Evaluating a New Steam Boiler

Upkeeper

I am helping a friend evaluate boilers at a local community center in the midwest. It is a 100+ year old 25,000+ square foot facility that has steam heat (radiators). I am looking for some professional advice.

We are replacing 2 tandem/ alternating boilers that were installed in the mid 1990s that are now failing and appear to have served their useful life.

We are considering moving to a single boiler which has the capacity to heat the building even in very cold weather. There appears to be a substantial cost savings in going with one boiler vs two. The HVAC salesman is recommending a Smith cast iron boiler model 28.

Are we taking a risk by installing a single boiler? Obviously, we won't have a backup if the new one fails.

Is Smith a good name in boilers?

Any other advice you can provide? Thanks.

pecmsg

As said on HVAC-TALK
2 boilers set up lead / lag. Bet efficiency under low load conditions and a back-up for when something goes wrong.

Sounds like you got a salesman. Contact a Commercial Contractor in your area and get several Proposals.

Where is this building located?
Have any improvements been made to the structure, windows, doors, insulation air sealing?
Community Center sounds like a government building?

Upkeeper

Building is located in chicagoland. No great improvements in insulation, sealing, etc. Windows have storms.

Jamie Hall

I am not convinced about lead/lag for steam. For hot water, yes. Steam... not so much., athough with a good control strategy it can be made to work very well, and does afford some (relatively small) gains in efficiency. The control strategy is not obvious, however -- it is not strictly lead/lag, but rather a situation of both boilers running initially in a cycle, and then one or the other dropping out while the other maintains the steam supply. If there is just one boiler, but it is really accurately sized to the system it powers, there is no gain at all.

Make sure that the boiler selected is correctly sized, however, for the connected load. Steam is not sized based on heat loss from the building, but on connected load -- a distinction which sometimes gets lost. It then becomes a matter of ensuring even distribution of the steam.

Smith is a good old name in boilers. So is Weil-McClain. Both make good commercial size boilers. Don't get hung up on AFUE label efficiency, though. And do insist on someone who really understands how steam systems work to install it -- a poor instal can cause all kinds of problems.

Upkeeper

It seems like there are a good number of fair size multi unit condo buildings that run on one boiler, i am just wondering how concerned i should be about switching from 2 boilers to one? we have no one that sleeps at building where new boiler(s) will be added

ethicalpaul

One is way easier to run and far less complex than two with less than 1/2 the things that can go wrong. Boilers run for months and years without anyone sleeping with them nowadays

RayWohlfarth

I would definitely look at two boilers for a couple of reasons

Back up capability in the event of a failure. The supply chain woes don't appear to be ebbing at all and if something goes down on the only boiler servicing the building, you may be waiting a long time for the part. I am hearing of long delays for low water cutoffs and pop safety valves.

Two boilers can better track the steam load and get better seasonal efficiency.If one goes down, you could limp along until the repair is complete

I would not control them like a hydronic system because you could have uncomfortable areas.

Consider replacing the steam trap inserts This could affect the system comfort and efficiency

Is there a condensate tank or boiler feed unit? Most commercial steam systems use a boiler feed system which can add to the price.

Be sure to get a contractor who knows steam and a water treatment company to properly treat the water.

Just some thoughts from an old steam guy in Pittsburgh

The Steam Whisperer

I have designed and installed a number of lead/lag steam heating plants in Chicago for large private homes to large condo/coops. If you're interested in professional assistance, we consult, install, and complete repairs throughout the 5 county area and sometimes beyond. A two stage steam heating plant needs to be carefully set up, properly managed and properly applied for the efficiency benefits to really shine. They can really work exceptionally well with properly set up two pipe steam/ vapor/ vacuum systems that have been upgraded to eliminate the radiator traps.

pecmsg

The Steam Whisperer said:

I have designed and installed a number of lead/lag steam heating plants in Chicago for large private homes to large condo/coops. If you're interested in professional assistance, we consult, install, and complete repairs throughout the 5 county area and sometimes beyond. A two stage steam heating plant needs to be carefully set up, properly managed and properly applied for the efficiency benefits to really shine.

@Upkeeper
Pay close attention here! 

Steamhead

pecmsg said:

The Steam Whisperer said:

I have designed and installed a number of lead/lag steam heating plants in Chicago for large private homes to large condo/coops. If you're interested in professional assistance, we consult, install, and complete repairs throughout the 5 county area and sometimes beyond. A two stage steam heating plant needs to be carefully set up, properly managed and properly applied for the efficiency benefits to really shine.

@Upkeeper
Pay close attention here! 

This! @The Steam Whisperer is one of the best.

EBEBRATT-Ed

Put two boilers in. Size each one for 70% of the load

ethicalpaul

RayWohlfarth said:

I would definitely look at two boilers for a couple of reasons

Back up capability in the event of a failure. The supply chain woes don't appear to be ebbing at all and if something goes down on the only boiler servicing the building, you may be waiting a long time for the part. I am hearing of long delays for low water cutoffs and pop safety valves.

Granted, I've never had to go on a service call at 5am to fix a boiler (except my own haha), but it must be many times cheaper to keep spare consumables on site rather than pay for the installation and maintenance on two boilers instead of one.

You could stock a whole trim kit and burner sets (multiple of them even) for way less than the upkeep, let alone purchase and installation of an entire second boiler.

The other reasons might be fine, but this one can't hold water.

The Steam Whisperer

ethicalpaul said:

RayWohlfarth said:

I would definitely look at two boilers for a couple of reasons

Back up capability in the event of a failure. The supply chain woes don't appear to be ebbing at all and if something goes down on the only boiler servicing the building, you may be waiting a long time for the part. I am hearing of long delays for low water cutoffs and pop safety valves.

Granted, I've never had to go on a service call at 5am to fix a boiler (except my own haha), but it must be many times cheaper to keep spare consumables on site rather than pay for the installation and maintenance on two boilers instead of one.

You could stock a whole trim kit and burner sets (multiple of them even) for way less than the upkeep, let alone purchase and installation of an entire second boiler.

The other reasons might be fine, but this one can't hold water.

WE typically install two smaller boilers instead of a single large boiler, so your are not paying double the cost of a single boiler. We have found in some cases, 2 smaller boiler are less expensive to install than a single large boiler. This is far more common with hot water, but does still apply to steam in many cases. Often the cost of installation of two smaller steam boilers is only slightly higher, especially if we can drop in packaged boilers rather than having to site assemble a large boiler. Also, small atmospherics can run at very high heating plant efficiencies with stage firing, largely erasing most of the efficiency advantages of a power burner boiler.

New England SteamWorks

One of the main benefits of steam is how simple, reliable, and fool-proof it is. Why mess with that and complicate things? I am a KISS guy, through and through. One boiler. You'll thank me.

BenDplumber

Has anyone asked the client what there expectations are? Do they have a 24 hrs maintenance staff or contract with a MEP contractor that will respond within a given amount of time? You can have every part for a boiler sitting around, but somebody has to install it. Depends on the mission of the facility, if zero downtime is the mission then approach it that way. Residential and commercial/institutional work are way too different angles of approach. Two is one and one is none is most common in industrial/institutional work. Hospitals or government requires two or three of everything. Multiple water services from different mains,multiple bypass piping, tripled on oxygen systems or anything else deemed life safety. Be careful removing and replacing existing equipment without a signed written contract from the client or a engineers stamp approving your alterations. A night without heat or domestic hot water in a residential setting is quite different in commercial work.

Mad Dog_2

Yup...mad dog