Steam radiators and programable thermostats

Mary_6

I live in a large 1917 home that is not very well insulated with the original single-pane windows.I have done my best to insulate what I could, not being able to afford new windows at this point, sealing cracks and using plastic on the windows, but,of course, I still lose a considerable amount of heat. I have a home office and am home most of the time, but I keep the heat low, or warm it up then turn it way down, and just heat my office with a space heater. I also close the radiator valves so the upstairs bedrooms aren't heated when no one is using them. But I would rather have a proramable thermostat do all the work, especially for when I am not home.
The house it heated with a Weil-McLain Series 2 Oil-Fired Natural Draft Steam Boiler. There is a basic digital thermostat to regulate the temperature. There is no mfr name on the thermostat and it has no controls, just temperature setting. The furnace turns on when the room temp differs by 1 degree, which on extremely cold, windy days, doesn't take too long to obtain. I would like to increase this to maybe 3 or 5 degrees, so when I am not here, it won't run as often. The previous owners must have tried to install a programable HW Magicstat 2400 because there is one here,on the other side of the way, not hooked up, but when I researched it, the manual states it cannot be used with steam heat.


I guess my questions are:
1. Is there a programable thermostat I can use with my sytem?
2. Is there a way to increase the degree difference before the furnace kicks on?
3. Is it more cost effecient to let the furnace run more frequently for less amount of time, or less often, for longer periods?

Thank you for any guidance you can give. I have searched for a specialist in this area, but havent located one. Our local HVAC guy said I have the only steam radiators in town, all others are hot water.

Mary_6

correction

The other thermostat that is not hooked up is a CT2600, not 2400. When I was researching the 2600, the manual suggested the 2400 but when I researched that, the compatability chart said it would not work with steam.

Sorry for all the typos and mispellings, too!

nicholas bonham-carter

set back thermostat

the consensus here seems to be that setting back the temperature for periods of less than a day can sometimes save no fuel, as the system struggles to regain the lost temperature.

if you wish to try it, the H/W vision pro is rated for steam.

therefore my suggestion is to make sure your system is in very good condition, and to keep the temperature constant.

check your main line venting-are the vents working?

keep your pressure as low as can be set- under 16 oz. is ideal[ you may need a good low-pressure gauge gaugestore.com 0-5 psi].

are your steam pipes insulated?

is your burner clean and adjusted?

i believe all of these topics are covered in better detail in dan's "the lost art of steam heating" available here.--nbc

Unknown

In general, it is more efficient to run longer burner cycles less frequently, than more frequent shorter cycles. The longer less frequent cycles may cause greater swings in room temperature however, but I believe you mentioned that you would be willing to accept 2 or 3 degree variations without sacrificing too much comfort.

The on-off thermostat temp setting difference on older mechanical thermostats was accomplished by either the anticipator or differential setting. On later electronic thermostats essentially the same function is provided by the "cycles per hour" setting. Check your existing thermostat and see if it has such an adjustment.

Jamie Hall

I sympathise!

My place was finished in 1893, with various additions from about 1780 (original) to then.

A few thoughts (mostly from my own experience).

Windows. The payback on new windows is long. Like, very long -- even at today's energy prices. Don't let a contractor fool you on that. You will do much better to make sure that they are in good condition (there will always be some draughts with old double hungs, but some gentle work can minimize that) and use plastic until you can afford to put good old-fashioned aluminium triple track storm windows on the outside. Much less expensive than whole new windows, and almost as effective.

As has been mentioned, most Honeywell digital thermostats have setback capabilities (and you can get some of them in big box stores; they aren't hard to install), and can be set to one cycle per hour, which is correct for steam and cast iron radiators. Not all. Check before you buy! I know the model RTH7500D will work. Putting one in will make a difference, really. The instructions which come with it are pretty good as to setup -- select 'oil or gas steam' (one cycle per hour) (that's well down the menu, but it's there). As to setback, that's kind of debatable with steam; I use a 5 degree setback at night (65 day, 60 night) and it seems to be as far as I can go before the boiler burns more fuel trying to heat up in the morning than it saves not running at night.

Good luck!

Unknown

Hi Mary -
I also have a old home and believe me I understand your frustration. If you don't have it already I'd get one of Dan's books (See "A Steamy Deal" at the bottom of this page)
I see NBC already mentioned "The Lost Art of Steam Heating" though I think I'd start with "We Got Steam Heat" as I think it might be a better "starter" book.

http://www.heatinghelp.com/shopcart/product.cfm?category=2-109


Dan's books are very easy to read, full of facts and examples on steam heating. The real benefit in reading Dan's book(s) is you'll then understand how your steam system works and not be at the mercy of your heating man who may or may not know how a steam system should work. Believe me there are a lot of heating men out there who don't have a clue about steam. (Ask me how I know!

With the knowledge you get you will be able to understand what areas of your steam system need to be checked to bring it to an optimum level of efficiency. (In correcting mine I gained close to a 20% saving in fuel)

I know you were asking about thermostats. Like Jamie mentioned, I found that about 5 degree setback seems to be practical for steam. I tried 10 degrees setback and am still evaluating the 5 degree.

You might want to look into using TRVs

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

They don't increase the heat but are less of a problem than shutting valves to control room temperature.

You also mentioned heating your work area during the day. Dan has a section in "We Got Steam Heat" about a method where you can put in a hot water heating zone using a steam boiler so that might be something to consider.

Steam is a really good heating system once you understand it and have it operating properly.