Room thermostat on Potterton Performa 28

[greenio]

Hi,

I've got a Potterton Performa 28 with an external clock (on a wall in the kitchen), the make is Lifestyle ACL LS111. I've also got a Honeywell T6360 room thermostat. It's a small problem, but annoying, and no doubt bad for my gas bill!

My problem is that the room thermostat doesn't do anything at all. I can hear the click, but it doesn't make the heating go off. So when the clock is telling the heating to come on, it's always on. I tried changing the thermostat for a Drayton RTS8 (as I only have two wires sticking out the wall), but this also doesn't switch the heating.

So I looked at the wiring in the boiler. THere are L, N, Earth, 1 and 2 terminals. The manual suggests a room stat should be wired between 1 and 2. This is the case. There is also a connection from the clock to L, N and Earth. This all kind of makes sense. But there is also a short wire that connects L to 1. I don't understand why. And when I removed it the boiler was dead. So this seems to be supplying the permanent live. If I need this do you have any idea how I can actually have a working thermostat?

Thanks for your help!

 

[matt1e]

There is also a connection from the clock to L, N and Earth. This all kind of makes sense

this doesn't make sense to me the time clocks switch should also be connected between 1&2 in series with the room stat and the boiler should have a permanent supply
also the link between L & 1 should not be there I suspect the reset switch has A problem and its been bypassed

matt

 

[greenio]

That was my first thought - to connect them in series. But to do that meant removing the link from 1 to L and then the boiler had no power. If it helps at all, the mains isolation switch for the boiler is directly above the wall-mounted clock...

 

[matt1e]

That was my first thought - to connect them in series. But to do that meant removing the link from 1 to L

sorry you've lost me again mate

1 where does the room stats wiring run to? boiler or time clock?
2 how many cores are there from the time clock to boiler?

matt

 

[greenio]

The room stat runs to the boiler (terminals 1 and 2).

There is one cable running from the clock to the boiler, which has red (wired to live in the boiler), black (wired to neutral) and green/yellow (wired to earth).

 

[matt1e]

this wiring is not correct

There is one cable running from the clock to the boiler, which has red (wired to live in the boiler), black (wired to neutral) and green/yellow (wired to earth).

wired like this means the pump over run is disabled, the boiler needs to have a permanent supply with all switching done via the 1&2 terminals (unless there is an internal clock)
given that, the room stat should still work the way its connected unless

1 stat is faulty
2 there is still the factory link fitted between 1&2
3 someone has been messing with the boiler wiring and swapped 1&2 (both black cores on the appliance side of the connectors)so that the time clock is now overriding the stat via the link between L and 1 that shouldn't be there

you need to get it all metered out really

matt

 

[greenio]

thanks for that. I'm pretty sure it's not 1, as i tried a new stat, and it's not 2 as there is no wire present linking 1 to 2.

so i guess it must be 3. do you know why it would have been set up that way so that the clock overrides the stat? (i only moved here 6 months ago, so i have no idea).

i have a (very old) multimeter. what should i look for?

thanks again for your help!

 

[matt1e]

I looks to me that its been set up that way because the boiler had a fault at sometime due to the (still knackered) reset switch
someone tried to repair it and started messing with the internal wiring then eventually found that putting a link from L to 1 would get the boiler firing

normally terminal 1 would be connected to the Live terminal via the reset switch it would then fire the boiler via the link or stat connected to terminal 2
ie if there is power on terminal 2 the boiler will fire

if terminal 1 and 2 have been reversed internally then now the boiler will fire on power to terminal 1 (which is now connected to live via the added link)with the room stat now switching to the knackered reset switch
a quick way to check is to connect the link from L to 2 and try the stat if it now works then 1&2 have been reversed

but you still have the problem of a knackered reset switch and no overrun as the time clock is incorrectly wired

matt

 

[greenio]

this is probably a stupid question, but what do you mean by pump overrun?

the pump does carry on for around 3 minutes (i can hear it) after the clock has switched to off - is this overrun?

and what does the reset switch do? (another stupid question?)

thanks again. i'd been puzzling over this for a while, and would never have worked it out myself.

 

[bengasman]

it sounds like the installer has tried to safe some money by re-using existing parts like the external timer and the room stat. chances are he could not get it to work and botched it to make it do something so he could get his dosh and leave.
probably a fairly simple wiring fault.
the really worry is the funny reset situation; hard to say from a distance, but it could be that he bypassed the safety.
get an RGI to make it safe.

 

[matt1e]

this is probably a stupid question, but what do you mean by pump overrun?

the pump does carry on for around 3 minutes (i can hear it) after the clock has switched to off - is this overrun?

and what does the reset switch do? (another stupid question?)
.

1) yes thats exactly what it is
but this means that the boiler must have a permanent live (which it should) and if so, seeing that the timeclock seems to work ok then one must assume that it is wired correctly and switching terminals 1 & 2 not just L on the boiler as I presumed.
are you sure that it is just the room stat connected to 1 & 2?

2)the reset switch resets the PCB after lookout
it also disconnects all external wiring while doing so (this is the part that has been bypassed by the wire link fitted between L and 1)
ie reset switch may still work but external wiring is still connected while doing so

if you are competent with electrics and the use of a multimeter then guidance can be given but some photos of wiring connections would be a good start

Bengasman is giving good advice it all needs looked at on site to be honest

matt

 

[greenio]

thanks for your help both of you! sounds like it's probably not something i should be doing myself (particularly at this time of year - i don't think i'd every be forgiven if i killed the boiler!)

i'll get someone qualified to check out the reset switch sometime soon!

thanks again

 

[namsag]

Be intersting to see a picture of boiler terminal strip cause it really doesnt make sense what they have done

 

[greenio]

terminal block wiring

• greenio
• 24 Dec 2008
• 1

it's hard to take an actual picture (dark and cramped) but here's a diagram. I can try an actual picture if that would help...

 

[matt1e]

terminal block wiring

• greenio
• 24 Dec 2008
• 1

it's hard to take an actual picture (dark and cramped) but here's a diagram. I can try an actual picture if that would help...

weird! it definitely doesn't fit in with the descriptions

the pump does carry on for around 3 minutes (i can hear it) after the clock has switched to off

and

The room stat runs to the boiler (terminals 1 and 2).

There is one cable running from the clock to the boiler, which has red (wired to live in the boiler), black (wired to neutral) and green/yellow (wired to earth).

could this become the xmas puzzle?

wouldn't mind seeing the time clock base-plate if poss

matt