Is turning off some radiators more or less efficient?

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Old 11-12-07, 09:49 AM
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Is turning off some radiators more or less efficient?

I have a 3 story older home. Oil fired steam boiler.

How can I determine if it is worth turning off some radiators on the 2nd/3rd floor. One room is directly above the room containing the thermo. Floors are not insulated. Carpeted though. I am very interested to hear the theories behind this one.
 
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Old 11-12-07, 03:21 PM
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No answers yet I see.

Common sense would have to say that a cold house would cost less to heat than a hot one where one might even have to rid unwanted hot air by opening say upstairs windows in rooms that were getting extra warm from heat from that rooms radiator AND from the floor.

The boiler would run less because there would be less heat being radiated away.

To any laymen, this would just have to make sense. But with a steam system, maybe there are certian other issues or needs to be concerned with?

Anyone else? - more familiar with STEAM heating?
 
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Old 11-12-07, 04:31 PM
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Originally Posted by ecman51` View Post
Anyone else? - more familiar with STEAM heating?
Not me, but I'm interested in what the answers will be too.

I will say that from what I have learned (not much!) about steam is that to properly size a steam boiler, it must match the installed radiation. With this in mind, it would follow that by closing radiators off, SOMETHING is going to go caddy-wompus somewhere.
 
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Old 11-12-07, 05:00 PM
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Trooper, yes, we know something will be DIFFERENT, but that doesn't necessarily equate to caddy wompus, or bad, always.

One could say that a room's lighting has been 'sized' to have so many ceiling light fixtures to produce "X" amount of needed lumens, and that by unscrewing some of the bulbs you will make something go caddy wompus. But is caddy wompus the proper term for simply having less light (less heat with boiler analogy) and a smaller electric bill (something desireable)?

But from what I've read here on STEAM systems, it is much more finicky than a hot water system. So - both you and I are anxiously awaiting the answer.
 
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Old 11-12-07, 05:32 PM
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This is a complex question and Searay has not provided enough information to give a detailed response.

Assuming this to be a one-pipe steam system then closing the valves on a few radiators will not have an adverse effect upon the system operation.

My personal opinion is that steam is a lousy medium for heating a residence because of severe control issues. Nonetheless there are many residential steam systems in existence that heat to the complete satisfaction of the occupants.

The one thing about one-pipe steam systems that is an absolute no-no is throttling the radiator valve. The valve MUST be either fully open or fully closed for proper operation.
 
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Old 11-13-07, 10:29 AM
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Follow up

The system is a one pipe system and I do keep the valves totally open or closed. I think the crux of this question doesn't really matter what kind of heating system is involved. Rather isn't it more of an overall question of having the thermostat be on for more or less time depending on what other rooms are surrounding the room containing the thermo and if they are being heated or not. I know it is complex depending on insulation in walls , leakiness of windows, etc.. What I was hoping to find here on the forum was something that breaks it all down such as: if the thermostat is set for 69degrees and the delta temp in an unheated room is x degrees then it is more efficient to close the other room down, etc..

Thanks
 
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Old 11-13-07, 06:12 PM
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Originally Posted by searayboater View Post
...I think the crux of this question doesn't really matter what kind of heating system is involved....
Well, that's true as it turns out, but we just wanted to make sure something wouldn't go wrong otherwise by doing that...

Furd said on a one-pipe it's OK, I still wonder just from an academic standpoint if it would be OK on a two pipe ?

As for your initial question... you are right, it would be kinda complex to figure that way. Personally, I don't think you would save a heckuva lot, maybe not even enough to notice.
 
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Old 12-17-07, 02:28 PM
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I'd say yes you will save, how much you save is the big ?????

For every radiator you have to heat-up, you use energy and energy=money.

Your system shouldn't blow up either - as long as the pressure cut-in is set and working properly (1-2psi ???). With fewer radiators to fill with steam, the system will pressurize faster which means the radiators you do have open will heat up quicker or more accurately earlier than if the whole system were all open. At least thats how I think of it.

I am not a pro but somehow the above makes sense to me.
 
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Old 12-20-07, 12:06 AM
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COME ON GUYS! You are all getting too deep into this! Remember basics!

From Moses' 10 commandmants on thermodynamics and energy conservation:

Energy in = Energy out

So........... if you do not use a few radiators in the house for certain rooms (AND keep the doors closed to those rooms, AND assuming there is no thermostat in any of those rooms, AND you will not be needing to heat any of those rooms for at least several hours) of course you will save in fuel! Prove me wrong! Let me see the jerk who says you will use MORE fuel for heating LESS!


This was a very refreshing reply. WHEW!

Charlie
 
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Old 12-20-07, 05:33 AM
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This is my theory just based on what I have read and learned from this and other forums. So maybe I'm wrong but I'll throw it out there.

Ok so lets say the thermostat is on the first floor so therefore, the system could care less how hot or cold the upper floors are, correct? Now, lets say his boiler was sized for X amount of Rads. by closing some off, sure he is saving energy because those rads will not require to heat up. Therefore, the system would have a faster recovery so the room where the thermostat is would be satisfied faster, correct? So wouldn't the boiler fire for shorter periods which would be less efficient?

On the hand, if the upper floors have poor insulation and leaky windows, all the cold would now radiate through the floors and walls which could possibly make the lower floors feel colder, which in turn could cause the boiler to run longer and more efficient, correct?

What do I know At least it make sense to me
 
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Old 12-20-07, 08:12 AM
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Well let me add my 2 cents worth. I think the answer very clear. To find out by running your own test to open radiator valve for X # days and than close for the same time period would not tell you anything. The variable there is outside temperatures will not be the same. It is not an apples to apples test.
My opinion is I don't think it would make much difference. It takes 970 btu’s to convert 1 lb of water from 212 water to 212 steam. This is 5 times the energy it would take to raise the temperature of water from 32 to 212. As we start to build pressure it is an exponential growth in the fuel bill. So as we increase the amount of cycles by reducing the load we build pressure more often thus using more fuel. The cycles will also shorten and decrease the efficiency.
On the other hand we will have less condensate heating fewer radiator to recover back into steam. This will save fuel. Remember the 970 btu’s.
This surely clouds a clear answer. I guess I don't know!
I do know what will help save fuel if you already have not done this. Set the steam pressure control to operate between .5 and 2 PSI. Less run cycles. Insulate all steam caring pipes in the basement, make sure your main line air vents work well. Maybe add another if needed. Verify all the radiator vents are working. Check to verify you have no water or steam leaks. A well vented and tight steam system works the best.
 

Last edited by rbeck; 12-20-07 at 10:07 AM.
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Old 12-22-07, 07:52 AM
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In my answer I am assuming since searayboater is so efficiency concious he has already addressed the issue of leaky windows, poorly insulated rooms, drafts under the front and rear doors, open refrigerator and freezer doors, the dog's trap door staying open, etc....

If the boiler fired shorter periods of time (example---25% duty cycle instead of 40% duty cycle given the same exact outside temperature) wouldn't that in itself prove less consumption of fuel? It depends on how you define efficiency. I think what he REALLY means is less consumption of fuel, which is a little different, but I'm sure that's what his goal is----to use LESS fuel.

I'm sure he does not mean: BTUs output/gal fuel

If he were to close off 1/2 of the radiators in the house because he does not need to heat up those rooms it would equate to having a 2 zone system, (kind of) both being about equal, and only using 1 zone because you only need to heat up the areas covered by the one zone. (Since this is steam it may not work out EXACTLY, especially if the are he want to heat up is upstairs)

IF he has a room that heats up INSTANTLY and happens to be the room with the thermostat in it (dumb) and finds the areas covered by the tail end of the loop not heating up enough he has at least 3 choices: 1) re-adjust the anticipator on the thermostat 2) ADD a thermostat in the colder room and wire it in parrallel to the first so that BOTH thermostats would have to be satisfied for the circulator to turn off 3) MOVE the thermostat to the colder room.

ANY way you look at it, the boiler will be on less time per hour because it doesn't have to heat up as many rooms.

For the technical people who don't like keeping things simple:

Using advanced mathematical skills:

Boiler on time/hour = less fuel consumed/hour

That was MY 2 cents. Sorry guys. My coffee is getting cold because I left it in the room with the radiators off!


Keeping it SIMPLE.

Good luck!

Charlie
 

Last edited by boilersrus; 12-22-07 at 07:56 AM. Reason: forgot 1 thing
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