2 pipe steam coil venting

clammy

Recently discovered a leaking tube in tube end coil steam coil very cool design and supposed to be able to handle outside make up air better then row coil design with higher output.The real question is this coil is controled by a honeywell steam zone valve and a f&t trap on it's return in this building all the originally installed traps are IB traps with all end of the main IB traps had a nice feature of having a standard rad trap mounted above the bucket inlet with a check (after the y strainer)and dumping into a common gravity return draining to a condensate pump .my question is as i think would installing this same set up on the outlet of the coil to aid in removing air out of the coil upon a call for heat.it sounds like a good idea to me but can anyone find fault with this design.As for this set up it work extremly well on venting the steam mains very quickly i belive that with this design it is far better then standard air vents and seems to last alot longer then a air vent design also i would fiqure that it also increase the vent capacity by aiding in venting capacity.Thanks for any input peace and good luck clammy

Steamhead (in transit)

Might still have frozen

any steam coil handling outside air needs a vacuum breaker, so vacuum won't hold water in the coil on the off cycle.

Can you post some pics of that fast-venting setup?

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Wayne Heid_2

If I understand your description correctly

If I understand your description correctly, I would assume the addition of the thermostatic traps to the mains was done because this is a system that is shut down frequently and this was an attempt to make cold start up easier. It works well for that purpose but requires more maintenance checking for failed trap elements that would blow by and waste steam. If the system is rarely shut down there's really not much to gain from this arrangement.

As for the coil, I don't recommend a bucket trap unless you're sure it's protected from freezing. It's also not going to pass the same amount of condensate as an F&T as you won't have much of a pressure differential between the coil pressure and the condensate return line. Remember also that the vent is there not only to aid in quick air removal upon coil start up but also as a vacuum breaker to help with drainage of the coil upon shutdown.

Without a vent, I can't visualize how the coil would drain with the trap arrangement you're proposing.

(Unless I'm missing something ...)

Wayne

clammy

Steamhead,wayne

The reasoning behind the use of type of coil would have been maybe because they are pulling outside air durning early spring and early fall before turning the a/c side of it on ,it is water cooled condenser using city water and is costing some coin to operate and due to the heat gain in the early season and may have been someone thoughts to delay running the a/c and save some it's ascoited costs,it defently was not original to that a/h install .One side note is that the original steam 2 pipe system is well over 100 years old the original burmham coal/oil boiler is still in place so is one of the 2 1942 vintage cleveland brooks fire tube boilers.I would believe that when the 2 nd boilers where installed there where water line issues about 1 1/2 ft between original and 2nd boilers and that is when all the mains where dripped and ib where installed and condensate pump added.The quick vent IB and rad traps where installed on a few mains which are located the furthest from the boiler room.My resoning for IB traps are that there are a few older a/h that are set up with the same Ib and rad traps without vacume and have pneumatic acutacted control valves there are still working quite well.The coil and a/h i'm concerned with was installed in the late 60'to early 70's and the f&t which looks like a recent replacement(10 to 20 years)does not jive with everything else as corcerning the A/H steam piping.I don't think there is any danger of freezing or fresh air being drawn due to the a/h controls are manual and some one would have to manual switch to turn on the intake blower as far as i have seen but i would gather futher investagation will be required.The burner is controlled by a heat timer type device which is not manafactured any more with no liturae and i have tryed to contact them with no responce ,the system does heat evenly and pretty quick 95% of all the piping is well insulated and there's no water hammer that is unless the IB get jammed with funk which has happen most of all the rads are installed with fulton slyphon trv which are original to the system and seem to still work and keep the building in pretty much desent balance except for a few which have been replaced with standard hand valves and those areas do over heat , anotherreason to stick to the IB is that they have seemed to work very well for over what 50 years and i know that not much maintance has really been doen to the system including trap maintance.Frank i'll dig through my pics and post some pics of the quick vent manifold and those trv thanks for the input and will take any other you have to offer sorry for the long post peace and good luck clammy

Wayne Heid_2

Tube failure mechanism

Clammy,

This sounds like a system with some interesting history. Like Frank, I'd love to see some pics.

I'm wondering if the real question shouldn't be "why has this coil failed?". Do you have any evidence of the failure mechanism? Is it freeze damage? Water hammer? Vacuum related failure (collapsed tube)? External corrosion?

Knowing this should make your trap / vent decision easier.

Wayne

clammy

Age

I'm believing this coil failed because of it's age from the dating on the carrier a/h i would estimate the coil was installed in the late 60 's so it would be at least 40 years of service plus the fact that before i showed up the system pressure was running over 5 lbs now she running at about 3 lbs i would run less except the boiler has a standard low start hi fire gun and is massivly oversized by about 100% and if i go lower she short cycles way to much for my likins.The power flame gun is a lower budget gun which according to a gentle man who specilzes with them stated that it cannot be converted to modulating gun and it's up to the building owners and property mangener to make that decession it could be down fired but it still would be oversized ,i have not added up all the edr of rads and coils but i would believe that about 1.8 to 2mbtu would cut it the promblem being the now working boiler rated output is 4.8mbtu.The original burmham was defently a vapor vacume with gravity return but as time went on things change and the dead men where not there to shed light on the system .One shining grace was that no one did much maintance so alot of the piping and traps are all original or at least from the early 40 from trap stamp dates on some marsh rad traps and moline IB traps another decent occurance was the close to 50%reducing in gas comsumption since straighten out the pressuretrolls and clogged IB traps and some left for dead a/h who's coils where pissing steam for who knows how long (these system where non functionally and where installed in the 80 abandead and left in place but not isolated from the steam mains ) As i told the property manager a old system like this requires some investagation and snopping around 90% of the basement has finished plaster cieling which makes it hard to trace out the mains paths and find all the supply and return risers and traps worst part is there is a buried return and no manual water feed to the boiler and no meter to record water lose.the new boiler has been running for about 10 to 15 years off of the dual lwco feeder and has no secondary lwco it was running off a single pa404 pressuretoll but it at least had a manual reset pressuretroll which the last guy removed because he stated it had no cut in setting i advised the PM not to let the guy back into the building.The pa404 was mounted off of the aux electronic lwco tapping so it was getting hammer by water and was not functioning properly it also had the rest of the pressuretrols mounted off a 1/4 manifold so it was not correct in my eyes .There's still alot of smaller repairs and improvements that need to done to make maintance a bit easier beside abstoces abatement.peace and good luckc lammy

clammy

photos

here's afew pics

clammy

some pics

Here's one pic having a hard time adding sorry will try to post a few more

clammy

clammy