2 Plumbers Stumped - The Gurgling Radiator!

ScottH20

I recently renovated my home and had a small addition built on the upstairs.  In the process, my bedroom radiator was moved 8 feet due to the back wall bump out.  That added another 15 feet or so of piping, so it's now the longest run in the house.  (and added two 90 degree turns) Also, the radiator is a little larger than the original radiator was (13 fins to 16 fins).  It's on a 1" pipe.  Okay, I'm not a plumber so forgive me if I don't do a great job explaining things...but here goes...

When the steam starts to reach my bedroom radiator and it's starts heating up, this awful gurgling noise starts to happen...It sounds like boiling water...And it surges from a loud boil down to a soft boil back to a loud boil, etc.  (almost like it's breathing!)  This continues for as long as the heat is on.  It's very annoying and wakes the wife and I up.  I've shimmed the radiator, so the pitch on the it is good.  I've purchased various air valves from slowest to fastest venting, but nothing stops the gurgling. 

Oh and as a side note, I had a "heat-timer varivalve" on the radiator and yesterday morning we woke up to water shooting out the side of it....A LOT of water!  I shut off the valve, and slapped a Gorton #2 on the radiator and haven't had water leak since...What's up with that?!? 

So what could be causing this gurgling/boiling noise?  It seams to be right at the cut of valve at the supply pipe.  When I close the valve, the gurgling stops instantly.  Do I need a smaller radiator for the 1" pipe?  Maybe the new line the plumber installed isn't pitched correctly?  Is my steam too wet?  (I don't even know what that means!)  Thanks in advance.  I'm learning a lot from reading posts here and I'm hoping this doesn't stump you, the experts!

Rod

Gurgling

Since it's "gurgling" that means that the steam and the condensate are getting in each others way and colliding. Make sure that the inlet valve to the radiator is fully open.  You could try slowing down the volume of steam (which also reduces the volume of condensate) entering the radiator by using a small vent or better still an adjustable vent like a Hoffman 1A at a low setting. Vari-vents don't hack it. A Vari-vent's very lowest setting is equal to a mid range on a Hoffman 1A. The reason that the Vari-vent squirted water and the Gorton vent didn't, is that the Gorton (like the Hoffman 1A) has a float valve which shuts off if water reaches it. The Vari-Vent doesn't have  a water shut off valve so water passes through it. Like the Vari-vent, the Gorton #2 is way too large a capacity vent for this situation.

Adding 15 feet, elbows and a larger radiator might be a bit much for your one inch supply piping. You'll probably have to go up a pipe size and make sure the pitch is correct to make it work. If you can give us the total distance from the main to the radiator and the EDR of the radiator we can tell you the size of piping you need.

- Rod

ScottH20

Additional information - Thanks Rod!

Thank-you for your reply Rod!  The inlet valve (which is new) is fully opened, which I should've mentioned.  One thing I'm trying tonight is to close the inlet valve almost all the way (I'm desperate) which seems to quiet the gurgling down a bit, but I'm told isn't a good idea to do.  I happen to have a new Hoffman 1A vent that I'm not using, so I'll try that too.  I'm so glad you replied because after trying the vari-vent at it's lowest setting and not getting any results, I tossed that theory out.  Now, knowing that it's lowest setting is like a Hoffman's midrange, I'll give it a whirl! 

What about "Vent-Rite"? - I've read some good reviews on their adjustable vent on this website...they're expensive, but I don't mind paying the extra money if the low setting on this particular vent is the best for my situation...oh and as long as it has a float valve too.  (Thank-you for explaining that problem I had with the vari-vent.)

It's approximately 45 feet of 1" pipe from the main supply.  This travels up two floors and has many elbows and even travels in the wall outside and along a cantilever.  It's insulated with open cell spray foam, but I thought I should mention that as well since it might have something to do with my problem.  I'm not sure how to figure out the EDR, but the radiator is 20" tall, 41" wide and 8" deep. 

Here are my options as I see them right now: 1) Try the Hoffman 1a vent at it's lowest setting 2) Swap out the larger radiator with the smaller one I have (that was there originally) and see if the gurgling stops.  That radiator is the same dimension as the one I described above, except the width is 33" not 41" 3) Open up the wall in my dining room to add a return from the radiator that's gurgling upstairs down to the return in the basement.  (This is what my plumber suggested.)  Is that a good idea?  4) Open up the walls, ceilings, etc and replace all of the 1" pipe and go a pipe size up  5) Wear earplugs to bed and try to forget I have an obnoxious, gurgling radiator.  What do you think? 

Rod

Gurgling

Thanks for the addition information.   On a one pipe system using large vents like a  Vari- Vent or a Gorton #2 on the radiator can be counter productive. I think people do this with the idea that the faster you get the air out, the faster steam will get in and heat up the radiator.  Let consider for a moment what happens when steam enters the radiator.

As soon as steam touches the cold walls on the inside of the radiator it condenses which means it collapses from a cubic foot of steam to a cubic inch of water. This creates a huge vacuum which much more steam rushes in to fill. The water (condensate) builds up but can't get out of the radiator due to the large volume of steam rushing in so the water volume builds up till the weight of it overcomes (momentarily) the incoming steam. This is what produces the gurgling noises you're experiencing.

What you are trying to accomplish, with a smaller capacity vent, is to slow down the condensing to a level where volumes of the steam and condensate produced can share the same pipe without interfering with each other.  Whether the one inch pipe can handle more condensing capacity of the larger radiator and addition piping is questionable.

Try the Hoffman 1A (the Vent-rite is very similar in construction. It has a float valve) and also check the slope on your radiator. You want just enough to "encourage" the condensate to go out the inlet pipe. Too much slope can cause problems. Throttling down the inlet valve doesn't work (other that to shut off the radiator) as all you are doing here is making the pipe smaller. (If you want to shut off the radiator the best thing is to turn the radiator vent upside down. This traps the air inside and doesn't allow the steam in. If you use the valve to shut off the steam sometimes a bit of steam can get past the valve and condense in the radiator. The water produced is trapped in the radiator and can build up over time)

Fix-  I think your option # 3 would be the best bet. What you'd be doing is turning this radiator into a two pipe system. That way the the steam would that the inlet pipe all to itself and the condensate would exit via the new pipe. I'm not sure you'd have to rip down walls as the piping could be copper and possibly 1/2 inch would do. They string larger cable through walls so It might be possible to do the same with the return pipe, Ideally it would drop into the wet return and would need a vent somewhere along the exit line.

I've attached a worksheet to figure out EDR of the radiators in you system. If you go to the two pipe style you'll need the EDR to figure out trap size. If you do this two pipe alteration I would also consider installing a TRV on the inlet pipe.  Try the Hoffman first and let us know how things turn out. If all else fails use the ear plugs!

- Rod

Edit: jpf is right. If you're going straight into the wet return it can be setup as a gravity return. It wouldn't need a trap and you couldn't use a TRV on the inlet. The radiator vent would be in the same position it is now, that is, attached the radiator. It was late and my mind was mainly thinking how to get the line through the wall without tearing it down so I was typing out a two pipe system rather than a drip system. I think Bob's idea of using soft copper tubing has merit as it could be snaked through like a cable line. LOL- you may want to call the cable guy for this operation rather than a plumber!

- Rod

jpf321

i'm with Rod .. option #3

option #3 is called a DRIP .. make sure you drop it into a "wet"/water bearing return .. i'm not sure why Rod is suggesting a vent on this line if you are dripping the supply line. try to make sure that the union on the bottom end is above waterline + 28"... also use swing joints on bottom and run a 45deg on the top end from the rad so that water"flows" and doesn't simply "drop" or "rain" inside.



i've investigated using PEX for drips .. but i couldn't find any steam rated PEX... perhaps someone knows of some kind of PEX that would work ..



i'm sure Dan talks about "DRIPS" somewhere in his books.

BobC

just a thought

How about using soft copper tubing, it's flexible enough so you may be able to snake up through a wall without having to destroy all the plaster.



Bob

Dave in QCA

Concur

I agree with the comments of Rod and JPF.   Bob, excellent idea for avoiding tearing up a perfectly good wall!



One additional thought on all of this.  The return will correct the problem if the problem is cause by the length of the lateral 1" feed pipe and the number of turns that were added.  If however, the problem is being caused by a slight dip in the pipe, that is creating a puddle, the added return line will not correct that.  The effect of the steam blowing by that puddle and taking a little water with it, and gurgling will continue.  So, I would recommend rechecking the pitch of all the lateral piping to this radiator with very great care.



I am helping some friends with a property near by.  They have the same phenomenon on one riser that goes to an upstairs radiator.  (This is a 2 pipe system)  It hammers just a bit, once or twice as steam is coming up, then it gurgles in the risor as the riser passes through the first floor, and in the radiator on the second floor.  The gurgling continues as long as the boiler is firing. The radiator heats, but only paritally.  In this case, the problem has been isolated to a latereral line in the basement that is not pitched correctly.



My point in this is that the piping pitch should be checked and rechecked, because if the pitch is not correct, the added return will not solve the problem.