Radiators, Slow Venting vs. Silent Venting and Boiler Run Time

gfrbrookline

@acwagner since you started me down this path I will add another level of complexity or tinkering. Have you played around with CPH? I am thinking that since the venting is much larger and the radiators respond faster there may be some efficiency gain from setting the CPH to 2 or even 3 since the properly insulated pipes will remain warm. I want to try it out but it's 62 degrees in Boston tonight.

ChrisJ

> @gfrbrookline said:
> @acwagner since you started me down this path I will add another level of complexity or tinkering. Have you played around with CPH? I am thinking that since the venting is much larger and the radiators respond faster there may be some efficiency gain from setting the CPH to 2 or even 3 since the properly insulated pipes will remain warm. I want to try it out but it's 62 degrees in Boston tonight.

I had a few times. From what I remember
3 tends to make the thermostat short cycle more often. 2 does alright and 1 sucks.

acwagner

I have. My thermostat is an older White-Rogers. It doesn't directly have a CPH setting, but it has an adjustable "anticipation" value which allows me to adjust the temperature range the thermostat will trigger on/off.

Anyways, a smaller range has the boiler run more frequently but for shorter duration. Everything stays hot or warm between firings, so there's less expansion noises. Also means fast venting is more critical because the pipes are still warm, so how quickly the mains fill is dependent on venting capacity. I'd say it's more comfortable as well since the temperature range is much more narrow, but that's reasonably subjective.

For a while I was tracking my burner time with a Raspberry Pi which was directly logging the gas burner valve state. Using that data, I'm probably running around 2 or 2.5 CPH but it has to be pretty cold out for me to actually see 2 firings in one hour.

In any case, I agree with you. With faster venting and a more responsive system you can pump up the CPH and see some benefits.

motoguy128

I find hot cycles to be noisier. I keep it at 1cph but might try 2 again see if it’s different. Especially on not steam specific short radiators. Steam travels to fast across the top of the radiator. Even as slow as my system heats up.

gfrbrookline

Just set it to 2cph, it is supposed to cool down tonight, it was 72 in Boston today so we will see how it works.

The owner of one of the units on the cool side of the building came back from vacation so I was able to adjust the venting again before it warmed up outside. We now have 2 D's, 4 C's, 2 6's, 3 5's, 5 4's, 1 Hoffman 40, 1 Hoffman 41 and 2 Hoffman 41's on TRV's. Bumping up the 6 and 5 on the cool side let me bump 2 5's one my side of the building to a C and a 6 without overheating. We are balanced again and everything is nice and quiet, running slightly below 2oz. Water level is steady and just checked the PH, it is at 9 so all is good.

gfrbrookline

@SteamingatMohawk at the beginning of this forum you asked about the formula that was used to determine the appropriate vent, In the introduction of the Gill/Pajek chart they include a formula that adds the edr of the radiator plus the edr of the run out divided by three minuted to fill the radiators. It works very well. I bumped the radiators on the cool/far side of my building up one level since my main vents are at the end of my drip/dry returns/extension of the main after the last run out or whatever we are now calling them in the boiler room.

BTW I grew up in Troy, NY. The great grandfather I mentioned previously ended his career as a professor at RPI.

gfrbrookline

Three days in at 2cph, I had to swap a D and C out for a C and 6 on two radiator on the side of the building above the boiler to stop over heating but other than that the heat is very even and very quiet. The pipes stay relatively warm and the overall run time seems to be limited to ten to twelve minutes per cycle. I rarely see more than on cycle per hour of heating but the temps have been in the 30's and 20's at night.

gfrbrookline

So the outside temp finally dropped into the low teen's for the last day and a half. The heat is very even now that I reduced the two vents, water level is even and everyone is happy. The only thing that I have noticed is when the radiator vents are about to close I get about 30 seconds of gurling and when the cycle ends I get about 10 seconds of a pronounced inhaling hiss as the steam collapses. Any thoughts on eliminating that either noise?

Mark N

Are the radiator vents closing on every cycle? Or after a recovery from a setback? I've had steam heat for 30 years and I don't think my rad vents have ever closed. I don't use a setback. I hear no noises from my vents. I use Gorton's for my main and radiator venting. My thermostat is set for 1cph, I've tried 2cph in the past and was not satisfied with the results.

gfrbrookline

I am set up for 2cph so the cycles stay short, about 10 min, to maintain 70. On most cycles they do close briefly with a gurgling buildup, then when the cycle ends and the steam collapses there is a pronounced inward his as the air is pulled into the radiator through the vent.

Mark N

Are you sure that you aren't shorting circuiting across the top of radiators with your fast venting? A 10 minute cycle isn't very long and no way should steam make it to the vent.

mikeg2015

Are these multipurpose radiators or steam only radiators? All of my universal short long radiators have issues with heating evenly. I think they probably worked great with a very slow Hoffman #2 vacuum vent on a coal boiler, but not so great now.

Really really wish someone made a #2 equivalent speed vent. #4 is still too fast. Ventrites get flakey under a 3-1/2 setting and they dont make a vertical vent for TRV’s.

FWIM, I switched to 2CPH myself and swings have been noticeably smaller but system still heats evenly.

Have some sub zero temps coming so should see how it does then.

nicholas bonham-carter

The main vents should open quickly to relieve the vacuum. How many are on your returns?—NBC

gfrbrookline

Single pipe steam radiators, 3 column type, 32" high.

Since I am running 2cph so the pipes stay warm and the steam comes up quickly, the pipes are also very well insulated. It is not short cycling, runs 2 10 min cycles each hour now that it is cold out.

I have 4 drip returns for 2 mains, the building is stepped, with a total of 6 big mouths and 3 Gorton #2's.

ChrisJ

I've done 3 cph where my off times were around 4 minutes. It was a beautiful thing.

My system does good at 3 cph until it's warmer than 15 degrees or so outside. Then I need to go to 2 cph.

gfrbrookline

The temps are going to be back into the 30's tomorrow so we will see how the 2cph works. It has been so nice and even and the heat has still been balanced throughout the building.

gfrbrookline

@Mark N the radiators heat fully, I was concerned about them heating on the top and sides only since I previously had that experience with Gorton 6, C, and D's but since I maxed out my main venting hasn't been an issue. The radiators heat section by section as they did with smaller vents just much faster.

gfrbrookline

This may be a long shot I noticed the top vent on the gorton radiator vent is not perpendicular to the radiator tapping. Should it be installed on the radiator in the same fashion to allow it to drain correctly and not pool water? I am relatively new to larger Gorton's, have always used Vetrite's and Gorton 4's on bathroom sunrads in the past, but really like how my system has responded to the larger Gorton's as advised by the Gill/Pajek formula.

gfrbrookline

@Mark N now that the temperature outside is in the mid 20's the boiler does not run long enough for the vents to close.

wz25

While I don't have any advice, I can at least say that I experience the same thing on colder days. The gurgling before closing is more variable, and I can hear it on a Hoffman 41 and one or two of my Gorton 5s, but not at all on any of my Hoffman 40s. I hear the whistling on shutdown in most of my Hoffman and Gorton vents, first and second floor.

Mains are all insulated. Maybe 50' of 2" between a primary parallel flow and a shorter counterflow. Each has a BM that seem to be working fine. Heat is well balanced and no complaints.

Mark N

@gfrbrookline, in a 10 minute cycle the boiler hasn't produced enough steam to heat all the rads fully, unless it is very oversized for the system. I would expect more like 45 minutes to fully heat the rads and close the vents.

gfrbrookline

The boiler doesn't have to come up to steam from cold, I have a hot water loop and two DHW indirect tanks that feed off it so the water is held at 160 degrees by the aquastat.

gfrbrookline

@Mark N I just timed a cycle, it's 28 degrees out side. At 5 minutes the steam starts to enter the radiator, radiator heats fully section by section, The one I tracked was a large 3 column, 6 section, 32" radiator, by 12.5 minutes the radiator is full, piping hot and the vent starts to close, 14 minutes the Tstat shuts the boiler down. It has a Gorton C on it and is on the 2nd floor. Since it is warmer the Gorton doesn't gurgle as much at close, not sure why that would make a difference. When it is colder out the cycles are shorter, I attribute that to a shorter interval between cycles and the system not cooling as much between cycles.

I think this is all because I reread the Gill Pajek venting chart and adjusted my radiator venting according to their formula instead of venting everything with Ventrite's and Gorton 4's. The system can now evacuate the cold air much faster making the system much more responsive. I turned vent your mains fast and your radiator's slowly to vent your mains fast and your radiators according to their edr and the edr of the run out attached. This is all predicated on having massive and balanced main venting.

I used to run 45 minute cycles with 1cph and slow vents. At 1 cph with the adjusted radiator venting I cut that down to 25 minutes, at 2 cph I run 10-14 minute cycles, seems to average about 45 minutes apart, and the heat is balanced with virtually no temperature swing.

Thank you @acwagner for opening my eyes and challenging me to try it.

Mark N

@gfrbrookline , it sounds like 2 cph is working well. Hopefully it will perform similarly with warmer temps. When I tried 2 cph I had cycles when the thermostsat turned off the boiler and steam hadn't reached the radiators or maybe just the first section.

gfrbrookline

I had a similar experience last year when I tried it with smaller vents. the downstairs heated ok but the upstairs never saw steam.

gfrbrookline

So after 2 plus weeks at 2 CPH I found the side of the building that is sandwiched with another building and is above the boiler has crept up to be two degrees warmer than the other side of the building that is exposed to the weather, we have had a few wind and rain storms lately. I reset the Tstat to 1cph and bumped the vents that I downsized back to a D and C's, all is quiet and the temperature has balanced out over the past 24 hours.