Tekmar 269 Settings

carol_3

Sounds like Derek is cookin'! Somebody help this guy!

soot_seeker_2

Hello all... monday we had our 269 installed on our 1 pipe steam system and since then I think the Condo owners have been putting their stew on the radiators in the morning instead of the crock pots!

I have gotten in touch with the HVAC installer and they are comming back in 2 weeks to put in 2 interior sensors but I can't wait that long to adjust the settings.

Currently I have the WWSD points set to 55 and the design out set to -40. The condensate return sensor is installed with the switch in the on position. The manual override is set to auto. My cycles are set at 60 min. Steam established is set to 170 with a lockout of 30 degrees.

I know my design out is waaay out of wack and coupled with the fact I am still getting overheat complaints something else must be wrong. So I read the manual and the only other thing I can see that would cause over heat is the steam established setting. I can do the procedure it describes in the manual but I dont know what "operating temperature" is or how to measure it. Again I could wait for the HVAC guy but again, 2 weeks is too long.

Anyone have any suggestions or instructions? I know the manual says its a "trial and error" process but I need to keep my Condo owners pets from becomming heat casualties!

Thanks
Derek

Empire_2

Ready?

SInce you need to do something to change this control, Set the dials as follows. Design out to 30* for now not -40*. This will cycle the system at 30 min on/ 30 min off time @ 30 outdoor temp. There is alot more to this system, but this should help you with overheating until the contractor comes back. Also, you can go to teckmarcontrols.com fot the complete tec. book.

soot_seeker_2

Design out...

Maybe I am reading it wrong in the manual but I believe the "design out" Is supposed to be the coldest day of the year, there for "design out" = 100% on time.

I am referencing Figure 3 on page 2 of the 269 Data Brochure. It says "Figure 3 illustrates how Outdoor Reset of a steam boiler changes the % on time from 0% at the Warm Weather Shut Down point, to 100% at design outdoor conditions (coldest day of the year)." about half way through the paragraph next to Figure 3.

So, if I am getting this right, my current settings of design out of -40* and wwsd at 55* it puts my 50% on time at about 10* which is over heating. And if I change my design out to 30 then it will be 50% on time at about 42 degrees?

Empire_2

I take that back

Your are correct. I was not taking into consideration that you set your wwsd to 57. I guess I was trying to shorten the cycle length on the system. At - 40 it seems that 50% run time is too much at this point. I was only trying to shorten the cycle to try and reach a happy medium until the cont. get there. Sorry about that.

soot_seeker_2

Last Night Changes

Alright...

last night I read even more about overheating right here on Heatinghelp.com and think I have found the problem.

I know the condensate sensor is on a return because I can see the main vent above it, the pipe heats up during the heating cycle, and the pipe runs vertically down from the main. So apparently, from what the overheating article says, if that main vent is undersized/clogged the steam isn't getting down to the sensor fast enough. Which means the boiler is "warming up" for too long at the 170* steam established setting.

So last night I knocked it down to 150* with only a 10* degree lock out. Better but still not perfect so I knocked it down again this morning to 140* with a 5* lockout. Hopefully that works.

Still, any help or suggestions would be greatly appreciated!

soot_seeker_2

Well... if I knock back the cycle length, how far do you figure I should go?

I am at 60 min right now and assuming its running at 50% that means I am getting 30 min of steam (more complicated than that but still). I know if I cut it back to 30 min cycles and it still is running 25% then it will run 15 min out of every 30, which is still 30 min out of every 60 (Again refering to page 2 figure 2).

I was doing some calcs and I am still ending up with about the same on time per hour no matter how long my cycle is. Now I know my lockout will effect this time too but its a little harder to figure in

Tombig_2

Tekmar 269

Derek, First, the return sensor.How long does it take from boiler fire to 'steam established'? Where is the return sensor located? Are the other returns (if any) getting hot way faster than the sensor return? Follow the return back to the last radiator. Is it far? Move the sensor to there. Maybe the radiators are venting faster than the mains (not good).
I think you'll have better luck adjusting the design temp to shorten cycle times temporarily. Also, with no indoor input, this control only knows OD temp to run itself. If the boiler used to run on clock and return aquastat, it turned OFF when the temp reached 140-180. This control STARTS the cycle time then. With no other control, stat, whatever to tell it to TURN OFF!! What's the pressuretrol on the boiler set at? It must be pretty high if this boiler can cycle for 50 min. and not shut off on pressure. Set the cut out and differential lower. Maybe 1.5 to 2 psi (depends on system) There's a lot more to your steam system than just the new toy. It's very smart but it needs input. Call Tekmar tech support if nec.
Get at least one indoor sensor on line. String the wire out a window and down to the boiler room if necessary. Otherwise you'll pay extra in fuel the next two weeks than that control cost and then some. I hope the installer is your brother-in-law from the next county and not a locaL pro. Two weeks? Somethings gotta give. Good luck.