Steam with timer control?

Steamed in Denver

I live in a large 1901 all brick condo building in Denver that has steam heat. Currently, it's controled by a mechanical timer system plus an outdoor temperature sensor. The heat only comes on when the outside temperature is below the set point and typically only twice a day for about 2 hours at a time. Of course, if it's too cold, someone must manually change the timer settings to come on more often or for longer. And since it's a huge brick building, when it's a little warmer, the building stays warm inside even though it's cold outside, so the heat comes on when it doesn't need to.

My question is: wouldn't it be better and more efficient to use a modern thermostat based on inside temperature? That way the system only runs when it's cold INSIDE and no one has to manually worry about changing the settings as the weather changes.

Are there any issues or gotchas with making this type of change? I've heard people say that the system needs to run for some minimum amount of time each time for efficiency, but it seems like the thermostat will still do that if the high and low set points are far enough apart.

Thanks in advance for the help!
Mark

oil-2-4-6-gas

answer

the problem with 1 thermostat or a few thermostats and an averaging controller --is location--- you can never satisfy everyone's individual heating desires --at 70 some people are hot and some are freezing --most apartments are overheated --to accomodate all --and manually regulated at each apartment ---windows --the idea of the timer -- most apartments i work at have A Heat-Timer set to give heat Below 55* day 45* night the cycle setting is based on a 60 min, timer once the average comfortable setting has been set --the Heat-Timer will leave steam on for a set-time/hour and this will increase as the outside temp decreases -proportionally or you might have the dummy clock a 7-day timer with set times with an outdoor stat to turn on the heat --what kind of control do you have ? You Should look into a Heat-timer model # EPU_CH outdoor sensor indoor return line sensor and proportional control of the time steam is on --////additionaly you can add a Digi-span with an indoor sensor wired in series to the B-B circuit that would not allow the system to run for heat if the building is warm--location and temperature setting would take a while to tweek but would be much more efficient then what you have now

Steamed in Denver

Current timer control

Thanks for the quick response! The current timer is most like the second one you describe. It's just a simple 24 hour mechanical timer with one tab for every 15 minute increment of the day. If the tab is up, it's on during that 15 minutes of the day. It's similar in concept to the old one my grandparents used to turn a lamp on for a couple hours when they weren't home. The thermostat is a separate unit and the two are wired together.

The Heat-Timer unit looks better than what we've got in that it heats proportionally to the outside temperature. But it doesn't solve the problem that our building holds a great deal of heat. If it's been warm, the building can stay plenty warm for a day or more after the temperature drops...even without heat!

I understand the problem about satisfying everyone's heating desires, but we'll have that no matter what. I think the best we can hope for is to more accurately control the inside temperature. Right now, it fluctuates wildly from freezing cold to open-all-the-windows hot.

Besides finding one spot to represent the temperature of the building, are there other difficulties in switching to an indoor thermostat?

Ken_8

Believe it or not,

the Heat Timer style control is an appropriate strategy. Better than a stat would ever be.

The problem is system balance, not ineffective control(s).

If this is a one-pipe steam system, the radiator air vents are key to system balance. The main vent(s) are too - as is the pressuretrol setting - and the Heat Timer should be tweaked and calibrated.

I'd bet you a nice lunch addressing these four issues alone would make the system sing and dance.

Now if you could just send me my roundtrip plane ticket to Denver and your street address...

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oil-2-4-6-gas

added to my above reply

Steamed in Denver

Still wondering

I'm an engineer, so please excuse my excessive questioning. I appreciate that your experience says that a timer control is the way to go, but I'm still wondering if you can explain better why. That's one reason why I like Dan's books so much is that they really get into detail about WHY things work they way they do. I do like the addition of the inside Digi-span, but doesn't that start to approximate a basic thermostat?

By the way, although I said the building was large, I realized that many of you are probably thinking New York-size large. It's only 4 stories with 24 units around 1,500 sq. ft. each. Large for 1901 Denver, not for NY. So the single temperature point may not be as hard as you may be imaginging.

And we are definitely working on the balancing issues as well as what I think is severe under-venting on the steam mains. It takes around 45 minutes to get heat to the end of the mains! I'll probably be posting a request for calculation on the vent sizes later.

Thanks again!
Mark