Efficiency - Heating whole house vs half a house...

Jamie Hall

is that the unheated rooms must stay above the dew point, or you'll get condensation in there and possibly mold.

Inwood Steam

Is it more efficient to heat all or half of a house?


In the winter I usually turn off the radiators in one of the back rooms and the top floor, because these rooms are not used all that much unless people are visiting.

Am I saving on my gas bill by doing this? Or is this silly, because all it does it make it harder to heat the rest of the house while not really using any less steam? Since steam expands so quickly and easily, I wonder if I might as well leave the rads on? Once the boiler is firing for the room with the thermostat, is there an appreciable difference in letting steam race to these extra rads vs not using them?

The total number of rads we're talking about here is 4 out of 9 (+ exposed bathroom riser).

In general, I also wonder if it is better with a steam system to maintain a constant temp all the time, more or less (say between 65 and 71 deg) vs cutting back to the 50s when out of the house.

Thanks for the tips!

V8toilet

By shutting off those 4 out of 9 radiators you have, you are putting the system out of balance. In a steam system the boiler is sized to the connected load (your 9 radiators) and runs most efficient this way. By reducing the connected load you are making the boiler, which still produces the same amount of steam, too large now for the remaining connected load and you may cause the boiler to short cycle on those really cold days, which will cause the boiler to use more fuel.

What you can do is reduce the amount of steam to those radiators in that part of your house you don’t want to heat as much by increasing the size of the vents on the radiators that are in the rooms you do want to heat more. This way the steam will tend to go to those radiators first and heat those rooms more quickly and most of the steam will heat the part of your house that you want too without causing the boiler to short cycle.

Jack_44

TRV's?

Sounds like thermostatic radiator valves might be a solution - set the part of the house you don't use down to minimal heat requirement (50° or so), enjoy the radiant elsewhere. If you're dealing with single pipe steam, you can't throttle the valves - they must be on or off. If you've got two-pipe, you still could control the temps automagically with TRV's.

TRV's allow you to zone each space at the radiator.

I also think daily setback should be minimal (5° or so), but maybe I misunderstand. Again, the TRV's would help.

(Just this homeowner's perspective.)

Inwood Steam

update

Thanks for the fast responses - I do love this discussion board. More info:

- single pipe system, so can't use thermostatics
- yes, already have "tuned" the rad vents with sizes from #6 to #D to heat the key rooms first
- yes, always above dew point - unheated rooms were, say, 60 deg rather than 70.
- previous owner replaced the boiler two years ago, so who really knows how accurately that was sized

I appreciate all the feedback and will try running the whole house for a while to see how that goes. It's no fun heating an uninsulated house with 1930s steel casement windows!

Leo_17

Say what?

"single pipe system, so can't use thermostatics -"

Who told you that? I have one in my son's room and it works perfect. I am in the business but learned it here from one of Steamhead's posts.

Leo

rich on heat

I've a one pipe steam system. I used these and they work well.
http://www.maconcontrols.com/pdfs/OPSK1204.pdf

Just make sure your steam pressure is below 2 PSI otherwise they can get damaged. On one pipe steam systems: lower pressure = better efficiency. My system now runs on less than 1 PSI.
If you haven't got Dan's books("A Steamy Deal" at the bottom of this page) I'd highly recommend them to you.

Edit: Here's another source:

http://na.heating.danfoss.com/PCMPDF/RA2000 1PS-DS.pdf

Inwood Steam

I had some incorrect advice on the TRV's, thanks for the tips. Will look into those. I do run my system at less than 1 psi, so pressure will not be a problem.

To get back to my original question though, is it more efficient to heat a whole house or half a house? Sounds like using only half the rads will result in a boiler that is effectively too big and cycles on and off too often.

David Nadle

\"Yes we can\"

I have one pipe steam and I use the Danfoss RA2000 series TRVs on my upstairs bedrooms. They work really well. I think the lowest setting maintains 50 or 55 degrees.

Unknown

I'm also looking for fuel efficiency especially after my fuel bill last year. If you lived near`me you could easily recognize me as I'm the one doing cartwheels down the sidewalk each day after I've just read that`the price of oil has dropped!


To answer your question on house heating, I don't know, I'm wondering that too. From what I've read on this board there seems to be the thought that if you setback your thermostat by more than 5 degrees you waste more fuel bringing the heat back up than you are saving going lower.
I've been shutting down a lot of my non used rooms by setting the TRV in that room to the minimum setting. (I've a old plaster house and can't let the plaster freeze)

I think the key to saving may be to just put on down vests and live with a lower temperature.

I also thought about getting a wireless thermostat and using that in the room where we stay the most though I'd have to change the TRV in the room to a fixed vent to make that work. Being wireless you're flexible and can try different locations.
The more cycling side I haven't figured out yet.

Frenchie

Cartwheels

No, kidding, Rod!! I know what you mean. I have been doing the cartwheels down the sidewalk as well. Too funny!! I hope the price stays below $2.50 for the rest of the season.