Boiler Never Gets Up To Full Power

[neerday]

I have had a Vaillant 630 system boiler for a couple of years and I have noticed lately that the LCD display showing the boiler output never reaches full scale (usually about 3/4 or a bit more). Seems to working OK and goes up and down a bit, just not at maximum. It's maybe always been like this - I've never paid much attention before, but recently after I noticed it I've monitored it more closely.

Does anyone know if the display should get to full scale and if so what would be holding it back? The house is a fair size with lots of radiators and it doesn't make any difference whether the hot water heating (tank is adjacent to the boiler) is running with the central heating or if only one or the other is on.

Thanks.

 

[The831Bunny]

The engineer who commissioned it probably set the boiler output to match your heat requirement and its less than 30Kw (full load). A rough rule of thumb is 1.5Kw multiplied by the number of radiators, i.e 16 rads x 1.5Kw = 24Kw.

The display will show the approx output relative to 30Kw.

 

[bell824]

like your general rule of thumb mr831, think we learned it from the same line of thought

 

[neerday]

Thanks for that Bunny. I suppose with your rule of thumb I'd want about 27kw so as you say the installer maybe set it down a bit.

No problem anyway as I say, the house warms up quickly enough.

 

[Agile]

If it warms up quickly then its possible you could operate the boiler more efficiently by reducing the power output a little.

That 1.5 kW per radiator is only a simple rule of thumb which can be used when talking on the phone to get a very rough idea of the heat loss.

When a typical towel rail is only giving 0.3 kW then it can easily give a higher figure then reality.

A possibly better rule of thumb is that each panel 600 mm high is about 1 kW per 1000mm length.

It is very easy to set that boiler's power output lower and to just increase it during the colder weeks. I change mine every few days but them I like over control.

Tony

 

[neerday]

If it warms up quickly then its possible you could operate the boiler more efficiently by reducing the power output a little.

Tony

Is that something I can do easily myself? It might be quite handy especially when the weather is milder but still want a bit of heat.

Looked in the operating instructions but not mentioned there.