New Boiler (Worcester Bosch Greenstar 4000)

CatLady87

Hi all,
I had the above boiler fitted in my attic today with a Honeywell thermostat downstairs.

For many years I’ve lived with old combi boilers and ancient thermostats so this is all very new to me!

I get that the thermostat controls the boiler and I’ve got it set on manual so that if the temperature drops below 18 degrees, the boiler will come on. I get this. The electrician said I don’t need to touch the boiler now. 

However, the boiler has a fancy-pants LCD screen and this is blank. It’s clearly working as the water is hot. What I don’t get is why there’s no display on the screen. Does anyone else have this? I’ve Googled and looked at the manual but come up with nothing. Is it the pairing of the thermostat and boiler which means the screen doesn’t need to show anything? Obviously the warm weather means the heating hasn’t kicked in so maybe that’s why the screen is blank? I wondered whether new boilers set the water to a certain temperature and that’s why I can’t alter this (e.g. the screen lighting up for me to do this).

Any other tips on this pairing greatly appreciated! I’m used to older boilers and this new technology is a tad confusing. 

Many thanks 😊 

JbobMSE

I have one of these and it’s a great boiler. It shows a ‘flame’ above the display when the boiler is lit. The main display is blank by default but you can change this in the ‘settings’ menu. Press OK on the display and it will show you the set CH water temp. Press the ‘menu’ button (three bars) and scroll down to settings. Press the ‘radiator’ button and you can alter the CH temp (and the HW temp) with the up/down buttons. It’s all explained in the operating manual which should have come with the boiler.

daveyjp

I would ignore anyone who says 'no need to touch the boiler now'.

Get the manual out and find out what temperatures have been set for hot water and heating circuit.

Many installers set them close to max so the hot water scalds and the boiler never condenses, both of which cost you money.

Once you know the figures and how to adjust the temperatures you can set hot water to a comfortable level for you and the heating circuit at a temperature which means the boiler  does condense.

Both measures will reduce your gas consumption.

milgo

The person installing the boiler should have left you with (amongst other manuals, instructions etc) a "benchmark" installation booklet type document that should have the inside back page filled out with the temperatures that the boiler has been set to for the heating circuit and also where appropriate the hot water. 

JbobMSE

To give you some idea my installer set the CH at 70C and I’ve just knocked it back to 65C after using it for the first time yesterday. The optimum temp will depend on your CH layout but the water will decrease in temp on it’s way round the circuit and I understand it needs to be around 55C when it gets back to the boiler in order to be condensing properly. If your outside flue is puffing like a steam train it’s not condensing as it should.

dosh37

Why worry?

Gas prices have gone through the roof.

Boiler efficiency is irrelevant now.

Get a log burner.

QrizB

dosh37 said:

Why worry?

Gas prices have gone through the roof.

Boiler efficiency is irrelevant now.

Get a log burner.

1. Boiler efficiency is twice as relevant with 5p/kWh gas as it was with 2.5p/kWh gas.
2. Logs are still 50% more expensive than gas: see https://nottenergy.com/resources/energy-cost-comparison/
   

CatLady87

Thanks all, much appreciated! I’ll have another look at the settings and have another read of the manual. Special thanks @JbobMSE, that’s good to know!  I’m so used to boilers will old dials and pressure gauges.. 🤣

I do know gas prices have gone through the roof and I can’t actually afford a log burner as I’m a single parent and it took me long enough to save up for a partially subsidised boiler but thanks for the advice 👍 

tux900

JbobMSE said:

If your outside flue is puffing like a steam train it’s not condensing as it should.

A visible plume is actually a *good* sign. Steam (water >100C) is invisible, so what you are seeing is water vapour resulting from a condensing boiler recovering some of the latent heat of the exhaust gases which cools them down to <100C hence becoming visible. 

MigsyBigsy

JbobMSE said:

To give you some idea my installer set the CH at 70C and I’ve just knocked it back to 65C after using it for the first time yesterday. The optimum temp will depend on your CH layout but the water will decrease in temp on it’s way round the circuit and I understand it needs to be around 55C when it gets back to the boiler in order to be condensing properly. If your outside flue is puffing like a steam train it’s not condensing as it should.

I am coming a bit late too this but bought this boiler last year and I have noticed the steam (this year) when i turn on the hot water for a bath. (also noticed that my bills are higher this year). Whats the optimum temp for water and CH? I have the water on the eco mode now - which i didnt before

frostysaver

tux900 said:

A visible plume is actually a *good* sign. Steam (water >100C) is invisible, so what you are seeing is water vapour resulting from a condensing boiler recovering some of the latent heat of the exhaust gases which cools them down to <100C hence becoming visible. 

This is kinda but not completely correct.

Some heat is recovered cooling hot gases and water vapour a bit, which would make a more visible cloud plume.

However much more heat is extracted by condensing the water vapour to liquid water, which runs down a drain. In that case there won't be a big visible cloud plume.
This is the "latent heat" to change water phase gas->liquid.