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So... while working on some reactor patterns, I got sick and tired of worrying about heat pipe throughput and distance, and ran some basic tests to see what I could get away with. Turns out that I'm worrying WAY too much about them. I haven't stumbled any dedicated threads like this previously, so other builders might find this stuff interesting.

Test Setup: A load of reactors on one side, columns of 10/18 exchanger/turbine rows on the other. The number of heat pipe paths bridging the two sides can be easily varied. I took extreme care to make sure all heat pipes were placed from teh reactor to the destination, since it's already known they tend to behave directionally.


Sure enough, the pipes seem to choke at roughly 1GW/pipe. There doesn't seem to be any pattern as to which paths after the chokepoint get the energy, but the final electricty output is quite definitely capped at ~1GW/pipe width. Replacing the missing pipe widths lets the system resume full power with little difficulty.


If there's a distance limitation to heat pipes, I haven't found it. Even at 1000 units of heat pipe, you can still keep a 10/18 configuration at full output. You will, however, wait a LONG time for the heat to actually reach the destination

Now try to lay down the heat pipe starting at the end and placing it towards the reactor.
This limits the throuput a lot.
In my tests it reduces the temperature by 16.66 degrees each tile, giving a total max length of about 500/16.66 = 30 tiles to go from 1000 to 500.
It looks like a bug, and is already reported in the bug portion of the forum. See viewtopic.php?f=7&t=44972

Yeah, the heatpipe directional thing is most definitely a bug. I hope they will fix it... or if it is not fixable then give the pipes arrows so that there is an indication that they work directionally.

Mehve wrote:Sure enough, the pipes seem to choke at roughly 1GW/pipe. There doesn't seem to be any pattern as to which paths after the chokepoint get the energy, but the final electricty output is quite definitely capped at ~1GW/pipe width.

That is interesting to know... I wasn't entirely sure about how much heat/power is able to be transfered over a single Heatpipe... Now I will consider that if I create bigger plants and start splitting up accordingly.

In my 2x3 setup with 800MW it doesn't seem to matter, since the entire plant is still below that limit.

Yeah, it's nice to have a hard number to work with, especially such a large number. But it also reduces concerns when you're only worried about a steady-state reactor setup - each heat pipe line can basically supply 100 exchangers without worry, as long as you make sure you lay them from the reactor outward. If you want to actively control the reactor it's a different story of course, but nuclear fuel is so cheap that I honestly can't be bothered to go down that path.

I originally figured that Factorio treated heat like it does liquids, which would explain why we get issues if you don't lay down the pipes in the right direction. But after playing around with this setup, they've clearly got their own behaviour that's unique from the quirky liquid flow we've come to know and love.

Mehve wrote:Sure enough, the pipes seem to choke at roughly 1GW/pipe. There doesn't seem to be any pattern as to which paths after the chokepoint get the energy, but the final electricty output is quite definitely capped at ~1GW/pipe width.

You're right about 1GW/pipe. they specified that in the base mod configuration. Also nuclear reactor can transfer heat. They have a 10GW/reactor limit.