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[coolidge]

Is there any benefit in keeping boiler water at 190/200?

[mlappin]

200 might be a bit high, but in theory the hotter you can run it the dryer the firebox should stay.

The hotter your water the less oxygen that can stay dissolved in the water.

Two interesting bits of info I’ve studied in the past.


http://www.engineeringtoolbox.com/air-solubility-water-d_639.html


http://media.wix.com/ugd/61224a_17e60b76c34a132746c5cb8a250cc526.pdf

[ambonci]

I ran 170 in the past and this year I am running 190.  in theory you should get a little more BTUS correct?

[BoilerHouse]

To me, higher temps is a trade off.  Heat flows with temp difference, so it will help your coils work better but you will be prone to a bit more loss in underground pipes and boiler skin.
Good points about oxygen solubility and temp and I am glad to see the graph posted. I have occasionally seen it posted that keeping water above 180 eliminated oxygen.  The graph and article shows that this is not the case.
Just want to add a couple points - while there is less ability to hold oxygen at higher temps, it does tend to be more reactive.  It is also hard to remove oxygen from a water system - temp alone won't do it.  As was pointed out in the article, industry uses an elaborate pre-boiler device called a deaerator. It's a thermo/mechanical pressure vessel to physically remove oxygen.  Even then it is critical to treat water with chemical oxygen scavengers.  So the take away is make sure you use a quality water treatment to counteract oxygen, which leads to rust/corrosion and metal wasting.

[mlappin]

To me, higher temps is a trade off.  Heat flows with temp difference, so it will help your coils work better but you will be prone to a bit more loss in underground pipes and boiler skin.

Thats what I’ve always noticed with my old boiler, the hotter I ran it, the more wood it took to keep those temps higher.

Of course being natural draft I liked to keep the temps higher as if the load was too high it took a long time to catch back up.