100 year old church steam system

JUGHNE

Really nice old church was first coal, then oil and then NG.  One pipe system with dry gravity returns into an accumulator receiver tank next to the boiler--piped into the boiler as part of it but no fire under it--more water content--make sense??.  No pumps involved.

Current boiler is NG CI 1986 525,000 BTUH input.  1218 total EDR connected; split almost evenly east side/west side.  100 feet of 3" main each side,  100' 2" dry return each side.  Only the first 25' each side is insulated.  Remaining pipe was never insulated, heated the basement  (school I attended over 50 years ago). Have been improving system over the last 4 years. (upgraded most rad vents from 9 different models to Hoffman #40) [have a collection of antiques including vapor/vacuum-coal days and someone even tried a HW hot water air vent!!]  There were no main vents.  One #75 was added on each side about half way down on steam main. (easy access plug)

Questions: Would more venting on the end of the dry returns be a logical choice?  However the two 2" dry returns bull head into a tee in the boiler room 7' above the water line with one drop to the floor into the Hartford loop.  I have read that this can cause problems but so far there has been no issue with this. I think the 100 feet of dry pipe keeps the condensate to an easy trickle. But would this change with air vents allowing steam this far??

Then would a vacuum breaker on the boiler be a problem??  When the burner stops the vacuum created causes the hissing Thur rad vents during services and tends to bend the needle of my nice 32 oz Wikai gauge.

This appears to be a good example of Dead Men piping,  it took a while for me to realize why the 30 psi compound gauge (still installed by the way) never moved except in vacuum.  The system heats nicely at 5 oz and the pressure controls never open to shut down;  the only controlling device is the programmable T-stat.  This whole system is fairly fast and quiet and I wish to make it better.  The insulation seems to be a no brain-er but I need to shoot some savings number to the "committee of one" to entice the installation job, as with more main venting.  And how about insulating the dry returns?  Piping is above a suspended ceiling in bsmt assembly room (has electric heating as needed).  Church is in use 5 days a week for less than 1 hour each day.  Bldg is all masonary walls with limited ceiling insulation, (20 to 40 feet high)

Since starting on this project in 4-2008 the CCF used per degree day has dropped from 1.48 to .59 mainly from programable T-stat and air venting upgrades. 

Steamhead

I'd put the vents

at the ends of the two steam mains. This way the dry returns do not fill with steam, which is wasteful. It also might get you around having to rework that bullhead tee at the boiler.



With the lengths and diameters of your steam mains, you're definitely into multiple-Gorton #2 territory. I would install five of these vents- the biggest ones made today- at the end of each steam main before it turns back toward the boiler as the dry return.



To do this, you may need to do what we did on the job featured in our Find a Contractor ad (click our company name below to see it). We had a welder weld thread-o-lets to the sides of the steam mains and built our venting manifolds off these. For a group of five Gorton #2 vents, we had him weld two 1-inch thread-o-lets onto the main and installed three vents on one and two on the other.



If you think it's working nicely now, wait till you see what these vents will do.

nicholas bonham-carter

Church system needs venting

Yes you need more main venting, not only to get the air out more quickly, but also to let it back in, without the radiator vents whistling during the sermon.

Why not cut the power to the aux electric heat permanently, and see how well the system handles the load. When the committee of one feels the chill, he, or she will be more understanding of any improvements which need to be made. You must have paid the fuel company a lot of money over the years to force the air out of those 2 hoffman vents. Probably one collection plate in 5 would not have been given to the fuel company if the main venting had been properly sized in the beginning.

Don't forget to check the pressure settings , as the main vents function better at low pressures-0-1.5 psi. The sermon is generating more air pressure than is needed for steam to heat the building!--NBC

JUGHNE

Thanks to Steamhean and NBC for replies;

The electric heaters in bsmt will always be needed as there is no radiation other than piping above  the ceiling.  Bsmt area used maybe 2 times a month. The savings thus far was from low hanging fruit repairs.  Boiler cycled constantly on old  T-stat because of a bad heating anticipater and no main vents and bad rad vents.  The 75's were added 4 years ago along with rad vents and setback T-stat. 

The questions remain of improved efficiency from:

   adding more main vents (10 %???); 

 insulating all steam mains (5%??),

  insulating dry returns (Less than 5 %??) 

 I am aware that all above will improve efficiency/lower gas consumption.  But return on investment??.  Cost of CCF NG about $1.10: typical January consumption of 1300 to 1500 CCF NG.  Normal annual heating degree days here are 7246.    Also 1986 boiler due for change out in the future;  would insulation drop the pick-up factor enough to down size boiler??  And by the way the system runs at 5 oz. And am I to assume that if main venting is added close to the ends of the 3" main steams the results would be nearly the same.  (The last rad on each side is on the south outside wall which now has a south addition heated by other means and makes these rads not so important for building heating--slow is OK.)

nicholas bonham-carter

Return on investment

Don't forget to completely disconnect the electric heating, in order to show what state the steam side is in. As far as return on investment goes, the life of the boiler will be greatly increased. Are you having some problem now which may indicate a boiler replacement? Suppose your present boiler could last another 10 years; would that be reason enough to rectify any deferred maintenance? I think that longevity is the sort of return understood by members of a church. Our 65 radiator system lasted 35 years, so with attention to these details, you may have another 10 to go.--NBC

BobC

radiator vents.

What kind of vents do you have on the radiators now? You said the last radiators on each side were in an area that was not in the main heated space. Maybe you could install one or two (a 1/8" tapping can support 1.2 cfm ) Gorton D's on those last radiators to help vent the last half of each main quicker and see what that does.



The Hoffman 75 is rated at 0.5cfm venting capacity, a Gorton D is 0.33cfm so two would be more than that single Hoffman 75.  If you want to save a buck use  maid-o-mist D's instead of the Gorton D on those end radiators. This is a good place to order air vents http://www.pexsupply.com/Air-Valves-300000  Usually angle air vents are used on radiators.



Each 100ft main has about 5.3 cbic feet of air in it so it probably should have 2 or 3 Gorton #2's at the end of each main. Ideally you want to vent the mains fast and the radiators slowly for economical even heating but trying the above might allow you to prove a point.



I don't know how long it will take adequate venting to pay back but I know fuel is expensive and anything you can do to let a boiler run less will extend it's life.



Bob

JUGHNE

Thanks to all responses;

Sorry for late reply; been putting out fires literally & figuratively.  The 16 rad vents are 12 Hoffman # 40's & 4 Hoffman # 1A's. (The 1A's were on site and working).

For main vent relocation there is access immediately after 3" steam main changing to 2" dry return via 3 x 2 eccentric reducer. 2" dry return is straight horizonal run for at least 60'.  I considered cutting in a 2 x 2 x 1 1/2" Tee with bull/takeoff pointing up and short nipple into 1 1/2" bull/takeoff tee above dry return branching out of each tee run to a antler configuration for 3 Gorton # 2 & 1 Hoffman # 75 (relocated from existing upstream locations).  This applies to each 110' 3" steam main.  Dirt strainers on each vent tapping.  Is 1 1/2" off of the 2" dry return enough venting for the 3" main.  The antler would have (easy) capability for added venting if needed.

Thanks for any input.   

Steamhead

That'll work

take some pics when you're done, and let us know the results!

JUGHNE

Insulation questions

Thanks Steamhead for your reply!  Hopefully can convince owner/committe for continued improvements.  The insulation inquiry is that if only the 3" main is insulated with 1" fiberglas and not the fittings (approx 30)  nor the 16 2" horizontal run-outs (most are short 4' to 8'); could this introduce some new noise/hammer problems?  The cost factor for ftg kits/labor is a concern. (The most "Bang for the Buck")  The residual heat would not be wasted in the finished basement; all piping is above the bsmt suspended ceiling and below the open floor joists of church area.  The objective is to speed up steam delivery upstairs for 45 minute services 5 days of the week.  On the Wall I see many pictures of hit & miss insulation jobs on existing resi jobs that probably do not do extreme setback.  This job has HW 8000 set back from 65* to 55* for 23 hours up to 45 hours per week.  So with increased venting/speed could there be issues??

Sometimes no good intentions will go unpunished.  (we all know)  Thanks to all for reading/responing.

SWEI

insulation cost

Insulating the pipes sans fittings should be quite inexpensive - materials are widely available and it doesn't require specialized skills.  I'd start with that and see how it goes.  You can always add the fitting kits later.