buderus logamatic not controlling mixing valve properly?

tbruntrager

I've recently purchased a home with a Buderus boiler with Logamatic HS 2107 controlling an ESBE ARA663 mixing valve on a radiant heating circuit with room sensor. Unfortunately, we are in a somewhat remote area and the plumber who installed this is out of business, and other contractors we've tried so far either won't work on the system type or are clearly not very familiar with it, and have failed to solve the problem.

If I understand how the actuator is supposed to work, when the logamatic is trying to open the valve, it sends current to "open" wire, which in my case is the black counter-clockwise wire, and to close the valve it sends current to the "close" wire, which in my case is the brown clockwise wire. What's happening is that sometimes (not all the time), whether the logamatic is trying to open or close valve, it appears to be sending current through same wire (right now the "close" wire). I can see the little arrow symbol appearing in the logamatic display, and if I turn the thermostat all the way up, I see the "open"/up arrow symbol, but I'm measuring 24V to the "close" brown wire. If I turn the thermostat all the way down, I see the "close"/down arrow symbol, but still measuring 24V to the "close" brown wire! In both cases nothing to the black "open" wire.

As I said, the above only happens sometimes. At other times, when I turn the the thermostat up, I get the 24V as expected to the black/"open" wire; and when turned down, it switches to the brown/"close" wire.

Has anyone seen this before and is there any reason why the logamatic would be sending current this way (other than it just isn't working?).

Thank you!

Big Ed_4

Was there a call for hot water ? Is there a problem with the heating on the radiant zone? What type thermostat is being used ?

tbruntrager

So I'm not sure what you mean by a "call for hot water". When the logamatic display indicates an up arrow, which as I understand is the symbol it shows when it should be opening the mix valve to add hot water to the radiant loop, it is sending the 24V current to the "close" wire on the mix valve, so the valve never opens. The boiler is plenty hot and heating the other zones fine.

The zone in question is the main zone which is on constant circulation. So when the mix valve is completely closed, it is just circulating cold water through the loop. In that situation, yes there is a problem with the heating in the main zone because there is only cold water running through the loop and zone doesn't heat up. The only way for me to get heat is to open the mix valve manually and then it heats up fine.

It is a Buderus thermostat that was installed with the original system.

Big Ed_4

The Buderus thermostat BFU ? is really a room sensor , it will adjust the heating curve and give you manual control for set back ..


The 2107 will shuts down heat zones when an indirect hot water heater which is connected to boiler needs to be reheated .. Normaly you will not noticed, now since you do . I would be looking on the radiant side . There is a card or board installed in the 2107 for radiant control, a power source to control mixing valve though board , the Mixing valve and sensors to send info back to the board . You have voltage across the transformer with good connections ,I believe you mentioned ? You mentioned the problem is sometimes ?. Normaly if the board , mixing valve or sensors go , they go . My first thoughts would check the program, electrical connections and the correct location of the sensors ... I find calling Buderus tech support 1(603)552-1100 with an electric meter would be a great start

tbruntrager

Thanks for your reply. I'm aware of the priority to the hot water heater, but that doesn't seem to be the problem, as this issue is happening most of the time. Thank you for the info and number for Buderus. I will try that. Whatever is going on with the heating curve, it just doesn't make sense to me that it would be sending voltage to the clockwise wire when both the open and close symbols are showing on the display. I appreciate your help and suggestions.

GW

I’d go to Relay Test and then Open Valve and then Close Valve to confirm. If you’re still getting erroneous voltage I would pull the wires off of the FM241 card inside the 2107 and try it there. If you get the same results something is amiss and you need a new FM241 module. Pretty basic to change

tbruntrager

Thanks for that suggestion. I didn't know where to find the FM241 card or how to access that end of the electrical connections. It sounds like it's inside the Logamatic unit somewhere?

Big Ed_4

Yes it is , optionally added for a radiant pump station ...It would be adjusted though circuit 2 in programing .. Call them , they are a great tech support ..