Boiler Short Cycling

Reply

  #1  
Old 12-22-13, 12:18 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Boiler Short Cycling

Ok...let me first start off by saying I'm just a typical layperson who knows her boiler is driving her nuts and is trying to find a solution. So please bear with me and I will try to give you as much info as I can so you can help diagnose.

Our home is a 1,400 square foot 1960's ranch. We have reinsulated the home and have done what we can to make it energy efficient. We have a fairly new heating system - a Buderus G115WS/4 with a 40 gallon Amtrol Indirect. The house has four zones and I am pretty sure the boiler is oversized (plumber never did a heat loss - - I wish I knew then what I know now!) because it is cycling weird. The first plumber that installed the system installed a Beckett AquaSmart 7600 with it. Unfortunately, he didn't know how to program it correctly so we needed to find another plumber. Well, that plumber came in and immediately recognized it was not programmed correctly so he changed the settings accordingly. He then said that he preferred to use Outdoor Reset for better savings (namely the Tekmar 260). Long story short, we felt pretty confident with him...until he installed it and left us with the factory settings and was insistent that they didn't need to be changed. Needless to say, we needed to find another plumber who was familiar with ODR settings. So the latest plumber discovered that the previous plumber never changed the AquaSmart settings when he set up the Tekmar so the two were conflicting with each other (at this point, my husband and I are pulling our hair out!). He said the AquaSmart should be set up as a basic "dummy switch" and he also said the programming on the Tekmar needed to be adjusted because our system could be set up as a cold start. These are the settings he programmed (I took notes while he did this).

On the AquaSmart:
Hi Limit 190
Hi Limit Diff 20
Low Limit Off
Low Limit Diff 20

On the Tekmar 260 (we don't use an indoor sensor - just regular thermostats and we do not use setback):

Room Occ 68
Room UnOcc 65
Design Temp 0 (we live in VT)
Terminal Unit 4 (we have copper baseboard with fins)
Design Indoor Air Temp 70
Design Supply Water Temp 180
Boiler Max 190
Boiler Min 120
Time Delay 10 seconds
Differential Adj
WWSD Occ 65
WWSD UnOcc 65

He said that these settings can be tweaked accordingly but he didn't perform any type of heat loss.

Before I call him back, I just wanted to run it by you folks in the forum to see if you had any suggestions. Our problem is...the boiler seems to short cycle, especially when only one zone calls. On certain calls, I hear the circulator start and run for awhile...then I will hear the boiler come on for a little while (about two minutes or so)...then I will hear the circulator again. Sometimes at that point, the thermostat is satisified and the circ will shut off. Other times, the circ will keep running and the boiler will fire up a second time and only for a few seconds (!) and then shut down. Is this what they refer to as bouncing off the high limit?

In any event, I just wanted to get some opinions on the settings and see if there is any way I can improve cycle times. First off, do these settings between the AquaSmart and the Tekmar seem set up properly so they aren't conflicting with each other? Do you have any suggestions for adjustments to the Tekmar settings which will improve the length of cycle times? Should I try a fixed differential maybe or should I look at changing boiler max or min temps? I am wondering if the boiler is cold start, why did he use a 120 minimum boiler temp as opposed to just setting it to OFF on the Tekmar? Also, he did not set our system up with the indirect on Priority (said there was no need). We always have enough hot water and temps feel pretty good/consistent in the home (never too hot or never too cold). I know from reading on this website, though, that these short cycles and numerous boiler firings are not efficient. We have two small zones on the top floor so another thought I had was maybe combine them into one and this would cure the cycling when just one zone calls. Sometimes its crazy - I will hear one zone call then do its thing. Not a minute later, another zone is calling...etc.,. Maybe too many zones for this tiny home. I just feel at this point the outdoor reset was a mistake..but I want to try different settings before I rip it out and just use the AquaSmart!

Any suggestions would be most appreciated and THANK YOU so much!
 
Sponsored Links
  #2  
Old 12-22-13, 01:07 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
Im not sure why your not using the ODR with the tekmar...

But I dont think you are to use both... You need to disable one of them...

The tekmar will give you more options...

If you just used the aquasmart to reduce short cycling just set the hi diff at a wider #... The hi should be 180F.. Yes LL off is correct and it should be set for indirect priority...

Now if you are just going to use the tekmar, ODR may be the better choice IMO... But how many indoor sensors are there?
 
  #3  
Old 12-22-13, 01:10 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
AquaSmart should be set up as a basic "dummy switch"
Probably just used as say a additional high limit only... It should not fire the boiler if using the tekmar......

You have zone valves or circs?
 
  #4  
Old 12-22-13, 01:12 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
should be set for indirect priority
If the boiler is truly oversized, then I don't think the indirect priority is an issue. There's probably plenty of 'reserve' in the boiler to heat the home and the indirect at the same time.

I need to cogitate on your info for a while Vic.
 
  #5  
Old 12-22-13, 01:15 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
I do not have any indoor sensors (plumber said just use regular thermostats, of which we have three).

Aquasmart came with the Buderus on the inital set-up. When the other plumber came out to install the Tekmar he reprogrammed the AquaSmart and said he was going to make it a "dummy switch" but that the Tekmar would control everything. Could there be a conflict of some kind going on between the two of them in the way they are programmed??? Are you saying it should be one or the other...either the AquaSmart or the Tekmar..but not both?

We have circulators....
 
  #6  
Old 12-22-13, 01:18 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
Here is the tekmar manual...

http://tekmarcontrols.com/images/_li...e/260_d_06.pdf


Could there be a conflict of some kind going on between the two of them in the way they are programmed??? Are you saying it should be one or the other...either the Aquastat or the Tekmar..but not both?
Yes... Dont know how he wired the aquasmart to make it a dummy switch..

1. Do you have the ODR sensor installed?
2. What type of heat emitters in the home?
3. Zones valves or circ pumps?

Take a pic inside the aqua smart so we can see how its wired....
 
  #7  
Old 12-22-13, 01:36 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
lawrosa, I'm a novice with this stuff so please bear with me.

There is a sensor on the supply side close to the boiler - it has grey foam insulation around it. The temp on the boiler gauge matches up to the boiler temp indicated on the Tekmar. We have baseboard - copper with fins around it - throughout the home. There are four circulators (one for the kitchen/living room/bathroom zone, one for the bedroom(s) zone, one for the basement zone and one for the indirect). We use oil fuel.

I'll have to get pics when I have a camera available (I'm old school when it comes to that stuff). I'm hoping it is wired properly... and it is the settings that aren't optimal. Plumber did mention the AquaSmart was going to be a secondary high limit - - and from what I can tell from the cycles, the boiler only comes on when the Tekmar tells it to.
 
  #8  
Old 12-22-13, 01:38 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Dont know how he wired the aquasmart to make it a dummy switch..
Not wiring, pushbutton settings:

Go into the "OPTION" menu on the AquaSmart.

Go to "Heat Manager Menu"

What is "ECONOMIZER" set to? ON?

Turn "ECONOMIZER" to "OFF" if it is not already.

for starters... you don't want the economizer running with the 260 connected.
 
  #9  
Old 12-22-13, 01:42 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Hi NJ Trooper:

The Economizer is already set to OFF and so is the DHWP setting.
 
  #10  
Old 12-22-13, 01:43 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Vic,

Economizer off, check.

Would it be possible to describe how the 260 is wired into the system?
 
  #11  
Old 12-22-13, 01:49 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
I am going to have my husband help me get some pics. In general, there is a TACO SR504 box, above it sits the Aquasmart and next to that is the 260.

Let me try to get you pics. Can you give me a link as to instructions that show me how to upload them so you can see them?
 
  #12  
Old 12-22-13, 01:50 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
Should help....


Name:  tekmar 2.jpg
Views: 1331
Size:  40.2 KB


Name:  tekmar.jpg
Views: 1263
Size:  24.4 KB
 
  #13  
Old 12-22-13, 01:59 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Let me try to get you pics
Pictures are generally not very helpful when it comes to wiring. It's nearly impossible to trace the wiring from a photo.

Let's do it this way... in the 260 first:

Terminals 1 & 2 are the 'boiler demand'. Where do they go?

Terminals 3 & 4 are the 'indirect demand'. Where do they go?

Is there anything wired to 7 & 8 ?

Anything on 9 & 10 ?

Where do 11 & 12 go ?
 
  #14  
Old 12-22-13, 02:04 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
Name:  tek 3.jpg
Views: 828
Size:  30.2 KB



-------------------------------------------------------------------
 
  #15  
Old 12-22-13, 02:05 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
On the 504 panel:

Depending on the age of yours, the 'endswitch' is either at the lower left, or in the top row to the left of the thermostat connections.

It will be labeled ... " X X " or " ENDSWITCH " or combinations or variations of these.

Where do those wires go ?
 
  #16  
Old 12-22-13, 02:07 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Pic

Just to give you a general idea of how it looks...
 
Attached Images  
  #17  
Old 12-22-13, 02:09 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
In the AquaSmart:

Terminals labeled " TW " and " TR "

Where do they go?

I realize that we may be looking at both ends of the same wires when I'm asking these questions... just so you don't get confused...

for example, you may tell me that the 260 11&12 are going to the AquaSmart TW & TR.

and vice versa for the above question...

That's fine, and sorry for the redundancy, just need to know how it's wired up.
 
  #18  
Old 12-22-13, 02:14 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
NJ Trooper:

Let me try to get these answers to you - it make take some time. I am feeling very overwhelmed by all this!!! You are guys are experts at this stuff and I know nothing. I was so hoping it was just the settings that were off - - but now I have a feeling that it may be way more complicated than that!
 
  #19  
Old 12-22-13, 02:14 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
By the way, I intend to go back to your first post and address some of your questions, but let's continue the line we're on now so as not to get pulled in too many directions at one time.
 
  #20  
Old 12-22-13, 02:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
I was so hoping it was just the settings that were off - - but now I have a feeling that it may be way more complicated than that!
No... don't get overwhelmed!

You are guys are experts at this stuff and I know nothing.
But my senses tell me that you are capable of comprehending... it will all come clear in the end, I promise!

All these questions because the first thing we need to do is determine if the stuff is installed properly.

Then we'll get back to the settings... which by the way from what I can see are not too bad, nothing glaring jumps out at me. Maybe just one, but let's continue forward before we get back to that.
 
  #21  
Old 12-22-13, 02:21 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,722
Likes Received: 2
You need to take the covers off the tekmar and taco to answer these questions....

Warning High voltage under there so just look dont touch....
 
  #22  
Old 12-22-13, 02:28 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Wiring

You guys - I am WAY out of my league here!! Can you get anything out of this pic??? Or is this a mangled mess??? I want to put the cover back on and hide - - SERIOUSLY!
 
Attached Images  
  #23  
Old 12-22-13, 02:56 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Can you get anything out of this pic?
No... not really... but there is something a little bit disturbing to me...

That wire nut on the right side... the one with the WHITE and GREEN wire connected together...

That is just SO WRONG. The NEUTRAL (WHITE) must NEVER be connected to GROUND (GREEN). I can't imagine what would possess someone to do that?! Even if the wires are not used, not connected at the other end either, they should have used TWO INDIVIDUAL wire nuts.

Tell me, was this system inspected after it was installed? Were permits pulled previous to the work?

I want to put the cover back on and hide - - SERIOUSLY!
If you feel out of your comfort zone, then do exactly that. Take a nice bottle of red with you when you hide! It really helps!
 
  #24  
Old 12-22-13, 03:03 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
NJ Trooper:

I take it I should get the plumber back here to relook at this whole thing immediately, which is what I will do. This is so out of my comfort zone it isn't funny. This plumber that programmed the Tekmar did not look at the wiring...he just reprogrammed the settings (he probably assumed the original plumber was competent enough to at least wire the unit properly). It was another plumber that initially installed it (the one that left us with the factory default settings). I will have the plumber who programmed it come back and recheck all the wiring.

Is there anything else I should ask him to do? Or just have him check all wiring?
 
  #25  
Old 12-22-13, 03:07 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Additionally, the installer shows a complete disregard for this from the manual:

Before removing the knockouts, check the wiring diagram and select those sections of the chamber with common voltages. Do not allow the wiring to cross between sections, as the wires will interfere with safety dividers which should be installed at a later time.
Then finally:

Install the supplied safety dividers between the unpowered sensor inputs, and the powered or 24 V (ac) wiring chambers.
In my opinion... and keep in mind that I am an absolute fanatic with OCD for proper wiring practices, the whole thing needs to be redone. If it were me/mine, every wire would be pulled and installed properly in a workmanlike manner.

I have little doubt that your guy will not agree with me, and will say, "naaahhhh, as long as it works"...

But please, for safety sake at the very least, ask him to investigate why a neutral and a ground are connected together in a wire nut. I'm telling you that if permits had been pulled and this installation inspected, that would not have passed.
 
  #26  
Old 12-22-13, 03:09 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Aquasmart

Not sure if you can tell much from this pic...but if anything looks crazy, please let me know...
 
Attached Images  
  #27  
Old 12-22-13, 03:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
if anything looks crazy, please let me know
Are those green wires connected to the ground terminal, or just hanging around in the box?
 
  #28  
Old 12-22-13, 03:26 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
The pea green colored wire on the left is just hanging in there - - but the green wire on the bottom is connected to the ground terminal.
 
  #29  
Old 12-22-13, 03:28 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Other times, the circ will keep running and the boiler will fire up a second time and only for a few seconds (!) and then shut down. Is this what they refer to as bouncing off the high limit?
Could be. In order to know for sure one would have to observe the controls and temperatures as it occurred to determine for certain.

First off, do these settings between the AquaSmart and the Tekmar seem set up properly so they aren't conflicting with each other?
I think that Mike already answered this, but yes, the potential is there for this to happen. With the economizer turned OFF, I don't think there should be an issue.

Do you have any suggestions for adjustments to the Tekmar settings which will improve the length of cycle times? Should I try a fixed differential maybe or should I look at changing boiler max or min temps?
I would increase the BOIL MIN to 140F myself, maybe even 145-150. I feel that 120 is too low... it means that the Tekmar can 'target' a temperature that in my opinion could lead to problems down the road. Before making a final determination on this, more information would need to be known... specifically the average temperature of the cooler water that returns to the boiler from the zones.

I am wondering if the boiler is cold start, why did he use a 120 minimum boiler temp as opposed to just setting it to OFF on the Tekmar?
Because this is the lowest temperature that he felt was appropriate for the system to 'target' as an operating temperature, which as you now know, is too low in my opinion.

Maybe too many zones for this tiny home
Maybe... probably? It gets into the area that we refer to as 'micro-zoning'. It's usually not advisable. The tiny load that the small zones put on the boiler is satisfied too quickly to get decent length run times out of.
 
  #30  
Old 12-22-13, 03:32 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
The pea green colored wire on the left is just hanging in there
The Tekmar has no ground terminal... and that same wire appears to be disconnected then on both ends. Not sure what to say about that... but I would have connected the end in the Aquasmart to the ground terminal even if it was open on the other end. And I would have put a green wire nut on it so it couldn't short out to something else.

Do you have a pic of the Taco panel interior?
 
  #31  
Old 12-22-13, 03:49 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
I will adjust the BOIL MIN to 145 and see how the cycles time out. Would you suggest leaving the differential on adjustable at this point? Or might a fixed differential work better?

I will definitely get the plumber over here to relook at everything. NJ Trooper, could I ask you what is involved if I wanted to convert the two smaller zones into one to get rid of the "micro-zoning"? Is that a complicated procedure or can a plumber do that fairly easily?
 
  #32  
Old 12-22-13, 04:24 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Would you suggest leaving the differential on adjustable at this point? Or might a fixed differential work better?
That's going to require some experimenting.

Fixed Differential
The boiler differential is divided around the BOIL TARGET temperature.
The contact will close when the supply water temperature is 1/2 of
the differential setting below the BOIL TARGET temperature, and will
open when the supply water temperature is 1/2 of the differential setting
above the BOIL TARGET temperature
Auto Differential (Ad)
If the Auto Differential is selected, the 260 automatically determines
the best differential as the load changes. This setting is recommended
as it reduces potential short cycling during light loads.
When in AUTO DIFF, the control _should_ learn, given time, the most appropriate setting. Whether or not the algorithm it uses is a good one or not, who knows? Given your experience, I would tend to say 'not so good'.

I myself would try a FIXED DIFF of 20F to start with and see how that goes.
 
  #33  
Old 12-22-13, 04:30 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
could I ask you what is involved if I wanted to convert the two smaller zones into one to get rid of the "micro-zoning"? Is that a complicated procedure or can a plumber do that fairly easily?
To actually physically combine two pumped zones into one could be a bit costly because it would mean piping changes.

How 'separate' are the two zones? Are there closed doors between them? Where are the thermostats located in relation to each other?

What I'm driving at here is to try and find out if one (or the other) thermostat would be able to comfortably control the temperature in both zones.

To 'logically' connect the two zones together might be a less costly approach, but the wiring has to be done properly.

To give me some food for thought, tell me what model circulator pumps are being used? (I need to look up the amperage draw on the pumps)
 
  #34  
Old 12-22-13, 04:33 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
I would like to see the inside of the Taco panel if not too much trouble...
 
  #35  
Old 12-22-13, 04:48 PM
Member
Join Date: Oct 2011
Location: canada
Posts: 568
short cycles

The design supply water temperature 180f , assumes that on the coldest day 180f water would have to circulate through the rads all day 24 hrs. to put enough btus into the room to keep the room at 70f and since this is not likely the case it can put you on the wrong heating curve and higher water temperature than would be required ,resulting in short cycling of burner. The RTU. is the answer to finding the proper heating curve or set thermostats above desired room temperature and adjust design water temperature to find where the water temperature will keep room at comfort level , this takes time and patience.
 
  #36  
Old 12-22-13, 05:20 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
The circs are Taco model 007-F5-71FC and it says HP 1/25 AMP .71 HZ 60 volts 115 RPM 3250.

Both zones are on the upper floor and there are closed doors between them. The thermostats are less than 25 feet apart. I have read that Tekmar makes thermostats that do zone synchronization or something to that effect but I imagine they are costly. I'd rather not get into costly piping changes either if I can help it.

I'll try to get you a pic of the inside of the Taco box - - and thanks again for being patient and not making me feel ridiculously stupid!
 
  #37  
Old 12-22-13, 05:29 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
TACO Wiring

Let me guess....some more nightmare wiring....
 
Attached Images  
  #38  
Old 12-22-13, 06:00 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
OK........................ now I'm completely puzzled.

On the bottom terminal strip...

I see black and white on the ZONE 1 terminals.

I see NOTHING on the ZONE 2 terminals. (unless a wire is hiding in the shadow behind that green wire)

I see a BLUE wire on the "H" terminal of ZONE 3.

Yet, it appears that there are thermostat wires on all three zones on the top strip.

Puzzled indeed.

How is this even working like this?

I'm going to have to ask you more questions now ya know...

How many pumps are on your system?

Can you tell me where the wires from each pump are going? If not to the PUMP SWITCH PANEL, then WHERE?

Looking at the 260 panel, it's possible (and likely) that the pump for the water heater is wired there, to terminals 9 & 10, but you have three other pumps, don't you?
 
  #39  
Old 12-22-13, 06:23 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Pic

NJ Trooper - I am so confused I can't even tell what goes where anymore. I am going to have wiring nightmares tonight - I can see it now - - I am entangled in a massive amount of wires that keep tightening around me....

Does this pic help with anything? Or just more of a mess?

What I am getting from all of this - - get a plumber here asap and have him rewire. What a wonderful Christmas I am going to have....NOT.
 
Attached Images  
  #40  
Old 12-22-13, 06:30 PM
Member
Thread Starter
Join Date: Dec 2013
Posts: 24
Another Pic

Not sure if this helps or not
 
Attached Images  
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes