Programmable Thermostat for steam boilers?

No Sleep!

Can I change my thermostat to a programmable thermostat if I have a steam boiler? If so can you please tell me what kind to get?

Also what is the differance between a water heater timer and a programmable thermostat?

Al Letellier

t stat for steam

No problem installing a programable stat for a steam boiler. Just be careful not to set back too far, especially if you have an older system. 5-7 degrees max setback suggested.
There are as many stats as cars out there. The more expensive ones have an adaptive memory which automatically remembers how long it takes to bring the house back to temp and will start the boiler soon enough so the set point is reached at the set time on the stat. Cheaper ones just step up at the selected time and you have to set them a little earlier. Honeywell makes one of the broadest spectrums of home thermostats out there and they are of good quality.


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Boilerpro_3

Recommendation

I'd use the Honeywell Chronotherm unit. I have these on both converted hot water garvity systems and on steam. On one steam system the setback is to 50F and then back up to 70F without any notable problems of overheat when recovering from setback. The system used to overshoot by 8F when using the old T87 Honeywell when setback manually.

Boilerpro

JM_2

Lux 500

Is what I use. Home Depot. It is cheap and seems to work well. 1deg. over shoot from 58deg. nightime to 65deg. day. I am not a pro but own 5 apt units plus my own house. some tenants dont use the setback feature. but some like the option. I have had to replace one which croaked after three yrs service. One thing i like is that they work on forced hot water, steam, and powerpile steam. My system works well I installed 2 hoffman #75 for the mains and all new #40 vents at the radiators
JM

BillW@honeywell

You could use...

Either the T8002C 1000 or the T8602D 2018 programmable thermostats. They will need to be set up for 1 cycle per hour to operate your steam system. These are available from your heating/coling contractor. There is no retail equivalent of the T8002C, the closest retail equivalent of the T8602 is the CT3600, but it lacks many of the features of the T8602.

Morgan Clark

3600

What's the 3600 lacking that the T8002/8602 has? You mention something about setting the 8002 or 8602 to "one cycle per hour"?? I have a steam system, by the way...

I just bought a 3600, and it seems to keep my boiler running for pretty long periods of time - just wondering how much better off I would have been with this T8002 or T8602... Hate to buy something then days later find out it's the complete wrong thing!

BillW@honeywell

In the directions...

that you got with your CT retail stat, there should have been info on how to set the cycle rate. Out of the carton, they are set for 6 cycles/hour, the usual setting for scorched air heating. Set the stat to 1 cph, following the directions. As far as features, the CT model has no outside air sensor capability, a smaller, dimmer lighted display, 5-2 programming, no lockout feature, copy key, programmable hold or daylight savings time key, and an older version of Adaptive Intelligent Recovery.

Al is right, don't use any radical setbacks, and remember that steam systems have a flywheel effect. Your comfort level and system efficiency also depends on how good your windows are, insulation, overall home tightness and your lifestyle. Thank you for using Honeywell products.

kk_2

Hi Bill,

Just here to keep you honest...

The CT3600 *doesn't* have 5-2 programming - every day is independent. It *does* have a copy key, programmable hold, and a daylight savings time key.

One difference that you didn't mention is that the T8602 can automatically (or manually) switch between heat/cool, while the CT3600 is manual only.

Also, the CT3600 manual tells you how to change "Feature 4" for your type of system (to 1,3,6, or 9.) It never mentions the fact that what you are actually doing is setting the cycles/hour.

I have a CT3600 which is why I'm familiar with what it has/doesn't have.

-kk

BillW@honeywell

I'll have to stop by the box stores more often..

The CT products are handled by another division, I wasn't aware they had been updated.

jim_14

i went back to the honeywell round from the CT3600

I wasnt using any of the features anyway, just as a regular tstat.

Does the ct3600 automatically determine the anticipator setting?

Arthur W.

prog. thermostat for gravity hot water?

Okay, I've read the messages about steam. What about gravity hot water? My wife & I just had a knock-down, drag-out fight about it at Home Depot (no blood was shed).

I wanted to buy one. She was told by a heating/cooling guy very explicitly that they were a waste for our system. I don't believe it. Can someone explain the logic here? What are the variables? Is the problem overshoot (which I could understand - since heat loss goes as T^4 - but which could always be solved by a smart feedback - as was mentioned in an earlier post) or is there something more subtle going on? I'm a physicist, so not understanding these things bugs me.

Thanks!

Unknown

Your understanding is OK

But guys in the trade have actually found out how much flywheel effect there is, and what the trade-offs would be.

The adaptive thermostats would be about the only way I'd try it, because seasonal changes would drive you nuts without it.

I'd be curious what you observed if you did use one. Not the boring stuff, but the things that surprise you about run time, overshoot, time lag, and operating cost.

I don't think it would be wrong to try it, in your case. It wouldn't be something I'd try to upsell to someone with your system, unless they asked about it.

The system is where there is room for improvement. That's where you would see return on investment. I'm more of a save the old stuff, kind of guy. I just like it.

Noel

P.S. Have you looked into constant circulation with water temperature reset, if it now has a circulator on it? That's the Cat's meow on an old gravity system. That's worth doing, most certainly. If it's still gravity, then the thermostat is basicly doing this already.

Boilerpro_3

My understanding....

I have used the Honeywell 8600 Chronotherms for gravity conversion systems very sucessfully. However, there may be some limitations. 1) The boilers they were controlling were sized to the current heat loss of the structure, so the temp of the rads tended to be limited by the output of the boiler, helping prevent overheating. 2) In my own home I have resized the rads to the current heat loss and replaced the piping with new smaller piping, again limiting how quickly the system can recover, helping prevent overheating, even with the el cheapo stat that currently is being used. 3) I've run into many people that have been told by contractors that setback stats will not work with gravity conversions. I can only suppose its due to the fact that the systems take a long time to recover. However, when recovering from setback the boiler is typically running at full output for a long period of time, typically improving its efficiency and saving fuel in addition to the savings of keeping your home at a lower average temperature. 4) Most contractors only know forced air and only use stats that are compatible with that type of system. Using one of these stats on a gravity conversion probably will never work. The cheap forced air stats are unable to provide "smart feedback". I think Honeywell pretty well has this piece of the market cornered. The competing top of the line White - Rodgers and others do not recover intelligently. They run the equipment full bore during recovery, tending to cause excessively high air temps and excessively low radiant temps when reaching setpoint. The Chronotherms cycle the equipment during recovery to allow a more stable transition to occupied temperatures.

Boilerpro

John Curley

Invensys: Better than Honeywell

We used to use Honeywell, but I would highly recommend the Invensys 7300 series. It has the features of the advanced Honeywell 8600 series, but is MUCH MUCH easier to program, operate, and read. These are really great thermostats. You can have 2,4,6 different temp settings per day and it uses logic to prevent overheating and safe fuel. You can also connect an outdoor sensor.

(It is also being sold now under Invensys's RobertShaw brand as the RobertShaw 7300 series. The 7301i is powered by a 24v supply (ie. you need a common wire in addition to just two wires to operate the boiler) and the 7300i is powered by batteries. (Great if you only have 2 wires to work with and/or your system is a millivolt system.

http://www.about-i-series.com/

Not connected to the company, just a very satisfied customer.