BTU setting for a Baxi gas central heating boiler

I would like to know if someone could give me some advice ? I have a Baxi WM 51/3RS boiler for my central heating system and I am trying to find out if it is running at it's proper setting for the amount of rads that I have. I know it has been extremely cold recently and also that the boiler itself is old but if I can solve my problem by adjusting then I would rather do this than buying a new boiler if it comes to it that nothing can be done then I guess I will just have to buy a new one. The thing is that since I we have had modifications / extension which means that I now have 3 more double rads an a towel rail and it seems that the radiators just do not get hot enough and really take a long time to get warm. I have bled the radiator in the bathroom where we always seem to get a build up of air and also tried the pump on different settings ( it seem to work best on it's middle speed setting for some reason I thought it would help turning it to high ) someone has told me that my BTU setting may need turning up for new rads but I cannot find anywhere on the web to tell me how to. I have got a cotract with British Gas but I suspect that they will just tell me that I need a new boiler if I call them out.
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Bobe

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Bobe wrote:

<SNIP>
Post to this group: UK.D-I-Y Jim
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Sounds like the additions have over taxed the boiler. Increasing the temperature may help a bit, but there is a maximum that is safe to operate at. In most cases, it is 180 F or 82C, but you system may vary. If your domestic hot water is off the same boiler, that may get too hot and scald someone.
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