Heat Differential on T-Stat

Bomba

Hey everyone. 

On my old thermostat I had a “heat differential” setting that allowed me to set the thermostat at 67, but the boiler wouldn’t turn on till 65. This allowed the boiler to run for longer periods of time instead of kicking on at 66 and heating till 67. The reason I liked this is because my one pipe system doesn’t always heat my master bedroom (2nd floor end of run) unless the system runs for ≈ 30 mins. I eventually will fix this problem, but can’t right now. 

My new thermostat (Honeywell Smart Color) doesn’t have this. I was wondering if anyone who has a 1 pipe steam system actually utilizes this feature (if their T-Stat has it) or if they just set to desired temp and jus leave it there (or runs a schedule). 

Thanks! 

Jamie Hall

That setting is also sometimes referred to as "swing" -- and usually a good deal of effort goes into keeping it as small as possible!

Have you checked your new thermostat for the correct cycles per hour setting? Something of the same idea can be achieved by making sure that is set to 1 cycle per hour.

EdTheHeaterMan

The only way to set the thermostat for the longest run time is by selecting STEAM in the "Type of system" on the setup menu. This may get you to a setting of near one cycle per hour. That will not allow for a 2° differential but it will reduce the short cycles. Maybe that will induce a 30 minute run time. This thermostat is not designed with a steam boiler with your particular idiosyncrasies in mind.

Bomba

It doesn’t seem that my thermostat allows me to adjust anything really. 

That’s unfortunate. Does anyone recommend a thermostat; preferably a smart thermostat, that works well with steam boilers and will allow me to make these type of adjustments?

dabrakeman

You can do all of that and more with the Ecobee 4. You can vary differential/swing or you can even go in and manually set up a minimum run time. Comes with a remote sensor as well so you could control temperature from your bedroom instead of the mounted stat location if you so desire. You can also vary at what interval during the day or night you use one or more sensors. You can get more sensors if you want... It is kind of expensive but if you want a smart thermostat and the associated benefits of it I have found this one to work quite well for me with my one pipe steam. Their technical support I have been pretty happy with as well.

nicholas bonham-carter

If that radiator at the end of the run is a laggard, then it may be due to ineffective main venting. The supply pipes should get full of steam before any steam begins to rise into the radiators, all simultaneously. The main vents must let the air escape with no resistance, for this to happen.—NBC

Bomba

nicholas bonham-carter said:

If that radiator at the end of the run is a laggard, then it may be due to ineffective main venting. The supply pipes should get full of steam before any steam begins to rise into the radiators, all simultaneously. The main vents must let the air escape with no resistance, for this to happen.—NBC

There is no main vent. I have a ton of issues with the system. Plan on getting it fixed this summer. Just trying to figure out what to do in the meantime 

nicholas bonham-carter

AHA, therein lies the problem.—NBC