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Topic Title: s plan with combi boiler??
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Created On: 25 August 2010 09:37 AM
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 25 August 2010 09:37 AM
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Grandfortune

Posts: 343
Joined: 10 April 2007

hi all,

doing a house extension, and the plumber has put a worchester combi boiler in with underfloor heating and value, house heating and valve, having trouble wiring it got it sort of working but cant find any wiring diagrams. any ideas?, i;ve seen the honeywell driagrams but the combi has a clock built in with wireless stat for the heating trouble is opening the valve with asking for heat?? anyone done one of these before?.

thanks
grand
 25 August 2010 10:06 AM
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chrishaworth

Posts: 247
Joined: 08 March 2003

There's usually a plc with the underfloor with inputs for room stats and an output to the ufh valve. Similar, room stat to conventional valve brown. Re-route the output from the timer to the valve grays, then connect the oranges to the boiler on where the timer output was connected. Stat calls for heat, valves open connecting gray to orange. If the timer is on, there will be 230 on the gray switching the boiler on.

Cheers
Chris
 25 August 2010 01:33 PM
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whjohnson

Posts: 699
Joined: 24 January 2009

There are numerous cct & plumbing diagrams available as pdfs on this U/F heating company website.

Here's a cct diagram using a 240V switch wire from the boiler -

http://www.ukunderfloorheating...load_file/-/view/343/

Another diagram here, but this time using a volt-free contact

http://www.ukunderfloorheating...nload_file/-/view/344/

-------------------------
Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.
 25 August 2010 05:23 PM
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dickllewellyn

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It's not an S plan as such in the traditional sense, as there is no hot water valve...

Try breaking it down into it's component parts.

Clock calls for heat and sends live to stat
stat calls for heat if required and sends live to open valve
valve opens and switches to send live to boiler
boiler fires and radiators get warm...

In this instance, the plumber has introduced another zone. Assuming it is controlled by the same channel on the time clock (likely if it's integral), you just repeat the process for this stat and valve.

You could in theory keep adding zones each with its own stat and valve...

Hope this helps, heating systems can be quite a ball ache when you come accross something you're not used to!

-------------------------
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Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 25 August 2010 06:13 PM
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whjohnson

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Because you have a combination boiler the radiators will need to be controlled with their own zone valve, you can use any wireless thermostats with the system
The Plumbing drawing I posted a link to shows a cylinder on it, just do not include this.
You will have one zone valve for the radiators.
The thermal actuator is just a zone valve so you are just wiring an S plan system.

I think that If you use an integral time clock / stat then you'll have no independent controls for the U/F HTG manifold.

The zone valve & thermal actuator allow for independent control of the zones and connect to a common point to fire the boiler.

You will need a 2 channel programmer fed by wiring centre with connections for-

Permanent Live
Neutral
Earth
Radiator demand
UFH demand

For the radiators you need a room stat fed by the programmer channel 1

You also have the zone valve for the rads

For the UFH you need a room stat fed by the programmer channel 2

You also have the UFH manifold controls.

At the wiring centre you will have the following connections:

Term 1
P/L from spur
P/L to programmer
P/L to boiler
Grey wire from rad zone valve

Term 2
N from spur
N to programmer
N to boiler
N to rad zone valve
N to UFH manifold pump
N to rad r/stat (if required)
N to UFH r/stat (if required)
N to UFH thermal actuator (or whatever they call it)

Term 3
All Earth connections

Term 4
Call from programmer for rads
L to rad r/stat

Term 5
S/L from rad r/stat
Brown wire to rad zone valve

Term 6
Call from programmer for UFH
L to UFH r/stat

Term 7
S/L from UFH r/stat
L to UFH pump
L to manifold temp sensor

Term 8
S/L from manifold temp sensor.
L to manifold thermal actuator head.

Term 9
S/L from manifold thermal actuator.
Orange wire from rad zone valve.
S/L to boiler.

-------------------------
Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.
 25 August 2010 06:22 PM
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deleted_2_tony30

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hope the installer has added plenty of insulation under the slab!.
with possiblke heat up time of 3+ hours i hope the end users are able to accept the lifestyle change.
personally i would stick up some evac tubes and a woodburner and link them with a lattomat for example.
but if you dont get the insulation right and the building isnt airtight as possible your heating sa sieve

tony
 25 August 2010 09:33 PM
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Martynduerden

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This is a boiler Schematic which is one I did myself for a "non designed" system I.e it was a collection of parts purchased by the client and I was asked to "wire it up", it is a UFH system with CH & stored HW.

-------------------------
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Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 25 August 2010 10:32 PM
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Grandfortune

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cheers for the reply's guys,

going to try and sort it 2morrow, the only thing that is worrying me is that the built in programmer calls for heat wirelessly, , but i dont know if it actually comes back to any sort of terminal so i can put the valve in to open it up,same with the UFH, just dont know where to wire them BROWNS of the valves to,


basically i;ve wired it up and it sort of works, i;ve used the existing room stat and the UFH has its own programmable stat, shes rang and said her heating isnt working, i;ve spoke the the plumber he tells me she has a wirless stat, just a bit worried about wireing that into what i have, surely it wont put a 240 live on the link you take out to put a stat in, i'll obvoiusly take the wired room stat thats there now out.

thanks grand
 25 August 2010 10:38 PM
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Martynduerden

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The wireless stat will have a receiver and in that receiver will be a pair of relay contacts which you can use for whatever you like usually live to the common and NO to the valve hence stat calls for heat valve opens boiler fires/ pump runs etc.

The easiest way to think about boiler wiring is as a series of 1 way switches just follow the trail... its easy really

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 26 August 2010 07:31 AM
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dickllewellyn

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The integral programer of the worcester boiler plugs into the PCB. In the terminal box you will find a green connector strip with 2 terminals linked (Ls, Lr). This link is removed, and replaced by your control wiring.

Bear in mind though that the programable stat for the UFH will almost certainly need a permanent L+N, and it'll make life easir if you take the supply into the junction box first and alter wiring to suit.

-------------------------
Regards
Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 27 August 2010 11:44 PM
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Grandfortune

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hi guys,

still no luck, i have the wired stat ,wired up and the wirless stat working together, if i discard the wireless stat and wire the hard wired stat only the boiler sends the signal out on Ls and stat calls activating the valve but not firing the boiler, but if i turn the wireless stat up it will.but, if i take the wired stat out the value dosnt open, it seems that the wiless programmer unit in the actual problem and i just need two wireless programmable stats one for heating and one for UFH, and open the values on Lr.
 28 August 2010 12:25 PM
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dickllewellyn

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Lr is the switched return to the boiler. It will need permanent L+N to the appropriate terminals, and the switch wire from the valves comes back to Lr to fire the boiler. There should be a schematic in the boiler literature.

-------------------------
Regards
Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 28 August 2010 07:28 PM
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shaner500

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Hi if it's a Worcester cdi boiler. And there is a time clock built into the boiler. The stat wires don't just go to ls and lr. There is a connection marked st8. Been a while since I done one. I do have a diagram in the van. But I'm on hol at the minute. Search the net or get a wholesaler to let you have a look at wiring diagram for time clock. It will show you how to wire with stat and clock together
 29 August 2010 06:41 PM
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Martynduerden

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Ls & Lr are terminals on st8.

Grand what is controlling what? if you are running UFH and CH from the boiler then you will need a minimum of two valves or one valve and actuator heads on the ufh manifold.

If you have actuators for the ufh make sure the stat is controlling that actuator, hopefully the actuator is a 4 wire version you use the spare pair to fire the boiler, just the same as the grey and orange in the standard motorised valve

If you are on 2 wire actuators then you will need at least one relay to produce that second pair/ start the pump (unless its a combi).

Upload a schematic of the wiring you already have and Ill show you where to modify it

Just remember its is a requirement of Worcester Bosch that you supply all controls from Ls terminal, you must not wire them directly from the fuse spur.

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 29 August 2010 11:13 PM
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Grandfortune

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there is no actuator, i'm sure i've wired it all up ok, the ufh is just a valve to open up via stat , trougle is the wireless stat for the combi opening the value, well not opening the value but the value opens and the boiler wont fire, basically i dont think the boiler time clock and the valves are the right setup for the boiler i have, its just a combi boiler dont think its designed for values and extra stats, its just a simple combi.
 29 August 2010 11:27 PM
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Martynduerden

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What combi is it?

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 29 August 2010 11:37 PM
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chrishaworth

Posts: 247
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If you've got to the point where the stats open the correct valves, then you're 90% there. Next is to identify which terminal in the boiler switches it on. Connect the outputs from the valve microswitches (orange) to this and the inputs (gray) to 230V. If this works, then route the central heating output from the programmer to the gray wires and disconnect the 230. My own underfloor heating takes about 6 hours to heat up so I would seriously consider connecting the timer only to the radiator side and leave the UFH connected to live via a switch.
Cheers
Chris
 30 August 2010 11:48 AM
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whjohnson

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Surely you have to have a separate zone control (timeclock and stat) for each valve - one for rads, the other for the U/F heating system?
So therefore, I can't see how an integral boiler-mounted single channel wireless clock/stat and one hardwired stat can do the job using only a single channel?
Surely you'll need a minimum of 2 stats, 2 zone valves, (or one zone valve for the rads, and one actuator mounted on the U/F manifold) and a 2 channel programmer?

Some boiler manufacturers do a 2 channel version of their plug-in programmer/wireless base.

I can't see how you can do it without 2 channels for such a setup.

-------------------------
Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Edited: 30 August 2010 at 11:54 AM by whjohnson
 30 August 2010 12:23 PM
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alancapon

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Originally posted by: whjohnson
Surely you have to have a separate zone control (timeclock and stat) for each valve - one for rads, the other for the U/F heating system?

True, it will involve a bit of messing around, depending on the boiler. You would need to add an additional zone valve to the original radiator circuit at the t-piece where the u/f heating is fed from. Each zone valve would need to be controlled by its own thermostat, so the original wireless stat would need to operate the new radiator zone valve not the boiler directly. The outputs from the two zone valves would need to be commoned, and this signal used to fire the boiler, in place of the original signal from the wireless stat.

It is possible, but needs a little thinking about with the circuit diagram provided by the boiler manufacturer and the data for the two zone valves.

Regards,

Alan.
 02 September 2010 11:55 AM
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Grandfortune

Posts: 343
Joined: 10 April 2007

yeah i think you have it alancpon,

i am switching the valves with stats the biult in time clock opens the heating value and boiler fires and a programmable stat does the UFH and opens the valve , havent been to it for a while so not sure now but..


i think the UHF wont fire the boiler if the built in wirless stat is not calling for heat even though the approprate wires are live, i just think there is a contactor or something in the programmer stopping the boiler firing up, i'm sure if i had no programmer in there it would work normally on the Ls and Lr terminals.

the boiler is a worchester 42cdi combi with a DT20RF programmer with wireless stat.
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