Control on boiler to reduce output?

reg091 · 10 Dec 2018

I am looking at adding some radiators so calculated that my existing rads come to 15.4Kw and my boiler (WB Greenstar 24i)has a 24Kw output.

So far so good, but I have read that boiler output is limited on installation to match the needed output. How?

I mailed Worcester Bosch who replied that the control on the front does this. Well, I know that sets the desired output temperature but is that the same thing?

Crofton Gas · 10 Dec 2018

Download the installation manual, will tell you all you need to know. Most installers don't bother rating boiler down, so you'll probably find its factory set to highest output, unless it was done right.

reg091 · 10 Dec 2018

So the advice from WB was b#llocks? The temperature control knob is not what sets output?

Crofton Gas · 10 Dec 2018

The knob on the front controls the temperature of the primary water (water going around rads)

reg091 · 11 Dec 2018

Thanks, I know that, which is what puzzles me by the WB advice that essentially says if you add more radiators you need to turn the water temperature up! This struck me as complete cr#p!

My question is: do modern condensing boilers have an output setting that is set according to the size of the installation, and is therefore something I need to look at when adding rads?

ServiceNumpty · 11 Dec 2018

The WB Cdi you can adjust the heating output. But that is done via the parameter settings.

muggles · 11 Dec 2018

reg091 said:
My question is: do modern condensing boilers have an output setting that is set according to the size of the installation

Good quality ones do. Yours doesn't.

reg091 · 11 Dec 2018

Excellent, thanks.

fixitflav · 11 Dec 2018

reg091 said:
The temperature control knob is not what sets output?

No, that only sets the flow temperature. The maximum output is adjusted by varying the gas input, via the parameter settings. When the flow reaches the control knob setting the gas input is reduced (on a modulating burner, gas stops if non-modulating), unless the room-stat temperature is reached first, when everything stops. If the boiler output is increased, that point is reached earlier, that's all.

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Control on boiler to reduce output?

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