Siemens RWB29 - no central heating

[jimmer01]

I have just replaced a Switchmaster 600 Controller with a Siemens RWB29 Controller, but for some strange reason I can't get any central heating to kick in.

I have wired the Unit correctly as per the instructions but when I switch the Unit on to CH or HW Manual, it ignites the boiler and then goes out in about 1 minute! I can hear the water pump start buzzing upstairs and the hot water cylinder is hot but i cannot get the boiler to stay fired up to get the central heating working.

I believe it initially worked on the first timed period that kicked in since installing, but I went to manually put the heating on for another hour or two and it just wouldn't keep working past the first minute.

The SwitchMaster 600's timer had gone so I replaced with this unit and right before i took the SM600 off the boiler and all parts were working fine when switched to constant so there can't be much wrong.

What am I doing wrong?

James


Read more: //www.diynot.com/forums/viewtopic.php?p=1747433#1747433#ixzz2ISWmBt2n

 

[petertheplumber12]

I think you had better check the valve operation in the loft it may be stuck on hot water.

 

[45yearsagasman]

You sure that the pump is actually running? They don't normally buzz.

 

[jimmer01]

Sorry, my terminology may be a bit off. The pump is humming a little, which though it may be old and decrepit, it stills seems to work as I have just put the old controller back on and switched onto constant and everything works fine. CH kicked in and HW on too.

I'm just confused as to why the Siemens controller won't do the same as the instructions show the wiring to be exactly the same so that can't be the issue.

Am I missing something? I'm pretty fresh to boilers, central heating etc.. so please excuse my lack of knowledge.

Cheers

 

[petertheplumber12]

Good call gman, unscrew the chrome cap and with a smaller slotted driver see if the pump spindle is turning or spin it with screwdriver in slot on end of spindle.

 

[doitall]

The two programmers are not exact replacements.

Pics show the old and new wiring please.

 

[petertheplumber12]

Sorry, my terminology may be a bit off. The pump is humming a little, which though it may be old and decrepit, it stills seems to work as I have just put the old controller back on and switched onto constant and everything works fine. CH kicked in and HW on too.

I'm just confused as to why the Siemens controller won't do the same as the instructions show the wiring to be exactly the same so that can't be the issue.

Am I missing something? I'm pretty fresh to boilers, central heating etc.. so please excuse my lack of knowledge.

Cheers

It sounds as if the pump is ok, and as far as the controller is concerned without visually looking and testing with a meter it is difficult to diagnose with any degree of accuracy.

 

[doitall]

T1 is the htg on in the SM600 and T4 is the htg on in the RWB29.

You also have to set the dip switched to match the system

 

[jimmer01]

Gents, I've taken a photo of the wiring diagram for the RWB29 below of which I've followed to a T.

@ doitall: based on what the wiring diagram shows what harm would be done if I hooked up the htg to T4 to try it as T1 is obviously not doing what it should.

Please also see the wiring of the SM600 in situ all fully working apart from knackered timer (hence replacement!)

The RWB29 looks the same when hooked up as all I have done is keep the terminal connections the same ie. T1 - CH, T3 - HW, all neutrals to N, Power to - L.

I also have the dip switches set to daily programming, and gravity system (which is correct as I have back boiler with hot water tank in airing cupboard, with cold and expansion tanks above it).

Rwb29 wiring diagram

• jimmer01
• 20 Jan 2013
• 1

SM600 wiring

• jimmer01
• 20 Jan 2013
• 1

 

[doitall]

T1 in the old is T4 in the new.

What are all the extra wires doing in the 600, where do they go/from numbers.

 

[jimmer01]

@ doitall : you are a genius. And I look to be a bit dense!! I didn't see that in the diagram. I just looked at all the brands listed and didn't realise that the Siemens at the top wasn't just a continuation of the list. Sorry.

Gonna give it a crack now.

The wires are for HW, CH and Power - 3 for each (Live, Neutral, Earth).

 

[MENTACATO]

T1 in the old is T4 in the new.

What are all the extra wires doing in the 600, where do they go/from numbers.

Nice earths, neatly parked !

 

[doitall]

T1 in the old is T4 in the new.

What are all the extra wires doing in the 600, where do they go/from numbers.

Nice earths, neatly parked !

Some green and yellow sleeve wouldn't go amiss.

 

[jimmer01]

Job done and pleased to say problem solved. Yeah, the earths looked a bit messy to me too but not being a pro I went with it! Point taken with the yellow and green sleeving.

Thanks for all your helps guys. Next time i'll read the instructions properly!!

Cheers