Huffing and Puffing Vents

PhilKulkarni

I have a one pipe system with a combination counter flow and parallel flow mains. I had a new Peerless boiler installed 2 yrs ago and ever since that time the larger rads on one side of the house with C size vents keep puffing until they close on steam( or out of sheer exhaustion) . The other side of the house has shorter mains and the rads on this circuit have size 4 vents and their puffing is a lot less labored. My boiler is rated at 308 sq ft while my EDR is 295. All mains and returns have 1” insulation.

The near boiler piping was done per the Peerless installation manual which assumes that you have a parallel flow mains. It was only when I looked into the bowels of the Peerless site that I found a more comprehensive installation guide that says to upsize the header to 3” and the equalizer to 1.5” for counter flow mains. Too late. Additionally, post install, I had to modify the mains to add the drips since those too were not in the manual that accompanied the boiler.

Other than the puffing which is more pronounced in the quiet of the night, the system heats all the rads evenly in 35-40 mins from a warm start. Both mains use Big Mouths with updated silicone O rings and vent very well but not as fast as they did with the previous boiler that was rated at 354 sq ft. There just isn’t enough steam to shorten the latency of heating the mains. It takes longer to close those Big Mouths. The boiler operates at 0.8PSI and seldom cycles on pressure.

Though the system is effectively undersized due to the above installation oversight, I am glad that steam is forgiving, nevertheless, are there any tweaks that anyone can suggest to quiet the vents? Reducing the vent sizes from C to 5 throws the sytem out of balance as the rads don’t heat that side of the house evenly.

Thanks in advance.

ethicalpaul

C is very large for a radiator vent.

Are you sure the mains are filling with steam before the steam starts to head to the radiators? It seems like they should be with Big Mouths on there.

I don't think the problem is a lack of steam.

What is the water level doing during a call for heat? Is it holding relatively steady?

dabrakeman

Which main is counterflow and which parallel? Verified the pitch on both mains? Could you send some pictures please.

AdmiralYoda

How are you measuring the 0.8psi? Did you install a low pressure 0-3psi (or less) gauge or are you using the factory 0-30psi gauge?

Your boiler is not undersized….it is perfectly sized….perhaps even a bit oversized. You mention the boiler has a steam capacity of 308 and your EDR is 295. That is 4.4% oversized…perfect.

And like @ethicalpaul said…what is the water line doing? Perhaps show us some pictures of the site glass and piping? If the water has oils and junk in it water can be getting tossed into the mains and making noise.

BobC

Check the pipe pitch on any radiator feed and mains that shows signs of huffing and puffing. That sounds like there is water lying in the bottom of a pipe somewhere. There might be sag somewhere.

Bob

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1822731#Comment_1822731

this^^^. Doesn't take much of a sag — or even too flat a pitch (particularly on counterflow mains) to do that.

ethicalpaul

That is great advice about the sag. But even just heating a cold main causes this behavior. The steam moves forward, hits cold pipe, then collapses, causing puffing

PhilKulkarni

Thanks for your questions and comments. I will address them sequentially.

ethicalpaul: The puffing starts 3-4 mins with a warm start, before the mains are filled with steam. It continues after the Big Mouths close and stops after the radiator vents close. While balancing the system, I started out with size 4 on the small rads and a 5 on the largest rad which is a Burnham 21”x63”. While they did heat up, only a few sections were hot and the vents would not close during the heating cycle. They do with the Cs. When the boiler starts and the pressure builds the water level drops to quarter in the gauge but stays steady until the boiler shuts off and returns to 85-90% the preheating level in 2-3 mins. I run the boiler at a water level an inch below the water line mark.

dabrakeman: I have attached some pics. There are two mains. The longer one supplies the front of the house, and the shorter one the rear. Each has a counter flow portion of different lengths with a pitch greater than 1” in 10’ towards the boiler. Each mains has a parallel flow section where the pitch is reversed. In the pics, I show both sections with a level indicating the pipe pitch for that section.

AdmiralYoda: I have a 0-5 psi pressure gauge. The water level behaves the way I described above.

BobC: The 1.25” horizontal nipple connections from the risers to the rads are visible when I take out the lower gratings and they vary in length from 2-3”. They are tensioned a bit since the rads are pitched towards the risers. These were not affected by the new boiler installation. However, that doesn’t mean there couldn’t be sags elsewhere before the rads. I will check some more. I have Clevis hangers supporting the mains and during the boiler installation, they were checked for sags.

ethicalpaul

I love a cute little peerless. is the water level relatively steady while it's making steam?

Was it skimmed?

This issue sounds very minimal IMO

dabrakeman

I generally don't "fill my radiators" except on the coldest of days. Even while doing a recovery I break it up so the boiler never runs more than 30min thus preventing most of the radiator vents from ever having to close on steam. I had noticed years ago that if I ran long cycles "filling my radiators" there would be a tendency for some of my radiator valves to accumulate a little bit of water in them as they opened and closed until the pressuretrol intervened resulting in a subsequent puffing in normal air release. One of the many reasons I had to focus on the control of my oversized boiler. Not saying it is your problem but you might want to take a couple of your offending vents off and just see if any water might be in them.

PhilKulkarni

After reflecting on the boiler water level raised by ethicalpaul and dabrakeman, I cleaned out the boiler and the returns. Used what remaining washing soda I had(nasty stuff, doesn’t mix with cold water well) heated the water and drained everything. That everything had a lot of stuff floating as well as bits of rust up to 1/8”. This after I had drained and filled the boiler in early October.

Now the puffing is imperceptible, the water level in the boiler drops by less than 2” but does oscillate. Critically, the pressure registered 0 for the entire 40 mins it took to raise the temp 1 degree. All the rad vents made a gurgling sound before closing indicating they had some retained water. I wish the vents had metal tongues to drain the water back.

Not certain the problem is solved, but a definite ‘tweak’ I was looking for. I can’t figure where so much floating gunk came from since I had replaced all the wet returns in 2002. The section of the parallel flow mains that transitions from 2” to 1.5” before dropping into the wet return looks to be the culprit and may have corroded a lot but since I am not loosing any water it may not be on a death watch.

Thanks for the incisive questions. They are a big part of what makes this forum useful.

109A_5

Hello PhilKulkarni,

Where did all this water go ?

PhilKulkarni

The boiler installer two yrs ago didn’t bother to clean and skim. I did it with the meter running instead of using the bypass valve as I did yesterday. Too much pipe dope got into the boiler and I had to use the dreaded washing soda three times to get it out. The installer who put the drips did so one at a time on different days and did the same- emptied and refilled the boiler with the water metered each time. So, most of what you see is the water consumed to clean the boiler in the first two years of operation which is substantial.

I drain a little water monthly to remove accumulated gunk which consumes 1-1.5 gallons cumulatively over six months.