Flow- Vent- Feed -Pump

[desktop987456]

As you have to stop it manually in Serv mode it must be getting a Fire signal independent of the roomstat. The puzzle is why it won't fire in normal mode. It's difficult to analyse remotely! It might be worth rechecking the wiring and ensure it's in line with the manual.
Any chance that Viessmann could throw any light on it?

Exactly. I am not getting any error or fault code on screen. I have sent Viessmann an email, lets see what they say.

 

[Madrab]

It probably won't be an issue with the boiler - where have you wired the the stat on the boiler? Where is the pump powered from? You need to be careful as you could end up blowing the board, if it isn't right.

The pump should be wired to the boiler through the patch lead supplied as I suggested and then plugged into the board. The stat should be wired to the board through the external accessories (230v) connectors, where and how to do that may be on a separate set of instructions that came with the boiler but it's also in the MI and the snapshot I posted. That's why I said remove the stat, if that's where it's wired to and put the bridging wire back in and run the boiler like that and see if it runs ok

 

[desktop987456]

where have you wired the the stat on the boiler

Boiler and Pump are connected in a wiring center with their respective N,L and E.
I dont have the cable or wire harness to connect the pump directly to the boiler.
I have tried to run it without Room Stat connected to the boiler with same result.

 

[Madrab]

Boiler and Pump are connected in a wiring center with their respective N,L and E.

Is that wiring centre just fed from the mains so permanent 240v to the boiler and pump?

I dont have the cable or wire harness to connect the pump directly to the boiler.

Should have come in the box with the boiler, ideally that's where the pump would be controlled from, may be an idea to mention to Vaillant and ask if that cable be supplied

I have tried to run it without Room Stat connected to the boiler with same result.

Was the room stat connected onto the 240V external control on the board after the link was removed? With that link in then there should be a permanent call for heat. Is the capacitor still in place?

 

[desktop987456]

Was the room stat connected onto the 240V external control on the board after the link was removed? With that link in then there should be a permanent call for heat. Is the capacitor still in place?

Room stat was never connected to the board. Capacitor is still in place on board. SL should have been taken from port 1 to Thermostat?

Is that wiring centre just fed from the mains so permanent 240v to the boiler and pump?

Yes

 

[Madrab]

L and SL (1) are to and from the stat, whereby the live runs to the stat and the SL (1) returns from the stat.

So that L/N/E are running from the 230V accessory connectors (G) out to your 'wiring centre'?

It does also state in the MI if there is no pump connected to that slot (D) then a frost stat should be connected, looks like it might be looking for a connection of some type at that point (D in the MI snapshot I posted)

 

[desktop987456]

L and SL (1) are to and from the sta

I can try connecting Room Stat to SL (1) to see if it works? You reckon that boiler should fire without anything connected to external control ports?

So that L/N/E are running from the 230V accessory connectors (G) out to your 'wiring centre'?

L/N/E are going out (F) to wiring center. Nothing going in to the board or boiler PCB.

Wiring center fed by Spur.

It does also state in the MI if there is no pump connected to that slot (D) then a frost stat should be connected

Could be. It does make clicking sounds after pre purging is done or when fan stops.

 

[fixitflav]

I can try connecting Room Stat to SL (1) to see if it works?

You mean it isn't already? How is the roomstat connected (or is it)?

You reckon that boiler should fire without anything connected to external control ports?

It has to have an input to tell it to fire (and to stop when the signal goes). Without a roomstat, if you link L and 1 on G (Madrab's diagram) it should fire, and run start/stop on the control-stat. But need to ensure the pump is running, powered separately if it's not fed from the boiler.

 

[Madrab]

I can try connecting Room Stat to SL (1) to see if it works? You reckon that boiler should fire without anything connected to external control ports?

As long as the bridging wire is in between 1 and L with the capacitor then that closes the switch for calling for heat, as far as external control are concerned. So the boiler should fire when set to on.

L/N/E are going out (F) to wiring center. Nothing going in to the board or boiler PCB.

That is the boilers main power connector, so the mains should be feeding that connection permanently, that can be via the wiring centre.

Reading through the user instructions the boiler should run without any external controls as long as the heating dial is set above 0 and the bridging wire is in place with the capacitor.

Looking at your picture I cannot see if there is a bridging wire between 1and L on connector 96 (G)? if there is no wire there (and capacitor) it will not run under normal mode. I can see the mains N and L beside it but nothing in 1 and L to the right of it or is the bridging wire hidden?

 

[desktop987456]

mains should be feeding that connection permanently, that can be via the wiring centre

I can confirm this is the case.

bridging wire is in place with the capacitor

No

Looking at your picture I cannot see if there is a bridging wire between 1and L on connector 96 (G)

No bridging wire between 1 and L on 96(G). That is exactly what it is doing and is not firing up. I'll try the link wire and report back.

 

[desktop987456]

You mean it isn't already? How is the roomstat connected (or is it)?

Room stat is connected via wiring center. Apart from mains power, we haven't taken any connection to or out of the board. I'll try the link wire and report back.

 

[desktop987456]

The link wire was indeed missing and it did the trick! Thank you @Madrab and @fixitflav

Couple of questions :
- The control wire from boiler (G) 1 which is SL should go to Thermostat terminal (call for heat); Correct?

- I haven't found what the second dial on the left do? Apart from setting the NG (0) and LPG (1) I haven't found anything in operating instructions. There is a key symbol as well on it but not sure what it is used for?

- The flame symbol on display (burner fire power) remains on min firing rate (see pic2 of boiler display), I have tried setting the flow dial to 4 or 6 but firing rate remains on min setting. In Serv mode as you increase the settings on dial from 3-6 th the firing rate goes up with the dial as well but not in normal mode where logic says it should. Instructions doesn't say much on using the dials except to go into Serv mode for flue analysis.

My understanding is that it is a modulating burner, correct?
Thanks again

 

[Madrab]

- The control wire from boiler (G) 1 which is SL should go to Thermostat terminal (call for heat); Correct?

Yes - is the Drayton stat like the RTS1? - if so then I believe that has internal switching so from G to the stat then take the N > N - L>L then from the stat take 3 >1 on the board, though do check that with a multimeter before connecting it to the board. Run the neutral and live to the stat and energise and then check there's 230v being sent out from 3 on the stat before connecting it to 1 on the board (take out the bridging wire but leave the capacitor).

- I haven't found what the second dial on the left do?

As you say that's for certain programming work, usually for the service engineer for programming settings.

My understanding is that it is a modulating burner, correct?

Yes the boiler will modulate and should really only fire at full rate when everything is cold until the system water reaches the dials set temp. if it never reaches the set temp then the only other process that would normally impact on that would be if the weather compensation module was fitted.

Has this boiler been gas rated and analysed? Again not sure what the US regs are but that is extremely important to ensure safety

 

[desktop987456]

Yes - is the Drayton stat like the RTS1?

It has N,L and 3 which is call for heat. Things are making sense and clearing up for me! So for Thermostat to work, the link between 1 and L has to be removed.
With Therm Stat out of the way, programmer doesn't need to get N,L from boiler? Does a SL or other cables need to go to Thermostat?

modulate and should really only fire at full rate when everything is cold

yes, it should but it is not doing it, it keeps the flame at min setting. Prior to the link wire glitch I tweaked settings in Serv mode. I will reset it again, I also read somewhere, don't remember, that in serv mode you can set burner modulation rate and leave the setting for 15 seconds to make them permanent. I will give it a go. I have checked it, the WC module is not fitted on this one. What is your recommendation fitting one for future?

The gas combustion analyses has not been carried out, will get hold of the equipment and get it done.

Thanks again for all your guidance and support.

 

[Madrab]

So for Thermostat to work, the link between 1 and L has to be removed.

The link is removed and the stat is connected to those terminals

programmer doesn't need to get N,L from boiler?

If you're installing a programmer then that's different again, especially if you are using zone valve(s) and a hot water cylinder? If I remember rightly there's a 3 port valve, if so then you need to go and look at a Y plan wiring diagram.



Yes, if you have been in adjusting the settings etc then I would recommend that it's reset to factory specs.

Does your state not require certain qualifications and certificates to allow testing and working on the gas side of appliances? Need to be sure everything is safe for you and yours and everyone around.