Successful first test of the season - TRV question

jch1

Just turned on my system for the first time this heating season. Everything went smoothly. I installed a 0-15oz gauge, and it climbed to about 4-5oz before the setpoint was reached. This seems reasonable, but I wonder how much pressure will increase when the boiler is on for longer cycles. I currently have one Big mouth vent and 3 Gorton #2s. I'm going to replace all but 1 Gorton with two more Big Mouths, so I think I'll be good with main venting (one-pipe steam system with a loop that rund through the basement). So, some questions:
- I noticed that one of the radiators (all of which are pitched pretty aggressively) was ticking/tapping before steam reached the main vents. Upon hearing the ticking, I checked the radiator valve and supply pipe, and it didn't feel like steam had reached that point. I quickly went to the basement, and confirmed that steam hadn't reached that point. Could this radiator vent somehow be venting faster than the main vents despite higher main vent rates?

- I plan on installing a few TRVs on various radiators throughout the house that I haven't been able to adequately manage via slower/smaller radiator vents. Will shutting these rads down when temperature is met have a significant impact on the system's total pressure?

Jamie Hall

The main effect of the TRVs will be -- when they are closed -- to make the system "look" smaller to the boiler, so the pressure will rise faster. What should happen in any case is that the pressure should rise to perhaps 4 ounces, as you have seen, and then more or less sit there until most or all of the radiators are pretty well hot. Then the pressure will start to rise again until the vapourstat is satisfied, and the system will cycle on the vaporstat until the thermostat is satisfied. The vapourstat should be set to shut the system off on pressure at a bit less than 15 ounces, or your gauge will be very unhappy... you shouldn't need any more anyway.

jch1

I have the 0-15 gauge on a needle valve w/ snubber, so I only keep it on when I'm actively observing it. If the vaporstat kicks in, how long does it usually take to drop 1-1.5psi? I'd suspect not very long. The reason I ask is because I could envision the system cycling a good amount once it gets colder.

Any thoughts re. the clicking I heard in a radiator? I'll also note that last night, I put a Gorton D on the rad. with the longest run. It normally stays freezing cold except for when the system's been on for a long time. I think that vent was a bit too big, as I noticed bubbling/water spitting this morning.

I don't know about you guys, but this is all really fun (and expensive) trying to get everything optimized.

Neild5

The ticking\clicking could be from movement of the pipes rubbing against a joist and the sound is telegraphing to that radiartor.