Need Help with 1 pipe system - recent banging in pipe when cooling

hadeone

Hello all, I've recently (2 weeks ago) had an issue where a vent for a large 1st floor convection radiator's vent went bad and steamed up the house. The vent seemed very old, I couldn't make out any markings on it or figure out what it was from its shape (cylindrical, straight, with 3/8" pipe size, but taller and wider than the varivalve) I replaced it with a Varivalve and it has been working so far until last night when I heard banging in the pipes while the system was cooling. Usually this system is very quiet, I've never heard banging for the 3 years I've lived here. However, after replacing the leaking vent I went snooping around the whole system and found some problems so I made the following changes:

1. The main vent was clogged and not working so I changed it to a Gorton No 1. It seemed to be a no-name brand, straight skinny 3/4". This is the only vent I can find on my main line. The main (2") and the return (1-1/4") meet at 90deg, with a tee, and this vent sits on top of that tee.

2. There has always been some gurgling in a 1st fl bathroom small radiator which seems to have gotten worse recently too. This radiator had a varivalve installed since I moved in, which I changed out last week because it was dirty on the outside and spewed water sometimes. I realized the water coming out of it is a problem with the drainage of this radiator but I figured I'd try a new vent in case it was bad. It did not fix the issue. Also, this radiator is on it's own piping (1-1/4" ?) from the boiler. From the boiler there are 2 1-1/4" pipes that Tee off, one going to this radiator and another to an upstairs radiator possibly. Then the 2" main goes around the basement with branches going up to the various other radiators. The main ends with a return at the end of the run and a vent on top. The return goes to the floor and runs to the boiler, all along the floor.

Thanks for reading so far. My question is, can changing these 2 radiator vents (2 weeks ago) and the main vent (1 week ago) be the cause of the banging or did something else happen? I read that banging on a cooling part of the cycle usually means the condensate is blocked from returning somewhere... However, The boiler water level is good. The system seems to be loosing less water than before I changed the vents.

Any info would be helpful. I've always lived with steam banging and thought it was normal. After moving here I was amazed that this system didn't make any noise. Now I messed with it and it's banging. I need to get it back to it's blissful state. Any insight is appreciated.

Additional info: the rest of the radiator vents are mostly hoffman 43 and a dole or 2. One of the hoffman's clicks and another one sounds like it's letting out steam (hissing) so I plan to change those too but I don't want to cause more problems.


Thanks again for reading.

EBEBRATT-Ed

First thing to do is to check the pitch of all your pipes and radiators. The radiators should be low on the pipe end so the water will drain. A crowbar and some shims can fix that. The piping in the basement needs checking as well as pipe hangers can break or sag causing a low spot in the pipes. This will cause hammering.

Changing vents may have caused the problem .....unintentionally. Venting faster through a sagging pipe may have started the banging. A little patience and some detective work should fix it

hadeone

Thank you. I will start with the radiator that is gurgling and go from there.

ethicalpaul

Also check the pressure that your system gets to. If a vent failed and filled the house with steam, it was probably due to too-high pressure. I think if a vent fell off one of my radiators, I would hardly notice.

hadeone

ethicalpaul said:

Also check the pressure that your system gets to. If a vent failed and filled the house with steam, it was probably due to too-high pressure. I think if a vent fell off one of my radiators, I would hardly notice.

Good idea. I'm guessing there's a gauge somewhere on the boiler and I should take a look at it when the radiators are up to temp?

ethicalpaul

There is a gauge, but it's probably broken and its scale is too large to be useful. It will be a 0-30 psi range and you would be better off with a 0-3psi gauge. Search the site and you'll see lots of recommendations. It's a good tool for a fellow steam homeowner to have.

hadeone

Here is a pic of my setup. It looks like the pressure is set to 2 PSI? I guess I need to figure out why it could be going higher?

Can I replace the gauge that is on there with this? : https://www.amazon.com/dp/B00H9ZWLZG/?coliid=I2KWJIZDE1T4B1

Chris_L

It should be going higher if the cut-in is set to 2 psi. That is the pressure at which the boiler turns back on after it cuts out.

The pressure the boiler shuts off at is the cut-in plus the differential. Remove the cover to see what the differential is set to. It should be about a pound. Then reduce the cut-in to give you the total (cut-out) pressure you want.

For example, I set mine to the lowest possible cut-in without the mechanism falling apart, and the differential to to as low as it will go to get a cut-out of just under 2 psi.

hadeone

Thanks for explaining.  I have some reading to do

ethicalpaul

Also feel free to lower your cut-in to the bottom of that scale (but don't go past bottom)

ethicalpaul

That gauge you linked to looks fine. Leave the old one on there, code requires that useless scale. Put another Tee under the pressuretrol and an elbow with a couple short nipples to add the new gauge.

Clean out the pigtail while you're doing that

hadeone

Makes sense. Will do.

Any reason the installers set the cut in at 2 psi and the system to run at higher pressure? I found a few threads where people posted the same picture as me, 2 psi cut in.

hadeone

This is what I found under the cover. So it seems the differential was set to a bit under the 2 mark, making the max pressure just under 4 psi. I set the cut in to the lowest (0.5) and I haven't touched the differential yet. Should it be set to 1?

What should I be looking out for after these changes? I understand the higher pressure could have been masking problems. Radiators not getting hot? One vent on the 2nd floor will click "open", then hiss for a bit, then click closed, I'm assuming that isn't normal but could it have been due to high pressure? Let's see what happens. Thank you for all the guidance.

ethicalpaul

Yes rotate that dial all the way toward the "1" until it stops.

Why do they set it higher? Because they are incompetent, I don't have any other answer. They think it will hide the fact that they installed an oversized boiler probably.

With these lower pressure limits, you should look for your system to be quieter and to burn less fuel.

And yes, that clicking behavior is rather normal. What you should see is this:

1. Call for heat starts
2. Boiler runs for awhile
3. Steam starts to be produced and starts to try to push air out of your system
4. You may hear or feel air escaping from vents (if your finger is in front of the vent)
5. Steam will reach the radiators and start to condense as it heats up the radiator
6. This slows the flow of remaining air from the vents
7. Eventually on a long call for heat, a radiator may get "fully steam hot" and steam will reach the vent
8. The vent will close against the steam and depending on the vent, you may hear a click or pop sound (Maid O Mist and Gortons don't make noise)
9. At this point where all your radiators are fully hot is where the pressure will start to climb. You normally don't see this unless you are recovering from a larger setback of let's say 3 degrees or more. This is one reason not to setback the thermostat, so you don't have to hit the pressure limit of your system. Really any time your pressure starts to climb, you are wasting fuel.

hadeone

OK, I set the differential dial toward the 1, as much as it would go. It seems it doesn't want to go all the way to one and I didn't want to force it but it's almost there. The cut-in is set all the way down (0.5). It seems like the system is making less noise overall. Here are a few more updates and my random ideas for critique:

1. The banging I have on that bathroom radiator is reduced to a couple of bangs. There is a varivalve on there set to the minimum setting (closed). I pitched the radiator toward the pipe a bit more but it still gurgles. I'm guessing there is an issue with the pitch of the piping back to the boiler. This is a branch right off of the main where it leaves the boiler and I don't think the condensate from this line goes to the return. Is it possible that it just comes back down the main? I plan on installing a ventrite adjustable vent here to slow the venting as much as possible. It's not critical that this room gets heat instantly.

2. Next to this bathroom is a large dining room radiator that had an unknown vent, which I previously described that it had failed and filled the room with steam. I changed this to a Varivalve in a pinch since it was all I could get quickly. It's set to the lowest setting since this is where the thermostat is located. I was thinking to change this to a slower vent but a Gorton 4 doesn't fit. I need something fairly narrow because the convection radiators are recessed into the wall with the metal frame very close to the vertical vent port. Should I try to find a slower vent or stick with the Varivalve?

3. There are 2 radiators with vents that are acting strange (or at lease different than the others which are silent). They are both close to each other, on the second floor, above the boiler somewhat. One is a small radiator in the bathroom with a Hoffman 43 that makes noise the whole time the heat is on. It's a whistling noise that pulses like pressure building and then releasing. I plan on changing this vent to a Vent-rite 33.

3b. The other vent is also a Hoffman 43 which I described in a previous post, it clicks on and off when the heat is on. It's happens multiple times a minute not just once when steam hits it for the first time. I'm curious why it does that since the others do not make any noise. Should I change it to a vent-rite 33 as well?

4. Last one: I have one main which is approx. 25' to an elbow and then another 15' to the end where it connects to the return and my only vent, a Gorton #1. Before the turn there is an unused Tee with a plug. Can I install an additional vent there or should all the vents be in the same place, at the end of the main.

I plan on changing the pigtail and adding the low pressure gauge soon. It's going to be very cold this weekend so I'm not touching anything until we get past this extreme weather.

Thanks again. Merry Christmas and Happy Holidays to all!

BobC

Is this a straight or angled vent? The Hoffman 40 is about as small a vent as you can usually find and they are available either angled or straight. Add a few wraps of teflon tape and screw it in.

Bob

hadeone

All vents are straight except in the small bathroom which gurgles and bangs.  That small radiator has an angled varivalve now.  

 i was reading that my dining room vent needs to be slow because its near the thermostat. So I’m looking for the slowest straight vent.

this was there before: 3/8 stem?

Now: it’s not set to almost closed

mattmia2

Those are some unusual radiators. Can we see som pics of them and the cabinets?

You may have a bigger problem with the boiler and its piping making wet steam.

hadeone

Typical:  

Problem bath:

Boiler piping:

neilc

post another picture of your header, from 90* from the shot above,
this shot looks like it restricts before turning down to the equalizer,
that would be wet and noisey

hadeone

There are no noises from the piping, except for that run to the bathroom

bburd

That varivalve on the bathroom radiator is a notoriously fast vent, even when “closed”. Faster venting can lead to the symptoms you described. You might try a slower vent there.

Per comment above, the equalizer on your boiler header should not reduce in size until it drops. That is certainly throwing some water up into your steam pipes.

The lack of pipe insulation isn’t helping either. Insulation keeps the steam dryer.

hadeone

I’ll be insulating the rest.  The VentRite #1 I ordered came today and I swapped the varivalve.  I feel like the banging is reduced but ill keep an eye on it.  The boiler is running pretty often since it’s 15 outside.  Otherwise it’s running smoothly on the reduced pressure.  Thanks everyone for helping 

hadeone

Happy new year everyone!

also, how bad is this?  Looks like a metal panel that has the water ports for the basement basebord heat.  It seems like its been leaking for a long time, a few metal rust flakes on the floor and more fell off when I touched it.  Theres a sticker saying “tankless water heater 5 gpm” on it. 

Can it be replaced separately, without changing the whole boiler?  Boiler is a Weil-McLain EG-40 or 45 based on the sticker.  Neither box is checked off.



I also changed the pigtail, original had gunk in it but not sure if it was blocked.  Also changed the 30 psi gauge and added a 3 psi.  So far it cycled once and there was no movement on either gauge.  Hopefully they start working once the pigtail fills?  Only the bottom of the pigtail got hot so far. Not sure what’s going on. 

Thanks again

mattmia2

If the boiler is sized right it should never build pressure.(or it could be leaking. Does it lose more than say a gallon a week of water?)

The tankless coil plate can be fixed, that gasket leaking is a common problem.

hadeone

The 3 PSI gauge needle now bounces around a bit but I can’t say it’s registering anything.  The system gets hot quickly and satisfies the thermostat.  I guess to really test it I’ll have to set the temp high.  

It does lose water but I wouldnt say a gallon a week.  I changed a few vents and have some more to change.  The consumption went down it seems.

ill look into what I need to change that coil plate and plan to do it after this season. 

TonKa

hadeone said:

Hopefully they start working once the pigtail fills?

You should fill the pigtail with water before installing the control/gauge on top of it.

hadeone

TonKa said:

hadeone said:

Hopefully they start working once the pigtail fills?

You should fill the pigtail with water before installing the control/gauge on top of it.

Too late.  Should i take it apart and add water?

TonKa

hadeone said:

TonKa said:

hadeone said:

Hopefully they start working once the pigtail fills?

You should fill the pigtail with water before installing the control/gauge on top of it.

Too late.  Should i take it apart and add water?

It couldn't hurt to check.

Disconnecting and unscrewing the control, then putting it back is maybe 15 minutes, tops. You don't need to remove the pigtail from the boiler in order to prime it. Just pour some water right in.

hadeone

Will do.  I put in a union so this would make use of it

edit:  The 3 PSI gauge is registering now.  The pressure doesnt get above .5 from what I’ve seen the couple of times Ive checked it.  

vhauk

A a one pipe system fills with steam, hence the vents, to let the air out. It takes very little pressure for steam to move very quickly. I had a radiator vent come out in our living room and that little 3/8” hole filled the room with steam in minutes. All increases in pressure do in a steam system is change the temperature at which the steam forms, higher pressure means higher boiling temperature, which makes things much more dangerous 

JUGHNE

If the bottom of the pigtail is hot and the top cool, I would say the loop self primed itself.

You just don't want the controls to get exposed to steam temps.

hadeone

Practical question:  what are your best practices for removing the corroded bolts holding the tankless coil in, hopefully without snapping them and having to drill and tap the boiler? 

hadeone

After observing the boiler with the newly installed low pressure gauge I’ve noticed when it has to run for a while, on colder days to heat 2 degrees for example, it does build pressure.  The pressuretrol turns off the boiler at 2 psi, per the gauge, and its at its lowest setting.  Boiler cuts back in at 0.5 as set.  It builds pressure from 0.5 to 2 psi pretty quickly,  a minute or so.  Sound normal?  I guess the boiler is oversized?

thanks again all

mattmia2

Not enough venting if it builds pressure that fast at the start of the cycle. Could be normal after it shuts off on pressure in the middle of a cycle if the boiler is very oversized.

hadeone

Makes sense.  This was after the boiler had been running for a while.  It shut off due to pressure a couple of times then the thermostat was satisfied.  So its probably oversized.  Is there an issue with it cycling on off so quickly?

mattmia2

Not really. If there is a vent damper it could reduce the life of that significantly. It is more wear on the gas valve but that isn't likely to be an issue for decades.

hadeone

Now that you mentioned the vent damper I remembered my next question. My flue doesn't have a draft control damper, the type with a weight that opens when the draft at the chimney is strong. At a previous place I remember there being one on an oil steam boiler. Do gas boilers not need it or was it just left out in my install? I do have the electronically controlled damper that closes the flue when the boiler is off.

Thanks again.

hadeone

Here's another newbie question for you guys:

I have very very limited amount of space for my radiator vents due to the steel cabinets they are installed in. So much so that I have to bend the cabinet steel out of the way to change a vent, then bent it back to be able to fit the cover on. Therefore I can't use Gorton vents and I'm on the hunt for reasonably priced Vent-Rite's.

Would a street elbow work to turn the vertical vent port on the radiator to a horizontal port so I can install Gorton angled vents or adjustable Vent-Rite #1s, or does it cause some sort of issue ?

mattmia2

You can extend it with black iron or brass fittings but you have to make sure the condensate can drain back to the radiator.

ethicalpaul

There is a full selection of 1/8" npt brass fittings at supplyhouse.com that work great for this