Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is ON

[rojroj]

Some time back I posted a query in this Forum about Boiler either ignoring the Room Thermostat or the Programmer.
I was suggested (by doitmyself and others) to get the Sunvic MoMo 3 Port Valve replaced by a Honeywell.
After getting this done (Honeywell V4073A), the Boiler is now completely ignoring the Programmer.
Whenever, the room stat is calling for Heat, the Boiler turns ON (irrespective of whether the Programmer is ON or OFF).
I have programmed it to be OFF between 10 pm and 6 am. However, whenever the room temp drops below 18 deg Centigrade around midnight (I've set the Thermostat at 18 deg C), the Boiler fires up. I've also tried switching the Programmer to OFF position during the day while the Boiler is running and it made no difference (Boiler kept running).
The Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting.
The Room Thermostat is a Honeywell (Electronic)

Anyone seen this type of problem or has any ideas ?

Thanks and Regards

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

S/L - Yellow - Should this be the Brown Wire from the SwL (Mains) Terminal of the Boiler ?

Yes. They must join somewhere - possibly one of the terminal blocks in the wall

P/L - Red - Should this be the Blue Wire from the Live (Pump) Terminal of the Boiler?

Yes. Again they must join in a terminal block

L - No Connection (always Live) - This must be getting it's Power from the Internal Wiring of the W/C - Should this be connected to the Brown Wire from the Live (Mains) Terminal of the Boiler?

1. Yes it gets power internally
2. If the boiler is getting power directly from the fused spur there is no need to connect this terminal to the boiler mains L

N - No Connection - Should this be connected to the Blue Wire from the Neutral (Mains) Terminal of the Boiler?

See 2 above

E - Earth

Not sure why this is connected; the boiler should be earthed at the Fused Spur.
Can you find the other end and say what it is connected to?

Am I correct in assuming that the Live Power comes from the Fused Spur (in the Wall below the Boiler) to the Live (Mains, not Pump) Terminal of the Boiler (via the Brown Wire from inside the Boiler)

That's what appears to happen. If you have a meter you can verify this

and then goes to the Live (Boiler) Terminal of the W/C?

But you have said there is nothing connected to the Boiler L terminal in the W/C and there doesn't need to be

If so, where am I currently getting my Live on the Boiler Terminal of the W/C with no wires connected?

You answered this question yourself earlier. The W/C Boiler L, N and E terminals are fed by the internal wiring from the W/C Mains L, N and E terminals.

Is the Live Input to the Wiring Centre (Red) Live coming directly from the Fused Spur in the Wall or should it come via the Terminal Block in the Boiler?

It doesn't matter. It would appear to be coming from the fused spur. which is OK. There is no need to change it.

It would be a good idea to check out how the wires are linked together in the terminal blocks behind the wall.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks doitmyself. Shall sort out the Wiring issues first.
Unfortunately I'd have to go on an overseas trip for about a month, so will probably leave it until the New Year.
Shall post an update once I am back.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Shall post an update once I am back.

Please post update to this topic.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sure .

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry for not being able to get back to this for so long - got involved with so many things after returning back.
Are you still tracking it ? If so, we can check the Wirirng issues. Let me know so that I can post a short summary to avoid you trawling through it all again.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

I hadn't been tracking this topic as I delete a subscription if there hasn't been any activity for a week; but I'm back on the case now.

Don't bother posting a summary - unless you think it would help you.

Check the wiring and post back.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

The Wiring in the Boiler are as below.

(Sticker) Programmer Wiring ………........ CH OUT ....... DHW OUT ......... DHW OFF OUT (Sticker)

------- PUMP ------- ........................ ------------ MAINS ---------
... L ……….. N ……...…… E ------------ Sw L …... N …………. L …………. E
Top
Yellow ….. Blue …..... Yellow …............ Red ….. Blue …... Brown ….. Earth
.. o .......... o ............ o ................... o ........ o .......... o .......... o
.. 1 .......... 2 ............ 3 ................... 4 ........ 5 .......... 6 .......... 7
.. o .......... o ............ o ................... o ........ o .......... o .......... o
Bottom
. Blue …… Black …... Earth …............ Brown …. Blue …... Brown …… Earth
...... Not Connected

I have measured the A/C Voltages across the Terminals now.
They are :
Between 6 (Mains Live) & 5 (Mains Neutral) - 247 ~ V
Between 6 (Mains Live) & 7 (Mains Earth) - 247 ~ V
Between 6 (Mains Live) & 2 (Pump Neutral) - 247 ~ V
Between 6 (Mains Live) & 3 (Pump Earth ) - 247 ~ V
Between 6 (Mains Live) & 1 (Pump Live) - 247 ~ V When Boiler not Fired
Between 6 (Mains Live) & 1 (Pump Live) - 0 ~ V When Boiler Fired

Between 6 (Mains Live) & 4 (Switched Live) - 189 ~ V
(with Boiler NOT Fired & Multimeter Red on Terminal 6 )

Between 6 (Mains Live) & 4 (Switched Live) - 150 ~ V
(with Boiler NOT Fired & Multimeter Red on Terminal 4 )

Between 6 (Mains Live) & 4 (Switched Live) - 0 ~ V (with Boiler Fired)


D C Voltage
Between 6 (Mains Live) & 4 (Switched Live) - 12 V (with Boiler NOT Fired)
– Is it from the Pump ?
Between 6 (Mains Live) & 4 (Switched Live) - 0 V (with Boiler Fired)


The Wirings of the Room Stat are as below

0 …………… 0 …………..….. 0
1 ………….. 2 …………..….. 3
Red ….. No Contact ….. Yellow

The AC ~ Volts across the Room Stat Terminals are :
Between 1 (Red) and 3 (Yellow) - 247 ~ V (1[SUP]st[/SUP] thing in the morning)
The DC Volt is 0 V.

However, after the Programmer is ON once (Heating), the AC ~ Volt drops to 120 V between 1 (Red) and 3 (Yellow) with Multimeter Red on Terminal 1 (Red) and drops to 20 V between 1 (Red) and 3 (Yellow) with Multimeter Red on Terminal 3 (Yellow) ???
The DC Volt at that time is 50 V.
This is when I think the Boiler starts misbehaving.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks for the updated information.

The voltages are OK but there are a couple which may appear strange to you

Between 6 (Mains Live) & 4 (Switched Live) - 189 ~ V
(with Boiler NOT Fired & Multimeter Red on Terminal 6 )

Between 6 (Mains Live) & 4 (Switched Live) - 150 ~ V
(with Boiler NOT Fired & Multimeter Red on Terminal 4)

These are due to back-feed from the V4073A motorized valve. This contains a complicated arrangement of microswitches, resistors and a diode, which allows the valve to stop in mid-position.

D C Voltage
Between 6 (Mains Live) & 4 (Switched Live) - 12 V (with Boiler NOT Fired)

This will be from the motorised valve. The diode acts as a half-wave rectifier to the AC current and one of the resistors reduces the voltage.


Several post earlier I told you to cut Links 1, 4, 5 and 6 in the Honeywell wiring centre. Have you done this?

To make it quite clear, this is not me taking a stab in the dark, to see if it works. They are Honeywell's own instructions!

Link 1 is cut because you have a Programmer
Link 4 is cut because you have a mid-position valve
Link 5 is cut because you have a mid-position valve
Link 6 is cut because you have pump overrun.

There is no point going any further until you have cut these links!

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Links 4 & 5 are already cut, but not Links 1 & 6.
I haven't done this yet, as, on your post dated 19th Nov (Post # 20), you suggested to wait until we have checked the wirings :

1 and 6 will have to be cut, but not until we have sorted out my queries above!

It appears now that the connections to the Bolier are OK, isn't it ?

However, those of the Room Stat are NOT. On your same post :

The Red should only be live if the programmer has turned heating ON

This is not the case. Do you think that this could be due to Link 1 being intact ?

Also, from the same post :

Grey should not always be live.
Orange and White do not both have to be the same. The orange is switched live for the boiler, but White (and Grey) are control signals to the valve.

However, my previous notes were without a multimeter. Let me check with the Multimeter and post the readings.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Links 4 & 5 are already cut, but not Links 1 & 6.
I haven't done this yet, as, on your post dated 19th Nov (Post # 20), you suggested to wait until we have checked the wirings

Point taken!

However, thinking it through logically, cutting all four links will eliminate four possible causes of the problem. So, if the problem still occurs, we will know the cause cannot be in the wiring centre - it must be elsewhere.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Just wondering if the Links were left intact (not cut) to cater for non-standard wiring ?
If you are sure that cutting the Links 1 & 6 wouldn't make it any worse, let's go for it.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Just wondering if the Links were left intact (not cut) to cater for non-standard wiring?

Unlikely. How would the installer know which links to leave and which to cut - the workings of the Honeywell are a mystery as dismantling one is not possible.

If you are sure that cutting the Links 1 & 6 wouldn't make it any worse, let's go for it.

Link 1 is cut if you have a programmer, not a "basic timer". The difference between the two is that the programmer allows completely separate timings for CH and HW (e.g HW from 6am to 7am, CH from 6am to 9am) while the basic timer only provided common times for both. The Honeywell ST6400C is definitely a programmer, so you should cut Link 1. It presumably connects two "programmer" terminals together in the Wiring Centre.

Link 1 has to be cut if you have a boiler with pump overrun. The fact that it is not cut could explain why your pump runs when it shouldn't.

I would go for it! We then know that any remaining problems cannot be caused by the wiring centre.

PS Your wiring centre is not popular as it's not possible to see exactly how things are wired together. Most pros just use a 10-pair terminal strip in a junction box. Honeywell also sell them and all their wiring diagrams are based on them. Here's the "standard" wiring diagram for a Y Plan (hold cursor over to enlarge).

.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

OK, I've measured the Voltages in the Wiring Centre (obviously with the Programmer removed) - not sure if it will add any value.

Boiler Terminals :
Between Live & Neutral / Earth = 240 V ~
Between Switched Live & Neutral / Earth = 10 V ~ (3V DC)
Between Pump Live & Neutral / Earth = 0 V ~ / 0 V DC

Pump Terminals :
Between Live & Neutral / Earth = 0 V ~ (Boiler / Pump is not runniong)

Programmer Terms :
Between Live & Neutral / Earth = 250 V ~


Room Stat Terms :
Between Live & Neutral / Earth = 10 / 16 V ~ / 4 V DC


Voltages in the Valve (with Programmer removed) :
Between Orange & White – 10 / 16 V ~

Voltages in the Valve (with Programmer connected and CH ON) :
Between Grey / Orange / White and Blue / Earth – 250 V ~


The only thing that appears to be glaringly wrong is the Voltages across the Live (1 - Red) and Call (3 - Yellow) on the Actual Room Stat :

A) Sometimes it is 240 V ~ even when the CH is OFF (@ Programmer) - I think this is when the Programmer is ignored and the Stat controls the Firing of the Boiler (Boiler ON when Stat calls for Heat even if the Programmer CH is OFF).

B) At other Times - it is 0 V (I guess that Call / Yellow also gets 240 V from somewhere) - I think this is when the Stat is ignored and the Programmer controls the Firing of the Boiler (Boiler ON when Programmer CH is ON even if the Stat doesn't call for Heat).


Anyway, please cross check the above to see if you can spot any other irregularity.
If not, let me know and I'll cut the Links 1 & 6 and take it from there.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

OK, I've measured the Voltages in the Wiring Centre (obviously with the Programmer removed) - not sure if it will add any value.

Anyway, please cross check the above to see if you can spot any other irregularity.
If not, let me know and I'll cut the Links 1 & 6 and take it from there.

Now you are just using delaying tactics!

CUT THE LINKS

Report the results.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

The Links were cut yesterday and manual testing seemed to have worked as it should.
Will observe for a couple of days with Programmed timings and update.