Very old apt bldg heating system questions

I inspected an apartment building that had a very old (address listed as being in New York, 18, NY) American Standard Boiler (model A-707-SC).

The rating tag indicated steam and the unit appeared to have the characteristics of a steam boiler (sight glass and other features consistent with a steam boiler), but the radiators and associated piping in the rooms had an appearance consistent with hot water heat, with narrower piping than I’ve typically observed in steam heating systems and no steam vents seen on the radiators.

The boiler appeared to be working properly, but many rooms had no radiators and though the building was quite warm despite the very cold weather, none of the radiators were noticeably warm.

Some of the radiators were missing, so my main immediate concern is regarding the piping. I know steam heat pipes tend to last very long, whereas hot water heat pipes deteriorate much more rapidly. There were no obvious problems with the heat supply piping, so that also suggests a steam system, as I’d expect widespread damage in century old galvanized boiler pipes.

Anyhow, I’d appreciate any thoughts from folks who are more familiar with large, old boiler systems than I am.

I did not get pics of many radiators, but here are a few pics representative of the system:

Picture 224.jpg

Picture 224.jpg

Picture 364bt.jpg

Picture 364_364_1b.jpg

Picture 182_182_1b.jpg

Picture 361t.jpg

Frank were the radiators heating up?
That is an old unit and I would always call for a boiler guy to inspect it however there are a few things I can say.
Check the site glass for proper level,check the steam pressure,look for leaks,make sure the apt units are not water logged as if there is no air vent they will not heat up properly and they should be located on the floor pip0e side.
Did they have knockouts to add the valves?

Good news is that appears to be a two pipe system and can be converted to hot water.
Bad news is that looks like asbestos above the boiler.

As far as missing radiators go they are often removed because it is perceived they are not needed due to the over heating at some locations since no unit will have a thermostat and tenants are at mercy of the boiler settings.

Guessing that is about a 12 unit building.What is that a 110 gallon HWH?

Thanks, Bob.

The water level in the sight glass was just about dead center, appeared to be right on the money. The boiler was not running when I got into the boiler room.

The pipes were probably insulated with asbestos, par for the course for a system of this age, but it has been my understanding that this is no big deal as long as it is not loose such that asbestos dust could enter the air. The only loose pipe insulation I observed was in maintenance areas not accessible to tenants, and there was very little at that.

I did not see anything that clearly looked like knock-outs for pressure valves, but I did not really look for them because I’d been under the impression radiators were either designed to have them or not have them.

Based on your info, it appears to me they should install pressure valves if possible and put radiators with pressure valves in the rooms that lack radiators or have poor heat (which a few reportedly did).

I wonder why it would be desirable to convert the system to hot water, which would either require extensive re-piping or cause the existing pipes to deteriorate rapidly, which would soon lead to the same, whereas pipes in a steam system last so long?

Seems the improvement in efficiency would not be worth the expense of the updates, at least not for a very long time, especially in a low rent building.

I did find it very strange that the rooms and the building in general were so warm on a sub-freezing, breezy day, and the radiators were not noticeably warm.

The building was a 3-story, with 8 units on each level and 2 basement units. 26 altogether. The water heater was 100 gallons, and appeared to keep up just fine. I ran lots of hot water in most of the units during the course of the inspection, and it was very hot all along.

Frank did you happen to get a shot or look at the steam pressure gauges?
Sure they may leave it,add electronic controls unless out of the picture,or do a number of other things to fine tune it.
Something that old is bound to cost a fortune in energy bills I imagine as it looks like it was converted from coal.
When I see something like that I sometimes call the heating outfit doing the servicing off the tags.
They can often tell you stories.

Frank -

Do you know the age of the building?

Wondering what you are referring to when you mention ‘pressure valves’? Are you referring to the vent valves often found on one-pipe gravity systems?

Your 5th pic seems to show a thermostatic trap close to the floor. If so, this appears to be a two-pipe system and won’t use ‘air’ or ‘vent’ valves. Part of the function of the thermostatic trap (among other things) is to act as an air or vent valve. Do you know if this was a two-pipe gravity system or pumped-return system?

Typically, one-pipe gravity systems will have large® pipes to allow for the flow of condensate back to the boiler at the same time steam is heading to the radiators (all in the same pipe).

Here is a good article on whether or not they are needed.

This paragraph addresses the question well.

No vents on radiators, system vents still needed
For a system with absolutly no venting, your’s is doing exactly what would be expected. The little steam that is making its way up part in the system is probably due to some air venting that might be occuring around loose valve stems.
Your contractor probably read that vents are not needed on a 2 pipe system, that is to say, vents on the radiators. That’s becuase the venting of the radiator takes place by air being pushed out through the trap, orafice, or whatever device your system is set up with. However, in order for the air to be able to be pushed out of the radiators an into the return piping, there has to be a way for that air to escape. That is what the vents in the return mains were for. And as for vacuum relief when the system shuts off, they perform that job too.
End of the steam main vents are necessary to allow the steam to run to the end of the main before entering the radiators nearest to the boiler. If you don’t have them, the system is very likely to heat unevenley, with some radiators getting much hotter than others.
I would suggest that you purchase the book availabe on this website, entitled, The Lost Art of Steam Heating. It is obvious that your contractor needs a copy too!

Bob/Frank -

I apologize for my vague comment. To clarify my original thought…On a two-pipe system (w/thermostatic traps) you should not see air or vent valves on radiators typically seen on a one-pipe system. As correctly stated in the article Bob posted, a two-pipe system will typically utilize vents on the return mains in addition to the thermostatic traps.

Again Frank, do you know the age of the dwelling? Also, was the system you looked at gravity return or pressurized?

I know many have little knowledge of steam heat and it has been very rare I see them myself as an Inspector now even though I baby sat them in my younger days but the one word to remember is Bell and Gossett when it comes to steam.
Below is a good tutorial.

You are looking at a two-pipe steam system. The stub left at the floor is a steam trap. The sight glass, among other things, is the obvious give away. Though most of the early boilers were rated for steam and hot water, as the tag suggests; this unit was installed for steam.

Taking out radiators is common in both systems. As the houses get tighter and the load is lowered less radiation is needed. Unfortunately, it can lead to discomfort if done indescriminatly i.e. without professional direction.

Most steam boilers are suffering from serious neglect and I would always call for a qualified professional to inspect the boiler. This would naturally eliminate power company employees and department store “technicians”. A local mechanical contractor or licensed steam hot water company could be the answer.

Steam can be very dangerous when neglected or improperly maintained.

Thanks for all the info and responses.

I did have some recollection of reading somewhere of steam systems with radiators that had no air escape valves, but my recollection of the details was fuzzy. Mnemonically challenged. 2-pipe system. Got it.

The building appeared to have been built in the very early 20th century, c. 1900ish to mid 1920s. Solid brick foundation, a style consistent with the era, and a location that was mostly built up around that period.

I did recommend my Client examine the servicing records for the unit and get a HVAC professional who is familiar with such very old units for large buildings to look at the system.

The resident manager – who appeared by all indications to be a rather credible and conscientious fellow – said the unit had been regularly serviced by a heating contractor.

The system appeared to be functioning very well, as the living spaces were quite warm, with the exception of only a few rooms, and it was a windy day with temperatures well below freezing – I think dropping from about 20 to about 10 F during the inspection, which was in the late afternoon into early evening.

There are many buildings in the city with very old steam heating systems in service, and as such, a number of contractors around who know these systems like the back of their hands. Likewise, with old plumbing systems, as there are many early 20th century fixtures still in service in these buildings.