Query on Worcester Bosch Greenstar 4000, modulation, and which 'Smart' thermostat to choose

Discussion in 'Plumbers' Talk' started by Ryanfsr, Sep 13, 2023.

  1. Ryanfsr

    Ryanfsr New Member

    Hi all!

    I'm in the process of looking to get a new combi boiler, and have decided I want to go with the Worcester Bosch Greenstar 4000 30kw. I'm replacing near 20 yr old Valiant combi boiler, with a very basic Honeywell dial thermostat.

    Looking on Boxt, I can see the Greenstar can be bundled with a few different thermostats. Google nest, ESI programmable etc

    I'm very new to all of this, but in doing a bit of research I have seen that most modern day boilers have an ability to modulate rather than being fully on / off to achieve and maintain the desired room temp.

    My question is, which thermostat is capable of allowing me to make the most of the modulation function on the boiler? Would it perhaps be best to go with Boschs own 'EasyControl' thermostat to make the most out of the modulation?

    As I understand, the Google Nest is an Opentherm device, but I'm not 100% if the Greenstar boiler is?

    Any help is appreciated!

    Many thanks
  2. penguinman

    penguinman Member

    Worcester do not support opentherm. If you want the best compatability go with the easy control, this will offer weather compensation or load compensation depending on which setting you choose. all others will give on off demands and rely on the boiler to do the modulating for a stable temperature leaving the appliance.

    Modulation is the ability to match boiler output to heat demand. So in that respect they are all the same, with the exception of the easy as it tells the appliance what temperature water to send to the rads.
  3. Baxi Boy

    Baxi Boy Active Member

    Think carefully before having your installation done by Boxt. The price might be the lowest,but they use a gas safe contractor that once he’s finished and got his cut of the job he isn’t interested in returning to fix snags etc. A friend recently had her system boiler replaced with a 30kw combi Worcester,the brick work outside wasn’t good,tile tiling inside removed in part untidy,and there were noises in the pipes,withe the boiler fan also coming on with the cold tap,so either a dead leg pipe left behind or it needed a shock arrester.
    After 2 weeks the boiler broke down and Worcester took 48 hours to replace 2 parts.
    I recommend paying a bit more for peace of mind with a local company installer who will return if necessary and do everything to your satisfaction.
  4. ItchySponer

    ItchySponer Member

    Worcester control would be best. Weather comp maybe too. Most important is a good local installer. If he/she is interested in doing the maintenance for the next 15years it's probably a good start. If they want to spend half a day plus flushing the system, another good start.

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