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[oaky]

I'll be running my P&M BL-2840 this fall for the first time, after I get it installed within a couple of months.

I was told it is better to connect the return to the top port opposed to the bottom port. BL manual says water return should be connected to the bottom port. My old Aqua-Therm was connected to the bottom. Any thoughts?

Still cold in Wisconsin, 43 for a high, Average high for today is 65 F.

oaky

[Steinacher Sales]

oaky,

The Shaver Furnace returns to the bottom. I do not know what P&M recommends.

Greg Steinacher
618-401-0726

[slimjim]

Gassers I like to return to the bottom, conventional's to the top, the hottest portion of a downdraft gasser is in the bottom, conventional's is the top, this tends to keep the water from boiling when it is run very hot as i normally do. does not affect the warranty either way but this is the way i do it

[mlappin]

Do what slim says, he seems smarter than the average bear.

Interestingly enough I've looked at every brand imaginable on line out of curiosity, some brands on their sites or literature show a top return while others show a bottom.

I posted a question about this once in the homemade section. Some seem to think  a top return promotes better mixing, while others don't.

I plan on taking some temp readings before insulating the next one I build.

[MattyNH]

Water returns to the bottom always..Thats for any system

[slimjim]

Matty, I beg to differ, I have seen and heard water boil inside OWB's, by returning to the hottest point of the boiler you automatically get the best heat exchange, sort of like why you plumb a plate exchanger in a countercurrent flow, that is the way to get the best and most efficient exchange, when you choose to run the boiler on an efficiency mindset with very low stack temps as well as very hot water temps, you come as close to boiling as you can without going over, by returning on the bottom of a gasser and top of a conventional you are returning to the hottest point,therefor getting the best heat exchange

[Jwood]

Good information guys!

[Crow]

 I don't know which is better but I do know that the manual stated return to the bottom ports on the BL. Another thing I learned when installing the pump in said boiler there will not be much room to work with if you choose to install the pump on the bottom ports, unless of coarse your pump is not located at the boiler. My 2 cents.

[slimjim]

Most folks it makes no difference, we did have a couple of people that complained of boiling by going that route as they were running very hot temps and when they switched the lines the boiling stopped, this tells me that returning to the top of the B-L is better for hotter running units.

[Scott7m]

Return water should come back to the top in a conventional folks, no question about it.  This creates further mixing of the water which creates a more balanced tank of water from top to bottom, equalling potential efficiency increase and added boiler protection. 

just as slim said, gassers are hottest in the bottom so returns should be there

[slimjim]

Thanks Scott, I'm not sure it makes a big difference if the unit is run cooler say 185 but when you run 195+ it sure does

[Scott7m]

Ive seen conventional stoves with water boiling in parts of the water and other parts 50 degrees colder!  Switched the lines around and it corrected 90% of the issue

[LittleJohn]

If you only turn pumps on when there is a call for heat, I could see the potential for heat stratification in the OWB.  But if you are running pumps constantly, I would think that water movement woudl keep the water mixed relatively well.

In regards to locating pump, I do agree with CROW; I have no idea how I would install a pump off the lower connections in my CB eClassic 2400.  By the way pumps are located in the house; haven't had to replace in dead of winter, YET

[oaky]

The water temperature varies in the water jacket in various areas?

oaky

[Scott7m]

The water temperature varies in the water jacket in various areas?

oaky

Yes, in some stoves like I said I've seen it be 50 degrees

Even on stoves that have proper port placement I've still seen them have a hot spot where you could hear water boiling and display temp be 180 under a hard burn

I've also used a infrared gun when doing some trouble shooting and noticed boilers with poor design, returns at the top, or a small pump would have much cooler temps in the bottom of the boiler than the top

This causes a whole array of issues, first of all u want a balanced "hot" tank of water!  If you are running your stove at 165 and have 165 at the top where your aquastat probe is, and have 135 in the bottom or cooler, you are causing the ash line to be very cool inside the firebox which will lead to condensation of moisture into the ash and premature failure of the firebox. 

Also, don't simply assume there is no internal plumbing inside ur boiler, because on a lot of different boilers there is pipe that put the water where they want it to go.  Most returns will extend over the top of the firebox towards the front of the stove.