Honeywell ST699 wired incorrectly?

[Rob Watt]

Hi, I have a honeywell st699. The controller works fine but in order to get my heating to come on I need to have the hot water going at the same time.

I suspect its either a valve issue or that the wiring on the controller is wrong. The wiring will be easier to fix if that's what it is. Can anyone in the know take a look and give me their thoughts?

Thanks in advance, Rob.

20211014_201612

• Rob Watt
• 14 Oct 2021

 

[RandomGrinch]

Hi,

I'm just a DIY'er, so may not be able to help, and may be completely wrong

But, I wondered what your boiler/heating system is?

According to the manual:

Does that make sense?

Manual here:
https://www.plumbworld.co.uk/docume...-programmer-installation-guide-data-sheet.pdf

 

[Rob Watt]

Hi,

I'm just a DIY'er, so may not be able to help, and may be completely wrong

But, I wondered what your boiler/heating system is?

According to the manual:

View attachment 247007

Does that make sense?

Manual here:
https://www.plumbworld.co.uk/docume...-programmer-installation-guide-data-sheet.pdf

That does make sense thanks. I'm hoping that's not the case though as if the water is hot already the heating doesn't come on at all. That's not too big a deal right now but will become one soon as the weather gets worse.

 

[ianmcd]

Nope that is not wired correctly post pics of everything else you have, motorised valves any thermostats and HW cylinder and we will tell you how to change your wiring

 

[RandomGrinch]

I'm afraid I can't tell if the wiring is correct or incorrect from your image.
There appears to be a link between the live terminal and terminal 5, is that right?
If so it looks as if the live is commoned to 5 and 6, and the outputs (switched lives) are on 8 and 3.
If this is the case, It is not conventionally wired, but should have the same functionality (if relays do the switching!).
But as ianmcd says, it depends what's connected at the other end!

 

[CBW]

There appears to be a link between the live terminal and terminal 5, is that right?

Yes, because if they want a 230v common, then they often use a link wire. 5 and 6 are linked, which shouldn’t be. Also a cpc/Earth has been used as a live, which isn’t good practice either.

 

[RandomGrinch]

Yes, because if they want a 230v common, then they often use a link wire. 5 and 6 are linked, which shouldn’t be. Also a cpc/Earth has been used as a live, which isn’t good practice either.

Hi,
Genuine question, coming from an electronics viewpoint and just trying to understand!

5 and 6 shouldn't be connected together, but if the switching was by relay, I don't believe there would be any difference which terminal (6 or 8 ), was switched live and which was live.
Does the unit use triac switching, or similar?

...and yes, the earth should be sleeved to indicate a switched live.

Thanks.

 

[ianmcd]

Hi,
Genuine question, coming from an electronics viewpoint and just trying to understand!

5 and 6 shouldn't be connected together, but if the switching was by relay, I don't believe there would be any difference which terminal (6 or 8 ), was switched live and which was live.
Does the unit use triac switching, or similar?

...and yes, the earth should be sleeved to indicate a switched live.

Thanks.

You are correct 5&6 should not be linked, by linking them the switching of the HW side has been disabled, reason I asked for a pic of the HW cylinder is I suspect the OP has gravity HW and that has been fitted as a bodge because whoever done that didnt know how to set the programmer up for gravity HW

 

[bernardgreen]

but if the switching was by relay, I don't believe there would be any difference which terminal (6 or 8 ), was switched live and which was live.

True if it is only a Make contact.

I personally would put Live on terminal 6 ( NO ) and Switched Live on terminal 8 ( Com ) which avoids the un-used terminal 7 becoming Live when the relay is de-energised.,

 

[ianmcd]

True if it is only a Make contact.

I personally would put Live on terminal 6 ( NO ) and Switched Live on terminal 8 ( Com ) which avoids the un-used terminal 7 becoming Live when the relay is de-energised.,

and what if it turns out he has a mid position valve, I dont think he does but no one knows as our crystal balls are all down because of covid, the two com terminals are called com for a reason, it is because they are common and need to be linked to whatever supply the other controls are using

 

[bernardgreen]

it is because they are common and need to be linked to whatever supply the other controls are using

Each Com is "common" only to the NO and NC contacts in the triplet of contact for that switch.

Whether or not the Comms of two or more switches need to be connected together depends entirely on the configuration of the system the switches are part of.

 

[RandomGrinch]

Each Com is "common" only to the NO and NC contacts in the triplet of contact for that switch.

Whether or not the Comms of two or more switches need to be connected together depends entirely on the configuration of the system the switches are part of.

That was my thought, the manual shows an inserted link to join the 'commons', so no fixed 'common' on board.
Hence my belief that the unit may be wired 'incorrectly' but functioning as intended.
And, as we have all said, we won't know for sure if anything is incorrectly wired, until we see the connections in the other end!

EDIT:
The ST699 does use relays, and there is no common 'Common'!
It should work properly in the current configuration, with connections the other end being:
Brown - Switched live, Hot Water
Green/Yellow - Switched live, Heating
Blue - Neutral

 

[Rob Watt]

Hello all, thanks for the replies. Hopefully the attached pictures help to show what the current setup looks like.

 

[CBW]

You have an S-plan, with what looks like a hive controlling the heating. It’s still been wired wrong. You still need a live from your programmer to the cylinder thermostat to control the zone valve.

 

[Rob Watt]

You have an S-plan, with what looks like a hive controlling the heating. It’s still been wired wrong. You still need a live from your programmer to the cylinder thermostat to control the zone valve.

Thanks, just searched for hive receiver and that does seem to be a British Gas supplied hive receiver. No idea where the thermostat control would be though. I do wonder if it got removed before we moved in.
Our plumber is coming tomorrow to service the boiler so I think we will get him to come in and see what he thinks.