How Figure The Best GPM For Oil Burner?

Fred Harwood

Firing

Excellent points, Jim (Davis).

John_40

.02\" drop

Are you referring to the pressure drop between the combustion chamber over the fire draft reading and the outlet of the heating appliance draft reading?
That drop is caused by the design of the heat exchanger. Some modern oil fired equipment fire with a positive combustion chamber pressure. .01+ and runs no barometric damper. My Weil Mclain gold runs -.01 over the fire -.02 flue draft. 13% Co2 375F. net stack with a zero smoke. Combustion efficiency close to 86% And I'm underfiring by 25%. At zero degrees out my boiler runs 100% of the time and maintains 72F. indoor temp. By increasing to the correct nozzle size I would have a standby loss. When I was running the correct nozzle size my combustion efficiency was 82%.
You have to take all factors into consideration when evaluating a boiler or furnace for a job.
John

S Ebels

Sooooooo Jim?

Where does this type of approach leave manufacturers like Weishaupt and Riello with their modulating gas burners, oil too for that matter. Is their research faulty? Why do I see $$$ saved in buidlings (especially commercial size stuff)when they switch to a mod. burner or even a lo-hi type unit. I have two instances in mind particularly that kept their equipment in very good repair and both showed in the neighborhood of 4-5% energy cost reduction when they went to modulating burners. These burners were installed on the same equipment at the same high fire rating. As far as I could tell (combustion tests) the burners which were replaced were performing properly.


To me it doesn't add up. If you meet the heating demand (a variable target) with 75,000 btu input instead of 150,000 why waste the difference in the two rates. If you burn 75,000 btus in an 80% efficient appliance you have 15,000 going up the chimney. If you fire the same appliance at 150,000 @ 80% efficiency you have 30,000 up the stack. Therefore you have reduced what is going out the stack by 50%. So what if your combustion efficiency drops a couple points at the lower rate, it's still less loss (say that 5 times real fast) than the 20% going up the flue at the high fire rate.

?????? are why this profession is so fun!!

[Deleted User]

Read the post

about the 600 & 200 HP Boilers. Very interesting. Wonder what was left out?

Were the automatic damper controls operative? Or did they go to full open & stay there until the burners cycled off?
Were the boilers sized correctly? Or were they sized for the inevitible building expansion? Were they staged to match the changing loads? What was the burner turn down ratio? Couldn't possibly have been so wide that low fire condensed, could it? Condensing in the 3rd or 4th pass is a guaranteed tube & stack liner killer. Did any one try to narrow the ratio? Maybe 2.5:1 or even higher? Hospitals, manufacturing plants, & hotels, are infamous for quickly changing loads. How much load response time was lost in waiting for the 4 pre-purge air changes and the added time before there was enough input to compensate for what was lost? Wonder what the tube sheets would say about the quick ups & downs? What added costs were incurred through cycling large burners on & off? Were the fuel savings calculated only in dollars or therms/gallons? There is a difference.

And. Why are modulating residential gas boilers selling like hotcakes? Did you know the Euros have a modulating residential oil burner? Are all of those Dollars & Euros being wasted in developing & manufacturing modulating equipment? Or. Are we not capable of applying it properly?