Replacing Drayton lp241 with Siemens rbw27

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Hi there, just got a replacement programmer as my old one is playing up.

I'm replacing a Drayton lp241 with a Siemens Rbw27. I think I need to change my wiring around a little to suit. On my old programmer I only have to control my heating and on my new one it only has the heating function. I have a gravity fed system. Here are some photos to help me explain.
 
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On my old programmer I only have to control my heating and on my new one it only has the heating function.
Don't understand what you mean. :confused:

The Drayton LP241 controls heating and hot water. Are you saying that you only use the heating channel of the Drayton programmer?

If so, wiring is as follows:

Drayton ...... Siemens
L .................... L
N ................... N
4 ................... 4

Link L to 2 on the Siemens.
 
For some reason I only use the central heating part of my programmer. I put the central heating on on the programmer and if I only want hot water I turn my thermostat down. Asked a plumber about it once and he said it was a weird way to run the system but my boss who knows quite a bit of stuff thinks my heating is just a really simple system. I'm not bothered anyway as we have the heating on for a couple of hours a day and it just heats the water then. In the summer months we just turn the thermostat right down.
 
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What about 3?
Not used.

I can understand why you are only using the CH channel of the Drayton, but it's a very unusual way of doing it. :rolleyes:

I assume you have a three-way valve, similar to pic below. Can you post the make and model no?

If it's a mid-position valve and the HW channel of the Drayton is working OK, you should be able to get independent control over CH and HW. It would mean running two wires, one from the Drayton, the other from the HW thermostat. The Drayton could be relocated close to the motorized valve, presumably in the airing cupboard.

The Drayton would then control HW and the Siemens the CH.

View media item 5946
 
I only have a 2 way valve Siemens 2pvz-v22. Do I move the yellow wire to 2 and link it to L and that should sort me out?
 
I only have a 2 way valve Siemens 2pvz-v22.
Only the one valve? Which pipe is it in?

Do I move the yellow wire to 2 and link it to L and that should sort me out?
Hang on a minute - I've just taken a closer look at your Drayton and it's wired very unusually, so my original instructions are wrong.

Can you confirm that it is wired as follows (from left):

N: Brown - should be Neutral in
L: Brown - should be Live in
1: Unused
2: Unused
3: Yellow - this is the HW ON terminal
4: Red and Brown - this is the CH ON terminal

You said that it is a gravity fed system. Do you mean:

a) you have a small tank in the loft to feed the system? or
b) it is a pumped heating and gravity hot water system?

If it's (b) you will normally have three or four pipes connected to the boiler (not counting the gas pipe).
 
I only have a 2 way valve Siemens 2pvz-v22. Do I move the yellow wire to 2 and link it to L and that should sort me out?

no
to fit it as a direct replacement then wire to 3 and 4 the same then link 1and 2 to L
But I think you possibly have a badly wired C-plan (apart from the fact someone has used the earth terminal as a neutral block then used a brown link wire) so more info would be useful
e.g pics of valve and its pipework, cyl stat if fitted and any wiring centre etc

Matt
 
Basically I don't really know whats going on with it but wouldn't mind to get it sorted properly now. In reply to last posts I'm not quite sure what system I have got but I was told that I may have a gravity fed system. Here are some more pictures and info


I only have two pipes coming out of the boiler and there is a small tank say half the size of my cold water tank in the loft for the central heating. Oh and no thermostat on the tank.

Not sure what other info I can give.

Hope it helps.
 

1. What does the branch pipe between pump and motorized valve connect to?

2. What does the pipe after (left side) the motorized valve connect to?

3. There is an arrow on the pump body (may be hard to find): is it pointing towards or away from the motorized valve?
 
Hello,

1. The branch pipe goes to the bottom of the cylinder about 100mm up the side. And also tees off to a drain.

2. The pipe after the motorised valve goes through the floor.

3. The arrow on the pump points to the valve.

Dan
 
Wont be a cylinder stat this was a cheap way of doing fully pumped and wired much the same as a gravity system.
Boiler and pump wired into HW outlet of clock and roomstat and motorised valve wired to CH outlet and clock set for gravity
 

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