Worcester Bosch Boiler

[Peter]

I have a Worcester Bosch boiler which has a wireless controller. 

I intend to remove the controller and wire the boiler directly to the miniserver. 

I guess I should ask Worcester this question but in the spirit of sharing info can anyone tell me what I need to change in the boiler control system?

Also, I already have some basic config files to achieve control of the central heating / hot water but would appreciate copies of more advanced versions or programming advice.

Many thanks

Peter

[Duncan]

this will help you with some overview of the basics


https://www.worcester-bosch.co.uk/files/troubleshoot/gas_wiring-guide_smaller_3.pdf

if your particular boiler model has a volt-free input then you can connect a loxone relay directly to that. if it doesnt, you will have to use a relay to switch the 240v input

[Lillpete]

I've not come across one with a wireless controller? Are there zone valves?

I would expect that you can simply put a240v feed onto Lr to get the boiler to run (I've used nano air for this before to make life very simple wiring wise)

[Peter]

Lillpete

We're installing the central heating system from scratch.

The system is not currently zoned, however, it will be. Some of the downstairs rads are already connected to a heating manifold which will be controlled individually by actuators. The upstairs rads are not yet installed but will use a manifold also and probably Tree actuators (to save on relays).

The Worcester Bosch wireless controller is very basic, whilst it is mobile, it can only set one temp for the whole house. useless really.

Duncan

Many thanks.

[Lillpete]

Where will you get your temperature feeds from?

[Peter]

Touch Tree

[Martyn]

Hi Peter,

Combi, System or Regular Boiler?

Martyn

[Peter]

Hi Martin, a regular boiler with a WB thermal store. The thermal store will eventually be linked to solar panels, although haven't got that far yet.

[Peter]

Since my original post over a year ago I didn't actually get round to connecting the boiler to Loxone, but now we've finally got the 240v actuator wiring in place and the actuators working via a DMX relay (thanks Duncan) we're ready to crack on.

The plumber was round recently and I took the opportunity to ask where I could connect a volt free contact and he showed me the top two connections marked B B of the grey terminal block in the right of the photo. There is also a 24V print on the label, which you can just make out in the video. I've looked in WB wiring documentation and I can't see this block mentioned or confirmation what it is for. 

My boiler is in the first chapter of the video.

https://www.youtube.com/watch?v=iJ3nPK9ZSJs

Said plumber is surprisingly not familiar with Loxone and didn't apart from suggesting using the grey terminal block wasn't much further help. 

So I'm wondering how best to fire up the boiler, both fot heating and hot water.

On Friday, November 4, 2016 at 8:27:28 PM UTC, Peter wrote:

[DavidL]

From watching some of that video, I think you may need to use 230v from a relay to the Lr input to switch the demand on and off.

I wouldn't want to comment without finding either an installers manual, or speaking to someone who knows about the volt free or 24V inputs, if there are some.

David

[DavidL]

Just had a look at the installation manual, which is freely available online (search google).

Looks like the inputs marked 24V are for external temperature control. The B B labelled inputs are for sense controls, whatever they are.

You may have to use the 230V input for heat demand.

[Peter]

David
Not sure where you found that wiring diagram, I’ve been all over WB’s docs and haven’t come across that particular drawing, but many thanks for taking the trouble.
I can take a 230v switch live either from a miniserver relay or preferably my SRS 230v DMX relay, although not sure if the latter is suitable.
Which leaves the L & N.
Am I replacing the existing boiler 230v power supply with those connections?
Also, whilst I get this is going to fire up the boiler if there is a heating demand, how do I manage tha HW demand?

[Duncan]

no, you have to leave the boiler existing 240v supply on all the time, just take a wire from the Ls, conntect to one end of your ssr, and the other end of the ssr return to the Lr connection - you dont need neutral to the ssr

[Peter]

Duncan, thank you for the reply.
I’ve thought about this some more and also a bit more research.
I don’t quite follow your advice.
LR is the switched live, which I take from a SRS relay ( you said SSR in your reply, which I think is a typo).
I’m not sure where I take the live from for the LS. I’m guessing that could come from the SRS common connection.

I find this incredibly frustrating as I’m not happy with just connecting wires, I really want to know what’s happening when they’re connected! And I don’t understand what the LS live actually is for.

I’m also struggling with replacing a wireless controller with Loxone. I get that a temp sensor will essentially open a radiator actuator and send a demand signal to the boiler. But I’m losing the functionality of the controller to heat the water in terms of when the water is heated. Mostly the controller is set to ON which allows the temp sensor in the tank to fire the boiler.
With the removal of the controller how do I achieve the same output?

Apologies for the repetition

[Andy Wain]

If I were installing heating control on this boiler I would take out the link between Lr and Ls, and connect the relay across it.

Loxone is now you programmer and thermostat.

On a traditional system the programmer would turn the supply to the thermostat on and off which would in turn turn the boiler on and off.

With loxone you programmer it by saying I would like it to be 12c all night. At 6.30am it is 20c until 8 when is 12c... And you get the idea.

The thermostat and programmer are combined and as such can go across the thermostat connections in your boiler. As you rightly say, the boiler programmer need to remain permanently on so the Ls terminal remains live

I trust that makes sense

Andy

[Duncan]

do you know how the plumbing is configured? if you have a thermal store, it could be that the boiler only heats the store, and both heating and hot water are run from the store. If this is the case, there will be some pumps and zone valves on the output(s) of the store and loxones control will need to be configured slightly differently.

[Peter]

Duncan. The tank is a solar thermal store. The bottom half is heated by solar panels and the top heated by a conventional boiler. I’m pretty sure that perhaps unsurprisingly a diverter valve is also fitted. I’ve sent a text to the plumber for confirmation so hopefully will have confirmation tomorrow.
Andy. Thank you for taking the trouble to reply. I mostly get what you’re saying but I’m afraid I’m still struggling with the live wire, argh!

[John Verdicchio]

Peter

try this picture and post of my wiring to my Bosch-Wocester boiler 

https://groups.google.com/d/msg/loxone-english/R5sFZgcgcOw/aGJXelAlAAAJ

[Peter]

John
I’d forgotten about that thread, thanks for pointing me back to it. Looking at your drawing the LS and LR connections are fed from the same relay, which is what I think Duncan and Andy were suggesting. I really need the Plumber to get back to me so I can understand what this actually does in electrical terms and how it fires the boiler to provide heating and HW. Until I get that straight I can’t do the config, although I think that’s going to be quite straightforward.

[John Verdicchio]

Peter

If it helps I'm a qualified electrician. So I'm happy that the wiring does what it's supposed to. I've also just had my boiler serviced by a certified Bosch installer and he seemed happy too. To answer your question about what happens:  I always have hot water , that's what the permanent live gives to the boiler. The Switched Line fires up the central heating circuit. ie the central heating pipe has hot water in it AND the pump within the boiler is turned on so the hot water is pumped around the central heating circuit.

Not all boilers have built-in central heating pumps so potentially you'd need a separate pump Line feed. This would look like the UFH section of that drawing.

Hope this clarifies things.

[Peter]

John, I think I initially read your diagram wrong. First look it appeared both your LS and LR connections were fed from the same relay, which would have meant the HW only being heated when there was a demand for CH. However I can now see that isn’t the case.
So tomorrow I’ll give it a go.
My only remaining observation is that by providing a live supply to LS the tank thermostat is in full control of when water is heated. I guess I could connect LS from another relay and then programme that in a config file? The alternative is that HW is continually heated even when I don’t need it. Away from home holidays etc.

[Dick Llewellyn]

I think you're misunderstanding the LS terminal. LS is a live output from the boiler which you would switch as required and bring back to LR. (LS - live switch output, LR - live return). In a traditional heating system you would take LS and N from the boiler to the programmer, this in turn would give 2 switch lines, one would go to the room thermostat, the other to the cylinder thermostat. When the programmer and the thermostat call for heat, this opens a valve, and a micro switch in the valve returns the live to the boiler in order that it may fire and heat the water to pump round as the valves dictate. The idea here is that we replace the prgrammer with Loxone, we use room sensors for temperature etc. At its basic level you have a single zone controled by a divertor valve to all rads, or we split it further with rad valves, underfloor heating zones etc.

[Peter]

Dick, I think you're probably right!!

I'm not normally this dumb, but for some reason I've (obviously) been struggling with this, mostly because I don't understand the basic principles of the electrical wiring of a boiler and the demands placed upon it.

Anyway rather than using the SRS DMX relay, I'll copy John's wiring suggestion, use a Miniserver relay and take it from there.

At this risk of continuing to sound stupid, I still believe I have surrendered control of the HW to the tank thermostat, unless I can connect the thermostat to Loxone and not the boiler? We do spend considerable periods of time away from home and I don't see the point of heating HW when I'm not here.

[Duncan]

there is no advantage to using a loxone relay rather than one of the dmx relays - as long as mains is switched by a device to the Lr input, the boiler will be on.

in order to give loxone control of your heating, you would disconnect 240v from your tank stat, and give it 24v from loxone, and connect the stat other connection to a loxone digital input - loxone then knows when the tank is requesting hot water.

in your config, you can then use a schedule block to set when you want the hot water on, and ADD its output to the digital input from the tank stat - the output of this is then on when the schedule is active and the tank stat says it needs heating up.

this output from the AND is linked in your config to the relay switching mains to the Lr (dmx, loxone, doesnt matter as long as it sends 240v to the Lr terminal) and therefore turn on the boiler when hot water heating is required.

in the real plumbing world, the 240v output of the tank stat drives a zone valve which opens the hot water to the cyclinder, and the mains from the stat is switched by the zone valve when fully open and this internal switch supplies the 240v back to the Lr input - that way the boiler is turned on only when the zone valve to the cyclinder is fully open (stops the boiler pumping against a closed valve and boiler cycling)

so, we leave the stat switching 240v to the zone valve, but connect the feed of the zone valve internal switch to 24v instead of 240v, and feed this to a digital input to tell loxone that the water needs heat.

or to keep things really simple you leave the zone valve switch using 240v, but disconnect it from Lr at the boiler and have its output drive a relay or 240v ssr which switches 24v to a loxone digital input

to add in heating control of your boilder, your IRCs are linked to an ITC and the digital output of the ITC effectively ORs any heating demand - this output connects to the relay firing the boiler.

depending on your plumbing theres probaby other zone valves at the output of the boiler to the manifolds, or at the input of the manifolds, again designed to cut off flow when theres no heating requirement, although its possible if its a Y plan theres a single 3 port motorised valve to split the boiler output to either the hot water tank or the heating (i would hope that a modern system isnt plumbed like this, it should have a motorised zone valve for the hot water feed and another for the heating)

assuming its got separate zone valves for hot water and heating, weve already dealt with the one for hot water, but we need to find out how the one for heating is connected. The heating zone valve has limited functionality with a manifold system, because if hot water demand comes on but all the manifold valves are closed due to lack of heating demand, no water can flow anyway round the heating. You need to ensure that the heating zone valve is on when heating is required - either its on whenever the boiler is powered up (probably connected to Lr) or another 240v relay controlled by loxone powers the heating zone valve separately.

we can add a time delay to the boiler demand for heating with an on-delay block, to allow time for the heating zone valve to open

[Duncan]

on my own house, ive planned loxone control before building, so dont use any mains controls at all or the tanks stats.

i have:
1-wire sensors inserted into the tank stat holes
a single zone valve to control boiler feed to the hot water tanks
dmx relay for the boiler firing with a switch-on delay to reduce rapid cycling of the boiler
dmx relay for the hot water zone valve
dmx relay for each manifold pump
dmx relay for each manifold actuator
an IRC for each room with a temp sensor
an ITC for each manifold to summate the demand for the IRCs of rooms fed by that manifold

hot water has a loxone schedule, and compares the hot water temp to a virtual input - not necessary but it allows me to adjust hot water temperature - minimum 60deg C for legionnela , but if the kids are all home and hot water demand likely to be high, i can increase the tank temperature thus storing more hot water. Demand for hot water heating powers the zone valve via the dmx relay, and powers the boiler via its dmx relay

each ITC digital output powers the dmx relay to power the manifold pump
all 3 ITC outputs and the hot water demand are ORd together to power the boiler dmx relay

[Peter]

Blimey Duncan, you've taken a huge amount of trouble to post all this stuff - thank you.

The boiler is fitted with a WB integral diverter valve assembly which comes with its own temp sensor, making the tank stat redundant.

The manifolds are not fitted with motorized valves - as i recall we hadn't really confirmed with the plumber how we were going to heat the house (use of manifolds) when the boiler was installed.

I think I'm just about there with the CH config:

Each room has an IRC with a temp input and actuator outputs - actuators downstairs are 240v connected to the DMX relay and upstairs are Tree.

I've added an ITC and assigned the rooms I want it to control.

I'd actually already added a 2 min 'On Delay' to the boiler demand to allow the actuators time to open (I got something right - wohoo).

So, just the wire to connect to the boiler from a relay and I'll see how it works.

Once I'm happy with the CH side, I'll take a look at the HW, but in the meantime, I'll essentially have HW 24/7 until I route the stat via Loxone.

I've also just been reading a WB Techincal Bulletin:

https://www.worcester-bosch.ie/support/literature/download/TB0052

[Duncan]

this diagram seems to show what you have with the diverter valve
,
if thats the case, then the 2 connections to the room stat need bridging at the boiler connector (4 and 5 linked together) and the programmer is replaced by 2 loxone controlled relays which switch 240v to connector 4 for heating and 6 for hot water - the relays are driven by the logic previously discussed, a scheduler block for hot water and the output of the ITC (s) for heating.

[Peter]

Duncan

No I don't think so.

Two pics attached. The coiled up cable is the tank stat which I assume was supplied with the diverter valve. This is plugged into the board just below the wiring loom.

The wire from the grey box with a temp dial on the front is the tank over-heat stat (the temp setting is redundant), The live is connected to the L connection on the green terminal block and the Neutral is connected to the live choc box terminal (boiler supply)

Edit: Don't forget this has a wireless controller.

Update. Well. that was disappointing.Connected the LR to a relay on the Miniserver and a permanent live from the other side of the relay to LS only to pop the breakers.On the plus side the Config is working as are the actuators.

[John Verdicchio]

Are you using RCBOs or a split board with RCD? If it's a RCBO then you need to have all the current that leaves it to go back in. If you have two RCBO cross-connected then they will trip. If it's a split board with an RCD protecting each side then you can't cross connect between the two sides. If you're not doing any of that and a breaker is tripping you've got a short circuit.

[Peter]

Wow!

The consumer unit is spilt, each with a RCD and individual MCBs

Loxone is fed from one side and the boiler from the other.

So, you seem to have hit the nail on the head! Presumably the solution is to switch either the Loxone or boiler supply to the other side of the board?

If it has any relevance, the Loxone enclosure has a number of RCBOs, each providing feeds for different stuff.

[John Verdicchio]

Correct.

An RCD and an RCBO in current balance mode check to ensure all the current that left the device returns to the device. If there is more then 30mA of imbalance it trips. The assumption being is the someone is electrocuting themselves. ie the returning current is going via the person to ground.

In your case no one is being electrocuted but the Loxone switched Line current from the relay is returning via the neutral to a different protection device.

Hope this helps.

[Peter]

Yes John, it really does. I don’t know how long it would have taken me to realise what was causing the breaker to trip. Will have another go today and fingers crossed will finally have ‘smart home’ control over the heating 😀

[Peter]

John.

Moved the boiler MCB to the other side of the board and the RCDs are no longer tripping - success thank you.

However (groan) have a run a wire from the permanent 240v supply side of a Miniserver relay to NS and a switched live from the relay  to NR (this digital output is in the config as a boiler demand) and the enclosure RCBO tripped.

Also tried a permanent live from the 240v common supply side of the SRS DMX relay to NS and a switched live to NR (nothing in the config for this relay) and it tripped the (different) RCBO.

Clearly there is still something wrong :(

Ok, so i don't think this has got anything to do with the RF controller. However, having solved the RCD issue I do wonder if the RCBOs in the enclosure are now causing a further complication.

The Loxone enclosure and boiler supply are fed from the Consumer unit - now from the same side. 

The Loxone enclosure supply from the consumer unit is then fed through 6 x RCBOs each of which supply power to the 24v power supplies, Loxone and DMX 240v relays etc.

Is the RCBO causing the problem, ie crossing over again?

[John Verdicchio]

Sounds like it. Remember, all wires out, all wires back in. NO crossing between any device

[Peter]

Ok, how does this sound?
Run a live from the Boiler MCB to a 240v Miniserver Relay and then to the LS (bypassing the Enclosure RCBOs). Permanent live.
Then take a switched live from the Miniserver relay to LR.

[John Verdicchio]

Yes. That sounds correct.

[Peter]

Spoke with Worcester Bosch today and confirmed how this wiring should work. Now I’ve got it clear I can see that some of the advice you guys offered was exactly right. Unfortunately I had a mental block with this subject and couldn’t grasp the ( what is a simple) principle.

No need to provide a permanent live from MCBs etc. Run a cable from LS to a Loxone or SRS relay which is the permanent live FROM the boiler. Then a cable from the switched side of the relay to LR. That’s it.

So the principle, room stat calls for heat which switches the relay, which in turn provides a live feed to LR (from LS) which then fires the boiler.

Quite simple really, sorry for the dumb approach but hopefully useful to any lurkers!!

[Andy Wain]

Peter

I am glad you got that connected correctly as otherwise you had a potentially dangerous situation where the boiler was supplied from two circuits. Everything in the boiler needs to be isolated when you turn off that circuit which you now have.

It is even more dangerous to have two different circuits connected to the boiler if there is a 3 phase supply as there is at the house I am installing Loxone in at the moment, then you could have 415v in the boiler.

Glad you got it sorted

Andy

[Peter]

Andy
Nice of you to comment.
Certainly no criticism from me of anyone who provided advice, not their fault I failed to understand the principles of what I was trying to achieve. It’s also actually very easy to misunderstand what someone is saying or asking and then doing the wrong thing!
I value this forum tremendously and hope that it will continue to grow.
I learned an important lesson though, phone the OEM first. WB were incredibly helpful and it took just five minutes to talk it through. 😀

[Peter]

Update: wiring for the heating now complete with the ground floor 240V actuators online along with the first floor Tree actuators.
Happy to report all is working as it should be.
😀