Tekmar d360 controller and mix valve control

hydronicsmike

...why don't you call me?

tekmar Tech Support at 250-545-7749, Ext. 214.

Mike

Brian Rosa

Tekmar Valve Controller (D360 and Mix Valve)

Lightning struck a tree last spring and fried my Tekmar 360 controller on my heating system. I had the unit replaced but never had to use it regularly until recently. The previous controller was set so it would heat my home evenly. Once I figured out the Heat Curve settings, I had no problems. The new valve controller has been set up with similar settings. However, it will only heat the home in spurts. I have the controller set such that the target heating temperature for the mixing zone is quite high. The controller will open the valve and close it to achieve the temperature. But then it quits heating the mixing zone. The control valve will not open, even though there is a mix demand. It continues to run and heat the boiler and its' zone, but not the mixing zone. What can I do to make it heat to the target temperature until the home is warm?

The settings are very similar to the default settings for the high mass radiant system. I have a boiler sensor on the return. The dip sticks are set for advanced, 10% enable, and Return. Thanks.

Adam_12

Check your return temps after the the mixing valve.The four way may be doing its job of protecting the boiler from a cooler return Temps{>130-135 degrees}.Was the actuator replaced besides the controller ? .Review your wiring and sensor placement,everything okay?.

Adam_12

Checkout page 9 of your manual ,what type of boiler do you have ,high mass ,low mass?.Your probably going to kick yourself when you find out whats wrong.I know this from personal expierience.

Brian Rosa

Wiring and Boiler Sensor

I did inspect the wiring, though I am no electrician. It looked like everything was connected the way it is shown in the manual. No wires were obviously out of place and they matched up with the cable that ran to the right place.

The boiler sensor is connected to the return (right before the water enters the boiler). I noticed in the manual that it may be located on the supply side if the boiler is the only being controlled by that single controller, which it is. Would this help out?

When we first had to use this system this year after switching out the controller (the mix valve was not changed), it did not work so well. I had experienced this before when we first got the system, so I went to the controller and changed some settings. The only way I could get it to heat well was to put the OUTDR DSGN at a fairly high temp and put the MIX INDR at a fairly low temp. In my mind, it made the heating curve have a larger slope, and therefore heated the house up faster. This last week, we have experienced our first temperatures outside that are below freezing. My OUTDR DSGN temp was set at 25 F, so I thought this might be the problem. Any thoughts on how to set up the curve?

I am fairly sure the system is a high mass radiant. That was something I considered, but it still exhibited the same response to mixing when I switched it. It seems the problem is with it mixing to heat the zones sufficiently. I don't want to damage my boiler by returning cold water to it as that is the reason we bought this new system. It just seems to shut off mixing until the boiler kicks in. How can I make it heat the boiler/boiler loop and still mix with the house loop? I thought it might be in the Boiler Min setting, but I am hesitant to change it from the default as I am no expert with boilers. Could it be an issue with the 10% enable switch? I thought it would automatically heat the boiler if the valve was more than 10% open.

Thanks for your time.

Adam_12

Sensor location [supply or return ]determine the placement of your dip switches 30% or 10% enable[page 14].Forgive me i do not have the manual in front of me I keep refering to the tekmar website.Your outside design temp should be st at the coldest day of the year.Your MIX INDOOR [page 7] should be set according to what type installation you have inslab ,staple up.The sensor on the return determines your dip switch setting to be at return .An aquastat should control the supply temp of your boiler it should be set to at least 180 degrees.Your boiler min should be set at 135 if you have a noncondensing unit.Ensure mix sensor is in proper location if all else fails get the installer come out and inspect the problem .Actually maybe a service call may be in order to make sure there is no something else wrong with the system.

Brian Rosa

Boiler type

The boiler I have is a castiron boiler. I'm not sure if it is non-condensing, but the boiler min is set at 140. It has a dial to set the temp of the boiler, and that is currently set at 160. I'll try 180 for a while. I believe the brand name is Burnham. If this is a larger problem than settings, I'll definitely be calling the installer.

Thanks again.

Adam_12

Brian a cast iron boiler should get up to at least 180 when you get close to design it should be close to 200.You want that cast iron to use its thermal mass to store and transfer energy when it is off cycle.Check out your dip switch positions make sure there at proper settings because you have the sensor on the return.

Brian Rosa

Settings

I did change the boiler setting to 180 F, and that helped with the cycling. It now mixes consistantly and I can feel my feet again.

It still is having problems getting the house up to temperature though. I found an issue with a zone valve that I think I fixed, so those all are working. I was just wondering, how hot can I get the mix zone without causing problems? It had really hot water going through it when we first moved in as it had no mix controller. Now it just seems to not be able to keep up with the heating demand. The boiler heats up to about 180 now. Should I turn it up to 200?

Brian Rosa

Final Post

After fixing all the problems mentioned above, I had the installer come take a look at it. Turns out there was air in the line in some zones and one valve isn't really opening. It appears the problems are now solved or will be shortly.

Thanks for all the help.

PS: I didn't call tech support because it was a weekend.

hydronicsmike

No worries Brian....

...as long as you know we are there for you when you need us.

Mike