Another boiler Q again

[Gaffar]

Could someone please explain what a fully modulating combination boiler is, or point me to a source online where I could read up about this myself

Also does anyone know were I could find documentation such as installation, maintenance and specification for the Vaillant boiler VCW GB 242 EH, I have tried the Vaillant litereture line several times, but they seem incapable of sending anything out.

If anyone knows and could tell me if this type of boiler is "fully modulating" it would be much appreciated

Thanks & Regards

Gaffar

[Christian McArdle]

A fully modulating boiler is one that can vary the heat output according to demand. A combination boiler is one that incorporates a hot water system to supply taps. Most combi boilers are of the instantaneous type.

It is essential for sane operation that such instantaneous combis are fully modulating. Otherwise, turning the tap down will cause the temperature to rise until the boiler decides it needs to cut out, turning the water cold. A fully modulating type will just turn down the gas to keep the temperature at the set point.

Christian.

[IMM]

Not quite. Some do. Some modulate down to maintain a flow temperature stetpoint, which may not be quite in synch with demand.

[Gaffar]

Thanks for the simple explanation, the concept is at least understood now.

I have finally received the installation ans servicing manual from Vaillant and in it, although there is nothing explicit which says that it is fully modulating, there is a section for fault finding of which 1 sheet is headed "check burner modulation" would this indicate that this boiler is fully modulated, or am I way off the mark

Thanks for the replies.

Regards Gaffar

[Ed Sirett]

I'm nigh on certain that all Vaillant combis are modulating. I think there may be some very early Vokeras which aren't.

-- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at

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