Whistling and hissing radiators after "maintenance"

Matt_in_MA

We have a one-pipe steam system, which heats our two-story apartment on the top floors of a two-family. Through reading posts here and elsewhere, I successfully managed to balance the radiators last winter and added thermostatic valves on the radiators in the upper story. The result wasn't perfect, but it was OK and relatively quiet.



This year I thought it might be a good idea to have our boiler serviced professionally. We had the plumbers who installed it come by. The guy who worked on it told us that our "gas pressure" was too low, and was resulting in the boiler taking too long to heat up as well as a lot of carbonization of our burners. He turned it up and cleaned off the burners.



Since then, the heat's worked OK except for one radiator that refuses to get warm. But all of the radiators are much noisier than before, hissing loudly. Two disused radiators that I thought I had turned off at the cutoff valve are now heating up. One brand new air vent whistles like a train!



I'm guessing this means that thanks to the newly hot boiler, we're actually reaching the pressure limits of the system, and the next step is to turn down the pressure from its current level. But I'm confused by the Pressuretrol. Do I adjust the main or the differential? What's the ideal pressure level, and what should the values be to reach that level? Any guidance would be appreciated.



Thanks!

Jamie Hall

Assuming

that that's a picture of your pressuretrol, it really isn't that much too high -- but it is too high.  Try turning the main down to 2 (much lower is tricky on a pressuretrol)  You can leave the differential alone.



However.



The whistling hissing radiator vents suggest to me that they are doing more of the work than they should have to -- and that your main vents aren't doing what they should.  What are your main vents?  And the sizes of the mains?  The idea is to vent the mains as fast as possible, and then use the radiator vents to allow reasonable steam to the radiators.

conversiontime

imbalance

The rad vents normally only whistle when air is rushing back in once the boiler stops making steam. On the upswing of the cycle the rad vents should just puff, hiss slightly or click at times. If the rad vents are whistling loudly during the burn cycle, then yes you have pressure that is probably getting too high. As Jamie mentioned this could be do to imbalance on main pipe vents which are essential to getting steam to all rads near the same time. The fact that one rad does not get hot while others are whistling indicates trapped air or vacuum somewhere in the path to boiler.



You should find out if the plumber really did need to adjust regulator gas pressure  or adjusted air/gas mix intake at burner. But either way the system is getting too much pressure so start with main vents. My steam single pipe had similar issues which were resolved by replacing main vents and most rad vents with  Gortons (mains) and Hoffmans (rads).

mcsteamy

Now wait just one minute, here.

So they added a few more BTUs to the system--probably less, I would guess, than is "added" by shutting off a radiator--and now you have whistling problems.  Uh-huh.  I'll bet that ain't all they touched.  Bet they did you another "favor" by turning up the pressure on the boiler too.



TURN THAT PRESSURETROL BACK DOWN AND TELL THOSE @$&$&^ PLUMBERS TO KEEP THEIR FINGERS OFF OF IT!



I would be more forgiving, but if they had half a clue what they were doing with a steam system, they wouldn't have put a pressuretrol at 3-4 pounds.



Crank it down as far as it will go without causing damage to it.  Just under 2 pounds should be safe.  Leave the differential around a pound.  That should solve an awful lot of your problems.  Then get good main vents on there if they aren't there already... That should fix 80% of the remaining balance issues.

Matt_in_MA

Thanks!

Thanks so much everyone! Turned down the pressuretrol to two PSI / 1 pound differential. We'll see how things go. Hissing / whistling is much reduced so far - I suspect I'll need to rebalance the radiators some more since we're back to having cold spots.



I wasn't entirely certain by what you guys meant by main vents - I found two that I think are what you're describing (pictures attached). Are they adjustable? Should I just replace them? Should I go down to the basement while the boiler's running and listen for noise from them?

BobC

VentRite?

That looks like a ventrite 35 or 77 it's a low capacity vent by most standards and it is not adjustable. You probably want to replace it with a higher capacity vent, how long is the steam main or mains and what size is the pipe?



Bob

nicholas bonham-carter

Bad main vents

Replace those main vents with Gorton 2's, to start with, and on your good low pressure gauge, you will then see what the back-pressure of venting is as the boiler begins to make steam. The ideal is 2 ounces, so that you know you are not buying extra fuel. Your decreased fuel bill will soon pay for the venting. If you have a higher back-pressure, add more main venting.

To balance the system further, use slower Hoffman 40's, and if some rads are slower, you can put on some faster ones.--NBC