Condensate problems with steam

[Deleted User]

the current boiler is an oil-fired replacement, and i don't know if the previous one was coaler, but i can find out what was removed because i know the guy that did the demo/removal and install of the current one. and supposedly by only two guys in less than 120 man hrs; which included all new near-boiler piping/surge and feed tanks/4 zoners/wiring etc. with the 4 zoners/piping being 12' off the floor/ladder work. methinks time has colored their memories

[Deleted User]

excessive watewr build up in steam system

I am currently working on a troubled one pipe steam system that is in a very large building. The system lacked main air vents on several of the risers and the preasure was set to high. We installed more vents and lowered the steam preasure under 2 psi. The problem is now the condensate feed tank fills up and floods the returns causing water hammer. We have to drain the tank once a week. The steam mains are not insulated properly so i am thinking that there maybe excessive condensate building up,or is the condensate tank not large enough. This problem did not occur before we lowered the preasure and added the main vents. Any help would be great.

Steamhead (in transit)

Is there

a ballcock on the tank to keep it filled to a minimum water level? If so, that could be leaking.

Is there a master trap on the tank inlet to keep steam out of the tank? That's the wrong way to pipe a tank.

But more importantly, why is the tank there in the first place? I'd be willing to bet, especially since this is a one-pipe system, that good old-fashioned gravity return would work just fine.

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[Deleted User]

a leaking ballcock

is exactly what i found, and, in conjunction with no prv on the feed line. city pressure at 45psi against a ballcock that's only designed for 18ish psi; not good

Steamhead (in transit)

That means

you have a boiler-feed pump rather than a plain condensate pump.

Next thing to check- are any radiators partially shut off? If so, water might be accumulating there while the boiler is steaming (accompanied by water hammer) and the pump is feeding the boiler to compensate. Then the steam shuts off and the water drains back- flooding the system.

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[Deleted User]

steamhead

That means you have a boiler-feed pump rather than a plain condensate pump.

were you responding to me?
if you were, i'm not too clear about the difference no matter how many times i read it. semantics?

what's on the system that i was refering to is a 75ish gal condensate? tank, no pump, that connects strictly by overflow/gravity piping to the 40ish gal, city fed, ballcocked feed? tank. but i do know that the larger tank was added at some point after the installation, because the feed tank was being flooded. and the prv wasn't added until i did it, after i discovered that the ballcock had been replaced many times over the course of a few years, and it was leaking again when i was sent to replace it

[Deleted User]

Range tank...

Never done it,but was told by a trusted supplier about doing that and calling it a Range Tank. Supposedly ads volume and mass to handle to start up load, and not feed water. A fat spot in the whole line if you will. Gives the system more "Range" before the make up comes on.

ME

[Deleted User]

range tank

yeah, i think i remember reading something about that, maybe not by that name, but as i watched the system for a couple hours one day, the 40gal tank gave up very little water during a call for firing, and the sight glass remains relatively constant at about 1/3 tank. which makes me wonder if the range tank was a coincidental
'solution' to a problem that's never really been solved

Steamhead (in transit)

Mike, the difference

between a "boiler-feed pump" and a plain "condensate pump" is this:

A condensate pump has a float-operated switch mounted on the tank. When the tank fills, it pumps out, no matter if the boiler needs water or not.

A boiler-feed pump has a ballcock on the tank to maintain a minimum level therein. The pump is controlled from a float-operated switch mounted on the boiler rather than the tank. It should not pump out unless the boiler actually needs water, and if the tank fills to the top it simply overflows.

But if something goes wrong with a plain condensate pump, it too can overflow. This is why we needed to distinguish between the two.

There are a lot of condensate- and boiler-feed pumps out there that don't need to be there. They add mechanical complexity and need to be serviced periodically. If a system was originally designed for gravity return, you shouldn't need a pump.

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[Deleted User]

Why range tanks...

I'm guessing that this is an older system. Possibly solid fuel fired in its infancy. The fire breathing dragon has since long been replaced with a newer, higher efficiency unit, that doesn't hold NEARLY the same amount of water as the old behemoth.

So....

You add the range tank to assimilate the quantity of water in the old one, which had a reserve so the boiler wouldn't run out of water before enough condensate started rolling back on start up.

By all rights, as Frank said, if it was gravity before, it should/could be gravity now. It's the simplest of concepts, and its ALWAYS there...

Maybe a time delay on the make up sensors curcuit... Ignore a LW condition for say 10 minutes. If it self corrects, than ignore it. If it remains, shut down and lock out. I think somebody (ITT) makes one already. The Watchman or some such.

ME

[Deleted User]

ok, now i got it

and i'm pretty sure that the system that i was refering to was originally a gravity return, and this brings up another situation that i 'cured', another 'question of balance' question, and another question

another question; since this system, to me, seems to be a combination of the two, what takes precedence as to what it's called, and why?

and originally, i was sent there to cure the constant overflow to the sump/perpetual sump pump operation/wasting water to the tune of approx 3gals+/hr. new ballcock and prv; bingo. but then came the failure of the feed pump which i discovered to be coming on for 10secs every 10secs, regardless of boiler calling or not; 24/7. again, a bit of observation of the up-and-down of the boiler sight glass told me that the check was leaking back to the feed tank. i removed the check and bingo; the swing and shaft had deteriorated to the point of almost complete failure. replaced the check, added a circuit setter, and the patient settled down

and the question of balance; when using a condensate/ feed tank operation, accounting for a bit of evaporative water loss, isn't there a point when the system should balance, where x gals of water will remain a 'constant' in the tank? and, when the x gal amt is determined from trial and error or the good math of a properly operating system, the surge tank could be removed? after all, it's just topping things off by a very small amt at that point.

and how about this kicker? not only was the feed pump being over-worked, it's also being used for chemical injection, something that the instructions clearly state that it's not to be used for. chemical injection to the tune of a ph of 14; for cleaning the system. some water treatment 'pro' huh?