Oil burning bopiler question

[Leschenauds]

I am putting in a central heating system and the only bit I have yet to get is the oil fired boiler. I have looked around and was ready to purchase when I was offered one from a large house which is being refurbished. The boiler is in excellent condition with regular service records and a new burner and control system, the former still boxed however. The boiler is bigger than I was proposing to buy with something like 2 to 3 times the rated output. The boiler itself is built from 5 and 7mm plate steel and much more substantial than those I have been contemplating.

The question is, is it as I suspect reasonable to use an overrated boiler which will, one presumes, just run for shorter periods to achieve and maintain the required heat level. I would be saving a considerable sum and would appreciate any comments on the pros and cons.

[johnjones]

[quote]I am putting in a central heating system and the only bit I have yet to get is the oil fired boiler. I have looked around and was ready to purchase when I was offered one from a large house which is b...[/quote]

The most economical boiler is one which is working close to its rated ouput, ie around 85% of its rating.  One with too much capacity will never achieve its maximum efficiency due to the constant fire up/cool down cycle and will thus cost you more to run.

[Nick Trollope]

[quote]The most economical boiler is one which is working close to its rated ouput, ie around 85% of its rating. One with too much capacity will never achieve its maximum efficiency due to the constant fire...[/quote]

The most economical boiler is one which is working close to its rated ouput

Quite right, but a few hundred Euro's could buy a years worth of oil. However, bear in mind that the bigger the burner, the noisier it will be (and boy, are they noisy - you can stand in the middle of our village on a cold winters evening & it is like being at Heathrow). Also, the older the boiler, the less efficient anyway.

Oil is getting more & more costly, so the savings may not be so valuable. And, using an inefficient boiler will do nothing for your Green credentials!