Boilers for Heating Hot Water and Steam

[MPdesign]

Guys,

I was sent this picture and I am just not well versed enough to know for sure[:-wiltel]. Can you help me?

Is this a steam or heating hot water boiler?

What are the signs to look for?

For example:

Is the piping different?

What will the temp gauges say for each?

Are the fittings different?

Will there be different clues at the AHU coils?

Hot water pump in one but not in the other.

What are the clues?

Also - what about high pressure vs. low pressure steam...

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[Inspectorjoe]

The main giveaways of a steam boiler are the presence of a pressuretrol (to turn the burner on and off) and a sight glass (to monitor the water level). The boiler in your picture looks like a hot water boiler. The last inspection I had (sadly, it was way back on Monday) had a steam boiler. You can see the pressuretrol and sight glass in the picture below. That one also had a coil in it for domestic hot water.

I can't tell if there was a circulator on your boiler. There doesn't necessarily need to be for a hot water system. A steam system will have two different size pipes. The steam pipes will be larger than the condensate pipes. Steam pipes are usually much larger than on a circulated hot water system, but older gravity systems had large pipes. The pipes next to your boiler look huge.

Older steam systems will usually have a Hartford Loop

A low pressure steam system should run at less than 2 pounds, which is much less than a hot water system would need. As for low pressure Vs high pressure, you will only find low pressure systems used for residential heating.

I've never seen a steam system that uses fan/coil units, but I have seen them with convectors in the supply ducts.

There's a great primer on steam heating here. Dan Holohan, the writer, has a terrific web site: Heatinghelp.com

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[kurt]

Can't tell anything from the picture, but the presence of a powerflame burner assembly makes me think steam.

After that, the piping has some characteristics of steam, but again, can't tell from picture.

Is it a house system? I doubt there's high pressure steam in any residential setting. At least, I hope not.

[MTL_Inspet_Man]

Looks like i could go either way.

Lack of expansion tank would indicate steam.

Also lack of sight glass means possibly hydronic

What do the dataplates indicate and also what is the operating pressure

These are usually give aways.

Hope it helps.

[Terence McCann]

That's a great looking boiler room - I mean it. Looks like someone really took pride on the installation. Was this residential? Has a very commercial/industrial look about it.

Kurt's right as far as the piping goes. With that kind of wrap (insulation) it would most likely be a steam installation however it could have been converted to hot water at some point in it's life. As others have said a dead giveaway would be a sight glass with the water riding around half a glass.

As far as finding low pressure systems on only residential that isn't true. When I worked with the Cleveland School Board we had a lot of systems that were only 5# heating four story brick school buildings. With steam you really don't need a lot of high pressure to heat. High pressure comes into play in hositals, power plants, industrial... A low pressure steam application is typically 30# and below.

[Inspectorjoe]

As far as finding low pressure systems on only residential that isn't true.

Reading back what I wrote "... you will only find low pressure systems used for residential heating", I see it's about as clear as mud. What I meant was, you won't find a high pressure system used for residential (single family).

Back in the 80's, I worked at a 100,00+ SF downtown department store that was heated with low pressure steam. It worked amazingly well, especially considering how convoluted and extended the system was. The newest sections were added long after 'the dead men' earned their moniker.

The worst job I ever had was a three month stint at a YMCA. There, low pressure steam heated the building, the domestic hot water and the pool. The boilers were massive. I don't remember the specifics of too many past New Year's Day's, but I remember January 1, 1994 like it was yesterday. I spent most of it inside one of the water heaters changing out the coil. Talk about fun.[:-cry]

[kurt]

Terrance and Joe are right. Hardly any high pressure systems outside of large institutional or industrial settings. I don't know squat about high pressure systems, as they are almost a different animal entirely, and if I ever saw one, I'd turn it over to an operating engineer or other firm specializing in high pressure systems.

The systems I see operate around 1-1.5 psi. Maybe 2 psi. Hardly any residential system gets up >3psi, or at least, I've never seen one.

[Neal Lewis]

The gauge on the front is indicating water temperature and pressure. I vote for hot water boiler.

[Bill Kibbel]

The main giveaways of a steam boiler are the presence of a pressuretrol (to turn the burner on and off) and a sight glass (to monitor the water level). The boiler in your picture looks like a hot water boiler. The last inspection I had (sadly, it was way back on Monday) had a steam boiler. You can see the pressuretrol and sight glass in the picture below. That one also had a coil in it for domestic hot water.

I can't tell if there was a circulator on your boiler. There doesn't necessarily need to be for a hot water system. A steam system will have two different size pipes. The steam pipes will be larger than the condensate pipes. Steam pipes are usually much larger than on a circulated hot water system, but older gravity systems had large pipes. The pipes next to your boiler look huge.

Older steam systems will usually have a Hartford Loop

A low pressure steam system should run at less than 2 pounds, which is much less than a hot water system would need. As for low pressure Vs high pressure, you will only find low pressure systems used for residential heating.

Not all steam boilers will have a pressuretrols. Some have vaporstats instead.

Steam boilers have either a float-type or a probe-type low water cutoff. Mechanical cut-offs will have a blow-down valve for maintenance.

Next question: How do you identify a "vapor-vacuum" system?

[kurt]

The gauge on the front is indicating water temperature and pressure. I vote for hot water boiler.

Could be. How can you see anything from the pic?

Then, there's the "extra" little pipe coming around the side that drains to the same floor drain the TP valve discharges to. Looks like the "blow down" drain pipe from a mechanical cutoff.

Maybe it's a nuclear reactor.....(?).....

[ghentjr]

Guys,

I was sent this picture and I am just not well versed enough to know for sure[:-wiltel]. Can you help me?

Is this a steam or heating hot water boiler?

Click to Enlarge

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Looks like an oil fired hot water boiler that was converted to gas. The barometric damper is not a gas flue damper. The PT valve on top indicates hot water. Williamson? Circa early to mid 70's? The front plate looks like one for a steel boiler and not a cast iron. That plate has asbestos packing around it. Had to be some circulators on the side not photographed, but based on the asbestos covered piping around the boiler it may be an old gravity feed system. Need to see the other two sides to be sure. But the flue damper indicates it gave birth as an oil fired boiler.

[Terence McCann]

Next question: How do you identify a "vapor-vacuum" system?

I'm not sure Bill. Some of the older schools use to run in a vacuum but I don't remember anything special about them.

[Neal Lewis]

Next question: How do you identify a "vapor-vacuum" system?

Bill, what's the answer? Of course you need a vapostat.

My "Lost Art of Steam Heat" is on loan at the moment.

[waynesoper]

Hot water boiler gas fired. At or past the end of its's design life. It's just a boiler, not a rocket engine.