Which? Smith Boiler 8 G-3 or G-4

Peter D

Time for a new boiler. The old oil fired wm-E66 sprung a leak.

Total EDR 330 sq.ft. radiators. I have nat gas avalible. Looking at Smith capacity rating chart for oil a G-3 will work. Then I look at the gas capacity rating chart -it needs to be a G-4. Why? Do you down fire the gas burner to match the 330 edr and why do you need to heat up another section of iron. and will it now not be cost effective to switch to nat gas? I'm confused which boiler do I need for gas?

Thanks, for your response. Peter

Steamhead

The Smith 8 series

has two available firing rates for each model on oil. On gas only the lower rate is used.



You'll notice that the lower rate offers slightly better efficiency than the higher, since there is more heat-transfer surface available per BTU. So no matter which fuel you're using, the lower rate is the better choice.



Go with the 4-section. If it short-cycles, it can be down-fired slightly, paying attention to the combustion parameters with a digital analyzer while doing so.