We want to add a circulator pump to a Bryant 234-4gw B series and are not sure which are the return lines?

What is year--make--model?
Usually with new pump, I rotate the old fluid out while putting new fluid in, that goes with the power steering pump change.
I take the return line loose from pump that should be low pressure line, usually held on with hose clamp. The high pressure line should have threaded fitting.
Aim the return line into container, turn pulley with my fingers, the old fluid should come out return line. At the same time, you have to add new fluid to the pump reservoir. When the fluid from the return line runs clear/new fluid, your done.
If no circulation, maybe a faulty or clogged power steering line?

if the water doesnt circulate, there could be many causes. start at the very beginning. does the pump sound 'normal'? if there is rattling or buzzing, the pump might not be turning and there fore no circulation. is there water in the system? even though most pumps are 'self priming', you should fill the hopper with water to prime it. are the lines open? make sure the supply to pump from skimmer is free of blockage and that the return lines to pool are open and free from blockage. if all this looks fine, then you have to get deeper into diagnosis.

Either a bad control board on the inside unit or a bad blower motor.

May be over heating. Should be installed on the return line near the boiler. Also, check for proper voltage.

This is true as long as it is not a heat pump. Make sure they replace the piston (metering device to match the outdoor units required piston size. Or if the indoor coil is metered via TXV, it will automatically meter the refrigerant flow. If you are mismatching a system, make sure an acid test is performed on the old refrigerant and take appropriate measures with the new system if the test shows positive acid. They need to definitely install a liquid line drier. Hope this helps.

would need a look but i suspect that the heater matrix is blocked ,drain antifreeze then fill with water and add half a cup of caustic soda and run car like this for a day or so and it may clear the blockage mif so drain the caustic soloution then flush really well then add the coolant ,never use plain water

http://waterheatertimer.org/Water-heater-recirculation-system.html

The circulation system should draw hot water directly from the water heater as shown on illustrations on link above.

The Grundfos pump works on a thermostat, and some work on a timer.
Can you hear the pump working?
There should be a humming sound.
Check the timer -or- thermostat setting.

It is possible the lines are clogged with sediment if you have hard water.

If I was going to fix the problem:
1) check thermostat or timer
2) listen for pump sound
3) check electricity going to unit
4) take apart the pipes and inspect for clogging
If there is a clog, I would flush the line or soak the part in CLR (calcium lime rust remover)

The circulation pumps are sealed and there is no way to take apart the motor, timer, or thermostat for repairs.

add a comment if you need more assistance.

Your circulator provides the draw necessary to fire the heater. You are defeating the purpose of this kind of heater by circulating the water. Add a second heater to fix this engineering fault.

Hydraulic fluid straight from the drum, has a typical cleanliness level of ISO 4406 21/18. A 25 GPM pump operating continuously in hydraulic oil at this cleanliness level will circulate 3,500 pounds of dirt to the hydraulic system's components each year! To add hydraulic oil, and not the dirt, always filter new oil prior to use in a hydraulic system. This can be accomplished by pumping the oil into the hydraulic reservoir through the system's return filter. The easiest way to do this is to install a tee in the return line and attach a quick-connector to the branch of this tee. Attach the other half of the quick-connector to the discharge hose of a drum pump. When hydraulic oil needs to be added to the reservoir, the drum pump is coupled to the return line and the oil is pumped into the reservoir through the return filter. As well as filtering the oil, spills are avoided and the ingress of external contamination is prevented. The benefits of carrying out this simple modification are well worth the minor cost involved.

Hydraulic fluid straight from the drum, has a typical cleanliness level of ISO 4406 21/18. A 25 GPM pump operating continuously in hydraulic oil at this cleanliness level will circulate 3,500 pounds of dirt to the hydraulic system's components each year! To add hydraulic oil, and not the dirt, always filter new oil prior to use in a hydraulic system. This can be accomplished by pumping the oil into the hydraulic reservoir through the system's return filter. The easiest way to do this is to install a tee in the return line and attach a quick-connector to the branch of this tee. Attach the other half of the quick-connector to the discharge hose of a drum pump. When hydraulic oil needs to be added to the reservoir, the drum pump is coupled to the return line and the oil is pumped into the reservoir through the return filter. As well as filtering the oil, spills are avoided and the ingress of external contamination is prevented. The benefits of carrying out this simple modification are well worth the minor cost involved.