ONE Hissing/Howling Radiator-Convector. Everything else FINALLY balanced.

cnjamros

Hello everyone.
( I just reread this and it turned into a novel.. but I wanted to give as much background info as possible. At the end of the day, I only really have one issue... the one just below... but I welcome ALL thoughts on anything in this post... thanks in advance)

I have a problem with ONE radiator that hisses/howls when the boiler gets to a certain pressure.

Here's some background info:

- just had near-boiler piping replaced with a proper drop header. Nice dry steam

- 1st floor is completely heated by In-Cabinet Convectors. These were installed by PO, replacing original 5-tube radiators. These put out much less heat than the radiators in the rest of the house (see below). Thermostat is on this same floor, in the living room...which only has ONE of these convectors (there used to be 2 units in the living room, but one of these was ALSO removed (can see the remains of the hole from the basement). Basically the thermostat is in the most under-radiated room in the house.

- rest of house is still heated by 5-tube radiators with a MUCH higher heat output than everything on the 1st floor.

PREVIOUS ISSUE:
- 2nd and 3rd floors very hot compared to 1st floor, because of larger radiators.

SOLUTION:
- Maximize heat output of ALL 1st floor In-Cabinet Convectors by building heat baffle (see attached photo) to direct hot air and replacing vents with Vari-Valve quick vents... all the way open. Can't think of any other ways to have these heat as FAST and for AS LONG as possible.
- turned off (inverted vent) one of the two 5-tube radiators in upstairs bedroom that is nearest boiler. The other does the job just fine by itself.
- in the upstairs bedroom that is near the END of the main loop, added a Danfoss TRV to one of the two 5-tube radiators so it will shut off when room reaches 69 degrees, allowing the other radiator in the room to work solo.
- downvented most remaining 5-tube radiators 1 step below Gill/Pajek calculations so they don't over heat by the time the 1st floor is able to come up to thermostat temperature

SO:
- As of now, all rooms in the house heat to a nice temperature, within a margin of 3 degrees or so, by the time the thermostat is satisfied. (took a LOT to get there... but it finally happened)
- With vaporstat set to 8 ounces/6 diff, the boiler cycles occasionally when heating. Not too bad. Our setback is only 2 degrees or so.

THE REMAINING ISSUE:
- The CONVECTOR/RADIATOR in the master bathroom, the only one like it in the house (see attached photo), makes a howling sound (like a hiss, but with a banshee thrown in for good measure). It's not super loud, but loud enough to wake myself and my wife in the middle of the night, when the boiler reaches a certain pressure... about 4.8 ounces (.3lb on my gauge). Some of the radiators will produce a MINOR hiss at this pressure, but nothing you can hear unless you're really paying attention.

WHAT I'VE TRIED:
- Before today, when I discovered EXACTLY at what pressure the hiss starts, I set the VaporStat to 6oz/4oz... and there was no noise during the immediate testing I did... HOWEVER, the boiler cycled quite a lot while bringing the house up from 70 degrees to 72 degrees for the test. After the first half hour or so, it cycled every few minutes for another 20 minutes till the thermostat was satisfied. I wasn't thrilled about the cycling, but was happy about no noise.
- THEN, last night, when the pipes were colder I guess, the screaming returned. Blerg.
- Over the past few days, I have tried venting this Convector/Radiator SLOWLY (MoM #4) so that it wouldn't vent so much air... this just caused the hiss to become a whistle because of the small orifice.
- My next thought was to put a LARGE vent on this unit to get it full of steam quickly and get the vent to SHUT DOWN so no air would be coming through the rad at all. No dice here either. Not a whistle, but a louder howling sound.

MY THOUGHTS:
- I may have an oversized boiler situation here... maybe not technically (haven't done those calculations yet), but maybe so for the way these units need to be vented in order to balance the temperature in the house.
- Why is it only this one radiator that makes all this noise?... it because of the type of radiator it is? Is there a way to SHUT its vent at a certain pressure (since the normal vents don't seem to be doing that enough) so that the noise can be eliminated?
- The VaporStat cycled the boiler every few minutes when set at 6oz/4oz... If I lower it to eliminate the noise (below 4.8 oz), it will cycle even a bit more. It will solve my problems, but will it be hard on the equipment?
- I have noticed that the basement is MUCH cooler with the boiler running like this (up to 6 oz and then cycling), which leads me to believe it might be a bit more efficient since I'm not heating the basement, just the radiators... any thoughts?
- I'm pretty sure I don't have the money to have the boiler down-fired right now, since I just had all the near-boiler pipes replaced this year, so I'm hoping to find some version of a workable solution at least for the rest of this year.

MY GOAL: Make that one Convector/Radiator be QUIET, so we don't have to worry about the boiler not running while we're sleeping.

MORE INFO:
- Attached is a diagram of the system. Note plenty of Main venting (4 Gorton #2s and 1 Gorton #1 at the END of the main (3/4" tapping), and 2 Gorton #2s at the end of a drip return that comes from 1/3 of the way down the main from the boiler...not ideal placement, but it's what I could do without having another tapping added.

Here is a log of a heating cycle from this morning. It may provide insight:

(Vaporstat was set at 5oz cutoff/3oz diff)
Thermostat started at 69 degrees, with a goal of 72 degrees.

0:00 Thermostat engages boiler
1:00 Steam at header (we have a hot water loop that keeps the boiler around 195 degrees most of the time)
9:07 Steam at end of Main
11:18 Last main vent gets hot - assumed all closed at this point
17:40 Pressure raises to .8oz
26:00 Pressure starts to rise
26:54 Pressure at 3.2oz
27:50 Pressure at 4.8oz (hiss starts in radiator)
28:45 5oz - Boiler shuts off
29:25 Boiler Back on... goes to back up to 4oz and then SLOWLY starts to rise
31:30 5oz - Boiler shuts off
32:10 Boiler Back on. Pressure slowly rises throughout
36:00 5oz - Boiler shuts off
36:33 Boiler Back on. Pressure slowly rises throughout
39:00 5oz - Boiler shuts off
39:45 Boiler Back on. Pressure slowly rises throughout
43:00 5oz - Boiler shuts off.
TEST TERMINATED - Kids woke up.
FINAL TEMP - 71 degrees.


Again, any thoughts are most welcome.

Thanks!

cnjamros

photo attaching issues... in case you can't see it, here is our system diagram.

Abracadabra

try a different vent? something like a hoffman or a ventrite? instead of the MOM/Gorton

Jamie Hall

Take the simple issue first -- you differential is so small that you will have cycling. Almost inevitable. You might be able to reduce the problem a little by putting a snubber before the vapourstat, but I'd go for a larger differential. Say an 8 ounce cutout and 5 ounce differential.

On the howl... yeah, that could be a nuisance! The only thing I can think of is to try different makes of vents. And make sure that the valve to that unit really is fully open!

cnjamros

@jamie hall: I agree about the differential. However, the cycling was the same when I had it at 8oz with a 7.999 differential. The pressure drops to zero within 30 seconds or so. I'm interested in this Snubber you mention. What is it?

@abracadabra: I'd love to try a different vent. Does anyone have suggestions from experiences as to which type of vent would be quieter in this situation? I've bought so many in this process that if like to try to nail it the first time.

Thanks!

Jamie Hall

Snubbers -- Wika makes a very good one; their 910.12.100 (http://www.wika.us/upload/DS_ACC_910_12_100_en_us_16736.pdf)
What they do is dampen the small pressure changes, which can trip the vapourstat before the pressure really is that high. You can also get them from Grainger and, I thin, State Supply (http://www.statesupply.com/catalogsearch/result/?q=pressure+snubber)
The pressure dropping that fast is perfectly normal.

Abracadabra

cnjamros said:

@abracadabra: I'd love to try a different vent. Does anyone have suggestions from experiences as to which type of vent would be quieter in this situation?



Thanks!

Abracadabra said:

try a different vent? something like a hoffman or a ventrite? instead of the MOM/Gorton

Steamhead

Have you checked to see if there is a leak at the packing nut or the union on the valve?

cnjamros

There was a drip at the packing but but I tightened it and it stopped.

Before I got my Header replaced, this radiator used to bubble like it was filled with boiling water and spit water out of the vent. Now it's dried out and does the howling thing.

Does that give any more insight as to what might be the problem?

cnjamros

Valve photo.

cnjamros

So, after finding another thread with the exact same noisy radiator issue, I put Vent Rite #1s on the problem radiator in the master bath, as well as the larger rad in the bedroom that hisses occasionally. I sat with them for a heating cycle and adjusted just below where they started to make noise.

My system seems to run at about 2.4 oz for most of its cycle. When it starts to go above that, the noisy radiators start and it continues to rise well past 8oz, or until the VaporStat shuts it down. So, I adjusted my Stat for 3oz with a 2oz differential.

With those changes, I'm now finally running a nice, quiet system with even heating in all my rooms. Finally. What a thrill!

Thanks again for all the assistance.
C.