Zone Length?

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Old 12-22-13, 07:08 PM
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Zone Length?

I read in an old thread about the length of a zone for 3/4" cu being 67 feet. Is this total piping for both supply and return or just the portion that is finned on the supply side?

I currently have 132ft of total piping just on the second floor alone of my home and I need to bump it up by 5 feet due to a remodel project.

My system was installed in the early 70's. Its an oil fired boiler (175,000btu) has 4 zones, 3/4 copper to and from boiler. The house is a classic gable L farmhouse (100 plus years old).

I had a recent quote to change the boiler out and was sticker shocked. The company wanted to change me over to a propane fired boiler etc. This will be another thread.

Thanks for any input.
 
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Old 12-22-13, 07:22 PM
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Is this total piping for both supply and return or just the portion that is finned on the supply side?
Just the finned portion.

Going up 5 feet probably isn't going to change anything, especially if you already have too much... if too much already, what's another 5 feet?

I had a recent quote to change the boiler out and was sticker shocked. The company wanted to change me over to a propane fired boiler etc. This will be another thread.
Think long and hard about going to propane. It's damn near as expensive as oil is.

Before doing ANYTHING when changing out a boiler, DO A HEAT LOSS ESTIMATE!

Your 175K boiler is likely at LEAST twice as big and probably THREE times as big, maybe even FOUR times as big as need be. I can tell you absolutely that I could heat my home AND two of my neighbors homes with a boiler that big.
 
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Old 12-22-13, 08:20 PM
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3/4" copper has a max of 40,000 btu's or about 68 ft. of finned radiation.

As NJ said if you've got 132ft. now, 5 more ft won't put you over the edge.
If it stops heating it won't be because of the added 5 ft.
 
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Old 12-22-13, 08:46 PM
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I know the 5 feet seems irrelevant but I was more worried about having a zone with that much lineal footage on it etc.
 
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Old 12-23-13, 06:25 AM
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Maybe a bit more explanation is needed?

The reason for the limitation of fin tube element is because of the 40K BTU that Spott mentioned. If you look at the rating of the typical fin-tube, you are usually right around 600 BTU/FT.

If you divide 40K by the 600 per foot, you come up with 66 feet.

The total length of the run including connecting piping and such is dictated by the 'head' (friction) of the piping loop. 132' is 'probably' around 8' of head which is within the capability of a 007 to pump.
 
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