Water hammer symphony

HenryT

Hi All. I have a question regarding my 1 pipe steam heating.

<strong><span style="text-decoration:underline;">Recent changes:</span></strong>

Upgraded a smaller radiator(14.5edr) to a larger one (37.5 edr).  The feeder pipe is 1" wide.



<span style="text-decoration:underline;"><strong>Problem:</strong></span>

All was fine until recently.  Upon the start of the heating cycle, usually after setback or call for heat, I would hear extremely LOUD banging noise on the pipes underneath my floor. The banging will be in sync with what I believe to be air coming out of my radiator. So for instance, if I hear three bangs, I would also here 3 puff of air leaving my radiator through my heat timer valves.



Is there a way to eliminate this issue other than downsizing my radiator?



Thanks in advance.

The Steam Whisperer (Formerly Boilerpro)

If the pipe is 1Inch Nom dia.

and not 1 inch outside, upgrading to a 1 1/4 inch valve may do the trick because a 1 inch radiator valve is too small.  Also, a 1 inch lateral runout is too small.  NOt doing setbacks will probably do some good too.

HenryT

Thanks

Thanks Boilerpro, so you suggesting swapping out the valve?

the supply is only 1" diameter, who would i be able to do this.

Are there 1" (connecting to existing pipe on floor) to 1 1/4" (feeding radiator)radiator valves? Doe this mean i have to replace the spud on the radiator as well?

the 1/4 is what causing the hammer?



Thanks

Rod

Big Radiator - Small Pipe!

Hi- According to the Burnham "Heating Helper" book, on a 1 pipe steam system, for a radiator lateral under 10 feet in length, a 1 Inch pipe is good to 25 ft EDR. 1 1/4 pipe is good to 55 Ft. EDR.  The larger radiator is creating a bigger vacuum which pulls a larger volume of  steam into the radiator which then results in a larger volume of condensate. The "banging" is most likely caused due to a collision of the incoming steam and the outgoing condensate as the two mixing is causing the steam to collapse.

As the greatest restriction is through the valve, the suggestion was to go to a larger diameter valve as this might work. (The operation word here is "might" as in "maybe")



One thing I would do is chuck the Heat Timer vents and use a smaller capacity vent like a  Hoffman 1A. This would slow down the escape of air from the radiator which would result in slowing down the steam entering the radiator and condensing. Hopefully with slower steam and less returning condensate, it would result in less colliding and less noise.

( The Heat Timer vent at the very minimum setting is about upper mid range on a Hoffman 1A)

- Rod

HenryT

Thanks ROd

Thanks ROD. Sorry 2 more questions.

As noted, this is in the beginning of the heating cycle and from the noise, it occurs when the air is being pushed out of the radiator. At this point, there is no condensation no?



If i intend to update the valve to 1 1/4. What are my options?  The inlet (feeder) pipe is only 1" diameter. how can i increase the size without repiping?



Thanks

Jamie Hall

Oh indeed there is...

condensation.  In fact, there is a lot of condensation going on -- both in the runout and in the radiator.  What you are describing is classic.  Some steam gets in the radiator (and the air puffs out).  It starts to condense.  The steam rushing in gets in a fight with the condensate trying to get out.  The steam is blocked, but what is in there is condensing so you may even hear air being sucked back in, and being blocked whangs the condensate up against anything handy -- the valve, an elbow, whatever is in the way.  Condensate gets organised and slips out the back way, more steam comes in.  Rinse and repeat until things are warm enough so the condensation slows down (that is, things warm up) enough so that you don't have a fight going on in there.



The idea of a slower vent just may help.

Rod

Water Hammer

Hi- As Jamie mentioned, there is lot of condensing occurring at the start of the steam cycle. The “banging” you hear is steam condensing (collapsing).  Steam,  when it condenses back to water  changes  volume,  1 CUBIC FOOT of steam  changes to 1 CUBIC  INCH of water. This occurs instantly and is why we term it “collapsing” Here’s a link to a good video which shows steam collapsing:

http://www.kirsner.org/pages/WaterCannonVideo.html



What causes the “ banging” in the radiator piping? - There are “waves” of returning condensate (water) in the lateral pipe and if steam happens to get “trapped” between two “waves” , it cools and condenses (instantly collapses) This leaves a huge vacuum void which the water  waves from both sides of the void  rush in to fill. When they collide violently together,  we get the noise we call “banging” or “water hammer”



Having  a pipe the correct size for the amount of condensate produced, helps insure that the steam isn’t “trapped”. By using a smaller capacity vent which will slow the rate at which steam enters the radiator, we are hoping to slow down the condensing so less returning condensate is produced which will then hopefully create smaller “waves” which will not “trap” the incoming steam.



I would try either a Hoffman 1A or a Vent-Rite 1A radiator vent.  Both are adjustable so you can change the venting rates a bit.  You can get a Hoffman 1A  at Pex Supply on the internet.

- Rod

HenryT

Thanks

Thanks all for the responses.

I am still hung up on boilerpros advice to upgrade to 1 1/4" valve. Can this be done without new riser pipe installation? Or is he referring to use a 1" - 1 1/4" coupling then connect the 1 1/4" radiator feeder valve?



Thanks

HenryT

Thanks

Thanks all for the responses.

I am still hung up on boilerpros advice to upgrade to 1 1/4" valve. Can this be done without new riser pipe installation? Or is he referring to use a 1" - 1 1/4" coupling then connect the 1 1/4" radiator feeder valve?



Thanks

Rod

Try the Slower Vent First!

Try the slow vent first as it is by far the easiest possible solution to the problem. I'm not a big fan of HT Varivalves as in my experience, while they may have some benefit in unique individual situations, they generally tend to cause more problems than they fix. (I have a dusty box full of them on my spare parts shelf)

As to the 1 1/4 inch valve. I think the idea here was to just use the  larger valve as the restriction though the valve opening would be less. You might want to check the inside of the 1 inch valve and see just how much the valve is actually restricted smaller than the 1 inch piping.

I would try this in stages:

1. First -  Replace the VariValve with a slower, adjustable vent and see how that works.

2. If not satisfactory, check and swap out the 1 inch valve for an 1 1/4 inch one.

3. If not satisfactory, Repipe the lateral properly to 1 1/4 inch and insulate.

- Rod

HenryT

Thanks

Rod, this may be a simple answer and i may be simply too dumb to understand but:

2. If not satisfactory, check and swap out the 1 inch valve for an 1 1/4 inch one.



How can this be possible? Do they make valves that are 1" connecting to the feed pipe/riser to 1 1/4" connecting to a radiator? is there a coupling of some sore i need to achieve this?

BobC

Pitch?

Before changing the valve or the piping try a slower air valve - maybe a Hoffman 1A  adjustable or a VentRite #1. Also put a level on the pipe that feeds the radiator from the steam main and make sure it has positive pitch back towards the main so the water can find it's way back.



The combination of a slower air valve and positive pitch might be enough to solve this problem. Adapting the 1" pipe to feed a larger valve and having to change the spud in the radiator is not an easy job and replacing the pipe from the main along with the valve and spud is worse.



Bob

Rod

Radiator Vent

Hi- Bob has outlined the situation pretty well and has given you a good answer on this.  Your piping situation is ruled by the narrowest gap and the probabilities are that the narrowest gap is in the present 1 inch valve. You might be able to get away with the 1inch lateral piping if there was some way to increase the internal valve size either by going to a 1 1/4 valve or using a full port valve ( If that isn't what you already have and that using a 1 inch full port valve would increase the orifice size over the present valve)  As Bob mentioned changing the valve isn't all that easy to do.

 Have you tried a smaller vent yet? Check the slope of the radiator as Bob suggested though don't over do it as that can cause problems too. Just enough slope to encourage the water to flow out the inlet pipe.

- Rod 

RDSTEAM

that was

a sweet clip Rod. very very nice find.  As far as the problem is concerned.  Why did you upsize your rad?? That is quite a size increase. Im assuming that rad is in a smaller sized bedroom (output is just under 3500 BTU) There are a few ways you can actually increase the output on your rad without changing it. Best case scenario, your old 14.5 rad is not leaking and painted silver with a poorly designed case over it. If that applies, your in luck. Scrape off that old silver paint and go with a white or terra cotta, then redesign your cabinet to allow for a more chimney type affect.