Steam injection water temperature

marty D_2

Recently replaced a smith steamer that had been converted
to oil from coal some years ago. Anyway, it finally passed
on and we replaced it with a Pierless 6 section. Being a large three story building, local supply house engineer said
to install condensate holding tank with a pump which we did.
Its a 20 gallon tank, injects domestic waster via a float
if the return condensate has not kept the tank full. Now the
question. On cold start up, it takes as much as 20 minutes for any condensate to start returning to the tank. So as
the water steams off at .6 gal/minute, we need make up water
and pump cold domestic water into a hot boiler. BTW, this
is my first steam job, and I have always tried to avoid
shocking boilers by installing bypasses when warranted.
When the cold water is injected, there are certainly a alot
of awful sounding pinging going on in the boiler. Is this
normal, or do I have a problem?

Thanks in advance

rookie steam guy

Kevin Jahn

feedwater tank

You don't say how many horsepower but in a 3 story building I would suspect that a 20 gallon tank is way too small. You mention a condensate tank but are decribing a feed tank. It should have a pump and be controled by the boiler. Some more info is required to asist you further. I would think that a 200 gallon feed tank would be more in line for you system and on cold start should have about 100 gallons of water and then drop to operating level as the system stabilizes.

marty D_2

Thanks for the response. Let me see if I can give the info
you are asking for. Condensate comes back to a 20 gallon
storage tank. The pump is activated by a probe control and
injects returned condensate, or domestic water (on start up)
as needed. We have had conflicting engineering advise from
the local engineer and Macdonald Miller engineer as to how
large the condensate holding tank should be. I do not know
how to calculate boiler HP, but the boiler net input is
about 1400 Sq ft EDR. Thats based on 347,000 Btu/240.
Again, new at this. The Miller engineer said we should have
a 100 gallon condensate holding tank, but local guy says
20 will be fine. At this point, we have skimmed boiler, and
letting all condensate returing, which is very contaminated,
being passed into a drain until it is clean. Boiler has had
cleaning agents added and flushed, but water level in glass
still fluctuates significantly. So probably needs to be cleaned again. Building is very strange as top floor radiators get steam, but second floor is running condensate
through the radiators for heat. Guess my original question
about potential shocking of the boiler with cold domestic
feed at startup is not a big issue. Was reading Lost art of
steam heat today, and understand that we need to keep the
distance (horizontal) of feed going into Hartford Loop as
short as possible to reduce hammer as the cold hits the
rising steam bubbles in the equalizer. Steaming all day today, only problem seems to be not being able to create
much more than .5 psi system pressure. We have a lot of old
vents to deal with. Will be putting a pressure gauge that
reads in ounces at last radiator (furthest) from boiler to
see what we get. Pressuretrol is set at .5 with psi diff
at 1. So far today did not get psi above .5, but most radiators starting to get warm. Sorry for long dissertation,
still leaning by what seems to be trial an error.

[Deleted User]

The boiler feed tank

should be sized to hold 15 - 20 minutes of boiler condensate output. The condensate output of the boiler should be in the I&O Manual.

The noise when the pump is returning condensate to the boiler sounds like either a Hartford Loop @ the wrong level or too much condensate on each pump cycle. On pumped return boilers, we install the H/L 6" below the recommended boiler water line. We install on the discharge line @ the pump the following: check valve, shut off valve, 60# pressure gage, balancing valve. We throttle the balancing valve until the gage reads 20# w/ the pump running. If the pump is sized correctly, that is the amount of condensate required to replace what is leaving as steam. Too much makes noise, short cycles the pump, and can affect the steaming capacity.

Good luck.

Blackoakbob

Holding tank

> Recently replaced a smith steamer that had been

> converted to oil from coal some years ago.

> Anyway, it finally passed on and we replaced it

> with a Pierless 6 section. Being a large three

> story building, local supply house engineer

> said to install condensate holding tank with a

> pump which we did. Its a 20 gallon tank, injects

> domestic waster via a float if the return

> condensate has not kept the tank full. Now

> the question. On cold start up, it takes as much

> as 20 minutes for any condensate to start

> returning to the tank. So as the water steams

> off at .6 gal/minute, we need make up water and

> pump cold domestic water into a hot boiler. BTW,

> this is my first steam job, and I have always

> tried to avoid shocking boilers by installing

> bypasses when warranted. When the cold water is

> injected, there are certainly a alot of awful

> sounding pinging going on in the boiler. Is

> this normal, or do I have a problem?

>

> Thanks

> in advance

>

> rookie steam guy

Blackoakbob

holding tank

Yeh, I got bit the first time I did this too! If you consider the volume of water the old boiler contained you can see the need for a receiver to hold condensate as it returns from the system after shut down and to again feed the system as it starts steaming up. The new boiler just doesn't have that volume of water waiting to steam away. Once you correct the traps and dirt holding the condensate up in the building you'll find an additional tank added to the system will hold this necessary volume. I estimated the volume of water in the old boiler and used it as the size for my holding/condensate receiver, minus the volume of my new boiler and it's work well each time I've replaced a large fire-tube boiler with a compact cast iron one. You MUST correct this problem or the bottom of your new boiler will fill up with scale and plug up. I walked down into a basement of a building with this exact problem, a 40 HP cast boiler with a 7 gallon receiver/feed pump and a automatic make-up water valve, all around the basement, stack up like tombstones, were broken castings split open at the bottom. An amazing sight, at least 12 of 15! I added 4 more to the graveyard that summer.
Best regards,

Blackoakbob

Excessive make-up....

water is what caused the failure of the cast sections I found on the job I related to on my reply. I happened to be the 4th contractor to look at this system in the 5 years since the boiler was installed. The building had changed hands 2 or 3 times in that 5 years. Each new owner bailed out due to high operating and repair costs. Each one would just repair the boiler to expedite the sale. That was the reason for all of the casting spread throughout the basement. I figured at least 3 or 4 cracked and leaked each year of the 6 or 7 ( I forget exactly) that made up boiler. I do remember it had rubber gaskets, which made it a piece of cake to pull the bad ones out. I was just a rookie then and couldn't convince that years owner to correct the problem... which is what we started discussing before I side tracked you.
The idea is to have a sufficient volume of water to handle the steam ouput of the boiler and the system volume of steam and returning condensate, and allow for your auto fill to make up for losses due to evaporation, blowdowns and water testing, etc. I liked the idea of the amout used in 20 minutes which should allow for each part of the system to reach its state of steam and condensate.
I still learn someting every day and yes, somtimes the hard way. I appreciate this forum's aid in that learning.
Regards,