switched from boiler).
Bosch seem to have a range of wiring conventions in their boilers some of them illogical.
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