Radiators

Apologies for bringing up the subject of my 40 year old central heating again.

In previous discussions I indicated I would prefer to keep my old radiators for reasons of economy. However, I have now realised that the modern finned radiators are much more efficient and will heat up the rooms much quicker, which in turn means the boiler is used for less time. I have also heard that boilers are more efficient the cooler the returning water from the radiators is. This all makes sense to me, but I am no engineer, so would like to hear this confirmed, plus any other comments people might have.

TIA

Keith

Reply to
Keith Dunbar
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Well yes and no.

Finned radiators have a larger surface area for a give wall space and thus will emit more heat. In terms of the effect, assuming you have the boiler output, the room will heat more quickly. However, if the radiators were adequately sized in the first place, the rooms will reach the required temperature.

If you have a conventional, non modulating boiler, the effect of the older radiators may be that the boiler will cycle. This happens because the boiler is producing heat faster than the radiators can dissipate it, and it therefore switches off. This behaviour is somewhat inefficient but only very inefficient if the cycles are very short.

That is only true for a condensing boiler. A conventional boiler is intended to work at a high temperature of 82 degrees. For condensing boilers, the lower the return temperature, the better.

This does relate back to your radiator point. If you were to go for finned radiators of the same wall space as the existing ones, they would have a larger heat output. That would make it possible for you to run the boiler at a lower temperature and make some savings.

Neither of these relate that much to the boiler running time, especially for a condensing model or one with output modulation .

Reply to
Andy Hall

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