condensate pump

joe_15

i just installed a steam to hot water heat exchanger. The diagram for the condensate pump showed no trap before it. when i turned everything on today i could't get the steam to stop going though the pump and back out the condensate line. should i have an f and t trap between the reciver and heat exchanger or can i just use a thermostic trap ?

Ben_3

Trap

Joe, you are going to need a steam trap on the outlet side of that heat exchanger, what else is gonna keep the steam out of that pump? I would use an F/T trap because it will have the ability to vent air through it while it is still collecting condensate, this means the air and water don't have to leave through the same opening as in a regular thermostatic trap. You will probably have a large volume of condensate if the hot water on the return side of the HX is cool it will condense the steam quickly, with a regular trap you would get a back up it the HX as well as you have to wait until everything cooled for the trap to re-open. With a F/T trap the the thermostat is seperate and will the system to vent/steam/condense without a problem, once there is enough condensate in the trap the float is lifted and it spits it out. The only drawback to this is if the trap is close to the reciever you might see some flash steam because the condensate leaving the trap may be very hot since the trap will discharge it's condensate regardless of it's temp. But this is very different from live steam, it's more like a vapor. Secondly size the trap to the amount of condensate the HX will produce not the line size. You can figure this by taking the EDR and divide by 4 or the btuh and divide by 960. This will tell you the lbs/hr the trap needs to handle, next you select one for a 2psig pres. diff if this is a typical low pres steam system.