1. Reprnow

    Bosche Greenstar pump on every hour

    Can't fix issue of my Worcester Bosche combi 25i. Since I moved to my new house back in February, I noticed that the pump kicks in every hour or so and the flow can be heard especially in the heaters upstairs. The flow runs for around 3-5min and then stops, the boiler itself remains silent. I...
  2. J

    Unusually water leak on a Worcester Greenstar 25cdi boiler. The plastic section behind the dhw temperature sensor has developed a slow leak.

    Hi As you can see on the attached picture a slow leak has developed on this large plastic piece. I am trying to find out is the leak is fixable and if so with what? If the leak cannot be fixed can that whole plastic section be purchased as a replacement part?
  3. H

    Worcester Greenstar 432kHz noise?. SOLVED. Honeywell Gas Control Valve, faulty batch.

    Worcester Greenstar 4000 combi boiler 25kW Install new September 2021. Last gas safety check October 3 2023 Combustion reading 0.0003 initial 0.0003 final. (is that very low?) 432kHz Drone, howl, noise from within boiler case. No pipe / rad knocks. Boiler located upstairs. External 30mm...
  4. R


    Hi all, I am looking to get a Hive thermostat installed but wasn't sure if it was compatible with our oil boiler as I recently found out the Google nest wasn't. Any help and advice would be massively appreciated!
  5. O

    Worcester-Bosch Greenstar 30Si two short bursts of noise when call hot water or heating

    Worcester-Bosch Greenstar 30Si (G.C. No. 47 311 85 N.G.) Had a new Flow Unit fitted as previous had developed a pin hole leak. Also topped up system inhibitor. Then this noise has appeared. I'm going to checking if anything that is easily accessible is loose, but apart from that I could use...
  6. B

    Worcester 32cdi and hive

    Had a greenstar 32cdi compact fitted years ago, after my old tank system failed. I had hive heating and hot water installed for the old system, as it would heat the water. When I had my Worcester installed, I kept the hive heating, the fitter said it would just work with the thermostat and...
  7. H

    Boiler short cycling for no reason- temp doesn't get any higher then 50deg

    Hi I have a Worcester Greenstar 32 with a Megaflow unvented cyclinder and its been running great for he last 4 years. This week we noticed the radiators are not as warm as usual, for some reason the boiler heats up but doesn't get much above 50 deg before cycling on and off every few minutes...
  8. M

    Worcester Greenstar 15ri pressure gauge

    Hi all My tenant has a Worcester Greenstar 15ri pressure gauge that isn't heating well (was serviced not long ago) and the symptoms sounded a little like low pressure. However, there's no pressure gauge on the unit itself nor an obvious water pressure valve / key. I found some online manuals...
  9. J

    WB Greenstar Heatslave II - CH flowing when no demand.

    Hello, I have a question about my WB Greenstar Heatslave external oil boiler which seems to be heating the Central Heating system when not being called for. I have almost no understanding of how these things work so it could be completely innocuous. I've noticed this only occasionally and for...
  10. G

    Anti cycle time and temperature not working WB Greenstar

    I monitor my gas usage in real time and notice that, once the house has fully warmed and the solid inner wall skin has absorbed the heat, the boiler starts to cycle more rapidly. see graph. It seems to cycle every 10 minutes off to off again. I have 4 separate demands underfloor, hot water...
  11. J

    Worcester Bosch Greenstar 28i Junior Combi Boiler - Help

    Hi there, Link to Manual: Not a plumber, just an infuriated owner of the subject boiler. I had a oil to gas conversion done and this boiler installed late 2013 by what I perceived to be a competent...
  12. M

    Worcester Bosch Greenstar 35 HE Plus - Secondary Heat Exchanger

    I have a service contract with WB for this boiler. Would a scaled up secondary heat exchanger be covered? For some years now our radiators have been getting hot in summer. In 2018 they changed the 3 way valve head. In 2019 they changed the complete 3 way valve. It still did it. In 2020 a...
  13. R

    Nest Thermostat E wiring to Greenstar 32CDi ERP Compact

    Hi I have a Worcetser Bosch Greenstar boiler with wireless Comfort 1 RF thermostat control. Please can someone help me replace this with the Nest Thermostat E? I have attached photos of my current boiler wiring below. Many thanks Dan
  14. A

    Has anyone successfully installed Nest hotwater function to 30cdi classic boiler?

    Hi all A new member here! I have bought a 3rd generation nest that I want to integrate with my Worcester greenstar 30dci classic boiler. The central heating control is straight forward enough but I can't find much advice on the hot water function wiring on my particular configuration. The...
  15. R

    Boiler won't output DHW & CH at the same time.

    Info: Worcester Greenstar Heatslave Drayton MA1 Mid Position Valve Actuator Summary: Had to replace the valve actuator as the old one was sticking. Wired up the new one with the same pinout as the original. Tested but got the following failed outcome; Off = DHW Water On = DHW Heating On = CH +...
  16. N

    Greenstar 28 jnr 2006 ev re pressure

    Hi in faq it says ... If you can't find one you can use a radiator bleed point, but that's in a pinch, because you'll be letting several litres of water out. Drain enough water from the system to drop the water pressure as read on the boiler gauge, to Zero. Close the drain cock. The boiler is...
  17. P

    Worcester 42cdi Hot water problem

    Hello, I have a problem with my Worcester Greenstar 42cdi. It was working fine until yesterday. when I noticed that the hot water would not get hot. upon further investigation, I am even more baffled. The boiler is in the upstairs bathroom. 1. Bathroom sink, (closest to boiler) gives warm...
  18. C

    Greenstar ri on y plan ....nest Nest

    Just putting a nest into my system. And was wondering if (lr) demand. on my boiler needs connecting. I have connected the nest as per manual. And heating is coming on when needed just testing though and boost is not working for hw. I have schematics for all parts of the system if it's any help...
  19. J

    help - worcester bosch greenstar not turning off with hive controller

    Hi, Brand new worcester bosch installed two days ago with hive controller. Turns on as per schedule in the morning but then does not turn off at all unless done manually using the boiler controls. Installer says hive is working fine as is the boiler and the fix requires a new 'suppressor'...
  20. C

    Worcester Greenstar 28i Junior; timer is losing time.

    My mechanical timer has started losing time, meaning my heating is no longer coming on when I want it. I assume the timer unit is failing and needs replaced (or is it fixable?) and was wondering what my best options are? I'm tempted by something like a Nest to give me more remote control; can...