Wiring an ACL Lifestyle LP111 to a Room Thermostat

[ace4000uk]

Hi Everyone, Can anyone confirm if i've got this right?

I want to add a room thermostat to my ACL Lifestyle LP111, which controls a woster 28cdi combi boiler.

I've got a Drayton Combi-Stat RTS8 room stat to hook it all up to, but i wanted to make sure that i've got the correct idea about the wiring - it's too cold to mess it up!!

I've got 2 guesses on how this thing will work - one from reading other posts on the forum, and one from the instructions

Suggestions on the best configuration please!

Untitled

• ace4000uk
• 15 Feb 2011
• 1

Thanks

Dan.

 

[DeviledAvocado]

Hello.

Guess 1 is correct. Oh, and guess 2 is correct also

Guess 1 is probably better, but will require a third wire - a neutral (which you already know.)

I had to look up this particular room stat because most of these 'bi-metallic' types NEED a neutral to work correctly. This particular one, however, can 'seemingly' get away with only two wires if you want by wiring the accelerator resistor in series with the load so the supply going to the boiler goes through a resistor.

However, [/i]I suspect it'll work a li'l bit more sensitively if 'guess 1' wiring is used. But it might not make any noticeable difference...

Anyways, what you SHOULD be fitting is a programmable room 'stat such as the Heatmiser which will transform how well your heating and timing is organised.

 

[ace4000uk]

Decided to go with guess 2 with the 3rd wire in the end - not blown up yet and it switches the boiler off when it gets hot so I’m happy!

Thanks for your reply DeviledAvocado - What are these mythical devices that will revolutionise my heating arrangements - went with the cheapo thermostat because of the cheapness!

Seems to work okay but it's a bit insensitive - if an ant farts and pushes the dial slightly the wrong way it can end up a bit too hot / cold - am thinking i should have gone with something more digital - any suggestions?

 

[Whitespirit66]

http://www.heatingcontrolsonline.co.uk/honeywell-dt90e-digital-room-thermostat-p-481.html

 

[matt1e]

use the 3wire option, a Worcester CDi requires the anticapator connected

This particular one, however, can 'seemingly' get away with only two wires if you want by wiring the accelerator resistor in series with the load so the supply going to the boiler goes through a resistor.

But not for the CDi series, refer to the MI's

Matt

 

[DeviledAvocado]

Hats off to Matt - you are absolutely right about the CDi. Phew, thankfully the OP went for the three-wire option anyway

(I guess the CDi boilers have a greater resistance in their switching circuit so a 2-wire connection of this 'stat wouldn't have enough current going through it to operate the 'series' accelerator resistor. The 'stat he's used has 2 accelerator resistors inside - one for 2 and one for 3-wire connection. But the 2-wire setup does seem a compromise at the best of times.)

Ace, if these electro-mechanical room 'stats aren't wired up correctly - so that the accelerator resistor isn't heating up as it should - then the symptom is that it'll be very 'sluggish' in performance. Ie: when it turns the heating on, there will be a bigger temp change before it 'clicks' and turns the heating off again. Expect a 2-3 degree temp change between switchings, which will be noticeable and probably uncomfortable. When wired correctly, they should actually be ok. The reason they need the accel resistor (heater) inside them is because the bi-metallic strip - which bends with heat to operate a switch - is a very crude device and doesn't bend much with tiny changes in temp. So, when it 'clicks' to call for heat a little resistor-heater comes on beside it to help warm it up and 'click' off much sooner!

Not having moving parts means that electronic room 'stats can be as sensitive as you want - in theory. Funnily enough, if it was TOO sensitive - keeping the room temp within a half-degree, for example - the boiler would be switched on and off continually which would soon wear it out. So, with these 'stats they have to do the opposite of the electro-mech ones; they have to built in artificial sluggishness!

The general consensus is, I believe, that the digital ones are superior, tho'. They are certainly more flexible and can have useful features such as 'temp hold' - keeping your temp high for an extra hour before going back down, etc -

And, the best of the bunch is the "Programmable 'Stat". These are no bigger than your current room 'stat and will fit directly in its place. It will take over both your programmer's TIMINGS and the 'stat's TEMPS.

For example (god, how many times have I explained this on Screwfix... ), you could program it to turn on the heating to 20oC at 7am, go back down to 16oC at 8.30am, back up to 20oC at 5pm, down to 15oC at 10pm for overnight use, back up to... All done automatically. AND it'll work out how early your heating has to come on each time to get the house to temp at the time you want. And it can be set to 'holiday' to keep your house from freezing when you're away. AND it can be over-ridden or delayed or whatever as you wish...

Cool? Yep. I just bought a brand new Heatmiser PRT (version 3) on eBay for £32 delivered. You can get them for around £40-odd on Amazon and other places. Once you've gone the Prog Stat route, there's no turning back... Cos it's cool.

Oh, and since you've wired up 3-cores + earth, do go for a mains-powered one like the Heatmiser (there are others, too) and NOT a battery-powered type.

 

[plumbandplumber]

use the 3wire option, a Worcester CDi requires the anticapator connected

This particular one, however, can 'seemingly' get away with only two wires if you want by wiring the accelerator resistor in series with the load so the supply going to the boiler goes through a resistor.

But not for the CDi series, refer to the MI's

Matt

How do you wire it up as 3 wire if its volt-free contacts?

If you look at fig.5 on the Drayton install PDF, 3 wire is for 240V

http://www.draytoncontrols.co.uk/supportingdocuments.aspx?id=1504# (click 'Heating Thermostats', then 'Combi Stat')

Figs. 6 and 7 show two ways of wiring up with 2 wires for volt-free. If you read the instructions to the right of the three diagrams, it tells you how to make sure it is wired up properly with 2 wires for correct anticipator functioning. You need to use a test meter. Perhaps the OP didn't do this.

Still don't see how to do it with 3 wires for volt-free??

 

[JohnD]

Still don't see how to do it with 3 wires for volt-free??

On a similar stat, there are terminals for live in and neutral in (to work the electronic stat) plus live in and switched live out to the boiler. You bridge the two Live In terminals together, either with a supplied copper link, or with about 25.4mm of brown wire.

BTW I have recently gone over to a programmable stat, and comfort levels are much improved. Very little manual fiddling is now required.

 

[DeviledAvocado]

Wait a minute - "2-wire" and "volt-free" are different things. Often associated, yes - but not in this case.

If the OP's boiler is being fed by an ACL Lifestyle LP111 Programmer, then it ain't 'volt-free'. That programmer delivers 240V. (Mind you, perhaps it can be wired just as a 'switch' so could be made volt-free?) HOWEVER, as far as I can see, the Combi-Stat RTS8 certainly AIN'T a volt-free device either.

The Combi-Stat RTS8 has a '2-wire' option only because it was designed to help out peeps with no neutral going to their wall position. For this, it was fitted with TWO accelerator resistors inside it, one working as normal in parallel with the boiler as in normal 3-wire room 'stat setups, and the other resistor is wired in series with the boiler should only 2 wires be available - live in and switched live out.

The Combi-Stat RTS8 has NO option for volt-free use shown in its instructions, so if it's wired that way then it certainly won't work sensitively enough as there won't be 240v across the resistor. What's more, if the ACL LP112 is firing 240V out to the 'stat and the boiler is a volt-free device, then the boiler is bu**ered anyway...

 

[matt1e]

How do you wire it up as 3 wire if its volt-free contacts?

If you look at fig.5 on the Drayton install PDF, 3 wire is for 240V

http://www.draytoncontrols.co.uk/supportingdocuments.aspx?id=1504# (click 'Heating Thermostats', then 'Combi Stat')

Figs. 6 and 7 show two ways of wiring up with 2 wires for volt-free. If you read the instructions to the right of the three diagrams, it tells you how to make sure it is wired up properly with 2 wires for correct anticipator functioning. You need to use a test meter. Perhaps the OP didn't do this.

Still don't see how to do it with 3 wires for volt-free??

Hi the answer is... you can't and you don't, you use 2 wire for "volt free"
if you again look right to the table on the right of the aforementioned calibrating instructions, you will see a small list of boilers that are marked either 2wire, 3 wire or 2/3*
the ones marked with a 3 are all 230v switching
the ones marked with a 2/3 are all either voltfree or 230v switchable or yhey are 230v and 2wire connection capable (but (*) 230v prefered)
the ones that are marked with a 2 are all "voltfree" and hence 2wire only

to help explain a bit further
when boiler manufacturers refer to "voltfree" switching or connections they are refering to the switching device and not the boiler connections as they are never volt free, they are extra low voltage ie not 230v mains
confusing I know but what they mean is "dont put mains voltage here just connect a switch between the 2 terminals"

the anticipator in the thermostat warms up due to current flow
when the switch in the stat closes it completes the extra low voltage circuit and hence current flows through the anticipator same as it would with any level of voltage (which is why its important to calibrate it)

but as already mentioned the digital ones are more accurate and less faff on
hope that helps

Matt

 

[matt1e]

HOWEVER, as far as I can see, the Combi-Stat RTS8 certainly AIN'T a volt-free device either.

I disagree, It is

The Combi-Stat RTS8 has a '2-wire' option only because it was designed to help out peeps with no neutral going to their wall position. For this, it was fitted with TWO accelerator resistors inside it, one working as normal in parallel with the boiler as in normal 3-wire room 'stat setups, and the other resistor is wired in series with the boiler should only 2 wires be available - live in and switched live out.

I agree

The Combi-Stat RTS8 has NO option for volt-free use shown in its instructions, so if it's wired that way then it certainly won't work sensitively enough as there won't be 240v across the resistor.

it doesnt need 240v across it, it needs current through it
but agree its not as accurate as using the L/N connected resistor

What's more, if the ACL LP112 is firing 240V out to the 'stat and the boiler is a volt-free device, then the boiler is bu**ered anyway...

true but the ops is 230v switching only anyway

 

[plumbandplumber]

Thanks very much Deiled, John and matt1e.

I see now, I think I was getting a bit confused before.

Thanks again for taking the time to explain it so well.

 

[Whitespirit66]

You bridge the two Live In terminals together, either with a supplied copper link, or with about 25.4mm of brown wire.

John, I have to strongly disagree with you.

I wouldn't use 25.4mm of brown wire. An inch is much better.Anything else is slipshod, slapdash and the mark of a true cowboy.

 

[JohnD]

I did say "about 25.4mm"

I can't be bothered measuring any more accurately than that, I'm just a naturally slipshod worker.

 

[DeviledAvocado]

Matt. Yes, 'volt-free' is a misnomer since there has to be some voltage there to control the boiler. And, yes, this is what is termed 'extra low voltage' which in the case of electronic control is usually either 5V or around 12V.

BUT, having double-checked the instructions, I am as certain as I can be that the Combi-Stat RTS8 does NOT have a 'volt-free' (ELV!) option at all. If you look at all the wiring options, 2 and 3 wire, they all have a 230V supply.

And this makes sense since the heat the accelerator resistor can give out is directly proportional to the voltage across it (and the current going through it - one varies directly with the other). So, if the resistor had only 12V across it as opposed to 230V, then frankly you'd barely get any heat out of it at all.

If that 'stat was used on a 'volt free' boiler (say wired as Fig7), then it would be very sluggish indeed. But, it's not meant to be.