Tekmar 360 and Erie AT33A00T

Sparky_RI · January 9

Hello There,
I am an electrician but limited in functional control experience. I have a 9 zone radiant system in my own home. Boderus boiler. I changed the controller several years ago when the existing one died. I put in the Tekmar 360. I also needed to change to a float modulator and used Eire AT33A00T. Has worked well since install until this season. I find my available hot water at the feed side of the Eire modulator is sufficient however the mix temp tends to be 15-30 degrees low to mix target 12" away from the modulator after the circ, (which appears to be working fine). The valve is randomly floating however when the mix temp is low, the valve seems to be closed more often than floating open. When I hit the test button the valve cycles open and closed and matches the LCD command screen. After the test, the mix temp is good. over a short time... it gets further away from the target. The LCD screen has "mix demand" on all that time however neither open or closed is on much of the time during mix demand. I would think the open command would be on if the mix target is not met. The boiler pretty much is running on high limit I presume whereas the burner icon is on but the boiler does not run at that time. I think it is telling the boiler to run whereas the mix is not met however the hot water is there, just not getting through. Any thoughts would be great.

hot_rod · January 10

Maybe that mix sensor is out of tolerance. The manual should have a chart to check ohm reading at various known temperature.

Is the sensor into a well in the pipe or strapped on?

Typically we use ice water and boiling water to test both ends of a range. The sensor strapped to a metal can or pipe if it is not a underwater type sensor

Sparky_RI · January 10

Thx for the reply! The sensor is strapped on. I have attached some pics. There is a pipe loop that mixes the feed and return, one with a valve cracked half open. The boiler sensor is on the return, in the pictures the armorflex insulation by the temp gauge is the mix sensor. I also checked all of this with a point radiometer and a infrared attachment for my phone. One item I think may play into this is the boiler min setting. That I am unsure of completely. I noticed the LCD showed Boil Min around 120 and right after that it was at 156 and the "min" disappeared. I also notice when it is warmer out, the delta is down to 3 or 4 degrees between mix and target. It seems the sensors are doing their thing whereas it is only the mix matching the target that is the issue. If the sensor was inaccurate, I would think it would be saying it matched but was still not to temp. The IR seems to verify that. You are the expert, certainly not me so I am definitely listening.

hot_rod · January 10

Great job on the documentation! More installers need to provide that.

The sensor installation looks good, far enough away and insulated.

If the sensor ohms out, I would suspect the control, again.

Where are you located. I've found the local tekmar reps are usually very well trained to support tech questions.

Or try tekmar directly.

https://www.watts.com/our-story/brands/tekmar/contact-tekmar

Sparky_RI · January 10

I am in RI. I have no issue having someone come out but seems that I am the one that resolves issues when I am paying someone who is standing next to me

I will look for the sensor value. I can love with it that way it is rather than replace the control but let me see if I can figure it out. Thanks for the help, I will also call Tekmar, they where helpful when I installed originally.

Sparky_RI · January 10

1 last question.. I cannot be certain the sensors are Tekmar whereas this was a replacement controller I installed years ago. Whereas we are talking about resistance, I would presume that whatever sensor brand is installed, the resistance value should match the chart for the Tekmar 071 sensor (found the chart on-line

hot_rod · January 10

I think the 071!is a universal sensor across the line. I think it needs to be that exact sensor

It seems like you have the skills to troubleshoot this, maybe face time a tekmar person when you are in front of it

dko · January 10

The Tekmar 360 comes with an outdoor sensor and two Tekmar 082's. Do you recall using the sensors that came with the control? Attached 082 specs

edit: Seems only difference between 071 and 082 is the length of the cable.

Sparky_RI · January 18

Thanks for the replies! I thought I would get a notification via email so I apologize for not seeing this sooner. So the sensors are working fine. I confirmed the temp on the 360 matches within a degree with my point radiometer and emissivity correction on both mix and return sensors. I did speak with Tekmar, they believe it is boiler protection happening (I was unfamiliar with this feature). I opened the ball valve (crappy drawing attached) open a bit more which increased the return temperature and that seemed to help. Prior to that the return temp was varying quickly from 85 degrees to 150 degrees. I am unsure why this is happening now but if you could look at the attached and my information here and make any suggestions, it would be great. I still have the burner relay icon present on the 360 screen, I still need to do some more investigation if that is just due to zones calling and mix temp not achieved..

hot_rod · January 18

What type of radiant. Do you have high mass concrete slabs, medium mass thin pour concrete, or low mass a dry system with aluminum transfer plates below the floor. maybe a combination of?

The mass of the system has a lot to do with how those bypass valve protection methods work, or don't work.

For example the system calls for heat, maybe 75- 80° water temperature comes to back the boiler. On a good day at full load, maybe the boiler can raise that temperature 10- 15 ° as it passes through the boiler. Depends on how many zones are calling and the mass involved.

Now you have maybe 90- 95° water coming out of the boiler.

What % would that valve need to be set to to get 130° return to the boiler? How does 95° water added to 75° water add up to 130°?

So ideally you want to shut off flow to the system, get 100% of the boiler output right back to the return of the boiler. In 10- 15 minutes, maybe less the boiler is now operating out of condensing mode. At this point some, maybe most of the flow out of the boiler can go to the system. It depends on the load again.

So the return protection device (bypass valve) really needs to be able to know and adjust to the ever-changing return temperature.
If you want absolute protection.

The adjustment you recently made works for that one exact condition, only. I'll bet it needs a different adjustment today.

Sparky_RI · January 19

Hello, The system is 8 zones, poured concrete 1.5" over foil bubble insulation on top of plywood. I have to get in to check the min. All seems correct today but I only have a few zones calling whereas I have the mini-splits handling most of the heat right now. Today the "min" was showing on the boiler mode screen however the temp was 165 F. I believe that means I am below the min and therefor that may need to be adjusted down to 140 F. I am at a loss how this has worked for years if that is the case. The temps leaving the zone valves have always been 110 or less, usually much less. Not sure how it was ever keeping above the boiler min whereas the ball valve in the loop has never been moved. Thank you again for your continued advice!

Sparky_RI · January 28

Good Afternoon! I still am having the boiler protection issue. Return temp at boiler dropping below min on a regular basis and keeping the float valve closed. Is there a reason why I could not put a simple pipe with a valve between the feed and return at the boiler with an aquastat on on the return where the sensor for the 360 is? The boiler is always going off at hi limit due to the mix target not being satisfied. I never paid much attention to this so it is possible it was always this way from the day they set it up. The only change in the system was a change out of the water storage tank. I checked and it is installed correctly but perhaps more elbows or smaller tank was enough to change the volume... not sure. Just trying to get it fixed up. Please advise.

Thx!!

hot_rod · January 29

The Erie valve should modulate to provide the mix temperature required. Or if the return drops it should also modulate to allow sufficient flow to raise the return temperature to the boiler by closing down flow to the manifolds
So the supply to the manifolds will vary as it protects the boiler

Dud you go over the setting with tekmar?

Any strainers in the system that could limit boiler flow
It sounds like the boiler is not keeping up with the load?

Sparky_RI · January 29

Hey Hot Rod, You are correct, that is what is happening. There is sufficient heated water at feed of mod valve but whereas the return boiler min is often not satisfied, the mod valve closes and does not allow the mix target to be satisfied. At the same time the boiler has gone to hi-limit around 175 f. I appears the available hot water is sufficient and the boiler can keep up (always has) it is only the fact the valve is closed for boiler protection. I did speak with Tekmar and they had suggested everything I just said. If I turn the boiler min to say 80 F, the issues goes away but of course another is created. Circs are all working so I am not sure why this is now happening or did I just notice it dues to a lengthy cold snap (longer then normal). I figure if I can get the supply water back to the return quicker to satisfy boiler min at 140 F, then I can keep the valve working properly my issue will be solved. Right now, it is a ball valve in the loop on the manifold board about 20' of supply away and 20' of return. I was figuring a simple electric solenoid type valve. or something similar, between supply and return at the boiler, controlled by aquastat, might be all I need. You are the expert, not me so I am hoping you can let me know if this is a normal solution or if there is a better way. Thx for any advise you can give me
Joe

hot_rod · January 29

Well the heat emitters connected to the boiler will try to control its operating condition, temperature. If the boiler hits its high setting and the system is underperforming on cold days? It sound like the piping or pumping. What is the cv of the Erie valve?

Is there any place you could have some blockage, y strainer or even air separators get partially plugged

Sparky_RI · January 30

I don't know the cv of the valve.. not even really sure of the question

I don think there could any blockage whereas I have sufficient heat at the feed side f the valve and there is nothing on the return to get blocked. The spirovent is on the supply but I don't think there is any issue getting the heated water to the valve, just the valve shitting from boiler protection.

hot_rod · January 30

That type of boiler and valve have low pressure drop, so any of the small 3 speed circs should be fine.
Looks like you have some zoned with valves, and the manifold with actuators?
A delta P circ works well with zoned systems, it will increase and decrease output as zones open and close.

The valve, as you know has a floating control, it is not an open or close type valve. So the position of the valve is based on what the tekmar tells it is required.

Is the outdoor reset function being used, that can sometimes limit the SWT to the system.

With a medium mass concrete system like that, when a zone opens it sends cool return back to the boiler. The sensor will see this and limit the temperature to the system to allow the boiler temperature to increase. So it is a Peter or Paul situation. The tekmar decides which sensor to respond to and modulates the valve accordingly.

If you are observing a low SWT it could be at the point a cold zone or two have just opened.
It takes some time sitting in front of the control watching or measuring temperatures to see what needs to be adjusted.

Sparky_RI · January 31

Hi there,
All the ball valves are service vales with the exception of the one in the return loop at the mod valve. I think the circs are just 007 types, need a mirror to see. I think where I get confused is the return loop. I understand there is a low temp coming back from the zones and there always will be. That will never be over 80 or 90 I would think whereas the max target I have seen is about 115. But that loop should be allowing enough hot water back to keep the boiler min up. I wish I was certain it ever worked properly and not having be boiler at 175 constantly. It would be easier to diagnose If I was sure it was right from day one. Now that the outside temp has come up, it is keeping up on all zones however the boiler is still going to high limit and the burner icon is on at any time any zone is calling but the boiler does not run much of the time whereas it has reached the high limit. I had checked the circs with a stethoscope (pipe in my ear) whereas I could not find my spinner. New one just came in and I will double check but they were all hot and sounded fine. I will check the outside reset function. I believe you are saying it should not be on?
Thanks for the help again

hot_rod · January 31

You would need more data to get an exact answer. Ideally the heat load calculation would indicate the required boiler output.
A radiant design would tell you what flow rate and gpm each zone requires. With that info you size the mix valve and the circulators. Manifolds allow fine balance/ tuning. Without that info it will be some trial and error to get it set to you needs and liking.

The difference between supply and return is referred to as delta T, ∆T
When you do a design you indicate a desired delta. The system delta will change a bit depending on the load of the room or zone. When you first start a zone the delta will be wide, could be 20 or more. As the floor or room warms the delta will tighten, the load is getting satisfied. Radiant designers shoot for a 10- 15 delta for radiant floor loops.

At some point the loop or zone will reach thermal equilibrium. Supply and return are stable and not moving up or down. You may need to sit and watch for some time to get all the info from 9 zones

So it depends on when you are observing the delta.

Bottom line is it heating adequately and comfortably. Is the boiler return getting above 120 or so when it shuts down?

Some boilers have outdoor reset control and the tekmar does also. I would use the tekmar ODR, takes some time to get it adjusted. What it will do is vary the supply temperature based on outdoor temperature. The goal would be to keep the zones running as much as possible, very few on off cycles. The mix valve adjusts the supply temperature to the exact need at any point. This provides the efficiency, best comfort, and would reduce the on off cycles.

Probably the boiler is over sized for the heat load. So expect it to turn off on its operating control from time to time on design days and any days warmer than design.

Are you familiar with the control settings, enough to check or adjust them. It really takes some owner input to dial in a control like that. IF you are trying to maximize its features and benefits.

Sparky_RI · February 18

I think I have it figured out... and feel a bit silly. I have 2) 007-f5 in the system. One on the boiler supply (loop) and one on the other side of the mod valve. I originally tested both with a caveman piece of tubing to my ear and they both sounded smooth and comparable. Hearing minor air in system, I was sure I had circulation....and I do, but I think only 50%. This boiler protection issue though has seemed bizarre. This AM, being 15 degrees outside, the boiler return temp was down around 100 and not coming up anytime soon. I took amp readings on both circs and IR temps corrected with proper emissivity. The boiler supply pump running at about 1.3 a (.71 nameplate) and the body temp 240 F. The one on the zone valve side of the mod valve is running at .6 and 145 f. Seems cut and dried to me. So, an new 007 is on its way. I am fairly certain that will solve the issue getting the hot water back to the return. I again thank you for your help and hopefully you wont hear from me for a while

Tekmar 360 and Erie AT33A00T

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