Whistling radiator vents with Vaporstat

Steve Garson_2

I have a WM SGO-4, single pipe-steam, with plenty of main Gorton vents, based on what I learned on the Wall. I have my Honeywell mercury Vaporstat set to cut out at 6 oz with a 2 oz differential. Due to the pre-purge and post-purge on the Carlin EZ-Gas burner, the pressure drops to zero before the pressure begins to rise.

My problem is that a number of my radiators whistle when the pressure rises above 4 oz. If I lower the pressure more, the system will be short cycling far more.

What is the best way to set the cut-out and differential? Is the pre-purge and post-purge reversing the benefit of running a lower pressure?

My primary concern is silencing the air vents. Is there anything else I can do? I am using Gorton vents.

Steve
Boston, MA

nicholas bonham-carter

I usually see noisy rad vents as a sign of inadequate main vents.
Take the main vents off, fire the boiler, and see if the whistling diminishes. Be careful as steam can burn. A helper on the phone, with his hand on the boiler switch would probably be needed to cut of the fire when you have completed this.
Do you know how closely the EDR of the radiation matches that of the boiler? If the boiler is oversized, then maybe it can be down fired by a tech with a combustion analyses.--NBC

Are the settings of the vaporstat being verified with a low-pressure gauge?

Mark N

Does this happen every cycle or only when recovering from set back. How fast does the pressure rise to 4oz? What type of vents are on the rads? In the LAOSH Dan Holohan recommends setting a Vaporstat to 10oz cut out and 4oz cut in. Is the boiler oversized?

Abracadabra

What's the attached EDR? SGO-4 is rated for 450. Do you have a gauge to properly measure pressure or are you going just on the vaporstat setting?

Fred

Make sure the pigtail the Vaporstat is mounted on isn't clogged with gunk. The Vaporstat may not be seeing the actual system pressure. Also make sure your pigtail is turned the right direction. When heated, they can swing a bit and throw the mercury tube off center, distorting the actual performance of the device.

Steve Garson_2

Thanks for all the responses. The boiler heats 450 sq feet of radiation. One room, with an EDR of 60, has a TRV since the room is rarely used, so it does not always vent like the others.

I have an accurate gauge that goes up to 3-psi with 1-oz markings.

When the boiler fires, you can hear the basement air vents working and all the rads start getting hot in just a few minutes. If I took the main vents off, the whistling would diminish because that would be the path of least resistance:-)

Sound is heard from a set-back as well as the first heating cycle after the system has not cycled for an hour or two.

BobC

What kind of air venrs are on the radiators?

Bob

Abracadabra

Steve Garson said:

Thanks for all the responses. The boiler heats 450 sq feet of radiation. One room, with an EDR of 60, has a TRV since the room is rarely used, so it does not always vent like the others.

Are you saying all the radiators attached to the boiler have a total EDR of 450? Or that the boiler is rated for 450?

Steve Garson_2

Radiators have Eder of 450

Mark N

I use Gorton vents also, mine are dead silent. My pressure is always below 1 oz. Take some off and blow through them. Do they whistle? Try running some water through them. Maybe there is some crud in them. Being that your attached EDR is so close to the output of your boiler I'm surprised you build any pressure.

Abracadabra

Mark N said:

Being that your attached EDR is so close to the output of your boiler I'm surprised you build any pressure.

yep.. me too.. wonder if there's a mistake in the calculation...

Fred

I'm wondering what exactly he is calling "whistling"? The vents should be closed fairly quickly. However, If he is using a 10 degree setback, the boiler may run long enough that he gets a lot of "sucking" of air when the boiler finally shuts down on temp and the vents open.

nicholas bonham-carter

When you hear the whistling vents, what is the back pressure on the gauge in ounces?--NBC

Steve Garson_2

6 to 8 oz

nicholas bonham-carter

The path of least resistance is what you want, so if the whistling stops when doing the open pipe test, you need more main venting.--NBC

neilc

OP,
I think you said it yourself,
when you take the mains off the whistleing diminishes.
either some of your mains aren't working,
or you still don't have enough.
send a picture of your main antler tree,
and model and type of main vent(s),
how long are your mains and what diameter ?

Steve Garson_2

I have four Gorton #1 vents. There are two 20-foot mains that are 2-inch pipe. The reduced whistling with a main vent off is because steam is shooting out, reducing system pressure! Maybe a just need to replace my eight year old radiator vents?

Steve Garson_2

Sitting at my kitchen table now as the system fires. All the radiators are now hot through half the sections without a hiss or any sound at all. System pressure is now 2-oz. Two minutes later, pressure is 3-oz, radiators are 75% hot, and the whistling starts on one radiator. The others are silent. Now boiler cycles off on pressure. Whistling stops, of course. 30-seconds later, the burner cycles back on. Now pressure rises quickly to 4-oz and three radiators are hissing, until they click off at this point, with 100% of sections hot. Burner cycles off. All rads hot. Silence.

Paul48

"The reduced whistling with a main vent off is because steam is shooting out, reducing system pressure"!

Yep...........That's exactly what you are trying to do. The whistling is being caused by building pressure in under vented mains.

Steve Garson_2

It's not pressure building in the radiator???

ChrisJ

I believe others are assuming your mains are still partially full of air, but I'm betting that's not the case.

I too noticed vents making noise at 4 ounces, 8 ounces especially.
I think when people see "whistling" they assume loud. I'm assuming your vents are hissing and aren't really loud but it's enough it's bothering you?

This was another reason I downsized my boiler. I never see more than a fraction of an ounce even during long cycles and the system is set to shut down for 10 minutes if it hits 1 ounce. I'm sure people roll their eyes at me for this but my vents never make a sound except when the system shuts down after a very long cycle you'll hear air being sucked in the vents as the steam collapses.

ChrisJ

Also, can't a Carlin EZ-Gas be downfired?
If so that would be my first step. The objective is to get the boiler's pressure not to go up much naturally using the radiation to limit the pressure, not limit it with the vaporstat. Once you do that set the vaporstat for something like 10 or 16 ounces off and 8 ounces on and just let the system run at a decently low pressure (1 to 2 ounces at most) on it's own.

Paul48

@ChrisJ

Chris....What size are your mains?

I hate when folks disagree then don't even post an opinion. It doesn't have to be done nastily, but it would be nice to know what you missed.

Dave in QCA

Paul48 said:

"The reduced whistling with a main vent off is because steam is shooting out, reducing system pressure"!

Yep...........That's exactly what you are trying to do. The whistling is being caused by building pressure in under vented mains.

While have adequate and effective main venting is needed to promote proper steam distribution, venting is ONLY intended to release air from the mains. Steam should never be released from the mains and any attempt to vent steam from the mains to keep the pressure down is a waste of energy and destructive to the boiler.

Paul48, I didn't think that clicking a disagree was being nasty. I did not mean to cause hard feelings. My apologies.

Paul48

This was to be done as a "test", not a long-term solution.

ChrisJ

Paul48 said:

@ChrisJ

Chris....What size are your mains?

I hate when folks disagree then don't even post an opinion. It doesn't have to be done nastily, but it would be nice to know what you missed.

I barely know you and you ask a question like that!!!!

One is 29' 2" and the other is 11' 2".
Five Gorton #1s on the 29 foot main and one Gorton #1 on the 11 foot main.

BobC

You can only reduce the firing on that boiler so much before running int problems, if you only need about a 10% reduction in the firing rate that should be fine.

Bob

Paul48

Six #1's across 40' of mains, and I believe he has 4?

ChrisJ

Paul48 said:

Six #1's across 40' of mains, and I believe he has 4?

I originally had 3 on one main and a Hoffman 4A on the other and still had pretty low pressure when filling the mains. He could probably use some more main venting, but I feel the boiler is still firing too high.

If it can be downfired at all without sacrificing efficiency too much I'd go for it.

Dave in QCA

I believe that the problems being experienced are from a combination of issues. Those are:

1. Short Cycling
   
2. Purge Times
   
3. Main Venting
   
   It appears that the combination of short cycling as a result of a very low vaporstat setting and the purge times with the oil burner cause the system to draw in air. It is normal for a vaporstat to cause short cycling when a system if fully heated and Dan's recommendation when applied to an atmospheric gas boiler would work great. You might try raising the settings so that when the boiler lights after a vaporstat shutdown, there just a little pressure in the boiler. You do NOT want to suck the system full of air in between firings. This is completely counterproductive.
   
   It also appears, as ChrisJ has stated, that your boiler may be oversized for your load and thus contributing to the short cycling issue. A closer match of load to boiler output would decrease the likelihood that the vaporstat is going to shut down the boiler so frequently, however, with your present settings, if it does occur, you will probably suck in a bunch of air. I would redo your radiation survey. Take some pictures and post on here and we can help to verify your numbers.
   
   Also, given that you are using the ever popular Gorton vents on your mains, they are probably adding to the problem, given the sequence of events that is occurring. When your boiler cycles off from the vaporstat and sucks in a whole bunch of air, it has to be vent again before steam can effectively flow to your radiators. The operating characteristic of the Gorton vents is that they are fully closed at 134F (if I recall the temperature correctly). Even though you have sucked in a bunch of room temperature air, it will be greatly heated by the 212F temperature of your steel mains, and thus the Gorton vent will be unable to open fully to vent the air, in fact, it will probably remain closed, or at least almost completely closed. This will leave the radiator vents to do the job. If they are still cool because the radiators are not yet fully heated, they will vent the air and probably whistle while they're at it, but if the radiators are fully heated, those vents will be mostly closed as well, causing the boiler pressure to rise even faster because the steam is being blocked or partially blocked from the radiators by that air that got sucked in.
   
   To recap, if this were my system, I would try raising the vapor stat settings first. Second, I'd recheck the EDR of your system and see if your boiler is over sized. If so, I would have the burner down fired. Third, if there is no way to avoid occasional short cycling, I'd add a Hoffman 75 to each of your mains. While the H75 does not match the Gorton 2 in venting capacity on a cold start up, if the mains are 150F or more, the Gorton will vent at zero while the H75 will vent at its full rated 0.5 cfm @ 1 oz. pressure until it is in contact with steam. It is either fully open, or fully closed.

gennady

Do you have master vents on the risers? Are you venting risers through radiator vents?

neilc

without going back and rereading everything , , ,
is the pigtail, boiler port, and bottom of pressure control clear?

If your 3# gage is on the pigtail with the ptrol,
you're seeing what the ptrol sees,
but is the pigtail clear to the boiler?
and the ptrol and gage seeing true boiler pressure?

Steve Garson_2

Yes, re: is the pigtail, boiler port, and bottom of pressure control clear?

No: the 3# gauge is on the pigtail and the ptrol is on a different pigtail. They both connect with a Tee to the boiler. All clean.

I think I will watch the gas meter and see what the firing rate it.

Dave in QCA

Sorry, I saw it was a WM SGO and I just assumed oil. I missed that it has a Carlin EZ gas on it. Very easy to verify firing rate, and while I'm not familiar with the burner in detail, I'm sure the firing rate can be adjusted. 10% below rated Input should cause no loss in efficiency.

Paul48

I can't get my head around how down-firing would help. I'm probably wrong, but in my mind, down-firing will only slow the boilers ability to initially make steam. Once it begins making steam, the surface area of the water determines how much it makes. If the boilers too big, you can't change that, unless you remove sections. IMHO

Dave in QCA

Paul48 said:

I can't get my head around how down-firing would help. I'm probably wrong, but in my mind, down-firing will only slow the boilers ability to initially make steam. Once it begins making steam, the surface area of the water determines how much it makes. If the boilers too big, you can't change that, unless you remove sections. IMHO

Paul, you are correct on the first point. Downfiring will lengthen the time that it takes for the boiler to begin to steam. However, it will also effect the amount of steam that it makes because steaming is dependent directly on the firing rate. Example, put a pan on the stove and bring it up to boil. Then, experiment with the fire. When you turn the fire up it boils harder and more steam comes off. When you turn the fire down, the boiling rate / steam making rate goes down. For the very same reason, some boilers are equipped with two stage burners, or even modulating burners, so the firing rate will match the load at any point in time. That what is needed here, it seems, is to make the boiler more closely match the load.

Paul48

@Dave in QCA

I understand what you're saying. Dave....Do those burners actually make less steam, or do they just lower their firing rate(for efficiency) because they no longer need the higher btus to make the same amount of steam? I know the definition of a btu, but I'm getting screwed up with the ever changing need of the boiler over time.

Dave in QCA

Whether in a two stage burner or a fixed rate Burner, a lower firing rate produces less steam than a higher firing rate.

ChrisJ

The amount of heat you put into the water determines the amount of steam not the surface area

Dave0176

I think with the Carlin EZGas the last nipple going into the burner is your orfice nipple, you go by a chart and drill it out and that determines the BTU output at a set manifold pressure. I suppose lowering the manifold pressure will reduce the firing rate some. But to reduce more you'd probably have to get another orfice nipple and step down to the next size?? Just a thought.

Anyway with all this, are you most definitely sure you measured all the radiators to come up with connected EDR. This way you'll be able to set the burner to the right BTU.

Also can you post some pictures of all the near boiler piping, we like pics here!!

Steve Garson_2

For a two minute sample watching the gas meter, the burner uses 165.13 cu feet/hour. If there are 1020 Btu in a cu foot, that is a 168,432 Btu/hour firing rate. Can I reduce this number without condensation issues? The boiler has a rated burner capacity of 1.2 gal per hour, or 168,000 BTU. I think we just found the problem. I guess I need a new orifice nipple and drill it for 10% less or 151,200 BTU/hour.

Now the challenge is to find someone to do that for me.