VECO with a vengence

EdTheHeaterMan

I replaced an oil burner with a PowerFlame gas burner only to find that this HB Smith model 28A-10 boiler replaced a VECO vapor system many years ago. I may have adjusted some pressure settings with what I thought was low setting only to find the 10 story apartment house is experiencing uneven heating from the radiators. I was able to find a VECO return trap and elbow on every radiator I looked at (not knowing what I was seeing at the time). After removing 85 years of paint I was able to identify the trap. My research indicated that the pressure needs to be much lower than 1 PSI on this system (I THINK) however I am not sure that 2 or 3 ounces will work on a 10 story building now that the original air vent that goes into the chimney is gone and there are 1/8” air vents sporadically installed on some radiators (on about 10 % of the radiators).

This is past my knowledge base and I am looking for any help or documentation that will address conversion of VECO steam systems. What is the best way to get this system operating properly? I read about Thatcher Heating and Air Conditioning of New Jersey replacing a Steam Boiler in 2013 that was formerly a VECO system. It appears that installing orifices in the supply valves and removing the traps (or drilling out traps) is one way to go. That is a lot of work in this building that I hope we don’t need.

I hope this post goes somewhere inexpensive for this building owner!

OK STEAM HEADS….. Ask what you need and I will try to answer!

DanHolohan

VECO, and Broomell, which was similar, would pop a relief valve if the pressure went above 10 ounces. If the pressure is too high, it will push steam into the returns, and that will keep the air from leaving many of the radiators.

EdTheHeaterMan

Thanks Dan!!!

I have ordered a 2 PSI gauge for the boiler and will be checking the actual pressure once the gauge arrives.

So I will start at 4 oz. and see if everything balances out...?

DanHolohan

Do you have a vaporstat for this one, Ed? That's what you'll need, and plenty of good venting. I don't know what condition the place is in at this point, or who has had hands on it over the years. If it was VECO, the designer would have sized the pipes for vapor.

Steamhead

I'd bet someone removed the regulator, which was also the dry return vent that was then piped into the chimney. You'll need to add a LOT of venting to make this one work- on both the steam mains and the dry returns.

Where is this job located?

DanHolohan

Yes to what Steamhead said.

EdTheHeaterMan

Thanks for the input Dan and Steamhead. Location is Atlantic City. Dan... I did purchase a new Vaporstat and left the old vaporstat in line with the manual reset limit required by code. the new vaporstat is to turn the new burner from high fire to low fire. Still waiting on the 2 PSI Gauge so i can see what is happening pressure wise.

i don't see the vent that goes into the chimney so the regulator is definitely gone. I will be looking for steam venting all over the building when I go back to install the 2 psi gauge

as stated before... some radiators have 1/8" Hoffman angle vents. only about 10 % of the radiators are equipped with them.

Now once I lower the pressure to say 4 oz for hi limit and maybe 3 oz for low fire... I will look for all the vents that hopefully someone installed when the boiler was replaces years ago.

I realize that I don't need a lot of pressure to get the steam up to the 10th floor... Steam is lighter than air so it will just go up there. but is 4 ounces enough to force the air out of the mains and radiators? Will I need to drill out all those traps? Will I need to install orifices on each radiator inlet? How do I know if these measures will work?

Abracadabra

If the boiler is oversized, even at low fire it may raise pressure above 10 oz. You may have to wire in a 2nd vaporstat. 1st vaporstat as a hi-lo control maybe set up for 4-8 oz. and a 2nd to kill burner if it hits 10 oz.

Jamie Hall

4 ounces is ample, @EdTheHeaterMan . That said, however, you will need really good venting -- and the place to start is not on the mains, but on the dry returns. Seems to me that they are often overlooked in this game, but if the dry returns aren't vented you'll never get even heat -- if you get heat at all. How much venting? You need to add the volume of all the mains together, and the risers since they are significant in your application. The venting on the dry returns should be enough to vent all of that within 5 minutes at 4 ounces. If all the dry returns tie together in one place (which wouldn't surprise me) all that venting can also be in that place.

Then trot around and see if there are crossover traps, which allow air but not steam to go from the steam mains (or tops of risers) to the dry returns. If there are, you don't need any more mains venting. If there aren't you will need to add main vents on the steam mains, sized for those mains.

Get rid of the vents on the radiators.

Check all the radiator traps; as a sort of broad brush generality, if the radiator heats the trap is at least opening. What you need to check then is if it closes, and for that you are looking for at least a 10 degree temperature drop across the trap when the system is operating at full song. If the radiator doesn't heat and others nearby do, the trap may be failed closed -- but make sure that the other traps on the same dry return are closing, as a failed open trap may keep other radiators on the same piping from heating properly.

You don't need to install orifices. They are nice to have, but if the traps are working you don't need them. And you don't need to drill out the traps -- just make sure they are working and fix them if need be.

DanHolohan

Good advice, Jamie. Thanks.

JUGHNE

I worked on a house that had a "Kelmac" system. The air vent device that was piped into the chimney was long gone. There were Kelmac traps with all guts removed. The dry returns and end of steam mains were piped down into the wet return at the boiler. No vents there at all.

The only 2 rads that worked had an air vent on them.

I put orifices in each steam valve. Sized by using "Napier Formula for steam flow though an orifice". The chart goes from 2 up to 32 oz.......from 1 EDR to 200 EDR.
My best guess was 12 oz to deliver only 80% or less of measured EDR. I had installed a vaporstat and probably run it at less than 10 OZ. The house had the R valve envelope upgraded since 1918 or so. With lower pressure less steam is delivered but HO seems happy.
As for venting the dry return are well vented with 2 G-2's each.
The steam mains are also vented with 2 G-2's each, It seemed like a pinch to vent the entire main at low pressure thru orifices that might be only a fractional drill size. (For example 56 EDR rad would get a 1/4" orifice supplying only 32 EDR at 12 OZ).

All orifices were ordered from Tunstall predrilled at 1/8". I started small, thinking I could redrill larger if needed.

As it turned out the condensate returns cool, the dry return vents could be an open pipe, if I were brave, but the G-2's are there just in case steam might show up.

Danny Scully

I did this with a VECO system, just to give you an idea.

Jamie Hall

JUGHNE said:

It seemed like a pinch to vent the entire main at low pressure thru orifices that might be only a fractional drill size. (For example 56 EDR rad would get a 1/4" orifice supplying only 32 EDR at 12 OZ)..

It would be a pinch. In fact, it probably wouldn't work well. Which is why you either need the crossover traps or the vents on the mains.

And I love @Danny Scully's picture! Now THAT is an antler!

JUGHNE

Looks like a candidate for several "Big Mouth"'s.

Ed, with 10 stories is it possible there is an "Express" vertical riser and the system is down fed from the attic?

Hoping for an elevator also....

EdTheHeaterMan

from Jamie Hall partial post:

"Check all the radiator traps; as a sort of broad brush generality, if the radiator heats the trap is at least opening. What you need to check then is if it closes, and for that you are looking for at least a 10 degree temperature drop across the trap when the system is operating at full song. If the radiator doesn't heat and others nearby do, the trap may be failed closed -- but make sure that the other traps on the same dry return are closing, as a failed open trap may keep other radiators on the same piping from heating properly"
.

The best thing I can think of is to make sure they are not clogged. Here is a picture & illustration. Notice the 3/16 fixed orifice drilled in the internal divider wall of the trap. My traps have no moving parts. no bi-metal no bellows nothing... Just a simple trap.

Some DEAD MAN sat at a desk and calculated how much air will flow thru that 3/32" hole and how much condensate needed to be trapped. So the ultra low pressure is the key. Pressure to high will blow condensate from the trap and end up steaming the returns. The key is to get the air out of the dry returns as close to the old VECO regulator as possible.

Am I on the right track?

removing radiator air vents make sense to me also. If most of them don't need venting to heat, then the ones that have problems have something else wrong... like clogged trap or something

EdTheHeaterMan

JUGHNE said:

Looks like a candidate for several "Big Mouth"'s.

Ed, with 10 stories is it possible there is an "Express" vertical riser and the system is down fed from the attic?

Hoping for an elevator also....

There is an elevator
Will this riser be vented in the original design? if not should it be vented now?

EdTheHeaterMan

Going out to work now... will look for answers tonight. Thanks everyone.

Jamie Hall

@EdTheHeaterMan -- you are very much on the right track on those traps. I had managed to forget that they are so darn simple. And yes, instead of thinking "failed open" or "failed closed" as those of us with mechanical traps have to do, you are looking at the water seal or the little hole being clogged!