Peerless Boiler Question

FredoSP

Hi All,

I've come to the forum to settle a debate I'm having with someone. I have a Riello F3 oil burner and a Peerless Boiler (WB3, 1995 Vintage) with a tankless coil. The question is how the boiler water actually gets hot? It was my belief that prior to the hot exhaust gas going up the smoke pipe, that it first comes in contact with the cast iron internals of the boiler. The water absorbs the heat from the hot cast iron and thus hot water for the heating system. I know the tankless coil is surrounded by the hot boiler water and the copper coil absorbs the heat.

My buddy believes that the flame of the oil burner comes in direct contact and touches the cast iron of the boiler. That doesn't seem to make sense to me, but he was very sure this was the case.

Can someone educated me or him to settle this debate.
Thanks!

Robert O'Brien

Direct contact with cold surfaces can cool the flame leading to high CO and potentially soot formation. This is called impingement and the boiler has refractory material to prevent this.

FredoSP

Robert O'Brien said:

Direct contact with cold surfaces can cool the flame leading to high CO and potentially soot formation. This is called impingement and the boiler has refractory material to prevent this.

Hello Robert,
Thank you for the response but it didn't really answer my question. Are you saying that all flames come in contact with the internal cast iron of the boiler thus that is the cause of the heat transfer? Maybe I was incorrect in thinking it was the hot exhaust gas.

Ctoilman

The flame does NOT touch the cast iron whatsoever.  If it does, it'll make soot, that's called flame impingement.

STEVEusaPA

In simplest terms. Burner makes fire. Fire heats the cast iron, hot cast iron heats the boiler water. The coil is (should be) immersed in boiler water. The hot boiler water around the coil, heats the cold domestic water going thru the coil on the way to the fixture.

FredoSP

Okay, I now understand. In an ideal situation the flame should not touch the cast iron for the reasons mentioned above, but it can, even though you don't want that.

I believe I was correct when I was telling my buddy that the heat given off by the burner (a.k.a. the hot exhaust) is the reason the cast iron is hot. I dunno, maybe we were both trying to split hairs on this one!

Thank you guys for the info, I will pass it along.

Jamie Hall

Actually, it's even a little more complicated than that... much of the heat transfer from the flame to the cast iron or refractory of the boiler is by radiation from the very hot flame (several thousand degrees Fahrenheit). Then the rest of the heat transfer is from the still very hot, but no longer glowing, gas as that gas passes through the boiler passages.

At no time should the actual flame ever touch either the cast iron or the refractory.

FredoSP

Thanks to all. You guys are teaching me a lot of good things! Till my next question, which will probably be tomorrow.