What is the best Thermostat for Steam?

Helpless533

I have two pipe oil fired steam with inlet orifices installed.  The system has been working great since i got some help on this site and installed the orifices. 

I was wondering if there is any advantage to buying a new thermostat?  Currently I have the old dial type and it seems like the swing is set for 3 deg F. 

Can I expect any advantages in switching to a programmable thermostat that would allow my to control cycles per hr?  Or something that could sense the outside air temp and adjust accordingly?  I am not looking to use any set-back functionality b/c my boiler is not large enough.  Is 3 deg of swing to much with my current setup?

Looking for any ideas

Thanks

ChrisJ

t-stat

You will probably get quite a few different opinions on this one.

My favorite thermostat so far is the Honeywell Visionpro 8000 series which can be set to 1 CPH or even 2 or 3 if your system likes it.

cn30

t-stat question

Can someone explain how the cycles per hour fits into the thermostat calling for heat and then being satisfied? I would have thought the boiler comes on when the thermostat calls for it, then stops when it's satisfied (putting aside pressure issues).

Rod

Cycle Thermostat

The cycle function allows a steam system to "coast" a while before coming on again. After the thermostat setting is satisfied and the burner shut off, hot big cast irons radiators keep giving off heat for quite a while which results in the temperature dropping at a much slower rate that with hot air or fin tube systems. When the temperature drops below the thermostat setting where it would normally turn the burner back on, the cycle setting lets the system "coast" a bit longer. As the temperature drop is so slow this extra lag isn't normally noticed by persons in the room.  Less burner time per hour means more fuel is saved. If the home really leaks air and has poor insulation, then the cycles can be adjusted to 2 per hour. The big thing about a thermostat to be used for steam is to have one that has adjustable cycles which includes a 1 per hour setting.

- Rod

cn30

cycles

Thanks for the info. A related question: I've noticed that my boiler comes on periodically even while the temperature matches the setting. So it's set at 70, the temperature reading is 70, and the boiler nonetheless comes on after a while for 10-15 minutes. In fact, unless I turn the boiler off for a while, I don't know that I've ever seen the room temperature register below the setting. Is this normal? It's a rental unit that's just now vacant, so I haven't watched it a lot.

Rod

Aquastat ?

Hi-  Does this boiler also supply domestic hot water? If it does, there is a control called an Aquastat which activates the burner if the water temp in the boiler drops below a certain setting.

- Rod

cn30

No

No Aquastat--just the boiler serving a 1-pipe steam system.

Helpless533

Coasting?

I understand the example of "coasting"but is a thermostat that has the ability to program cycles per hour (1 or 2)  measurably better then one that is set with an appropriate temperature "swing" set with an anticipator or an ancient thermostat? 

crash2009

I'd probably keep

 the old thermostat and learn how to set it correctly.  Chances are it was set correctly originally, but it might have got bumped, or fiddled with.  The anticipator setting (at least mine) is extremely sensitive.  You need a steady hand and good eyes.  One small adjustment can make a big change.  I think I fiddled around with mine for a month before I got it where I wanted.  Here are a couple ideas  http://www.heatinghelp.com/forum-thread/138952/Mike-Anticipator-Settings

David Nadle

digital

The VisonPro 8000 works like that. Set it to 70 and at basically never leaves 70. But it maintains 70 very well.

ChrisJ

Crash

Speaking of this, did you try out my old t-stat yet crash?

crash2009

I ran a couple wires

 to some potential locations from the boiler room.  Still trying to decide on the best place to put it.  I might have to put it in the basement.  Thermostats, renters, and open windows don't mix well with an oversized boiler.

The Tstat was packed well. Thanks. 

nicholas bonham-carter

One nice thing

The new ones allow you to make small changes to the temperature setting (one degree), and that is a big improvement over the old honeywell round thermostat.

Do a search here for "setback" and you will see how that function is not useful for our systems in general. In the late fall, and early spring, you may need a little temperature adjustment, and the ability to bump up or down one degree can be very useful. Also useful is the visionpro remote sensor located in a more chilly part of the building.--NBC

Mark_125

Honeywell RTH2310B

I just use the basic Honeywell RTH2310B set at 2 CPH for my oversized one pipe steamer. You can set it at one temperature and just leave it, or program it if you want to experiment with set backs. My boiler is oversized to the point that I can use a 4-5 degree setback and have it make up that difference in under 30 mins.

BobC

same one

I think my thermostat is the same one and what I do is to set the stat down at night and then bring it up in stages, one at 0630 and the last at 1600. That way it never has to recover more than 3 degrees at a time. My old Burnham v75 was 3X larger than I needed and that setup worked

good with it. That same scheme seems to be working with the new Smith

that is 33% oversized.



I've been retired now for a few years but back when I worked the 1430-2300 shift I had the heat come up at 0630 and set back at 1300; when i came in from work at 2350 I'd sit and watch TV for an hour with a jacket on. Of course I'd have a couple of bourbons to take the chill off!  The system is happier with the staged recovery than it was with the one large one.



My old Burnham v75 was 3X larger than I needed and that setup worked good with it. That same scheme seems to be working with the new Smith that is 33% oversized.



Bob

Helpless533

Cycles Per Hr and low water

Maybe a stupid question.



How will my boiler shutting off due to a low water cut off interact with the cycle per hr setup on a new thermostat?



In a normal 20-40 min boiler run it shuts off 2 to 3 times due to low water.



Thanks

BobC

LWCO or pressuretrol?

Are you surer it's the low water cutoff and not the pressuretrol that is shutting the boiler down? If the boiler shuts down because of the LWCO and then turns back on you probably have a problem with a slow return that's not feeding water back to the boiler fast enough.



Bob

Helpless533

LWCO

Its the LWCO thats shutting the boiler down.  I have a undersized boiler for my home. (Utica 3100 373 sqft of steam, home 591 sq ft of radiation)



I am trying to see if a thermostat with a CPH setting would help me run the system on a more regular cycle keeping the pipes at a higher temp and saving wasted energy.

Any ideas??

Rod

Boiler Water Capacity

Hi- As I see it, any thermostat isn't going to help with your problem. As you mentioned, it would seem your boiler is very undersized. With the orifices, how well does the system heat the house?  If the boiler didn't stop operating due to shortage of water, would the heating be satisfactory?  What sort of shape is your wet return in? Are you sure it is unobstructed and not clogged up?  What make/model is your boiler?  Sorry for all the questions ,I'm just trying to get a better idea of the problem.

If the problems is slow return of the condensate and therefore the boiler is running out of water, there are ways of increasing the boiler's water capacity. I've attached a pdf on this that might be of help to you. There are also easier ways to do an reservoir tank than what they suggest.

- Rod

Helpless533

Utica Boiler

I have a Utica boiler.  I think the model # is 3100.  With the orifices installed it heats the house just fine.  Except for low water shutoff issues.  I don't seem to burn crazy amounts of oil either. 



I have not checked the condition of the returns.  I moved in December of 2011, the previous owner had the boiler replaced there were some issues that came out of out home inspection with the near boiler piping that were address but no one ever mentioned the size of the boiler.  After reading some books and getting some valuable help on this site I installed orifices at the inlets of all the rads in the house. (two pipe steam, no steam traps, nothing on the return side of the rads at all.  One large vent in the dry return for the entire house.

I now have a warm home and am looking to tinker with the system to improve what I have.  I wanted to start with a thermostat and maybe add some more vents?

Thanks.

Helpless533

Utica Boiler

I have a Utica boiler.  I think the model # is 3100.  With the orifices installed it heats the house just fine.  Except for low water shutoff issues.  I don't seem to burn crazy amounts of oil either. 



I have not checked the condition of the returns.  I moved in December of 2011, the previous owner had the boiler replaced there were some issues that came out of out home inspection with the near boiler piping that were address but no one ever mentioned the size of the boiler.  After reading some books and getting some valuable help on this site I installed orifices at the inlets of all the rads in the house. (two pipe steam, no steam traps, nothing on the return side of the rads at all.  One large vent in the dry return for the entire house.

I now have a warm home and am looking to tinker with the system to improve what I have.  I wanted to start with a thermostat and maybe add some more vents?

Thanks.