Looking for thermostat recommendation

adamdivine

I just purchased and moved in to an older house with steam radiators.  I have some experience with steam as I work for an engineering firm that designs HVAC systems for residences in Manhattan and the surrounding areas.  I have gone around and leveled all of the radiators and replaced the air vents (used Heat Timer Vari-Valve vents).  I also reduced the pressure on the boiler down to its lowest setting (around 1 psi or less) from its initial setting of almost 3 psi.  The system seems to run fine and is relatively quiet but I want to replaced the thermostat.  Right now, I have a simple non-programmable thermostat.  I would like one that will allow me to turn the system down at night and during some days.  Also, my second floor is colder than my first floor.  I think that the thermostat is reaching temperature on the first floor before the radiators on the second floor have had enough time to heat the second floor.  I am not sure if I should relocate the thermostat or if a programmable one would allow for longer run times.  Any help would be appreciated.

jpf321

system balancing item #1

before you try to solve the problem by looking at the thermostat .. you should really "balance" the system .. balancing refers to a system whereby steam arrives at approximately all rads (and end of rads) at approximately the same time .. have a look at: http://www.heatinghelp.com/forum-thread/129085/Uneven-Heating#p1184396



additionally, if you are steadfast on a new t-stat .. please note that the recommendation is to never drop down more than 3dFahr difference during a "nighttime" setting .. have a look at what happened to my boiler runtime and firing cycle when I increased temp 3dF here .. http://www.heatinghelp.com/forum-thread/129235/Pressure-Cycling-Illustration#p1185223



but balancing is the first task you should have on your list... it should increase your comfort and may reduce your fuel costs.

Jamie Hall

Thermostat

A lot of folks (myself included) like the various Honeywell VisionPro models -- there are several, some 7 day, some 5-1-1, some 5-2.  They work well with steam (remembering to set the cycles per hour to 1 -- which is not what they come set for).  White-Rodgers also seems to be OK; again, one has to reset the anticipator on those from what they ship with.  The manuals are pretty good.



On the uneven temps, your best bet is to fiddle with the venting rates.  Depending on how closely the radiation matches the rooms, you can sometimes do pretty well.  If you are noticing a big time lag, though, between when the downstairs radiators and the upstairs ones get heat, it is sometimes possible to put an additional vent on the upstairs risers (in addition to the radiator) at the top of the riser, and that can help, too.

Joe V_2

Why?

I just bought a honeywell digital round and set the DIP switches to 1 cycle per hour but have not installed it yet...  Is that literally 1 cycle per hour?  No possibilty of short cycling?  Why would they have this feature?

Jamie Hall

The one cycle per hour

accounts for the generally very large thermal inertia and lags of steam (and gravity hot water) systems.  They keep heating for a while after the thermostat shuts off.  In very simplistic terms, it simply means that the thermostat will wait at least an hour between calls for heat -- although it is actually more complicated than that (this does not necessarily mean that the boiler will be off for an hour -- if the boiler ran for 40 minutes on the first call, and then shut off, it's quite possible for it to come on again only 20 minutes later).