diff --git a/code/ATMOSPHERICS/components/binary_devices/circulator.dm b/code/ATMOSPHERICS/components/binary_devices/circulator.dm
index b6c5d55e5a9..a0f563669c1 100644
--- a/code/ATMOSPHERICS/components/binary_devices/circulator.dm
+++ b/code/ATMOSPHERICS/components/binary_devices/circulator.dm
@@ -7,29 +7,30 @@
 	icon_state = "circ1-off"
 
 	var/side = CIRC_LEFT
-	
+
 	var/global/const/CIRC_LEFT = WEST
 	var/global/const/CIRC_RIGHT = EAST
 
 	var/last_pressure_delta = 0
-	
+
 	var/obj/machinery/power/generator/generator
 
 	layer = 2.45 // Just above wires
-	
+
 	anchored = 1
 	density = 1
-	
+
 	can_unwrench = 1
-	
-// Creating a custom circulator pipe subtype to be delivered through cargo	
+	var/side_inverted = 0
+
+// Creating a custom circulator pipe subtype to be delivered through cargo
 /obj/item/pipe/circulator
 	name = "circulator/heat exchanger fitting"
 
 /obj/item/pipe/circulator/New(loc)
 	var/obj/machinery/atmospherics/binary/circulator/C = new /obj/machinery/atmospherics/binary/circulator(null)
-	..(loc, make_from = C) 
-	
+	..(loc, make_from = C)
+
 /obj/machinery/atmospherics/binary/circulator/Destroy()
 	if(generator && generator.cold_circ == src)
 		generator.cold_circ = null
@@ -38,8 +39,10 @@
 	return ..()
 
 /obj/machinery/atmospherics/binary/circulator/proc/return_transfer_air()
-	var/output_starting_pressure = air1.return_pressure()
-	var/input_starting_pressure = air2.return_pressure()
+	var/datum/gas_mixture/inlet = get_inlet_air()
+	var/datum/gas_mixture/outlet = get_outlet_air()
+	var/output_starting_pressure = outlet.return_pressure()
+	var/input_starting_pressure = inlet.return_pressure()
 
 	if(output_starting_pressure >= input_starting_pressure - 10)
 		//Need at least 10 KPa difference to overcome friction in the mechanism
@@ -47,17 +50,17 @@
 		return null
 
 	//Calculate necessary moles to transfer using PV = nRT
-	if(air2.temperature > 0)
+	if(inlet.temperature > 0)
 		var/pressure_delta = (input_starting_pressure - output_starting_pressure) / 2
 
-		var/transfer_moles = pressure_delta * air1.volume/(air2.temperature * R_IDEAL_GAS_EQUATION)
+		var/transfer_moles = pressure_delta * outlet.volume/(inlet.temperature * R_IDEAL_GAS_EQUATION)
 
 		last_pressure_delta = pressure_delta
 
 		//log_debug("pressure_delta = [pressure_delta]; transfer_moles = [transfer_moles];")
 
 		//Actually transfer the gas
-		var/datum/gas_mixture/removed = air2.remove(transfer_moles)
+		var/datum/gas_mixture/removed = inlet.remove(transfer_moles)
 
 		parent1.update = 1
 		parent2.update = 1
@@ -71,6 +74,43 @@
 	..()
 	update_icon()
 
+/obj/machinery/atmospherics/binary/circulator/proc/get_inlet_air()
+	if(side_inverted==0)
+		return air2
+	else
+		return air1
+
+/obj/machinery/atmospherics/binary/circulator/proc/get_outlet_air()
+	if(side_inverted==0)
+		return air1
+	else
+		return air2
+
+/obj/machinery/atmospherics/binary/circulator/proc/get_inlet_side()
+	if(dir==SOUTH||dir==NORTH)
+		if(side_inverted==0)
+			return "South"
+		else
+			return "North"
+
+/obj/machinery/atmospherics/binary/circulator/proc/get_outlet_side()
+	if(dir==SOUTH||dir==NORTH)
+		if(side_inverted==0)
+			return "North"
+		else
+			return "South"
+
+/obj/machinery/atmospherics/binary/circulator/attackby(obj/item/weapon/W as obj, mob/user as mob, params)
+	if(ismultitool(W))
+		if(side_inverted == 0)
+			side_inverted = 1
+		else
+			side_inverted = 0
+		to_chat(user, "<span class='notice'>You reverse the circulator's valve settings. The inlet of the circulator is now on the [get_inlet_side(dir)] side.</span>")
+		desc = "A gas circulator pump and heat exchanger. Its input port is on the [get_inlet_side(dir)] side, and its output port is on the [get_outlet_side(dir)] side."
+	else
+		..()
+
 /obj/machinery/atmospherics/binary/circulator/update_icon()
 	if(stat & (BROKEN|NOPOWER))
 		icon_state = "circ[side]-p"
diff --git a/code/modules/power/generator.dm b/code/modules/power/generator.dm
index 0ff6289ea66..a61aca5661c 100644
--- a/code/modules/power/generator.dm
+++ b/code/modules/power/generator.dm
@@ -10,23 +10,23 @@
 	var/obj/machinery/atmospherics/binary/circulator/hot_circ
 
 	var/cold_dir = WEST
-	var/hot_dir = EAST	
-	
+	var/hot_dir = EAST
+
 	var/lastgen = 0
 	var/lastgenlev = -1
 	var/lastcirc = "00"
-	
+
 /obj/machinery/power/generator/New()
 	..()
 	update_desc()
-	
+
 /obj/machinery/power/generator/proc/update_desc()
 	desc = initial(desc) + " Its cold circulator is located on the [dir2text(cold_dir)] side, and its heat circulator is located on the [dir2text(hot_dir)] side."
-	
+
 /obj/machinery/power/generator/Destroy()
 	disconnect()
 	return ..()
-	
+
 /obj/machinery/power/generator/proc/disconnect()
 	if(cold_circ)
 		cold_circ.generator = null
@@ -38,10 +38,10 @@
 /obj/machinery/power/generator/initialize()
 	..()
 	connect()
-	
+
 /obj/machinery/power/generator/proc/connect()
 	connect_to_network()
-	
+
 	var/obj/machinery/atmospherics/binary/circulator/circpath = /obj/machinery/atmospherics/binary/circulator
 	cold_circ = locate(circpath) in get_step(src, cold_dir)
 	hot_circ = locate(circpath) in get_step(src, hot_dir)
@@ -61,13 +61,13 @@
 	power_change()
 	update_icon()
 	updateDialog()
-	
+
 /obj/machinery/power/generator/power_change()
 	if(!anchored)
 		stat |= NOPOWER
 	else
 		..()
-	
+
 /obj/machinery/power/generator/update_icon()
 	if(stat & (NOPOWER|BROKEN))
 		overlays.Cut()
@@ -79,7 +79,7 @@
 
 		overlays += image('icons/obj/power.dmi', "teg-oc[lastcirc]")
 
-/obj/machinery/power/generator/process()	
+/obj/machinery/power/generator/process()
 	if(stat & (NOPOWER|BROKEN))
 		return
 
@@ -128,11 +128,11 @@
 		// update icon overlays only if displayed level has changed
 
 		if(hot_air)
-			var/datum/gas_mixture/hot_circ_air1 = hot_circ.air1
+			var/datum/gas_mixture/hot_circ_air1 = hot_circ.get_outlet_air()
 			hot_circ_air1.merge(hot_air)
 
 		if(cold_air)
-			var/datum/gas_mixture/cold_circ_air1 = cold_circ.air1
+			var/datum/gas_mixture/cold_circ_air1 = cold_circ.get_outlet_air()
 			cold_circ_air1.merge(cold_air)
 
 	var/genlev = max(0, min( round(11 * lastgen / 100000), 11))
@@ -146,12 +146,12 @@
 
 /obj/machinery/power/generator/attack_ai(mob/user)
 	return attack_hand(user)
-	
+
 /obj/machinery/power/generator/attack_ghost(mob/user)
 	if(stat & (NOPOWER|BROKEN))
 		return
-	interact(user)	
-	
+	interact(user)
+
 /obj/machinery/power/generator/attack_hand(mob/user)
 	if(..())
 		user << browse(null, "window=teg")
@@ -168,29 +168,35 @@
 			connect()
 		playsound(loc, 'sound/items/Ratchet.ogg', 50, 1)
 		to_chat(user, "<span class='notice'>You [anchored ? "secure" : "unsecure"] the bolts holding [src] to the floor.</span>")
-	else if(istype(W, /obj/item/device/multitool))
+	else if(ismultitool(W))
 		if(cold_dir == WEST)
 			cold_dir = EAST
 			hot_dir = WEST
-		else
+		else if(cold_dir == NORTH)
+			cold_dir = SOUTH
+			hot_dir = NORTH
+		else if(cold_dir == EAST)
 			cold_dir = WEST
 			hot_dir = EAST
+		else
+			cold_dir = NORTH
+			hot_dir = SOUTH
 		connect()
 		to_chat(user, "<span class='notice'>You reverse the generator's circulator settings. The cold circulator is now on the [dir2text(cold_dir)] side, and the heat circulator is now on the [dir2text(hot_dir)] side.</span>")
 		update_desc()
 	else
-		..()	
-	
+		..()
+
 /obj/machinery/power/generator/proc/get_menu(include_link = 1)
 	var/t = ""
 	if(!powernet)
 		t += "<span class='bad'>Unable to connect to the power network!</span>"
 		t += "<BR><A href='?src=[UID()];check=1'>Retry</A>"
 	else if(cold_circ && hot_circ)
-		var/datum/gas_mixture/cold_circ_air1 = cold_circ.air1
-		var/datum/gas_mixture/cold_circ_air2 = cold_circ.air2
-		var/datum/gas_mixture/hot_circ_air1 = hot_circ.air1
-		var/datum/gas_mixture/hot_circ_air2 = hot_circ.air2
+		var/datum/gas_mixture/cold_circ_air1 = cold_circ.get_outlet_air()
+		var/datum/gas_mixture/cold_circ_air2 = cold_circ.get_inlet_air()
+		var/datum/gas_mixture/hot_circ_air1 = hot_circ.get_outlet_air()
+		var/datum/gas_mixture/hot_circ_air2 = hot_circ.get_inlet_air()
 
 		t += "<div class='statusDisplay'>"