pressure in 1 pipe steam

acwagner

I recommend adding the timer. I have a similar situation to you mikeG2015. We do a temperature setback at night for comfort, and when it recovers the system runs long enough to build up a few ounces to the point my vents start making noise. My timer is in series with the thermostat, and, with trial and error, I set it to fire long enough to satisfy a normal call for heat followed by a idle period. Usually the thermostat is satisfied sometime during the idle period. It keeps the system from building any pressure even during a long recover period. It also limits the tendency to overshoot the temperature, so we don't have wild temperature swings anymore. An easy, affordable fix, in my opinion to address symptoms of an oversized boiler.

PMJ

Guys, now I am really encouraged. Several of you now working on timed cycle control/vacuum. And in one pipe no less. I expect you all to be teaching me things about this shortly. I am looking forward to it.

Koan

@PMJ Still working on mine, got the TECO to interface with my laptop! moving forward sloowwwwly...too many projects!

PMJ

Koan said:

@PMJ Still working on mine, got the TECO to interface with my laptop! moving forward sloowwwwly...too many projects!

Great. You aren't planning to move are you? - so there is no deadline. Matter of fact this job is never complete. You just keep trying things as you get time. Have fun with it.

mikeg2015

My problem is my vent noise is mostly all just after the mains are full. Radiator venting is at max rate as radiator are not yet producing heat. My problem is that my boiler is too big. If I vent too fast vents get noisier and steam rushes to the end and get this... boiler pressure was higher. As I slowed the radiator venting, boiler pressure dropped .. Gauge sits on 0oz on a 8oz gauge.

Other noise is vacuum on shutdown. I tried to add a check valve. But if it reduce the cranking pressure it’s started to leak a little steam. Can’t get spring preload low enough.

So the duty cycle timer would overall possibly increase how often it makes noise.

Gonna leave it for now and when I replace, go really small and maybe switch to a vacuum system. Just need 13 more working Hoffman#2s or run small copper tubing to each vent.

Might Put my energy into repacking the valves to eliminate leaks.

Marc_18

Fred said:

You asked where the energy went,not which of those two options was more efficient. I happen to have a steam boiler that is about 33% oversized (above and beyond the pick-up factor) and I have a lot of main venting so that I minimize the amount of time my boiler spends pushing air out of the system and building pressure and I run on a Vaporstat set at 12 ounces Cut-out. My boiler runs virtually every cycle at 2 ounces of pressure or less. I can recall twice last winter when it did hit the 12 ounce cut-out, once on each of two cycles. Of course, I set the thermostat and leave it set for the season. Those who think they need to adjust the tstat every time they pass by it or who think they are saving money with set-backs when they are not home or when they go to bed are kidding themselves, unless they actually have a boiler that is very, very well sized.

Reviving an old thread…

I would really like an explanation of why maintaining a living space at a constant temperature for the entire heating season could possibly be more cost efficient than using a setback, say, overnight or when one is out of the house for several hours (or days, for that matter). The greater the temperature differential (gradient) between a heated space and the outdoors, the larger the rate of heat loss is over time.
Clearly, keeping the thermostat set at 70 deg for the heating season would cost a homeowner more than a setting of 65 deg over the same season. Utilizing setbacks, effectively lowers the average living space temperature and therefore the heating cost.

EBEBRATT-Ed

@marc-18

That is true. But many steam boilers are oversized and many times the radiation is oversized. In most cases the boiler has to be sized for the radiation for the steam to distribute properly.

That being said some have installed smaller boilers than the radiation calls for in order to save fuel they reduce or eliminate the "pick up factor" from the steam calculation. Insulation and energy upgrades help as well so then they can get by with less radiation.

That is where the time delays and various timers come into play. The idea is to have the boiler do a longer steady burn and then stay off for a while. To do this the boiler is shut down when the thermostat is still calling and the radiation being hot continues to heat. This will satisfy the stat and prevent over heating.


Many who have tried this say they burn more fuel with a deep setback although a moderate one may be ok.

Steam is a different animal than warm air or hot water. It takes 1000btus just to make 1 lb of water into steam. Water and air heat faster but lose heat faster than steam.

When you go into a set back it is not just the "air temperature". If you set back from 70 to 60 for example your rugs, furniture, walls, floors ceilings plaster sheetrock etc etc all drop back to 60 degrees

Now you raise the stat to 70 and as the air heats all the contents listed above have to come back to 70. Its the mass of these items that matters. You may get the air to 70 fairly quickly but you have 60degree "ice cubes " sitting in the space. Every building reacts differently.

PMJ

@Marc_18,


You are correct. The heat that must be replaced is what flowed to the outside. The rate of that flow is determined by the difference of inside and outside temperatures. Lower that difference and you lower the rate at which you lose heat.