wet base boiler

[Jesjen829]

what would define a wet base boiler? and is there a dry base boiler?

[George Fernandez]

There are three types of boiler. Wet base, wet leg and dry base.
Wet base is a boiler which has water in the cast iron sections, under the combustion area. As the name implies. Other wet leg types are steel like Energy Kinetics. They have water surrounding the combustion chamber.
Wet leg boilers have, legs on either side of the boiler, that are part of the cast iron sections. The last section of the boiler on a wet leg type has no legs, but is a full section. In these types water does not pass under the combustion area.
The last type is dry base these are usually steel construction. The fire in these is in a dry box type combustion chamber. All the water for heating is above this box in a steel vessel.
An example of each would be, Weil Mclain 66,68 and Gold series are wet base. Burnham RS series are dry base. American Standard Arcoliners are wet leg.

[heatingman]

There are three types of boiler. Wet base, wet leg and dry base.
Wet base is a boiler which has water in the cast iron sections, under the combustion area. As the name implies. Other wet leg types are steel like Energy Kinetics. They have water surrounding the combustion chamber.
Wet leg boilers have, legs on either side of the boiler, that are part of the cast iron sections. The last section of the boiler on a wet leg type has no legs, but is a full section. In these types water does not pass under the combustion area.
The last type is dry base these are usually steel construction. The fire in these is in a dry box type combustion chamber. All the water for heating is above this box in a steel vessel.
An example of each would be, Weil Mclain 66,68 and Gold series are wet base. Burnham RS series are dry base. American Standard Arcoliners are wet leg.

Just to add, most smaller boilers are dry base boilers, cast iron included. And in the case of power burning boilers, there are also wet back and dry back boilers, both of which are typically wet base, but the wet back has heat exchange surfaces at the target wall, and the dry back does not.

[Jesjen829]

which is most efficient(wet, dry base) or does it vary. also, circ on return side or supply. always get mixed answers on this. i was tought supply side but was recently told this is wrong.

[George Fernandez]

ok its like this. the most efficient I have seen is wet base. Buderus is wet base triple pass. I achieved a 89% efficiency with a Riello burner. Also, if you have ever read the book Pumping Away by Dan Holohan you'll see pumps on the supply side are the better option. On the supply side your pump creates a push effect on the water and forces any air trapped in a system back into the water solution, back through the boiler and out the air separator, which ever one you choose. And you should also look into the point of zero pressure drop.
It is a simple concept once you see it, Out of the boiler supply into an air removal device, then to a circulator. out to the system piping. Also feed your system at the air removal device. Better if you read about it than for me to try to explain it. Just remember high pressure goes to low pressure. Just as hot goes to cold.

[Jesjen829]

ok its like this. the most efficient I have seen is wet base. Buderus is wet base triple pass. I achieved a 89% efficiency with a Riello burner. Also, if you have ever read the book Pumping Away by Dan Holohan you'll see pumps on the supply side are the better option. On the supply side your pump creates a push effect on the water and forces any air trapped in a system back into the water solution, back through the boiler and out the air separator, which ever one you choose. And you should also look into the point of zero pressure drop.
It is a simple concept once you see it, Out of the boiler supply into an air removal device, then to a circulator. out to the system piping. Also feed your system at the air removal device. Better if you read about it than for me to try to explain it. Just remember high pressure goes to low pressure. Just as hot goes to cold.

good explanation. thanks

[rich pickering]

So, how come most modcons have to be pumped into the boiler?

[meplumber]

Rich,

To your question of pumping away from mod/cons:

ModCons, due to their high head loss through the heat exchanger, require two circulators. One on the boiler side and one on the system side, this is why we must do primary secondary piping or hydronic separation.

With the circ on the return side of the boiler, the manufacturers are able to achieve the highest flow rate with the smallest wattage circulator. (I have no idea how. Just what I was told by one of the design engineers from one of the ModCon manufacturers.) The system circulators would then be placed on the secondary side, on the supply pumping away from the closely spaced tees or hydronic separator which becomes the point of no/low pressure drop.

I hope that I got that right. Just regurgitating seminar info from a couple years ago.

[rich pickering]

Close. Some modcons only require one pump, but you still have to pump into the boiler.

[heatingman]

The reason you pump into the boiler on a mod/con is b/c that is the highest restriction.

Most pumps have a Net positive suction pressure requirement. If you were to pull through the boiler, you might end up reducing the pressure on the suction of the pump too much and create excessive cavitation within the pump.

Pushing into the load helps ensure against pump cavitation.

Regardless, you are still pumping away from the point of no pressure change when piped properly.

[rich pickering]

What it boils down to (pun intended) is there are many different ways to pipe a system, different types of boilers, heat emitters, pumps, control strategies and even piping. Combustion efficiency is only one part of the equation.

One type of boiler is not "better" than others, it depends on the application.

[heatingman]

There is more than one way to fry an egg.

You can pipe a boiler a thousand different ways, but only a few would be totally wrong.

But, when it comes to mod con boilers, most manufactures are fairly specific with how they want them piped. You can pipe them in other ways, but that's on you if it all hits the fan.

[SolarMike]

ALWAYS pump into your highest head. This is the case with ModCons. If you have primary secondary pumping, you guarantee the flow needed for the boiler to operate properly and that is the most important thing.

Look at what happens if you take a low mass Laars boiler and run it without the pump. It will bounce across the floor (and it is not even modcon).

Non- wetbase are 50s technology......go Viessmann go....ra ra ra LOL