Heating Help

wiring, debris, flow ?

@ April 4, 2011 6:57 PM in Small Zone Troubles

It sounds like the temp switch on the operator works fine. Here's a few ideas.



Check to see if the boiler shuts of properly (at a low aquastat
140°Fsetting) when only the upstairs zones are calling. If it does, then it
sounds like the new zones wiring is bypassing the aquastat and cutting
out only on the high limit. Check the wiring.



If the boiler stays on past the aquastat setting when the other zones
call, then it sounds like the installation of your old leftover radiator
may have thrown some debris at the aquastat well.  Maybe some wood
chips/debris (I saw a dead mouse cause this!) are blocking flow around
the well or in the zone itself. Either way the temperature at the well
may not be accurate. Check the well.



Check the flow in the zone. Is there an air lock? Does the new piping allow for proper

pressure difference between supply and return to generate flow? etc.



You also mentioned that the new zone is small compared to other zones.
Even once you get everything running, a call from this zone will probably
lead to short boiler cycles. There is a feature called 'Zone
Synchronization' on tekmar Thermostats / controls that  can synchronize
all your zones together. This can really help reduce the chance of that
one small zone calling by itself. E.g. tekmar 400 House control with a couple tN2 thermostats. You would get Zone Synchronization and Outdoor Reset.

expansion noise reduced by reset temp.

@ March 8, 2011 2:14 PM in Noisy Pex

The more the zone cycles the more temperature variation and expansion noise you will have. If you use an outdoor reset control to effectively lower the supply temperature then the thermostat will have to call for much longer cycles.
Two fold effect is that you have less cycling so the pipe is not expanding and contracting so often and with lower temperature there is physically less expansion of the tubing.
Slamming a zone with full design temperature water then shutting it off all the time to control temperature will lead to the most noise. This would probably be worse during milder outdoor weather.

In a theoretically perfect zone the supply water temperature would be so low that the thermostat / zone would stay on continuously at this low temp. So once it started up the only time you would get expansion/contraction noises would be more gradually as the outdoor temperature changed.
Plus you get energy savings and fewer room temp swings. not a bad deal.

073 sensor reading too high

@ March 8, 2011 1:49 PM in Tekmar Slab Sensor

The 667 can use a slab sensor for system not requiring automatic start.
one possible issue with slab temperature reading too high would be that the sensor is located too close to a supply pipe. Can you push or pull the sensor into a spot that is not as close to the piping?
Another possible cause is that the sensor has become infiltrated with water which reduces the resistance, leading to temp reading too high.
Often you will see that the conduit that the sensor is inserted into is filled with water. That is not good. You should make sure the slab is warm and blow out the conduit with compressed air. Then seal it or extend it so it can not fill up with melt water.
If the sensor is water damaged then you will need to replace it with a new 072 or 073.
You should be sure to get the newer version of the sensor (Manufactured after June 2010). These sensors have been changed to an over-molded design which provides much better water resistance. They are also a little smaller so they are easier to fish into your conduit.
Here is a link to the new sensors: http://tekmarcontrols.com/media/literature/072_d_06.pdf

steam and hydronic boiler controls

@ March 8, 2011 1:23 PM in Retrofit Boiler Controls

For steam boilers you can get excellent operation and energy savings by
using an outdoor reset control. This adjusts the running time of the
boiler based on how cold it is outside. You can also add Indoor Sensors
which provide further information to the control to fine tune the
running time if the building is over or under heating.

tekmar Control Systems makes a steam control Model 279 that has outdoor and indoor sensing capabilities.

Keep in mind a good control won't fix all your steam problems. Clean steam traps, vents and good balancing have a big role.



For hot water heating systems they also have single or multistage boiler controls for same.

Here is a link to the steam control promo document.
http://tekmarcontrols.com/media/literature/p376.pdf

tamper proof temp control for steam system

@ March 8, 2011 12:58 PM in Thermostat for 4 fam building - tamper proof

Just wondering if you have an 'outdoor reset control' for your steam system. You could use an Indoor sensor instead of a thermostat, which has no adjustment on it . They would have no way of playing with the thermostat and your setting would be on the main control in the boiler room.
If you don't have a reset controller on your steam system, not only would you get the tamper proof sensor but your system would adjust itself based on how cold it was outside. This can lead to large energy savings for your steam system.

'remote' DHW tank control

@ March 8, 2011 12:49 PM in remote control

You could look at a tekmar 161 "setpoint" control. It has an LCD digital display and special DHW Mode and would allow them to see and adjust the tank temperature. You would place the tank sensor (included) in the 1/2" well and run the two wires to the controller which could be placed any distance away.
The control needs 24Vac power and has a 24V 2A rated contact that closes to turn on your heating device.

alternate method of solving heat loss from wind.

@ March 8, 2011 12:39 PM in Low-tech ways to adjust outdoor temp sensor based on wind

srega:
 I agree that the wind can have a huge effect on heat loss of a building re: your very first post - "i've been thinking about the problem where wind has a

HUGE effect on the heat needs on any given day -- and the fact that the

outdoor temperature sensor doesn't reflect this."

I guess you could try to use some wind factoring device to compensate but another easier way I think would be to look at the net result of the wind problem which is the underheating inside the building.
If your Outdoor Reset steam control has the option for adding an' Indoor Sensor'  then any underheating in the building caused by the wind would be addressed by the 'Indoor Feedback' shifting the outdoor reset curve higher. This should solve the problem of extra heat loss due to wind.

279 settings with some explanation

@ March 8, 2011 12:16 PM in Tekmar 297 Steam Boiler Controller - Share Your Settings

Here is some explanation and suggestions for settings
on the tekmar 279 steam control. Note: Generally the factory settings are a good
starting point.
Your list of settings:

Minimum On Time -  does not apply if using
a condensate return sensor

Indoor Design – typical standard room air temp = 70°F

Outdoor Design – set this to the coldest outdoor temperature experienced in
your town.  E.g.-10°F.

Boiler Design % - 100% is good, unless your boiler is oversized. Turn down if
you want less than 100% run time on coldest day. E.g. 90%



Room (OCC) – Leave it at 70°F for most applications. If
using an indoor sensor this is like the thermostat setting.
Room (UnOCC) – Set lower than Room Occ to shift Heating
curve lower. E.g. 60°F. Only used with setback.                                


CycleLen – Usually a longer cycle length is better for steam. This allows the
outdoor reset to have more
chance to alter heat output. Automatic is usually best or, if manual, try
starting at 60 minutes.


 Lockout Diff – Keeps boiler off until condensate temp. drops this amount below
the ‘steam established’ setting. It ensures that the condensate gets back to
boiler before refiring.


 Setback Hours – If you want setback set up a schedule
and times. E.g. 24 hour, Occ = 5:30 am, Unocc = 10:30 pm. The control uses the lower (Room Unocc)
Heating curve, and WWSD Unocc.


WWSD (Occ) – Warm Weather Shut Down, disables heating when outdoor is above
this E.g. 70°F.

WWSD (UnOcc) – If setback = On. Warm Weather Shut Down at night. E.g. 55°F.



Optimum Start? – On or Off. Only available for setback with Indoor sensors. If
= On control learns to start early.


Boost? – Only for setback without Indoor sensors. You can set a Max time
control boosts output when coming out of setback.


Limited UnOcc? – Only for setback. Limits on-time calculation to 85% during Unocc.
Energy saving feature.


 Hope this helps.



 

tekmar control option for Boiler, DHW and 8 Mix temp zones

@ February 22, 2011 7:50 PM in Boiler Controls

One control option you could look at would be a tekmar 402 House Control with a 313 Wiring Center and eight 527 Thermostats.
It would be an easy retrofit as the thermostats use only two wires. You get a nice digital LCD display and they are very simple to operate.
The 402 House Control would operate the Boiler, DHW, Mixing and four of eight Zone valves. The 313 Wiring Center would operate the other four Zone valves.
Your radaint floors would require the use of some form of Mixing. Either Variable Speed Injection using a pump or Floating Action using a 3 or 4Way Mixing valve & motor.
The 402 supports either method. This would allow you to run the boiler hotter for DHW and to prevent condensing, while running full outdoor reset to the radiant zones.
Here is  link to a promo document for the House Control system.
http://www.tekmarcontrols.com/literature/acrobat/p523web.pdf

outdoor reset mxing with a tekmar 360

@ February 22, 2011 7:34 PM in Coal Boiler & Outdoor Reset

The tekmar 360 control can operate a 741 motor mounted onto your 712 three way mixing valve. It would be best to connect at least the pump for the manifold ('Mix System pump') to the control. That way it can turn on the pump when the thermostat calls and also provide Warm Weather Shut Down WWSD to disable the pump and save energy.
The 360 can either control the boiler directly or enable it or do nothing with it. The choice depends on your system and your preference. If you don't want to control the boiler, or the system doesn't allow for it, then make sure you set the 360 Boiler Sensor DIP switch Setting = Return. The control then uses only the floating action mixing to keep the Mix Supply temperature at the calculated target. 

tekmar 256 boiler operation

@ December 23, 2010 1:39 PM in Hydronic Heating with Tekmar Control - Intermittent Problems

The tekmar control uses a split differential.  The split differential is 1/2 above target - 1/2 below target. So it will always fire above the target. The average temperature output will therefore be equal to the target.
 This "Automatic Differential" can also dynamically adjust itself. The control watches how fast the boiler temperature is changing (an indication of the system load) and will get smaller or larger. If the temperature is rising rapidly this indicates a small load on the boiler. Small loads can lead to short cycling so the control will expand the differential to help prevent this from occurring.The differential is constantly adjusting every cycle.
The boiler aquastat / high limit is no longer the 'boiler control'. The settings on these should be set high enough they do not interfere with the operation of the 256 control. Set the operator at least 25°F higher than the boiler design temp entered in the 256 control. and the high limit above that. This should allow the tekmar 256 to control the boiler and prevent it from tripping on high limit.

tekmar 260 with setback

@ May 14, 2010 5:57 PM in Tekmar 260 OTR Loooonnnng Recovery

Not sure if you are aware of the option to add an indoor sensor and setback to the 260 control. If you added the indoor sensor and then wired in a switch to the unoccupied Switch terminals the 260 control could do setback with indoor feedback. This can work really well to help eliminate the longer recovery times when trying to do outdoor reset.
The unoccupied switch could be a simple manual device or a timer. You just need a dry contact. When closed the control starts using a Room Unoccupied setting.
Now when the switch is opened in the morning the control goes from Unoccupied to Occupied. It would be seeing that the Indoor Sensor (room temp) was now  further away from the desired Room Occupied temperature. This causes the heating curve to shift up and the result is that the target temperature is boosted until the room temperature reaches the setting. Voila you have a faster recovery time.
The thermostats would be operating independently of this.

tekmar steam control and tech support email

@ May 14, 2010 5:19 PM in tekmar 269 question

First off for tekmar tech support you can email : customerservice@tekmarcontrols.com or call 250-545-7749.
 As for the steam control / indoor sensor question: If the indoor sensor sees the room temperature fall below the controls 'Room' setting it will cause the heating curve to be shifted up. In most cases this will cause an increase in the % on-time calculation.
As long as you are not in WWSD. 
The control will fire for a longer period in the heat cycle - phase2 . The greater the amount of error the more shift will occur. There is a limit on how much shift is allowed. Usually recommend a heat cycle length of about 60 minutes to give the reset a good opportunity to vary on times.

solar control

@ May 14, 2010 5:03 PM in Controls for solar hydronic, overheat and freeze protection

Yes you can, depending on your piping. You could use a tekmar 157 control to do variable speed through the panel to optimize output and then bring on a Heat Dump pump (piped in parallel) to operate when the tank and panel got too hot. This would be set up in a Mode 3 application.
There is optional freeze protection but should only be considered for locations where the outdoor air rarely falls below 35°F, otherwise consider glycol or drainback system.
Check out the Data Brochure D157 and the application brochure A157 for more information on this product. I believe A157 page 4 is  an example. www.tekmarcontrols.com
You would use standard wet rotor circulators for the two pumps.

361 mixing demand

@ December 23, 2009 2:45 PM in Mixing Demand on Tekmar 361

You state that: "The Tekmar indicated a mixing demand, which as far as I know should not happen when the room is already up to temp."  For most applications the demand should drop out when no zones are calling, so this may be a mechanical issue.
I am wondering what is providing the control with the mix demand. If you have zone valves with end switches or a pump relay end switch, then the end switches should open when the thermostat is satisifed and the control should shut down.
Try turning all your thermostats down and check the 361 LCD to see if the Mix demand pointer turned off. If not then check your end switches. Is there a zone valve that is sticking open? 

tekmar 274 boiler demand wiring

@ December 23, 2009 2:32 PM in applying 24v to Tekmar 274

To provide a 24V powered demand to the tekmar 274 do the following: Run two wires from your end switch (let's call it X1-X2) to the 274 enclosure. Connect one of these wires, let's say X2, to the 274 boiler demand terminal 22.  
Now run two wires from your 24V transformer R & C to the 274 enclosure. Connect the C wire to the 274 boiler demand terminal 21. Connect the R wire to your end switch X1 wire with a wire nut.
Now power the system and transformer up. You had it turned off right?:)
Now whenever the end switch closes the 274 boiler demand will be energized and the control will start targeting based on Outdoor Air temperature. The Application drawing A274-5 shows something similar.
The boiler T-T connections are wired to the tekmar boiler dry contacts. This should fire the boiler(s) when it closes. I hope this helps and have a Merry Christmas!

512 wiring

@ November 20, 2009 6:45 PM in 24V transformer

As already mentioned many jobs with 'bad' thermostats turn out to be a wiring problem. You did say your stat had already been opened. To test it and also to eliminate a bad wire between the stats and the mech. room try wiring the stats R & C terminals 1 & 2 directly to the transformer. If the screen powers up and looks ok then it is a wiring issue . If it doesn't power up then the stat must have been fried by the first guy that opened it.
If it powers up then look at your wiring and maybe try a continuity check on all your wires. Lastly these stats need a minimum of three wires. You say you have 24V R and C wired to terminals 1 & 2 and then jumpered the R from term 1 over to terminal 6, that's all good. Now make sure that term 5 (call for heat like a W wire)  is wired back to one side of the relay coil. As long as the other side of the coil is wired back to 24V C on the same transformer you should be good. The relay on the stat (and the external relay contact) should close when the stat calls, It shows an H1 icon on the LCD.
If you have a powered relay (T-T connections) then you need to wire up 5&6 to the T-T and wire 1&2 (R,C) to a transformer.
The thermostat uses about 2VA of power.  I have seen quite a few wiring problems on the neutral connection causing blank screens.

362 mixing return sensor only in Mode 2

@ October 26, 2009 1:52 PM in Tekmar 362 Mixing Return Sensor - Used in heat mode?

The Mixing Return sensor on a tekmar 362 is only used in Mode 2 for a snowmelting application. In this application it allows the control to provide a maximum Delta T between the Mix supply and the Mix return temperature to help reduce thermal stress on the snowmelt slab.
In Mode 1 for building heating a mix return sensor is not used.

tekmar 362 vs boiler aquastat

@ October 26, 2009 1:29 PM in Will differential of aquastat clash with Tekmar 362 differential function?

The 362 control can be set to operate two different ways. If you want it to control the boiler (with differential) then set it's boiler sensor = Supply. This is typical if the only load on the boiler is the mixing device. The 362 will now become the 'boiler operator'. Your boiler aquastats should be set up higher than any target the 362 would be trying to fire the boiler to. Usually 20°F higher should work. E.g. tekmar 362 target = 180°F then boiler Aquastat = 200°F and high limit to 220°F. In effect you have two high limits.
The other set up is to have the 362 just enable the boiler. This is typical if their are other loads on the boiler other than just the mixing. In this case set the 362 boiler sensor = Return. The 362 will now just hand off boiler operation to the existing boiler aquastats and they would be set normally. E.g. operator 180°F, high limit 210°F.   

floor heating temperature & control.

@ October 23, 2009 6:13 PM in slab in basement how long to heatup

First off your supply temp of 160°f is way too high for radiant floor heating. You will experience excessive temperature over / undershooting without providing a lower temperature. typical design is around 110-120°F. You should add a mixing / reset control that would allow you to operate at a lower temperature, do outdoor reset and still provide boiler protection (ie keep it from condensing).
Secondly you should also consider a proper radiant thermostat. These work on PWM (pulse width modulation) which provides nice long cycle lengths, e.g. 20 minutes, to reduce the short cycling you would get otherwise. tekmar control systems provides several products that should work with your system
By running at a lower temperature you will will have much less room temperature swing, reduced cycling and probably better efficiency as well. Let's see... improved comfort, lower energy use, reduced wear & tear....not bad.
Your concern about how fast the slab should warm up is moot when you control radiant properly because you are actually trying to maintain the room temperature with a fairly constant slab temperature with constant circulation.

Piping comments

@ October 23, 2009 4:20 PM in Piping schematic

a few comments / ideas about your proposed piping:
 1- You show your heating zones piped in primary-secondary which means that each one will be supplied with a progressively lower temperature (if all running). I would suggest piping them in parallel so they each get the same supply temp. each with a check valve and that also allows you to eliminate the extra loop pump.
2 - you have your boiler pump in the wrong location, you should locate it just past your air separator before the DHW tees.
3- your heat exchanger tees on the boiler loop should be placed right close together to eliminate the chance of the boiler pump forcing flow through the Hx.

There are of course other ways to do it. E.g. Zone valves instead of zone pumps. etc.

piping/control clarification

@ July 1, 2009 1:21 PM in Best Efficiency: Multiple Condensing Boilers

Fixitman, Your points are well taken. Here are my thoughts to your reply, for what they are worth... Points: 3,4,5,6 - I agree, if your DDC has a method of tracking the worst zone requirement, that is better than straight outdoor reset which may or may not be dialed in perfectly. I often add an Indoor Sensor to the control to provide 'indoor feedback'. This allows the reset to be further modified by the building temperature and how far away it is from setpoint to provide the perfect supply temperature. This sounds similar to what you're doing. I agree it is best to try and use an interrupted demand, so the control only fires if at least one zone is calling. This is definitely the preferred method to reduce costs of heating the water and also pumping it. This interrupted demand is usually provided by end switches wired in parallel to the control demand. For even better operation the operation of the zones can be 'Synchronized' which eliminates the random calls from various zones. By synchronizing the calls you can dramatically reduced boiler short-cycling which increases efficiency and reduces wear and tear on the boilers. The other thing I might add here is that in some larger buildings with long runs and large mass the wait time for heat with interrupted demand can be too long. This of course is mitigated by the fact we are running hopefully at the lowest possible temperature. In this case the coldest zones should be calling pretty much all the time. Unfortunately in many buildings the end switches and wiring are not available for an interrupted demand, especially in retro-fits, so you are forced to go with a permanent demand. You can still provide a warm weather shut down which can help quite a bit. 1. Perhaps my piping explanation lacked some clarity. The method I described was not to pipe each boiler primary-secondary individually into the main loop. In this case you are absolutely correct to point out that the boilers then get a progressively hotter return temperature which reduces condensing benefits. The method I described (or tried to!) is parallel primary-secondary. That is, all boilers are piped in parallel to each other with their own pumps. The supply and return manifold serving all these boilers is then piped into the main loop, ala primary-secondary. There is only one set of pri-sec tees tapped into the main loop. This provides the hydraulic isolation between the main loop and the boilers and allows each boiler to get the same return temperature water. Hope my ramblings make better sense this time.