Logic Combi ESP1 35 always showing demand for Central heating

[theboyroberts]

Hi folks,

I've got a potential problem with my Logic Combi ESP1 35. When the boiler is set to Central Heating and Hot water mode, the boiler indicates that there is a constant Demand for Central heating.

When the thermostats (TP5000 Si) are turned off (both pulled from the wall and also simply by turning off the heating either via temperature or timer) boiler continues to fire. The boiler indicates that the temperature of the system is always around the 50c mark and as soon as the temperature drops, the boiler kicks in and heats the water again.

I have a dual zone system with some form of valve system which is controlled successfully via the thermostats (photo attached) and as the radiators do not get hot unless triggered by one of the two thermostats i can only assume that it is working as expected.

Initially I believed that this was by design, however after finding a similar post on this site, I'm now not too sure.

I suppose my question is this; when the two thermostats are set to off, should the boiler be continuing to heat that water system or should it go into standby mode and allow the temperature of the system to drop until the thermostat kicks in to show a demand for central heating?

I've also included a picture of the thermostat wiring, which I believe to have been correctly wired.

Thanks in advance for any advice.

Shaun

 

[John.g]

Terminal (from left) 3 Shaun if terminal 4 is live with link removed?? (post 15).

 

[Deleted member 120897]

It’s as easy as removing the red link and installing the black wire in where the right hand terminal where the red link one eg closest to the live terminal

EditEd, I see it now

 

[theboyroberts]

Just like the attached ShaunCorbs?

 

[theboyroberts]

John.G - not sure if you've noticed, but there's blue sleeves on the grey wires.

 

[Deleted member 120897]

John.G - not sure if you've noticed, but there's blue sleeves on the grey wires.

That just denotes the grey wires are being used as neutral wires.
My bad, just noticed the grey from your zone valves are connected to lives, the neutrals are connected to grey sleeved wires acting as neutrals. So yes, just connect up as Shaun has said, just the black wire to the terminal closest to the incoming live - NO LINKS!

 

[Deleted member 123817]

If the link is just removed and the stats are still switching the supply then thiseans that they are fed from elsewhere and the black wire should be inserted in terminal 3, period.??

 

[Deleted member 123817]

What number terminal is this please, from the left.

 

[theboyroberts]

I believe i understand this now

The black wire which enters to the bottom of the Room STAT/Timer block link is carrying power which is carried over through the link into the red wire leaving the bottom and activates the demand for central heating. Hence the boiler firing constantly.

By removing the link and placing the black wire in the 4th position (counting from the earth as number 1) as soon as the thermostats activate, power travels down the black wire and the demand for central heating fires the boiler.

Is my understanding correct?

 

[Basher]

What number terminal is this please, from the left.

I agree with your post #36
From the technical sheet, diagram C, the boiler requires switched mains on terminal 3 from the left - ie the left hand connection of the red link, which will be removed.
So the black wire goes there, and nothing goes in the next one, according to diagram C.

 

[Basher]

I believe i understand this now

The black wire which enters to the bottom of the Room STAT/Timer block link is carrying power which is carried over through the link into the red wire leaving the bottom and activates the demand for central heating. Hence the boiler firing constantly.

By removing the link and placing the black wire in the 4th position (counting from the earth as number 1) as soon as the thermostats activate, power travels down the black wire and the demand for central heating fires the boiler.

Is my understanding correct?

No that is not consistent with what Diagram C shows. Surely the power needs to be fed into the next terminal along - the 5th position as you are counting?

 

[theboyroberts]

Got it

 

[Basher]

Got it

But I'm not buying a new boiler if it's wrong

 

[theboyroberts]

Just heading out folks - really appreciate the help.

I'll make the change when I get back at about 7:30pm and will report back.

Thanks again!

 

[Basher]

This assumes that all the wiring centre power is coming from the same supply circuit as the boiler.
That is the proper and most likely arrangement.

But if you get issues with an rcd tripping (not MCB) then that would point to them being on different circuits from the consumer unit, which would need to be corrected.

 

[theboyroberts]

They are on the same circuit - checked this when I flipped the RCD during testing last night.

Will report back later folks

 

[ShaunCorbs]

I believe i understand this now

The black wire which enters to the bottom of the Room STAT/Timer block link is carrying power which is carried over through the link into the red wire leaving the bottom and activates the demand for central heating. Hence the boiler firing constantly.

By removing the link and placing the black wire in the 4th position (counting from the earth as number 1) as soon as the thermostats activate, power travels down the black wire and the demand for central heating fires the boiler.

Is my understanding correct?

Edit correct

 

[Deleted member 123817]

To be sure to be sure, remove the link and check for power at terminal 4 (from left)) if 230V there and 0V at termina 3 then black wire goes to terminal 3 .

 

[ShaunCorbs]

Terminal (from left) 3 Shaun if terminal 4 is live with link removed?? (post 15).

Sorry just seen instructions yep

 

[ShaunCorbs]

Just like the attached ShaunCorbs?

Without the red link linking live to room stat

 

[theboyroberts]

Sorted!

All working as expected

Really can’t say thanks enough for all of your help - really amazing bunch of folks here on the forum.

Chuffed to bits!

 

[John.g]

That's great news.

During all the time your boiler was running on/off with the zone valves closed how did the boiler have minimum circulation?
Is there a ABV installed and if so is/was it noisy in operation, if installed, what make.

 

[theboyroberts]

Abv?

I don’t think there is one.

 

[John.g]

Your boiler may have its own internal by pass which must be pretty good otherwise all that running with no flow wouldn't have done the Hx any good or maybe its stainless.