Taco Radiant Mixing Block mix sup setting trouble

dlabrie

When I shut down my radiant floor heating system last spring everything was working fine. I have it set up in Outdoor Reset mode. When I turn on the RMB the display gives the outdoor temperature(currently 57") The target temp is 120. max mix design temp is 140. The problem is I am only getting a mix supply of 69. The pumps in the RMB seem to be running fine, The thermostat is calling for heat, the actuators to the zones are open. THe display shows... mix sup, 69 , min, an icon with a circle and arrow inside, a furnace icon, and dem.

How do I get the mix back to 120?

Thanks.

Gman66

Check to make sure your "warm weather shutdown" value is higher than outdoor temp.

Dave H_2

There should also be another icon, it looks like 5 bars that are ramping up. What does look like on yours?
small bottom bar means the injection circ is moving very slow, meaning that it is at or near design target temp. 5 full bars means the injection circ is running full speed, and the target temp vs the actual temp are very far apart.

Is the boiler hot?

Dave H

dlabrie

I think the top, 006 circulator might not be working. On a regular stand alone circulator, I could remove it, put power to it and see if it worked. I am not sure how to do it with this set up. I spoke with TACO service and they said to check the amps of the motor and it should be .52amps. Can some one explain what I'll find when I take the cover off and how to check the amps?
Thanks

dlabrie

Dave H_2 said:

There should also be another icon, it looks like 5 bars that are ramping up. What does look like on yours?
small bottom bar means the injection circ is moving very slow, meaning that it is at or near design target temp. 5 full bars means the injection circ is running full speed, and the target temp vs the actual temp are very far apart.

Is the boiler hot?

Dave H

Here is a pict of the RMB when it is running. The furnace is about 8 feet from the rmb. It gets up to temperature and runs fine to supply my domestic HW. When the RMB is running, the pipe from the boiler is hot at the boiler but not at the RMB. The RMB is not pulling the Hot water in to it. I took off the HY-Vent and there was no air at the top of the RMB. I took the HY-Vent apart and cleaned it and it appears fine.

It is hard to tell if the top, 006 circulator is functioning because the bottom, 008 circulator is and the sound and vibration carry. The bottom circulator is hot but the top circulator is just barely warm. The temperature of all 4 pipes comming to and from the rmb are all at ambient temp, about 69 degrees.

I need to verify if the top circulator is working, but am not sure how to go about it.

dlabrie

Gman66 said:

Check to make sure your "warm weather shutdown" value is higher than outdoor temp.

WWSD is 72. Outdoor temp- 50-60. The RMB is demanding hot water but it isn't pulling it from the boiler.

rick in Alaska

What is the boiler pressure? It needs to be around 12 psi. Also, if there is air in the system, the pumps won't move any water.
Can you show us a picture of the piping from a distance?
Rick

dlabrie

The boiler pressure is around 12-15 lbs. I had my oil service guy here and he spent 1.5 hours purging the system but couldn't figure out what was wrong; that is money down the drain. Here is a pict of the system. The furnace is on the left of the pict. It runs fine and keeps my superstorer (just out of the pict on the right) domestic hot water at temp. I can post any other picts that might help. Does anyone know what the T between the output and return line on the right of the RMB is for?Thanks,

rick in Alaska

So is the loop from the boiler and back getting hot? If the top red Grundfos pump is not working, then there will be no flow past the T's that the RMB feeds from, and it will not work.
Rick

Zman

I assume the vent on top is open?
Have you checked that all of the sensors are secured?
You could download the Danfoss magnetic tool on your phone and determine whether or not the circs are spinning.
I would like that you are either airlocked or you have a bad circulator.

dlabrie

Rick, Thanks for your help. Are you saying that the Grufundos circled in red should be on when the RMB is on? I tried calling for heat and the RMB was on but the Grufundos was not. The furnace also did not come on, but I think it was up to temp because everyone just used the shower. The area circled in green does not get above 69-70°.

dlabrie

Zman said:

I assume the vent on top is open?
Have you checked that all of the sensors are secured?
You could download the Danfoss magnetic tool on your phone and determine whether or not the circs are spinning.
I would like that you are either airlocked or you have a bad circulator.

Thanks for the help. I took apart the Hy-vent on top of the RMB. It looked fine. I cleaned it, blew air through the vent hole and reinstalled it. How do you use the Danfoss magnetic tool to tell if circulator is working? The sensors look good and read out on the display.

rick in Alaska

If the red circulator is not working, it will not pull any heat past the two t's that the RMB gets its heat from, and you will not get any heat out of the RMB. You will need to check if the circulator is getting power when things are running, and if not, where did it get lost at.
Rick

dlabrie

rick in Alaska said:

If the red circulator is not working, it will not pull any heat past the two t's that the RMB gets its heat from, and you will not get any heat out of the RMB. You will need to check if the circulator is getting power when things are running, and if not, where did it get lost at.
Rick

Rick, I think you may be right. Just behind that pump is another that Ts off and circulates to the Superstorer. I was there when the Superstorer was calling for heat and that pump came on. when it shut off, I turned on RMB again and realized that I was hearing clicking coming from the furnace control. I put my ear on the red circled pump and I could hear it try to start. It seemed to work a little then stop. Now the question is, is it the pump or the furnace control?

What do you think of this idea? There is a spare Grufundos pump that you can see in the top right of the picture. It was installed for a future application. What if I swapped out the red circled pump with the spare? If it works, we are all set, if not, it must be the relay. The only thing I am worried about is if the flange gaskets are shot.

Zman

What kind of "tech" did you have out that could not diagnose that the main circ was not running?
It would be easier to check if it has power with a multimeter than to start swapping parts.

dlabrie

Zman said:

What kind of "tech" did you have out that could not diagnose that the main circ was not running?
It would be easier to check if it has power with a multimeter than to start swapping parts.

After he got here, I learned that he was the ONLY tech for the fuel co. I use. I also learned that he was a "gas" guy, not oil. He had never seen either the RMB or the Logamatic control on my Buderous. He was a good enough guy, but out of his wheelhouse. He kept saying that there was air in the system and that was why the hot water wasn't getting to the RMB. He never mentioned the Grufundos circulators.

rick in Alaska

Check to see if there is 120 volts going to the pump. If it is, and it isn't moving water, it is most likely shot. You can actually just take the 4 screws off the pump where it bolts to the cast iron, and take the "head" off. That way, you do not have to deal with leaking flanges. Just leave the flanges in place.
Rick

dlabrie

rick in Alaska said:

Check to see if there is 120 volts going to the pump. If it is, and it isn't moving water, it is most likely shot. You can actually just take the 4 screws off the pump where it bolts to the cast iron, and take the "head" off. That way, you do not have to deal with leaking flanges. Just leave the flanges in place.
Rick

Thanks Rick. I will probably be tied up tomorrow so I will do that on Tuesday. If I don't have 120 at the pump then I will have to figure out how to find the relay in the Logamatic.

Alan (California Radiant) Forbes

I was there when the Superstorer was calling for heat and that pump came on. when it shut off, I turned on RMB again and realized that I was hearing clicking coming from the furnace control. I put my ear on the red circled pump and I could hear it try to start. It seemed to work a little then stop. Now the question is, is it the pump or the furnace control?

Sounds like the pump is fine and the control has a problem.

rick in Alaska

I haven't had much experience with the Logomatic, but I believe it is set up to run the system pump continuously unless the outdoor shutoff activates. I am not a fan of them for most of what we deal with around here, as far as how our systems are set up. I like to be able to tell the pump to come on when I want it to.
Rick

dlabrie

I just tried testing the voltage at the grundfos pump. I had the RMB on and calling for heat. I had the black probe on the ground wire and the red on the 'L' wire coming from the furnace. The meter was just flashing .03 volts. The relay wasn't making any clicking sound this time.

Then I shut everything down and pulled the fuse leading to the furnace. I disconnected the L and N wire from the pump and with an extension cord, plugged the hot and neutral (blk & wt) wires into the L and N slot on the pump. It did not come on. Did I try to wire it correctly?

I also broke off the speed selector switch while trying to remove the pump wires :-(

When/if I have to replace the relay in the Logamatic, how will I know what I am looking for?
Thanks, David

rick in Alaska

If you put 120 volts to the l and n terminal on the pump, and it did not come on, the pump is shot or your power cord is messed up. That speed selector switch is very easy to break off. It is not a good design.
Rick

Zman

When you put the meter on L and N it should read +/- 120 volts.

dlabrie

rick in Alaska said:

If you put 120 volts to the l and n terminal on the pump, and it did not come on, the pump is shot or your power cord is messed up. That speed selector switch is very easy to break off. It is not a good design.
Rick

OK,new development this morning. Rmb came on and the furnace came on. I got 120V at the pump AND the pump was running. I don't know if any water was moving and there was no change in the mixing temp. The furnace shut off and so did the circulator, even though the rmb was calling for heat. I could here some clicks from the furnace control and now had 0 Volts at the pump.

I just left everything on for the last 15 minutes and the furnace is still off because it is up to temp and no water is circulating. But, I held the probes on the pump and a couple of times I got a reading of 120v when the clicking came from the furnace. I took the cover off of the Logamatic but couldn't locate exactly where the click was coming from. Here are some picts of the logamatic.

Zman

A change in temp will indicate flow. Just touch the pipes and you should be able to figure it out. Anytime the mixing valve zone is calling for heat, the main (red) pump should be running and the boiler loop should be too hot to touch.
This is sounding more like a control issue.

dlabrie

Zman said:

A change in temp will indicate flow. Just touch the pipes and you should be able to figure it out. Anytime the mixing valve zone is calling for heat, the main (red) pump should be running and the boiler loop should be too hot to touch.
This is sounding more like a control issue.

Would it be the relay in the logamatic? If so do you know where it is in the picts above>

dlabrie

I just held the probes on the pump for a while. I would hear a click from the logamatic and I would get 120v and the pump would come on. then 10-20 seconds, clicks and it would read 0 v and the pump would go off. the hot water is getting past the pump, but peters out before it gets to the rmb. I am sitting in another room right now and can hear it clicking continuously.

Zman

The RMD should be getting a call for heat from the t-stat. If you jumper from com to heat demand that will verify the t-stat circuit is good. Jumping the boiler terminals should make the boiler fire, the boiler should turn on the red circ.
https://www.tacocomfort.com/documents/FileLibrary/RMB01.pdf

dlabrie

Zman said:

The RMD should be getting a call for heat from the t-stat. If you jumper from com to heat demand that will verify the t-stat circuit is good.

Zman, Thanks so much for trying to help me. Please bear with me as you can tell I am not too experienced in this, but am willing to learn.
Here is a pict of an old control from the rmb. There are 2 com ports. Do I jump the one on the right with heat next to it? Also, when you say 'Jump' do you mean take one wire and touch both the com and heat. What will I be looking for when I jump it. Do I do this while everything is running?

Zman said:

Jumping the boiler terminals should make the boiler fire, the boiler should turn on the red circ.
https://www.tacocomfort.com/documents/FileLibrary/RMB01.pdf

Is that the com and boil that are right next to each other?
This morning when I first turned everything on, the rmb turned on the furnace and the red circ was running until the furnace shut off. Then the intermittent clicking started.

dlabrie

I sent a pict of the RMB while the clicking was going on with the Logamatic to Taco. He responded...
"The RMB would not make a clicking sound. It sounds like it might be the relay. The picture I saw looks like it's ok. You would see an error code.. if something was not right on the screen. " then... " You will need to contact Logimatic."

Is there a replaceable relay on the Logamatic or does the entire unit need to be replaced?

dlabrie

I just got off the phone with Bosch, who bought out Buderus. They do not make relays for the Logamatic 2901 any more. They do not even have a part number. They said I need to replace the whole unit with a R2107 Logamatic Control (w/ DHW Package).

jpulls11

dlabrie said:

I just got off the phone with Bosch, who bought out Buderus. They do not make relays for the Logamatic 2901 any more. They do not even have a part number. They said I need to replace the whole unit with a R2107 Logamatic Control (w/ DHW Package).

Sounds like you found the issue. Just giving you a heads up, the logamatic isn’t not cheap.

dlabrie

I was able to get a knowledgeable technician here this morning. With help from Buderus phone support, It was determined that the current R2901 is shot. As there are no parts available for this ''obsolete control, we decided to get a replacement, which is a Logamatic R2107.

Thank you for all of the help. Hopefully I'll be back up and running soon.