As mentioned.

It looks like either I'm misunderstanding how to use this mod, or the front connection isn't connecting as of latest version.

Thoughts?

I've just tried the current version myself, and it seems to work fine :)

What is the temperature on your input heat pipe?

And where have you placed the different pipes (input and output) on the pump?

I've just played around with it some more. You wouldn't happen to have rotated it after it was placed? Cause that seems to break it :p

-Temperature of heat pipe
900Cish. Not far from a nuclear reactor.
- Where the pipes were placed
Heat input at one of the three connections at the back (away from the arrow when in alt mode). Heat output (that doesn't connect). Heat output at the other end.
- Rotated?
No, but the way you're mentioning it does clue me in on a possible reason why I'm having trouble. Give me a few to test and I'll report back.

Update:
My hunch was right, at least in my save, they only work when hand-placed - when they're placed either by bots, or by other mods (like Quantum Fabricator), they don't seem to spawn the productive entity - the one that converts the heat object back into heat. Which would make sense about the rotation - it's removing the functional end and not putting it back, because it wasn't placed by hand.

Additionally it looks like hand-removing one of these broken half-pumps by hand, while another one of your mods - Asteroid Belt - is installed, causes a crash:

Error while running event AsteroidBelt::on_player_mined_entity (ID 71)
AsteroidBelt/control.lua:46: attempt to call field 'remove_heat_pump' (a nil value)
stack traceback:
AsteroidBelt/control.lua:46: in function <AsteroidBelt/control.lua:45>

I'll test out if space platform placement is functional.

EDIT: they're also non-functional on space platforms

Okay, I believe I've fixed all of these.
The causes were:
- Built by player and built by robots are different events (so both now perform the correct function)
- Surface of the productive entity was locked to Nauvis (now inherits surface of the placed heat pump)
- There are leftover code in AsteroidBelt (fixed with an update to AsteroidBelt, removing it)

I don't know if it works with other building mods, but it should work with everything else :)

This does also mean that all heat pumps placed outside of Nauvis should be removed, as it has placed an invisible productive entity on the same coordinates on Nauvis.

Thankfully I haven't been using them out of Nauvis because I haven't LEFT Nauvis with my character, but will test and report!

Update: Good news bad news.
Bad news: The placement fix didn't work, it still puts only one half of the setup.
Good news: Your fix actually fixed the rotation problem, which DOES spawn the productivity half despite the bug - so for drone placement, other mod placement, AND platform placement, you can just rotate it twice to fix it
Also the crash is fixed :)

I do wonder if it's possible to make it work faster though, maybe have it have a speed bonus depending on heat?

And as an addon - I don't know how possible it is, but I thought of helping heat transfer by having "bus bar" - a 1xn / mergable heat pipe that had a solid heat and connections on all sides? kind of like how reactors can be used for heat transfer, but cheaper and more convenient to place

I've successfully started using them in my nuclear setups though - I quite enjoy this mod :)

I'm gonna need more description of the problem that are still present, if I am to fix it :)

About the pumping speed, I could probably make a multiplier setting to control it.

Adding you on discord, figure it might be easier that way :)

ah, that was you xD Could you do that again?
I usually ignore random friend requests from strangers, at least when they don't send a message with it :p

Sent again.

Would have loved to send a message but we didn't share a server so I couldn't