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Bosch Worcester greenstar 30 SI with danfoss tp5000+rf RX

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Bosch Worcester greenstar 30 SI with danfoss tp5000+rf RX 1 control.
The hot water works fine but cannot get central heating to fire up.
No lights or warnings on boiler side , blue light illuminated, indicating all is normal.
On controls RX 1 shows red led at the CH1 position, but when calling for heat the boiler fails to fire up.
Went through the controller reset procedure for the TP 5000 & Rx1 and as per the manual , green light on the RX 1 illuminates and then goes out indicating conected.
When the stat calls for heat the boiler will initially fire up , (green light for flame illuminates and hear the firing ). but after say 5 seconds will then shut down.
The Red led at CH1 remains illuminated .
Any ideas ,a controls issue or a boiler component issue .

Hi , it could be either. First I would bypass the room stat within the boiler wiring centre.this will run the heating . connect a small wire between ls and or. If the boiler runs the heating fine then the problem will be with the stat.

If you have a multimeter electrical tester then you could simply see if you have power to lr

Customer: replied 2 years ago.
Sorry that means little to me . How would I go about that.
Customer: replied 2 years ago.
Please Explain where Ir , Is and or might be .
I've carried out some basic checks as explained .
You seem to be assuming I have something stripped down and visible to me and am into a wiring loom from the answers you are giving . That is not that case at this time .
Are you directing me towards boiler,stat or Receiver checks ?

Hi , the boiler case needs to be removed. To access the wiring centre.there will be two screws at the top and two at the bottom .the case then pulls off . then a screw holds the wiring centre/ control facia , remove this screw , this will drop down .

Customer: replied 2 years ago.
ref the last question , which direction are you pointing me in.
Back to the start , does a red led on the reciever indicate a signal is or is not being received ?
If signal is being received , I am assuming we are invetsigating a problem between the reciever and the boiler , it being in either of those that correct,
Your recommended inspection , are those terminals easily identifiable ?
Hi can you run through the reset and reconnection process first , thanks . this may be easier
Step 1 TP5000-RF
Reset the unit by pressing and
holding -, +, V and Λ together
until display goes blank.
Step 2 Press and hold V and +
buttons for 3 seconds (TP5000
now transmits unique signal continuously for 5 minutes).
Step 3 RX1
Press and hold buttons PROG
and CH1 for 3 seconds until green
light fl ashes once.
Customer: replied 2 years ago.
Toby are you reading my questions ?
That is undoubtedly easier and I have Explained in my first description that I have gone through the reset procedure , as per the manual the free light comes on , boiler will fore when heat is called for ,green light on etc
Please review my first description of the problem
OK ,if you have been through the reset process then it will be a reciever rx1 issue or a boiler issue.
This is why I wanted to bypass the reciever so the boiler is receiving a live signal asking the boiler to run ,
If the boiler runs and stays on then it is a reciever issue( they have a switching component that fails) .
If the boiler doesn't run then there is a boiler issue( could be poump or flow switch or a stat) .
Customer: replied 2 years ago.
Sorry I had to go out .
Ok I understand where we are heading .
Have dropped the control panel down.
Where are and how do I identify the terminals .
Does the unit need isolating and lid taking off
Hi yes turn power off .once the wiring box cover is removed thee terminals should be marked .
Its quite safe to remove the cover once power is off . the bottom part of the case is on two runners, noite where these are , as this will make it easier to put back .
Customer: replied 2 years ago.
Relist: Incomplete answer.
Seems to be taking a long time possibly off line. We took quite some time to get to cover the original question. I'm also unclear if you now open the original question , or you If visibility of the previous thread. I'm assuming the latter as it would seem silly to loose what we have took time to get to

Hi , I was out , my apologies. How do you feel about taking the case off ?

Customer: replied 2 years ago.
No problem with that, bit of a delay there and possibly the communications crossed.
I will try that tomorrow . Is there a good time when you are on line ?
well I'm not on here all the time , usually busy on weekends, but will check on it throughout the day
Customer: replied 2 years ago.
When I take the cover off, pls confirm I need to connect a wire between IS and OR if the boiler runs , I assume this overides thermostat input and the RF reciever input. You mentioned I could check if there was power to Ir , is a certain input command necessary to establish power to that , and what should it be ,ie 12v 240v etc
If the boiler runs I guess it will need to be shutdown by virtue of removal of the previously connected wire .

Hi , wire between Ls and Lr, thanks . boiler will hopefully run confirming a fault with the stat

Customer: replied 2 years ago.
Ok will do, jumper between Ls &lr
Customer: replied 2 years ago.
Toby , put jumper in , no change.bolier fired up for approx 15 seconds then shut down .
Hi , OK so it is a boiler issue , thanks .
As your hot water is working OK , that proves most of the components . could you check one thing .
The issue could be with the diverter valve. This defaults to hot water but when heating is required it diverts the heated water to the radiator circuit.
Turn the boiler off. Let cool for few mins . put boiler on and feel if the pipes are getting hot anywhere, thanks
Customer: replied 2 years ago.
Hi toby
When turned back on it only fires for a short while say 10 / 15 seconds
The only pipes that get hot are
1 the bottom pipe to the heat exchanger
2 the top pipe to the manual vent port connected to heat exchanger

Hi ,it may be that the diverter valve is stuck, or the head motor is not moving it across.or could be a PCB issue. To check, to the right o the pump us the diverter valve with the motor on top (will be a lead running to it from the board . If you take the motor head off ,reset the boiler and watch for movement from the inside of the motor head. If no movement then either the head is faulty or PCB, ( would need a multimeter to confirm

Customer: replied 2 years ago.
Hi Toby
The motor head pulled in downwards in sequence and then returned to its extended position.. The actating lever on the valve appears to be in a midway position.

OK , thats good , I'm beginning to think it may just be the flow stat. Hopefully i this and not tge pcb .Pretty easy to change. It may be that is its faulty and not recognising the need for heat . Relatively cheap and easy to change . Flow temperature sensor - (NTC) 8 716 106 688 0 GC No. H26 542

Customer: replied 2 years ago.
Hi Toby thanks ,
I've identified that part in the manual , they call it DHW temperature sensor and also control sensor same part number . It seems to be located on the left hand side above the siphon bottle, does that sound right?
I guess I need to get the part before moving on further . I have a multi meter if there any other checks needed,
To replace this - is it straight forward or will I need to drain down the system etc
Hi , yes they use the same one for hot water and heating.
Will be offline for a few hours
Customer: replied 2 years ago.
When I put the motor head back on and fired up again. The heating worked. I had just gently "wiggled" the actuating lever of the valve itself prior to replacing the motor.- maybe just stuck.
Anyhow will ke an eye on it.
Does that make sense ?
Thanks for your help

Yes , that does make sense , maybecvthge diverter was getting stuck , that's great , all the best . Toby

P.s , would you mind rating me , thanks

Plumberpro and other Plumbing Specialists are ready to help you
Customer: replied 2 years ago.
Yes happy to rate you ,
Many thanks
Your welcome