multi-pass boilers

Jon S.

Could someone explain to me how a multi-pass boiler works.
Thanks
Jon S.

Michal

WHAT HAPPENS IN A NORMAL BOILER

is that the flue gasses pass through verticle passages in the boielr and go straight up and out the flue. in a multi pass boiler, the fluue gasses pass through a lower chamber horizontally, then go to a second chamber and finally a third chamber anfd out the flue pipe. As the gasses pass through the chambers they cool as they give off all theior heat. The best thing for you to do is look at a weil mclain gold boiler and look at the buderus boilers, their websites are a good place. You will notice the way they are built is different. Hope I didnt confuse you.

Kevinj

Multi pass

This is a link to my favorite boiler. they have up to 4 pass units.


http://www.johnstonboiler.com/

Unknown

Ill take a stab at this,..

The goal of your boiler is to heat the water that is inside of it. There are a few components to accomplish this that Ill point out. Ill use an analogy to heating a pot of water on your stove

1; The fuel source - Lets say a gas stove (or your oil/gas burner to your boiler)
2; The vessel - the pot (the boiler itself)
3; And finally the water inside

You place the pot of water onto the burner on yout stove and the heat the burner produces heat the pot (vessel) eventually heating the water inside the pot.

In the pot example the flame/heat only hits one side of the pot. That is like a single pass boiler.

A multi pass boiler isa different shaped pot that allows the same flame from the stove to heat up all sides of the pot instead of one. So in a three pass boiler the heat produced by the burner directly heats more of the vessel before it exits the boiler.

You will typically see a lower stack temperature indicating that more of the heat produced by the burner was used in heating the water inside the boiler than in a single pass boiler.


It should also be noted that more efficient units (like multi pass boilers with low stack temperatures) may require a more modern chimney.

In older homes chimneys may have been designed for coal, or a coil conversion system that dealt with much higher stack temperatures 800+ degrees. As burners have become more efficient, and stack temperatures have been lowering,.. the wear on the chimney increases due to condensation (and most likely a hole host of other factors I am unaware of)

With these heating systems I recommend having a chimney liner installed by a chimney professional to fascilitate and ensure proper draft

- Norm

Unknown

Multipass Boilers

Here is a link to part of our web site that pretty well explains how multipass boilers operate.

http://www.burnham.com/mpo/3-pass.cfm

Joe Brix

Burnham Web site finally updated!

Thanks for all the literature on the Burnham web site for the MPO, Glenn. Nice to see the American answer to Buderus has finally shown up.