What is the best/correct temperature for condensate

Ken Sappio

feed water at for returning it to a 15 PSI steam boiler?

Glen Aspen_2

I would have thought -

you would have rec'd a reply from the astute folks here on the wall by now; here is my take: at 15 psig your steam temp is about 250 F as it leaves the boiler. Depending on the type of traps, condensate return (eg condensate receiver or??)and a number of other factors the condensate returning back to the receiver could be as low as 170 F, or even lower. If your makeup water is tied into this receiver then the feed water injected into the boiler would be lower than the 170F due to the dilution of the condensate by the city main water temp. So like so many other questions here the answer is "it depends". So if you can - could you describe the system? type of traps, feed water piping etc.

Ken Sappio

The condensate is coming back from steam coils (unit heaters)

and back into a stainless steel condensate tank which is at atmospheric pressure. The condensate tank has a steam heater. City water is used to keep the tank at a min level.

Jamie Hall

There really isn't

a good single answer to your question. Ideally, your feedwater (condensate plus makeup being injected into the boiler) would be just below the boiler water temperature. But... where are you going to get the heat from to get it there? There's no free lunch! It will help if your returns are all insulated -- that will reduce heat and temperature loss in your returning condensate. However, unless you have a setup (rare in smaller boilers, and very rare in heating boilers) to use waste stack heat to heat up the feedwater (referred to as an economizer in marine practice, or a feedwater heater in rail practice, and both using otherwise lost heat in the stack gas) you might just as well heat the returning feedwater in the boiler as anywhere else...

Tom Blackwell_2

Ideally the condensate should be heated to to at least 200 degrees in the feedwater tank to drive out as much dissolved oxygen as possible. After the feedwater is in the boiler, the released oxygen will cause waterside corrosion.

Jamie Hall

Quite right

indeed! My question still stands, though -- in a domestic or non-power larger steam system, where do you get the heat from for the feedwater heater?