Position of Water Feed and Return Lines.

[dean06919]

Just wondering why all of the OWB's I have see have the feed lines at the bottom of the water jacket and the return lines at the top of the water jacket?

I would have assumed that the feed lines would have been at the top of the tank, as this is where the hottest water can be found. Does this have to do with the pumps pushing and not pulling, or an attempt to help maintain a somewhat constant temperature throughout the water jacket to alleviate stress on the firebox?

Thanks for helping me think this problem through.

Dean

 

[mtfallsmikey]

Huh?...not on a Central Boiler....makes no sense to me. My supply(s) feed from top (upper) tappings, returns on bottom. Circ. pump on supply, yes it is easier to push than pull...go to heatinghelp.com, order the book "Pumping Away"...then you will understand the concept.

 

[John D]

My circ is at the top,pushing the water to the house,then back thru the bottom fitting.You are right,why take cool water from the bottom?Take the hot,use rising heat to your advantage let it work with the pump.You want your incoming water as hot as possible without running the owb any hotter than necessary.

 

[beagledog]

First off, cold water rises. Warm water sinks. Opposite of air. Thats why ice floats...density. My owb has an extra circ. pump to circulate the water within the jacket to keep it from stratifying or seperating in any way. I think the outflow on bottom is just to help flow.

 

[LANNY]

Are you sure cold water rises? I think cold water only rises as ice, when the density markedly increases. When diving, the water below the thermocline is much colder, warmer at the surface. Therefore the hottest water would have to be at the top, assuming none is frozen and salinity is unchanged...Lanny

 

[Stihl310]

First off, cold water rises. Warm water sinks. Opposite of air. Thats why ice floats...density. My owb has an extra circ. pump to circulate the water within the jacket to keep it from stratifying or seperating in any way. I think the outflow on bottom is just to help flow.

I guess I'm confused then... how can hot water be more dense than cold water... makes no sense at all... cold water is not nearly as "excited" as hot water, it's molecules are simply in suspension. When water heats up it expands because the molecules begin to move faster and faster...

 

[beagledog]

Water is the only substance that loses density when it freezes. When ice fishing, the water on the bottom is always between 35 and 37 while right under the ice is 32-33. But as water warms up above 39F, this all goes out the window and since water in the water jacket is way above 39F, I was wrong to say the the hottest water would go to the bottom of your water jacket. I had ice fishing on my mind and was not thinking clearly...lol.

 

[LANNY]

Beagledog, I know what you mean. Water also does what is called a temperature inversion in late fall here and "turns over", who understands the laws of physics re water?........Lanny

 

[derwood91]

My assumption would be for circulator protection in the event of a leak. If the boiler system developed a leak you would have more time to realize the water was low before the pump cavitated and burned up. Funny you don't see low water cut off devices in OWB's. My main boiler loop in the house has one. Just a guess..........