Webster Steam system with vacuum pumps

Double D

It's definitely on my list of things to do. I will update as I progress with the system corrections/ repairs. Something else I noticed the last 2 times I was there. As the temperature goes up on the return line, the main vacuum pump runs less. One of the many challenges here is trying to get them to understand more pressure doesn't mean more heat. They turned on the other boiler today and they were operating it at 5+ psi. You  can fry eggs on top of the boiler feed tank.

dopey27177

Boy there is a ton of reading on this one.

Basically what I understand about what is happening here is that there is three systems in the building.

Two vacuum pumps or (just air removal pumps) and a very large plenum with a fan coil unit.

Several things may be going on here,
1, low steam pressure heating for radiators
2. 2 psig or greater steam supply for the fan coil unit.

Question>

Are there zone control valves on the the radiator steam supply units for each vacuum pump?

Is there a zone control valve on the fan coil unit?

Was there at one time a combination condensate boiler fill tank with a 50 to 100 gallon storage capacity that may have been replaced by that condensate receiver in the boiler room?

I ask these questions because the steam supply to the fan coil unit can be as much as 5 psig where the steam supply to the radiators tat are supported by air removal pumps not vacuum pumps can be as low as 3/4 a pound of steam pressure.

Jake

Double D

@dopey27177
One thing I can promise is this will not be the end to this one. 

Correct, there is more than one system in this building but maybe not what you are thinking.
There is a steam system that consists of a combination of cast iron radiators, recessed convectors and several large fan coils with 2 vacuum pumps and a condensate return pump.

There are zone control valves Everywhere. In some cases in places where they should Not be.

The system does have a boiler feed tank.

The building has multiple issues but I'm not getting the idea that they don't care to address the issues and that includes repairing all of the failed traps.
This building is a historical lankmark.

I did get a chance to look over the original blueprints from 1939. The drawings do show vacuum pumps. Although they did provide a coal room, the boilers were never coal fired. The first burners were oil fired Stoker. They later switched to gas.

In 1996 there was a major renovation and a chiller system was added to the building. None of the combination chiller/steam coils that replaced the cast iron radiators are properly piped. They have never worked. One of the points of interest when they had me look the system over were those convectors. They said they haven't worked for over 24yrs which puts us right back to the time of the installation. 

This building has multiple issues and it's going to take some time to iron it out. The vacuum system is only one of the many problems. I am thankful for @DanHolohan site and its incredible wealth of knowledge. I also can't thank Dennis @Pumpguy enough for his help and guidance with this project. 

dopey27177

Just seeing something not shown n the blue prints.

Condensate from hw gen storage tank. Should go to a condensate pump not vacuum pump.
Condensate from fan coil units should go to a condensate pump.

I see three zone valves

Are zone valves original or were the replaced?

Zone valves for radiators (size could be smaller than supply pipe?)

Control of zone valves and vacuum pump.

1. Micro switch to activate vacuum pump.
2. Temperature indoor controller
3. Pressure controller down stream of zone valve. Pressure controller to close zone valve at max designed
steam pressure of heating system to prevent over pressurization of rad heating system which can cause
overheating of radiator heated spaces and high condensate temps. that will prevent the vacuum pumps
from pulling the the designed vacuum. Additionally the pressure controller will allow the zone valves to
open at designed pressure to continue heating cycle.

Best set up for pressure controller example ( if radiators require 1 psig steam pressure set pressure
control to 1. 25 psi close down and 1/2 psi to open. This will cause a modulation effect where steam
pressure will always be present during the heating cycle and not cause overheating and hot condensate.

All of the above dependent on good steam traps.

Question> The fan coil system, in my experience, 5 psig steam pressure was supplied up to the control valves to the coils. Coil control valves are they steam pressure reducing valves set to 2 psig and a zone control val down stream of the PRV. Does the condensate from the unit go to the holding tank or to the condensate pump. Are there louvers allowing out side air to mix with the returning air from the theater.

Had one similar to this at the Beacon theatre up town Manhattan about 30 years ago. Management at that refused to do repairs on the system due to the cost.

Do not know what happened since as I was brought in as a consultant and made recommendations as to repair and upgrade to the system which if my memory serves me was in excess of $100,000.00

At that time # 6 oil was cheap.

Jake

Double D

The storage tank has been shut down for years. It's still connected to the system but it's valves off. They use a standard water heater now.

The original zone valves are pneumatic. They are in the process of changing them over to low voltage electric. I'm not seeing additional valves downstream that would be controlling pressure.The new zones that are in place are modulating type. 25,50,75 & 100%. They are controlled by a computer that has sensors throughout the bldg. I asked if the zones that are controlling the steam modulating. They said they think they are but we will confirm it with their IT man. I told them it's not a good idea to be modulating zone valves for steam. Full open or full closed only. 

One of my issues I will be bringing up at a meeting is the operating pressure of the boiler.They are operating at 5+psi. 

Numerous failed traps in the bldg but with the pressure as high as it is, it could be a combination of steam from failed traps and hot condensate.

There are louvers allowing outside air to mix with the returning air from the theater. 

Pumpguy

The duplex vacuum pump set shown appears from their outline drawings to be Nash Jennings Manifold Type Vacuum Heating Pumps. This type was Nash's standard offering in the late 1930s.

If true, these are (were) combination vacuum/condensate pumps having both an air pumping rotor and a condensate pumping impeller mounted and spinning together on a common shaft.

Their pumping action was simultaneous, removing air from the system to produce a vacuum, and pumping whatever condensate was available at the suction eye of the impeller.

These units were fitted with float and vacuum switches wired in parallel so the pump(s) ran on demand of whatever switch was calling.

They were fitted with a toggle switch to open the leads to the vacuum switch and in this FLOAT ONLY mode, the pump(s) just ran start - stop like any other condensate pump.

The attached file shows a cross section of the pump and also an outline drawing of the unit.

dopey27177

To pump guy

Great cut sheet. Does Nash repair these units or GE Specialties if they are still in business.

To Double D

Question> plenum with louvers, is there a pan in the discharge of the plenum that holds water and has steam coils in it, if so that is the building or zone humidifier.

Modulating steam pressure is not new. Dunham varivac systems have been around for more than 60 years and work just fine.

As to the pnematic Zone valves if they are original they are sized to put out the proper EDR at 5 psig, they originally should have opened only enough to supply the steam needed at at a given outdoor temperature and closed if the system was becoming over pressurized.

Modulating two pipe steam heating systems can and will save fuel and excessive trap replacement over time.

Care should be taken when sizing and replacing the old zone valves.

Example> Vacuum return system
2" Zone valve @ 2 psi inlet pressure 932 EDR
2" " " 5 PSI " " 1322 EDR
2" " " 10 PSI " " 1940 EDR

Atmospheric return
2" Zone valve 2 PSI inlet pressure 679 EDR
2" " " 5 " " " 1124 EDR
2" " " 10 " " " 1764 EDR

I did not include the pressure drops across the valves as this is only an example.

If the boiler operating pressure design is 5 PSIG that is for the air handlers operation and the shut down hw maker storage tank.

The zone valves were designed to provide the measure of needed steam at 5 psig inlet pressure.
The control of the heating system steam pressure is dependent on the proper control of the zone valves.

Jake

Pumpguy

@dopey27177, Nash, while still in business, no longer supports their old steam heating pump product line, but we still do.

That said, supplies of NOS or re-manufactured parts are becoming more scarce as time moves on. We still overhaul them though; I'm doing 2 as I write this. I have many part prints so certain parts are available on a made to order basis.

We also offer modern conversion pump kits to fit these old receiver tanks. These are available both with and without a vacuum pump.

Don't know anything about GE Specialties.

jumper

Ideal way to go with vacuum generator is to eliminate zone valves and traps where possible. To maximize air removal. I understand that pipe work is problematic but those unitary vacuum/condensate devices were a way to sell pumps and packages instead of optimum solutions. A blower and vacuum tank eliminates air and collects condensate. Subsequent condensate handling and boiler feed can be done independently. Plus the tank can be located where one wants. Instead of so low down that special low NPSH pump is needed.

>>Modulating two pipe steam heating systems can and will save fuel and excessive trap replacement over time. Care should be taken when sizing and replacing the old zone valves.<<

dopey27177

Ge Specialties is or was in Long Island City, New York

They had real Field Engineers that could solve and or repair nearly anything.

Jake

dopey27177

@jumper

In my experience which spans more than 40 years I learned by other peoples mistakes and my own not to redesign a carefully thought out boiler plant and heating system design.

The mechanical equipment if original can be removed from the air control and replaced with electrical operated valves, if the control system will be done by computer you must write the logic for control and provide to the computer control company. In the contract you must include a 3 year warranty and guarantee that the control system will interface correctly with all the controls. Here is a problem with many
computer systems. Pressure sensors supplied by computer company are generally not good, (use pressure controllers and or vaporstats, mycro switches on zone valves, Vacuum switches on vacuum pumps.

I gave you an example on zone valve capacities at different pressures and vacuum. You must double check the EDR of each zone and size the zone valves at 5 PSI. The 5 psi is to supply enough steam to the coils in the fan blower unit. You mentioned there are many filters in the plenum, if these are flat filters look into converting to bag filters.

Just a note>your zone valves need to be sized at 5 PSI inlet

A zone valves pipe size can be smaller than the piping, Some zone valves may be the same size
as the piping but have reduced sized seats.

Jake

jumper

In my far more limited experience somebody modifies large systems & then later somebody else modifies that. If you know that original operated satisfactorily then by all means undo the butchery if you can. Of course why did somebody butcher that carefully thought out piping in first place?

>>In my experience which spans more than 40 years I learned by other peoples mistakes and my own not to redesign a carefully thought out boiler plant and heating system design.<<

dopey27177

people in this business do not try to use the original prints when available.
many trades people think they have a better way.
sometimes a system gets so butchered that some people grab at straws to figure something out.
Many building owners do not do maintenance because in their view it cost to much.
Additionally they also look for the cheapest repair contractor because they do not understand how much money is lost in fuel consumption.

You need to find what is in the blue prints and try to duplicate that which was there.

Jake

jumper

>>people grab at straws<<

Takes time & effort to think steam through. A sketch helps.

OP mentions hot feed tank. Is that intentional to purge oxygen & CeeOh2 ?

Double D

All work that was done on the system appears to be people grabbing at straws.
The issues with the vacuum system is only Parr of the multiple problems in the building.

The hot feed tank is not intentional. Combination of steam and flash steam. 

jumper

Guess I'm grabbing as well. For me easiest (not necessarily easy) place to begin with condensate handling.Vacuum to be applied before cut in. Not initiated by float switches.

Pumpguy

In a typical and conventional system, the vacuum producer(s) for air removal are controlled by the vacuum switch(es) and the condensate pumping function is controlled by the float switches. These are separate and distinct functions handled by the same equipment.

Oftentimes the vacuum function is controlled by other devices, frequently in conjunction with vacuum switches, like outdoor temperature sensors, boiler burner operation, condensate temperature, or whatever fancyness has been added or designed into the system.

Double D

In going through this system repairing the numerous failed traps, I noticed on a few of the zone valves there are WYE strainers on the inlet side. I'm saying they shouldn't be there. Any thoughts?

Double D

Does anyone know of a supply house that has these vacuum switches in stock. 

109A_5

Double D said:

In going through this system repairing the numerous failed traps, I noticed on a few of the zone valves there are WYE strainers on the inlet side. I'm saying they shouldn't be there. Any thoughts?

Why not ? As long as they are kept clean, probably there to keep the crud out of the zone valve. Maybe certain places in the system had issues.

Vacuum Switch, how close a match do you need ? A few on eBay

SQUARE D 9016GVG1J09F SER. C 3-8"HG NSMP
https://www.ebay.com/itm/333952759034