Steam System

George_37

Just looked at an old Smith 340 Mills boiler. The system has both radiator air vents and steam traps on other radiators. The boiler is set in a pit to maintain the "A" dimension.

The owner does not want to pay for the old boiler removal.

I'd like to install a new steam boiler higher then the old using a simplex condensate return pump and receiver.

? Do I need a steam trap before the receiver tank?

? Should the return piping remain at its current elevation? (in the pit)

Jamie Hall

Can you arrange things

so that the water line in the new boiler matches that in the old?  New boilers are often much shorter than the big old ones, and it is often necessary to put them up on a pedestal -- you may find that you can match the water line without doing that.



If you can do that, you won't have to disturb the return piping at all -- just make sure that you have a drain for flushing at the lowest point.  The return water will happily seek its own level -- the same as it was before -- without your having to do anything.  You shouldn't need a condensate pump or receiver or a steam trap at that location at all, and they are a first class pain in the...



You may, however, want to examine all of the rest of the system and repair or restore any kludges, busted traps, or whatever that you find.  If this was a two pipe system, and some of the radiators have vents on them but others still have traps, you may find that you have problems out in the system.  Further, you may find that you don't have adequate -- or any! -- main venting.



If you don't fix those issues, installing a new boiler is, bluntly, a waste of time and money.

JStar

Steam

Doesn't want to pay to remove the old boiler = Doesn't want to pay to do the right job.



Condensate pumps are one extra part that requires a lot of maintenance and service. Try to avoid them whenever possible.



You do not want to put a trap at the receiver/pump. You will also need to repipe all of the returns to gravity return to the pump. You should have no instance of the return being trapped anywhere (ie: going down and back up). Make sure all of the steam mains have F&T traps installed, and working properly.



How much will you decrease the A Dimension by raising the boiler?



You will most likely regret doing the job this way.

George_37

Steam System

The "A" dimension would be cut by 2/3. The old boiler is coated with asbestos, the owner just doesn't have the funds to remove it.

Steamhead

Mills boilers are rather tall

if you can find a replacement on which the waterline is no higher than the Mills when placed on the floor close to the pit, you should be OK.



But not wanting to remove the old boiler is a red flag to me too. Be very careful when dealing with this customer.

Jamie Hall

But the real question is...

What would the A dimension be?  I have to confess that unless I'm missing something, putting in a condensate receiver and pump is a kludge on a residential system, and a pretty poor one at that.. 



Your critical dimension is from the boiler water level to the steam mains.  Period.  Unless that is one heck of a deep pit, putting the new boiler on the basement floor beside it should still work -- without the need for a pump.



If you don't have 28 inches or so from the water line to the steam mains, you might have a problem -- but it you don't have 28 inches or so from the water line to the steam mains, you're going to have trouble with the near boiler piping anyway.



Frankly, if your customer doesn't want to pay to do the job right -- the whole job -- do you really want the job?

George_37

Steam System

Thanks for the advise.



Just a few more details: The job is a 600 MBH boiler in a commercial building.



The pit is 30" deep. I'm going back today to measure the water line to steam header.