Hello hope someone can clarify for me. Have a Worcester 30 CDi combi , am installing a UFH system and a separate zone for the remaining rads. Both zones will have wiring centres and these both have a demand cable going to the boiler with switched Live, N and E . The ST10 connector in the boiler has LR,LS and NS connections . Does the Switched lives from the wiring centres go to the LS and N to the NS ?and if so what is the LR for?Is this just not used in this situation. Thanks in advance
Connection to combi from external programmer with UFH on.
- Thread starter glasshouse
- Start date
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B
baz1968
The boiler should have a pemanent live and neutral fed via a switched fused unit. The other connections at the ST10 are,
Ns = Neutral connection from boiler to external stat or programmer
Ls = Live from boiler to power external stat or programmer
Lr = Switched live from external stat or programmer to fire boiler.
Connections are made in this way so that isolation of the fused outlet feeding the boiler will isolate the boiler and all external controls. Ideally this should mean that the wiring centre and pumps for the underfloor heating will be isolated as well. Ls and Lr sometimes has a link that needs removing to allow additional controls to be connected.
Hope this helps
Ns = Neutral connection from boiler to external stat or programmer
Ls = Live from boiler to power external stat or programmer
Lr = Switched live from external stat or programmer to fire boiler.
Connections are made in this way so that isolation of the fused outlet feeding the boiler will isolate the boiler and all external controls. Ideally this should mean that the wiring centre and pumps for the underfloor heating will be isolated as well. Ls and Lr sometimes has a link that needs removing to allow additional controls to be connected.
Hope this helps
Thanks for reply but still not clear, the boiler is as you say fed by a switched fused unit. However the wiring centre for the UFH is shown as having it's own supply via the programmer which in turn is fed by a separate switched fused unit. So the demand comes from externally . Does that make sense?And if so does that alter your previous reply? Thanks
B
baz1968
If you look at the wiring diagram on page 27 here
http://www.emanuelspence.info/Heating Boilers/Worcester/28I JUN INSTALL.pdf
The boiler supply also supplies the programmer (from Ls and Ns) which controls the room stat and should also control all other external controls. You should not have to isolate at two different locations to turn off your boiler.
Any device that needs a supply to power it should be connected to Ls. And any switch wire demand (to fire the boiler) should be connected to Lr
If your wiring centre is fed from the programmer then the supply to the programmer should be taken from Ls and Ns.
Single point of isolation.
At the wiring centre, manifold and pump for the UFH, i would fit a double pole isolator for local isolation and mechanical maintenance
http://www.emanuelspence.info/Heating Boilers/Worcester/28I JUN INSTALL.pdf
The boiler supply also supplies the programmer (from Ls and Ns) which controls the room stat and should also control all other external controls. You should not have to isolate at two different locations to turn off your boiler.
Any device that needs a supply to power it should be connected to Ls. And any switch wire demand (to fire the boiler) should be connected to Lr
If your wiring centre is fed from the programmer then the supply to the programmer should be taken from Ls and Ns.
Single point of isolation.
At the wiring centre, manifold and pump for the UFH, i would fit a double pole isolator for local isolation and mechanical maintenance
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Baz1968 that is a very clear concise answer , thank you. I will need to draw this up to get it clear in my head as a logical procession and if o.k with you post the drawing to see if I have got it straight? Thanks again
B
baz1968
Glad to help
Finally got it down as I now see it, is this what you meant BAZ1968??
If so is there any issue with bulking up the demand wires in the Wiring Centre as it's done either here or at the boiler position I suppose. Your comments most welcome.[/img]
B
baz1968
Not Bad Glasshouse, just need to clarify a few things
I take it that the two channels of the programmer are for controlling the UFH and the Central heating
The switched lives from the programmer should power open the motorised valves and the micro switch of these valves be used to send a demand to the boiler via Lr, this will prevent any backfeeds.
The valve connections are normally,
Brown = Valve open
Gray = Permanent live
Orange = switched live
Blue = Neutral
You have a neutral connection from both the wiring centre and the programmer going to the UFH, only one is needed.
Not sure why you have that Conn block, the boiler demands should just go to one connection, Lr which will fire the boiler. These switch wires can be bulked up as you say as long as they are switched through the valve. This will enable seperate control of Radiators and UFH.
Does the UFH have any means of temperature control?
Is the RF receiver for a remote room stat? All that is showing in your drawing is a permanent live and neutral to it. Ideally you want the stat to be powered from the programmer and the switched output from the stat connected to Lr, that way the the programmer will determine on/off periods for the radiators.
I would imagine a method of operation as follows:
Permanent live to boiler provides on demand hot water
Channel 1 of programmer provides power to room stat and demand from stat opens motorised valve and sends a demand to the boiler via Lr. When the room stat is satisfied or the programmer times out, the valve closes and the demand to the boiler is off.
Channel 2 provides power to motorised valve and pump for UFH (via some sort of temp. control) valve opens and switch wire fires boiler via Lr. As above, when required temperature is reached or programmer times out, the valve closes and the demand is off.
If your still unsure about this, tell me how you posted your drawing and i will try to post a similar diagram.
I take it that the two channels of the programmer are for controlling the UFH and the Central heating
The switched lives from the programmer should power open the motorised valves and the micro switch of these valves be used to send a demand to the boiler via Lr, this will prevent any backfeeds.
The valve connections are normally,
Brown = Valve open
Gray = Permanent live
Orange = switched live
Blue = Neutral
You have a neutral connection from both the wiring centre and the programmer going to the UFH, only one is needed.
Not sure why you have that Conn block, the boiler demands should just go to one connection, Lr which will fire the boiler. These switch wires can be bulked up as you say as long as they are switched through the valve. This will enable seperate control of Radiators and UFH.
Does the UFH have any means of temperature control?
Is the RF receiver for a remote room stat? All that is showing in your drawing is a permanent live and neutral to it. Ideally you want the stat to be powered from the programmer and the switched output from the stat connected to Lr, that way the the programmer will determine on/off periods for the radiators.
I would imagine a method of operation as follows:
Permanent live to boiler provides on demand hot water
Channel 1 of programmer provides power to room stat and demand from stat opens motorised valve and sends a demand to the boiler via Lr. When the room stat is satisfied or the programmer times out, the valve closes and the demand to the boiler is off.
Channel 2 provides power to motorised valve and pump for UFH (via some sort of temp. control) valve opens and switch wire fires boiler via Lr. As above, when required temperature is reached or programmer times out, the valve closes and the demand is off.
If your still unsure about this, tell me how you posted your drawing and i will try to post a similar diagram.
Only unsure of that stat connection really [Not Bad Glasshouse, just need to clarify a few things
I take it that the two channels of the programmer are for controlling the UFH and the Central heating
yes
The switched lives from the programmer should power open the motorised valves and the micro switch of these valves be used to send a demand to the boiler via Lr, this will prevent any backfeeds.
The valve connections are normally,
Brown = Valve open
Gray = Permanent live
Orange = switched live
Blue = Neutral
yes ,the connector blocks in the wiring centres are set up like that
You have a neutral connection from both the wiring centre and the programmer going to the UFH, only one is needed.
oh o.k the one from the wiring diagram for the UFH shows L, N and E going to the boiler so I just copied that So i do not need the N back to the boiler?
Not sure why you have that Conn block, the boiler demands should just go to one connection, Lr which will fire the boiler. These switch wires can be bulked up as you say as long as they are switched through the valve. This will enable seperate control of Radiators and UFH.
Yes sorry about that the connector blocks are where all the valves and Programmer and stat is all wired together it was not to show the Lr wires
Does the UFH have any means of temperature control? Yes there are two room stats that all wire through the UFH wiring centre which is basically taking the feed from the programmer in as power and taking the switching cable out the other end which will switch the boiler on if there is demand, the zone valve and UFH pump also are controlled from this wiring centre.,
Is the RF receiver for a remote room stat? yes All that is showing in your drawing is a permanent live and neutral to it. Ideally you want the stat to be powered from the programmer and the switched output from the stat connected to Lr, that way the the programmer will determine on/off periods for the radiators. yes this is the bit that had me stumped , it is (or will be) a Danfoss RETB-RF with a receiver unit RX 1. Is this the right sequence. Channel one of programmer goes to receiver unit (3 c&e) is connected at receiver unit N-N Channel one of programmer to L which is in turn linked to COM the third switching wire then goes to Zone 1 (on) termination of receiver which is terminated to the brown (valve open) of the zone valve back at the wiring centre.I am not sure if this bit is right have asked Danfoss but they are slow to reply.My concern is does the receiver require permanent live?
I would imagine a method of operation as follows:
Permanent live to boiler provides on demand hot water yes
Channel 1 of programmer provides power to room stat and demand from stat opens motorised valve and sends a demand to the boiler via Lr. When the room stat is satisfied or the programmer times out, the valve closes and the demand to the boiler is off.
see above, the orange of the valve will be connected to the Lr
Channel 2 provides power to motorised valve and pump for UFH (via some sort of temp. control) valve opens and switch wire fires boiler via Lr.
As above, when required temperature is reached or programmer times out, the valve closes and the demand is off. yes
If your still unsure about this, tell me how you posted your drawing and i will try to post a similar diagram.
BAZ1968 Sorry ran out of room and couldn't work out how to change text colour so my replies are same colour at the end of each of your questions. Hope it makes sense.Thanks
B
baz1968
There is a link to that type of stat here
http://www.plumbnation.co.uk/site/d...rx-1-radio-frequency-receiver/RET B Guide.pdf
They recommend that the suply for the receiver is NOT taken from the programmer(guess the electronics bit likes a steady supply) So the supply for the receiver as you have shown, should be from Ls and Ns.
The switch from channell 1 of the programmer should be connected to terminal 2 of the receiver unit, and then connect from terminal 3 to power motorised valve open.
Hope this all makes sense
http://www.plumbnation.co.uk/site/d...rx-1-radio-frequency-receiver/RET B Guide.pdf
They recommend that the suply for the receiver is NOT taken from the programmer(guess the electronics bit likes a steady supply) So the supply for the receiver as you have shown, should be from Ls and Ns.
The switch from channell 1 of the programmer should be connected to terminal 2 of the receiver unit, and then connect from terminal 3 to power motorised valve open.
Hope this all makes sense
Great stuff, does the link still go in from L to terminal 2 at the RX1 receiver unit ? If it does and you have the patience could you explain why . Thanks
B
baz1968
No it should'nt need it. Com will be powered from channel 1
Baz1968 thanks for your time and advice , plumber coming Monday fingers crossed, should be able to give him a nice schematic to work to now although he said i've got to run all the cables !!! Cheers
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