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# Copper fin tube

Member Posts: 414
Is there a rule of thumb for how much temperature drop per foot of fin tube? Also BTU/ft? What supply temps would you normally run baseboard at? I know there are many other factors involved in why a room or building can't keep up temp's in very cold weather but I would like to determine if the baseboard is putting out what it's supposed to. Then I can figure out if they have enough in there.

Thanks, Rich

• Member Posts: 1,718
bb

You can make the BB put out different btu's. You need to know what the heat loss for the room is first. Then you can figure out how much bb to use and at what temp water.

Did you get the free slant/fin heat loss program? The link is available on this site. The link "Heat loss calcs" is at the top of the page.

Massachusetts

• Member Posts: 1,790
baseboard

It depends on a few things, but in many cases the planets align, the math works out, and you have 1°F temperature drop per foot with 180°F supply temp at 1 gpm water with a 500 btu/ft rated baseboard. Of course after the first foot,the drop begins to drop.

• Member Posts: 178

Andrew. With all due respect would this mean if I have a zone with 60' of fin tube supplied by 180* water will my return water temp really be 120*.

Just curious
• Member Posts: 299
Depending on air temp and flow it certainly could...

• Member Posts: 1,790
Nope

But for the first foot it's a decent approximation that it will drop 1°F if supplied with 1gpm of 180°F water. I apologize if the statement I made earlier was misleading. The temperature drop is not linear over the element length.
• Member Posts: 178

Uni R: Come on down to my house and make it work like that

My 67' of BB with a 15/58 on low speed gives up 3* max for the zone.

Dinner is on me
• Member Posts: 102
That's pretty funny

67' with a 3° delta t on slow speed.

How many BTUH do you suppose you are delivering at that flow rate?

Noel
• Member Posts: 299

I'll be opening windows and closing valves! Hope you don't mind... ;-)

I'll bring dessert!
• Member Posts: 1,790
hmm

Apparently he/she doesn't even have an email address.
• Member Posts: 2,393
But that is why the Average Water Temperature

is so darn useful. One may safely assume that halfway down the element more or less, the temperature is halfway between supply and return.

As one of my mentors illustrated to me when describing a long row of double-tier radiation served in a "U" or switchback pattern:

Draw a line across any point top to bottom. All will be at the average water temperature. Think about it.
"If you do not know the answer, say, "I do not know the answer", and you will be right!"