Counterflow main sizing

SeanBeans

I need to run two separate counter flow mains, one will be 22’ long and the other will be 12’.

The EDR of the boiler is going to be 283.

The connected load is less than that on both sides obviously.

I should be fine running 2 2” counter flow mains right?

EBEBRATT-Ed

Depends on the pitch. 2" is good for 275 with a 1" pitch. with 1 1/2" pitch 333. Page 162 in LAOSH new edition.

SeanBeans

So I have about 130edr on north side of house and 150 on south side of house.

My plan is to run a 2” counter flow for each side

EBEBRATT-Ed

2" with only 1/4" will do 171. or 1 1/2" with a 3" pitch (not likely) will do 187 for the south side.

1 1/2" with a 1" pitch will do 132 for the north side or 2" with a 1/4" pitch.

2" with at least a 1/4" pitch is probably the best for both

SeanBeans

1/4 per foot you’re saying

SeanBeans

I’m not seeing what you’re seeing on page 162

JUGHNE

The Revisited, new book has it on 137. 162 in this book has pipe capacity for counter flow.

It is 1" for every 10', sloping back towards the boiler with top steam feed into pipe and drip connection on the bottom of pipe main.

EBEBRATT-Ed

LAOSH...revisited......... page 162 is the counter flow pipe chart.

yes you can reduce the pitch if the pipe is oversized.

The south side needs 2". You said you needed 150edr the pitch can be reduced to 1/4"/10' of pipe and the 2" will carry 171edr with that pitch.

If you want to pitch it more have at it.

The north side you said you needed 130. 1 1/2" will carry 132 with 1 1/2" pitch/10' of pipe.

2" is probably the best choice for the north side as well. 2" with 1/4" pitch will do that one as well

With a large pitch you can use a smaller pipe....to a point. Bigger pipe can get by with a lesser pitch....for a given load