Combi-boiler wiring, unusual wiring set up, need advice

Max Q

I have a gas combi-boiler which was installed when the property was built about 12 years ago. The wiring set up seems very strange to me - could anyone with any experience in this area comment on how this is set up?

The boiler does not appear to be connected to a permanent live. The boiler only receives power when the thermostat 'calls for heat'. The thermostat has been wired in between the live feed and the boiler itself. The boiler's internal PCB thermostat connections have been 'jumped' with a wire link. The thermostat is acting like a temperature control switch between the boiler and the live and not a control on the central heating function of the boiler directly.

The only way I can keep the boiler powered is to set the thermostat target temp much higher than ambient temp and then just switch the central heating button on the boiler on and off as I need it manually.

How usual or unusual is this arrangement and is it safe?

EdgeCase

You'd actually need to contact an RGI (Registered Gas Installer).

That doesn't sound right as the boiler should not be cut dead. There are fans and circulation pumps that usually need to overrun to clear the combustion chamber of gases and to keep the boiler from running too hot in the case of the pump.

I don't think an REC could advise on this as it's really about gas boiler installation.

jaffa20

Sorry to hijack but I have a similar case. Bought a house approx 40 years old and gas guy said there is no permanent live during the recent service. He told me to contact and electrician about this.

It's to ensure the boiler runs frost protection during very cold nights as far as i'm aware. Boiler is located in a boiler house outdoors and is a fairly new boiler so guess need to get it done fairly urgently before cold weather comes.

EdgeCase

It should be wired exactly as per its installation instructions. I would suggest googling the manual.

meercat

As edgecase says,you both need an rgi for final connection into boiler. It’s a criminal offence for anyone other than rgi to work on the boiler

however you may also need a rec to do the main electrical control work,switching and circuit installation for these boilers

2011

@Max Q: Different boilers require different wiring configurations of external control wiring. There is not a “one size fits all” solution. The first step should always be to get the wiring diagram from the manufacturer. As EdgeCase suggests a quick Google of the make and model of the boiler is normally enough to get this. Once the wiring diagram has been optioned it can then be compared to the installed wiring.

I do not work in the domestic sector (and I am not a REC) but I would be very surprised if a REC is not permitted to connect a boiler. This seems utterly bizarre to me as a qualified electrician would have far more electrical training than an RGI. Having said that a REC will advise you either way. Perhaps someone has a link to support this?

EdgeCase

Any installations I've seen the electrical work is done by an REC but the connection between the installation and the boiler is overseen by an RGI due to gas safety requirements and to ensure the boiler and flu are operating safely.

It's one area that is highly regulated.

I know when we were doing domestic boiler upgrades recently the RGI brought an REC wish him.

2011

EdgeCase wrote: »

Any installations I've seen the electrical work is done by an REC but the connection between the installation and the boiler is overseen by an RGI due to gas safety requirements and to ensure the boiler and flu are operating safely.

It's one area that is highly regulated.

I know when we were doing domestic boiler upgrades recently the RGI brought an REC wish him.

It makes sense to me that an RGI would be the one to turn the power on to the boiler when it is being set up and commissioned during installation. However this is a boiler that is already installed. It should be connected as per the manual. No gas safety regulations or RGI are going to suggest otherwise. The safe operation of the boiler and flue should be ensured by regular servicing by an RGI.

Dardania

2011 wrote: »

It makes sense to me that an RGI would be the one to turn the power on to the boiler when it is being set up and commissioned during installation. However this is a boiler that is already installed. It should be connected as per the manual. No gas safety regulations or RGI are going to suggest otherwise. The safe operation of the boiler and flue should be ensured by regular servicing by an RGI.

I think the specific issue is taking off the boiler cover - that's the trigger for a RGI.

@OP: I would suggest getting a smart thermostat installed (like Electric Ireland have an offer n it) - that way they should be dual qualified and capable of doing both tasks (opening the cover, and fixing the wiring) - just make sure you have the manual to hand, and before letting them go test that you can get hot water even when the thermostat is set lower than ambient temp. That'll prove you have permanent live.

meercat

2011 wrote: »

It makes sense to me that an RGI would be the one to turn the power on to the boiler when it is being set up and commissioned during installation. However this is a boiler that is already installed. I.

The regulations are quite clear
No one other than a rgi is permitted to remove the cover or work on a gas boiler. Irrespective of new or existing installation.

EdgeCase

There's also an issue if the boiler's systems have been bypassed to 'hack on' a control system. There are plenty of reasons why a gas boiler needs access to continuous power.

When a modern gas boiler's burner goes off, the ignition chamber is usually purged by the fan blowing air (drawn from outside) through the combustion chamber to clear any flu gasses.

Also, in stark contrast to old cast iron oil fired boilers, they have very little ability to lose or absorb heat if there's no water flowing through them. They've usually got very dense and efficient heat exchangers that transfer energy to flowing water very efficiently. That's why they need control of at least one of the pumps to ensure circulation happens.

If there's no circulation, they will also often use the fan at full speed to cool the heat exchanger to prevent damage.

Basically, what's made a lot of the modern condensing boilers possible is sophisticated always-on control systems.

They can cool passively, in the event of a power cut, but it's definitely not something you should be putting a boiler through on a regular basis.

So all in all, you should not have a situation where there's no permanent live.

That's why I'd strongly suggest an RGI has a good look at what's going on as you could be drastically reducing your boiler's life by just cutting the power to its systems and treating it like as if it's an old oil burner.

An RGI should be able to properly diagnose any issues with the boiler's systems and installation.

Without access to wiring diagrams, there's no real way of advising on a boiler and the RGI route is the only legal one.

Max Q

Many thanks for all the replies. I will get on to an RGI today to come out and look at the set up and take it from there. I'm concerned about the lack of a permanent live inhibiting the safety features of the boiler.

2011

Dardania wrote: »

I think the specific issue is taking off the boiler cover - that's the trigger for a RGI.

Fair enough, as stated above I don't do domestic wiring. Although I take your word for this I have never seen this in writing, so I am just wondering if this is an established practice or if it is indeed a legal requirement.

Either way my, preference would still be for a REC / electrician to do the external wiring even if this means that an RGI would terminate the 4 core to the boiler itself. The reason for this is that even though qualified electricians know less about the internal workings of a boiler they receive more electrical training than RGIs. In addition they are generally expected to take ownership of the entire electrical installation, all wall chasing, cable routing, cable segregation, electrical connection of all zone valves, thermostats, time clocks, circulation pumps, immersion heaters and other heating controls.

Many moons ago when I did this I would wire up the boiler myself (generally the gas was not even connected at this stage) and leave the supply locked off for the RGI to power on. Perhaps I would get in trouble for this now, but I never had any complains from RGI's back then.

Dardania

2011 wrote: »

Fair enough, as stated above I don't do domestic wiring. Although I take your word for this I have never seen this in writing, so I am just wondering if this is an established practice or if it is indeed a legal requirement.

Either way my, preference would still be for a REC / electrician to do the external wiring even if this means that an RGI would terminate the 4 core to the boiler itself. The reason for this is that even though qualified electricians know less about the internal workings of a boiler they receive more electrical training than RGIs. In addition they are generally expected to take ownership of the entire electrical installation, all wall chasing, cable routing, cable segregation, electrical connection of all zone valves, thermostats, time clocks, circulation pumps, immersion heaters and other heating controls.

Many moons ago when I did this I would wire up the boiler myself (generally the gas was not even connected at this stage) and leave the supply locked off for the RGI to power on. Perhaps I would get in trouble for this now, but I never had any complains from RGI's back then.

Don't take my word for that - I am going on what I was told here a few years ago - it's just the logic makes sense to me (horsing a cover off a boiler is probably a good way to knock components or sensors out of whack).

There is this> https://www.cru.ie/wp-content/uploads/2009/07/cer09083-7.pdf
And it makes the point about exceptions:

The Commission advises that Domestic Gas Works will cover any work on a natural gas fitting within the scope of I.S.813 with the following exceptions;
The design of gas works;
Work on the point of delivery and upstream of the point of delivery;
Work on gas fittings for the supply of gas for automotive use;
Work that is specifically designed to be effected by a person without the use of a tool; and
The manufacture of gas appliances/natural gas fittings.

Maybe the fact that one uses a tool to take off the cover...that's the regulatory trigger? Similar to distribution boards, and finger safe covers being needed until a tool is used to go further?

My knowledge of the wiring end came about similar to yours, in that I was designing the electrical so had to know what the sparks would face (and so help them with the expectation that they'd need to do the controls).

2011

So I decided to look into this "legal" requirement for an RGI to make the electrical connections, here is what I found:

Page 53 of the Registered Gas Installers Technical Guidance Document 2017 suggests that only a REC should make the electrical connections to the boiler:

Where the dwelling is a new build and the gas installation is being installed for the first time it is the responsibility of the Registered Electrical Contractor to ensure that it meets the requirements of ET 101, National Rules for Electrical Installations.

Will a REC take ownership of electrical work carried out by others? Often the answer is no.


Page 56 states the following, I have bolded the important part:

Minor electrical works remain outside the scope of Restricted Works. These include the replacement of an electrical accessory such as a light switch, the replacement or relocation of light fitting where the existing circuit is retained or the provision of an additional socket to an existing radial circuit. These types of work, which includes the electrical work associated with the installation of gas appliances and equipment in domestic property, may be carried out by a Registered Gas Installer.

Instead of stating that gas appliances (which would include a boiler) must be connected by a RGI it states these may be connected by a RGI. So an electrician / REC can do this.

Page 59, Annex K states that in fact a "competent person" may deal with the requirements of the electrical supply:

This Annex deals with the requirements for the connection of the electrical supply by a competent person to a gas installation, the associated protective devices (RCBO or MCB and RCD), earthing and equipotential bonding connections necessary for safety, in order to ensure compliance with the National Wiring Rules for Electrical Installations, ET 101. Other
requirements in the Rules may also be applicable, and these should be checked by a competent person.

So there yo have it, anyone deemed competent can electrically connect a gas boiler according to the RGI

Based on the above I think that this supposed "legal" requirement for an RGI to make the electrical connections to the boiler is an urban myth. Maybe someone can prove me wrong?

2011

Dardania wrote: »

Maybe the fact that one uses a tool to take off the cover...that's the regulatory trigger? Similar to distribution boards, and finger safe covers being needed until a tool is used to go further?

Regarding requiring a tool to remove the cover, my understanding:
A distribution board, or control panel (or whatever) is permitted to have exposed live parts once the panel can only be opened with a tool. If no tool is required to open it should not even have live terminals exposed.

I don't see anything in what you have quoted that indicates than only a RGI can make the electrical connections to a gas boiler. In fact "RGI" is not even mentioned in the above.

I agree than an RGI is permitted to to this, all I am arguing is that so is an electrician. Since I did a bit of Googling I now believe that anyone deemed "competent" is permitted to do this.

Dardania

2011 wrote: »

Regarding requiring a tool to remove the cover, my understanding:
A distribution board, or control panel (or whatever) is permitted to have exposed live parts once the panel can only be opened with a tool. If no tool is required to open it should not even have live terminals exposed.

I don't see anything in what you have quoted that indicates than only a RGI can make the electrical connections to a gas boiler. In fact "RGI" is not even mentioned in the above.

I agree than an RGI is permitted to to this, all I am arguing is that so is an electrician. Since I did a bit of Googling I now believe that anyone deemed "competent" is permitted to do this.

Why I reckon a RGI might be necessary is because you need to take a cover off (using tools).

EdgeCase

The rules sound a bit self contradictory.

The way it was done with my boiler replacement and system controls update was two guys arrived on site. An RGI led the project and an REC came in briefly to do all the electrical work up, including the boiler but it was signed off and supervised by the RGI for the gas installation, including testing and commissioning the systems and the REC left a completion certificate for the new circuit added for the new control system.

Basically the REC left everything ready to connect and tested all the electrical aspects.

He basically just installed a small din rail cabinet in the boiler house and a bunch of contactors and between the two of them then figured out the interfaces between the control system, the boiler and a solar heating system.

Seemed like an ideal pairing to me.

I would suspect if you get an RGI in and it's minor work they'll do it. If it's major work they'll bring in an REC.

2011

Dardania wrote: »

Why I reckon a RGI might be necessary is because you need to take a cover off (using tools).

I'm not trying to be smart, but every electrician has a box full of tools.

When I worked as an electrician I spent much of my time taking covers off all sorts of fancy pieces of kit and connecting up power, control and communications cabling. This was a normal part of my job and many of the packages I connected to contained far more dangerous / volatile / explosive gasses and liquids than natural gas.

Dardania

2011 wrote: »

I'm not trying to be smart, but every electrician has a box full of tools.

When I worked as an electrician I spent much of my time taking covers off all sorts of fancy pieces of kit and connecting up power, control and communications cabling. This was a normal part of my job and many of the packages I connected to contained far more dangerous / volatile / explosive gasses and liquids than natural gas.

Not at all doubting an electricians (not your) ability to take a panel off without injuring anyone or damaging anything. I’m talking about the responsibility that the CRU seems to imply - it seems to imply that only RGIs are permitted legally to take the covers off boilers.

2011

EdgeCase wrote: »

The rules sound a bit self contradictory.

I don't see any contradiction. Everything I have found (from official sources) is consistent with a competent person making the electrical connections.

The way it was done with my boiler replacement and system controls update was two guys arrived on site. An RGI led the project and an REC came in briefly to do all the electrical work up, including the boiler but it was signed off and supervised by the RGI for the gas installation, including testing and commissioning the systems and the REC left a completion certificate for the new circuit added for the new control system.

.........and I am saying there is nothing wrong with that at all.

My point is that an electrician is permitted to make the electrical connections to the boiler. I believe that anything contradicting this is an urban myth. If I am incorrect (maybe I am), show me the link.

EdgeCase

Do RGI's have not have basic electrical training - enough to wire a boiler / deal with controls etc that are mostly still in place. I can appreciate the need for an REC for major wiring.

The worst wiring I've seen has been around oil boilers where someone's done a complete bodge job.

The most frightening one I've ever seen was someone who used the earth on the back plate of a metal 1970s time clock as a hot chasis to connect other lives. The only reason it wasn't tripping out was it was that it was mounted onto a block of wood. Nothing was earthed none of the plumbing was bonded.

If you removed the cover and adjusted the clock, the entire chasis was live!!

Generally natural gas boiler installation seem fairly standardised and good.

2011

EdgeCase wrote: »

Do RGI's have not have basic electrical training - enough to wire a boiler / deal with controls etc that are mostly still in place. I can appreciate the need for an REC for major wiring.

In my opinion they do, but there is more to it than that.
IMHO more electrically complex systems are best done by someone that has been electrically trained to a higher level.


However when I was a REC half way through wiring a large house I maintained proper cable segregation to mitigate the risk of interference on coaxial cables and other communications cabling. I had drilled holes in joists for cabling and kept all of these types of cables separate from power cabling. Everything was neatly loomed and looked the part. Anyway I came in one day and the RGI had filled many of my neatly drilled holes (some of which were through RSJs) with his cabling. It looked horrendous! My segregation of cabling, neat looming and general professionalism of the 1st fix meant nothing to him. Worst of all is that he had managed to damage the insulation on many of my cables by roughly pulling his cables through by not feeding them carefully. So who will take ownership of cabling issues in the event of an issue? After a chat with the customer I ripped it all out and agreed to rewire on the understanding that I took ownership of everything electrical in the installation.

Generally natural gas boiler installation seem fairly standardised and good.

There is no standard.
Even within this thread your standard installation seems to differ from mine.

2011

Dardania wrote: »

I’m talking about the responsibility that the CRU seems to imply - it seems to imply that only RGIs are permitted legally to take the covers off boilers.

With what statement? Please quote.

Dardania

2011 wrote: »

With what statement? Please quote.

See my post 14 above
https://www.boards.ie/vbulletin/showpost.php?p=109151184&postcount=14

the specific bit (selecta-copy-pasting a bit...)>

The Commission advises that Domestic Gas Works will cover any work on a natural gas fitting within the scope of I.S.813 with the following exceptions
...
Work that is specifically designed to be effected by a person without the use of a tool;

To me, this means that the inverse is true - if you need to use a tool on a boiler (which presumably is under the scope of IS 813), you are subject to the Domestic Gas Works (and thereby RGI)

2011

Dardania wrote: »

To me, this means that the inverse is true - if you need to use a tool on a boiler (which presumably is under the scope of IS 813), you are subject to the Domestic Gas Works (and thereby RGI)

I think that is a quite a leap. I think you are reading too much into a something that is intended to prevent someone without proper training messing around with the internals of a boiler. It is not supposed to prevent a "competent person" making an electrical connection that is as simple as connecting a plug.
If this was the case would you not expect something a bit more definitive? There are no such regulations in place for systems using far more dangerous gasses / substances / liquids.

Natural gas is safe compared to many of nasties we have on site (large pharmaceutical plant) with electrical and automation systems controlling them. Many of these are carcinogenic / highly toxic / highly flammable / explosive / asphyxiants / highly corrosive. Not just that but we have them in very large quantities. Heck we even had Butyllithium for many years :eek:
...and not a dicky bird from the CRU.

There is no such mention of this restriction in ET101 or the RGI's own technical guide, both would have been very good places to spell this out.

EdgeCase

2011 wrote: »

In my opinion they do, but there is more to it than that.
IMHO more electrically complex systems are best done by someone that has been electrically trained to a higher level.

That's precisely how my RGI approached it. He just let an REC do all the house wiring aspects and was left with just the cables to the boiler to terminate and a few minor things.

2011

EdgeCase wrote: »

That's precisely how my RGI approached it. He just let an REC do all the house wiring aspects and was left with just the cables to the boiler to terminate and a few minor things.

Sounds like a good plan. Once there is an agreement in place that works for both parties there is no issue.

My point is that connection of a cable to a boiler is not beyond the ability of an electrician and they are legally permitted to do this. The same applies to RGIs.

tomoliver

2011 wrote: »

In my opinion they do, but there is more to it than that.
IMHO more electrically complex systems are best done by someone that has been electrically trained to a higher level.


However when I was a REC half way through wiring a large house I maintained proper cable segregation to mitigate the risk of interference on coaxial cables and other communications cabling. I had drilled holes in joists for cabling and kept all of these types of cables separate from power cabling. Everything was neatly loomed and looked the part. Anyway I came in one day and the RGI had filled many of my neatly drilled holes (some of which were through RSJs) with his cabling. It looked horrendous! My segregation of cabling, neat looming and general professionalism of the 1st fix meant nothing to him. Worst of all is that he had managed to damage the insulation on many of my cables by roughly pulling his cables through by not feeding them carefully. So who will take ownership of cabling issues in the event of an issue? After a chat with the customer I ripped it all out and agreed to rewire on the understanding that I took ownership of everything electrical in the installation.



There is no standard.
Even within this thread your standard installation seems to differ from mine.

i had the same issues with alarm installers messing up installation work


i can't see how the RGI is more qualified to connect a boiler than a REC

Dardania

2011 wrote: »

I think that is a quite a leap. I think you are reading too much into a something that is intended to prevent someone without proper training messing around with the internals of a boiler. It is not supposed to prevent a "competent person" making an electrical connection that is as simple as connecting a plug.
If this was the case would you not expect something a bit more definitive? There are no such regulations in place for systems using far more dangerous gasses / substances / liquids.

Natural gas is safe compared to many of nasties we have on site (large pharmaceutical plant) with electrical and automation systems controlling them. Many of these are carcinogenic / highly toxic / highly flammable / explosive / asphyxiants / highly corrosive. Not just that but we have them in very large quantities. Heck we even had Butyllithium for many years :eek:
...and not a dicky bird from the CRU.

There is no such mention of this restriction in ET101 or the RGI's own technical guide, both would have been very good places to spell this out.

I’m semi tempted to write to CRU to adjudicate this one. I tend to think extremely defensively in case anything will ever be challenged legally, after the fact.

With respect to your point about no regs or limited regs for much nastier stuff, it’s a question of access to it.
In an industrial facility, you only have trained staff who are regimented not to touch things they aren’t meant to. There is employment law, lock out tag procedures, SHEW regs, possibly environmental discharge licenses (which drives Hazops and explosion protection documents). All of these different “instruments of law” place controls on what people do so as not to kill themselves or others. Not to mention a thriving compensation culture in Ireland so employers have quite an incentive to ensure these guidances are followed.

Then, you have a gas boiler in every second house in the country, with easy access by the public. And they have an incentive to be cheap and try to skimp on proper practice.
Natural gas may be safer than some of the chemicals you mention (I recall an arsenic room in a plant that I worked in, and possibly you did if I recall a discussion we had a few years ago) but it is still hella dangerous, either in its raw form with an ignition source, as an asphixant, or if it’s badly combusted such that there’s a load of CO resultant.

Your point about the level of competence needed to wire up the boiler is equivalent to wiring up a boiler - in terms of the physical actions I agree, but look at the inception of this thread? It’s obviously easy to screw up the wiring of a boiler if you don’t understand the need to have a permanent live as distinct from a switched live, particularly in the case of a combi. Is your normal sparks aware of that?

From my own experience in places I’ve lived in the past, I’ve had to fix wiring or controls on boilers multiple times due to:
- the permanent live being switched (same problem as op) in one house, via a DIN rail mounted time clock
- no power out through the time clock so all it functioned as was an on off switch (and again it was switching the permanent live) in another house
- the space heating actuator and the DHW actuator mixed up in an apartment (took me an embarrassing length of time to figure out why the water only heated in the mornings when the apartment was cooler...)

My point is, a lot of sparks and RGIs don’t get controls wiring as well as they should. The RGIs should understand more, due to the boiler function being that of giving heat out proberly means they should be more sympathetic to the end users needs, and from troubleshooting boilers.

Maybe the hybrid model where both trades work together is best, as another poster has experience of. Or you have dual qualified staff

2011

Dardania wrote: »

I’m semi tempted to write to CRU to adjudicate this one. I tend to think extremely defensively in case anything will ever be challenged legally, after the fact.

Sure why not? I did, as can be seen here the reply was very interesting.

In an industrial facility, you only have trained staff who are regimented not to touch things they aren’t meant to. There is employment law, lock out tag procedures, SHEW regs, possibly environmental discharge licenses (which drives Hazops and explosion protection documents). All of these different “instruments of law” place controls on what people do so as not to kill themselves or others. Not to mention a thriving compensation culture in Ireland so employers have quite an incentive to ensure these guidances are followed.

I agree, but my point is that electrical / instrument trades are still permitted to do this work without the oversight of another trade. Clearly this has been looked at and the requirement for additional safeguards have been deemed necessary, for example there is a legal requirement for Compex training for work on Atex systems.

HAZOPs tend to deal with operability of a system under normal and fault conditions so as to ensure that the design is robust and safe. It is not so much the actual installation or construction of a system. The EPD is referenced to ensure that the correct equipment is selected in terms of gas / dust group, temperature classification and zone. The EPD has nothing to do with who can legally install a system or what training is required.

Then, you have a gas boiler in every second house in the country, with easy access by the public. And they have an incentive to be cheap and try to skimp on proper practice.

..........and you have a potentially lethal voltage present in every house that the CRU let any "competent person" cary out minor works on and this is explained quite clearly.

Natural gas may be safer than some of the chemicals you mention (I recall an arsenic room in a plant that I worked in, and possibly you did if I recall a discussion we had a few years ago) but it is still hella dangerous, either in its raw form with an ignition source, as an asphixant, or if it’s badly combusted such that there’s a load of CO resultant.

Yup, but it is still very difficult to go wrong with the wiring, and if you did go wrong clearly you are not a competent person so you should not have been at it in the first place.

It’s obviously easy to screw up the wiring of a boiler if you don’t understand the need to have a permanent live as distinct from a switched live, particularly in the case of a combi. Is your normal sparks aware of that?

Speaking as someone that spent many years in my youth working on my tools as a "normal sparks" I would say yes. If in doubt I would have done as I advised, which is RTFM.

This is not rocket science. As a REC I would first fix wiring for many a boiler before I had any idea of the make or model of the unit. I would know that wiring a permanent live, switched live, neutral and earth would get me out of most situations. Some would require a dry contact to start the boiler. Additional wiring could be added following a conversation with the plumber for stats / motorised valves / pumps etc...

My point is, a lot of sparks and RGIs don’t get controls wiring as well as they should.

Agreed.
There are plenty of trades that are not as good or contentious as they should be. I have to deal with this in my job on a continual basis. Unfortunately no amount of regulations are going to change this.