Thermostat control and Pressure control

Sly

How do i prevent the burner from coming back on once a heating cycle is starting.

If the temp has to move from 68 to 71 the boiler builds up steam then cuts off.  Then it will come back on in a few minutes because the desired temp is not reached.  How can I control this better so it does not keeping running on off so many times before it reaches the desired temp.



thanks

sil

DavidK_2

depends on what kind

 of thermostat you have. If it is an old style with an anticipator you want to set it so it runs longer (higher number). If it is a new fangled electronic type, you probably have to reduce the number of cycles it allows in an hour. Apparently most of these come out of the box set for forced air heat, with steam you want less cycles per hour (the usual recommendation is 1 cph). First step is to determine if it is the thermostat is shutting of the boiler, or if it is shutting off on pressure - an easy way to do this is the crank the thermostat up, and see how it behaves.



I'm not a heating pro. Just a homeowner.

Jamie Hall

Pressure

if it is shutting off on pressure (quite likely) before the thermostat is satisfied, and the initial run is short -- say 15 minutes or so -- and the radiators aren't hot all the way across -- you probably have venting problems.  Like... you need more venting.  On the other hand, if this is happening towards the end of a long run, it is more or less normal and won't hurt anything.  Which is it?

Sly

Thermostat control and Pressure control

Its after a long run.  I keep the temp at 68 during the day because most of the people are working at 4pm i crank it up to 71 for the rest of the night. 

Should I just leave it at 71 for the entire day? I use a visionpro thermostat by honeywell.

Jamie Hall

Probably fine

That 3 degree setback sounds quite reasonable.



With single firing rate burners -- which most of us are still stuck with -- you can expect exactly that behaviour when you are recovering from a setback.  The reason is that you need one firing rate to bring the whole system up to temperature and fill it with steam, and then a somewhat lower one to maintain the steam in the system until the thermostat is happy.  Back in the days of coal, this was done by an automatic gadget which adjusted the draught (the efficiency was horrible, but who cared?); nowadays, the way the system accomplishes the same thing is to just turn the burner on and off to maintain the proper steam pressures.  Oddly, you don't really lose that much efficiency (although you do lose some), as the boiler and water is already hot, so the burner doesn't have to run long to start generating steam again.  Lower steam pressure (say 9 ounces at cutout or so) and a relatively small differential (say 5 to 6 ounces, giving a cutin of say 3 ounces and a cutout of 9) will help -- but that presumes you have a vapourstat.



The VisionPro is a fine thermostat.  Just make sure (I'm sure you have) that it's set for 1 cycle per hour.



Anyway, I'd say to stay with it.

Sly

Thermostat and Pressure control

thanks Jamie

I have one last question, I use to have a heat-timer but i switch to this vision-pro.  I have a two story building with eight one bedroom apartments.  4 on each floor.  I put a remote sensor in one of the apartments and connected it to the visionpro.  i thought the heat-timer used to much fuel.  What are your thoughts on this setup or do you think i should switch back to heat-timer?



thanks

sil

Unknown

Thermostat/Pressure

What sort of steam system do you have ? Do you have a single stage or a multi stage burner?

- Rod

Sly

Thermostat Control and Pressure control

I am not sure.  i have a powerflame burner.  I think its single stage since I have steam heat.



thanks

sil

Unknown

Tekmar 269 / 279

Hi Sil- You might want to take a look at the Tekmar 269 or 279.

http://www.tekmarcontrols.com/prod/269.shtml

http://www.tekmarcontrols.com/prod/279.shtml

These controls are very sophisticated and might work well for you.   Read the Literature section on each unit as there is good documentation on the operation etc.

- Rod

FJL

Vision Pro

I use the vision pro in my building, which has four units on four floors.  We put the sensor in the top floor apartment, traditionally the coldest apt in the building.  It seems to work well for us.  We have some heating issues but I don't think they're related to the t-stat. 



Our contractor had recommended  Tekmar but the people in my building were afraid of the technology.  They thought that there would be times when we would not get enough heat depending on the weather outside. 



Anyway, is it true, as I read somewhere, that a Tekmar is not user friendly and if something goes wrong with it you would need a pro to come and service it?

nicholas bonham-carter

user-friendly heating contrpls????

even the visionpro leaves much to be desired for user friendliness. it's a drawback to have to refer to the manual for the category numbers as you are setting it up. as the tekmar is steam-specific, there is less setting up to be done: just low temp setting for your area, and steam "arrival" temperature.

you can do a search here for past discussions on the tekmar 269/279. most people seem to like it very much, and i am tempted myself. the advantage over the visionpro, as far as i can see is the ability to average 2 sensors, where the vision pro can only average 4 sensors! the other advantage is that opening windows for fresh air in the sensor location has less impact, due to the temperature being controlled by the outdoor sensor

do you think steam is getting to that cold apartment later than the others on that floor. remember that money spent on extra main/riser venting is never wasted! --nbc.

Unknown

Tekmar 269 / 279

First of all I must say that I'm not speaking from practical experience as I don't own a Tekmar 269/279.  A 279 is on my wish list and if the cost of fuel goes up again I will probably buy one.  The reason I don't have one now is that only my wife and I live in the house, I'm retired and we observe strict usage of the heating system. (I'm the Thermostat King! ..(I'm a human 279!   However if it was a situation of having to share "thermostat power"  with multiple family members or tenants /co -op owners (and I was paying the fuel bill) I'd definitely get a better control immediately, either a Heat Timer or a Tekmar and from what I've read I'd favor the Tekmar.

Is it "user friendly"? No, like the Vision Pro, it does require you to read and understand the manual. The more settings/ features it has, the more understanding you need to have of the unit's operation.  However the 279 is not just a fancy "on-off" switch like the Vision Pro, it is a computerized control with multiple sensors which will minimize your fuel usage.  If you burn fuel at 1 1/2 gal an hour @ $2.75/gal. fuel for your boiler is running close to $0.07 a minute. If the 279 saves you a minute here a minute there during the hour this very quickly adds up and contributes a substantial saving to the monthly fuel bill. If you are interested I'd suggest you read the 279 manuals yourself as it has a complete explanation of the operation. It has multiple sensors - out side temperature, inside temperature (you can put a sensor in every room if you like) and also senses the temperature of the condensate coming out of the radiators so it can tell when the radiator has extracted most of the heat from the steam. 

Ideally the 279 would have pressure input so that it would integrate the function of the Vaporstat too. Why in this day and age of electronic computer controls and senors why we have to put up with an expensive piece of beer can with a manual switch and a few springs that they call a Vaporstat is beyond me.

- Rod

FJL

Cold Apt

The steam gets to every apt pretty quickly.  The issue is a heat loss issue.  The top floor loses heat faster than the others, so the sensor calls for heat more often that it would if it were in another apartment.  Two year ago, we added Gorton 1 vents on each riser in the building and that greatly helped getting steam out of the risers and to each radiator quickly, at which point the radiator vents are venting only the radiator.

FJL

Tekmar

What is the difference between and 269 and 279.  How do I know which one I need for my boiler (Burnham Independence 11)?

Sly

Thermostat control and Pressure control pics

Jamie,here some pics of my system and what I have it set too.



thanks

sil

Unknown

Tekmar 269 / 279

The difference is features. Use the link in the post above and compare them. The 279 is a later unit and is the one I'd consider.

- Rod

FJL

Tek

Thanks.  I'll look at both.  My contractor had recommended the 269 (I think) when we had a new boiler installed in the summer of 2007.

jpf321

SMC Pressure Sensors and Switches???

Does anyone have any experience with the SMC digital pressure controls for steam? http://bit.ly/4BXjq9 are they suitable for steam?

Sly

tekmar vs heatimer

Rod,

do you thinkg the tekmar does the same thing as heat timer or it does a better job? 



thanks

sil

Unknown

Choice?

Hi Sil-  Both Heat Timer and Tekmar make good controls. I think which unit gets used on a job depends a lot on what the heating man putting it in is familiar with. Making a choice between the two I'm not qualified to do and as heating men generally stick to one brand or another you may have a problem finding someone that is familiar with both. If you're seriously interested in these, I'd get the literature on the Tekmar 279 (links above) and then call Heat Timer and as what they have that is comparable or better and why, and where do you get the literature as you wish to compare the two. One of the factors may be whether you are prepared to maintain the unit and settings yourself or whether you will have someone do it for you. In that case you probably need to go with the unit that your heating man is most familiar with.

- Rod

Jamie Hall

At the risk of sounding like a fuddy-duddy

(which accusation is probably partly true!), there is an awful lot to be said for the KISS school of system control.  Since it is now impossible to get mercury switch or straight bimetal thermostats, a relatively simple thermostat such as the VisionPros, which allow for automatic setback, is probably fine; properly adjusted to the building, with a properly adjusted system, it should keep the temperature in the building to plus or minus a degree or so.



Unless you are blessed with a full modulating burner for the boiler, there again I would stay simple -- a vaporstat or pressuretrol, again properly adjusted.  The old vaporstats had a mercury switch, and were pretty close to bullet proof.  The newer ones have some electronics in them, and can be fiddly to adjust at first.



But I have to admit that I don't see the point, for a steam system, for anything much fancier than that...



Hydronic is a different story.