troubleshoot constant call for heat

Paulypfunk

Hi gang,



I am having trouble with the retrofit of the boiler room.  The system runs but I am getting a constant call for heat from my floor zone.  I have attached a diagram showing how I wired things together and hopefully it will shed some light on things.  Using uponor four wire thermal actuators, power from 24v transformer, two wire wirsbo thermostats and using a Taco 504 to act as my relay to fire the pump and command the boiler.  I did cycle the actuators out of the box to make sure they open and close properly.   I have the red wires from the actuators plugged into one of the top tstat terminals on the Taco 504.

Rich_49

Pauly

Are those Uponor T Stats ?    I suggest you use Uponor 2 wire heat only thermostats (A3030101), a 3 zone control module (A3031003) and use all 2 wire actuators . Wire the 24v to the module , Wire the t stats to the module , the actuators to the module ,  and the end switch to the SR504 and call it a day .  A whole lot of ugly where it was not required .

icesailor

Troubling constant heat:

Two things:

You have two sources of 24 volt power. Very strange things can happen when you have two separate sources of low voltage.

The wiring as you show it, might not be actually how you drew it. End switches aren't always meant to be a source of power. Sometimes, you need isolation relays.

Zman

Wiring

The ends switches look fine.

On the yellow wires, the wire nut in the center should not be tying every thing together. The wires coming from the t-stats should go to there respective zone valves.

The sr 504 is not really the right product for this. The ZVC 403-4 would clean this up nicely.

Carl

Paulypfunk

more info

Sorry guys, more information.  This is an existing installation that I am trying to clean up.  There are actually two manifold stations, the second one being in a fairly remote location from the mechanical space, so getting new wiring over there would be problematic.  All thermostats are remote locations also with wirsbo 4 wire, circa 2004 and I would like to avoid replacing all of them if I can.  I don't have separate runs from all the tstats running back to the mechanical space, just single end switch wires that are all daisy chained together.

My diagram shows the exact wiring that I though germane for this discussion, for one of the manifold stations at least.  Yes I was concerned that the TT terminals on the top of the taco 504 were powered and that might be problematic.   Since the end switch loop is from the TT to the red wire connections on the boiler I didn't know if that would be a problem.

I talked this around a bit elsewhere as well.  It was suggested by someone that my problem is ghost signaling and to place a 1K ohm resistor between the outgoing Tstat wire and back to the 24 vac transformer. 

I am not familiar with the ZVC line.  I will look into it.

JStar

Wiring

Is a zone valve open when it's not supposed to be?

Have you isolated which zone is the problem by disconnecting individual wires?

icesailor

Differences:

As I understand it, the original installer installed Taco SR 400's on the zone valves? They should have used Taco ZVC 400's on zone valves. The other control SR's are switching relays to operate circulators.

In the case of SR's, it is important that there be a specific amount of voltage going to the thermostat for the heat anticipators to work properly. But the ZVC (Zone Valve Controller) provides 24 volt power to the thermostats and to the zone valves through one source. If you start adding additional 24 volt sources, you can get into trouble. If the distant SR or ZVC is wired properly, it should only need the two thermostat wires going back to the main control.

I still think that you are clouding your mind with the way you think it should be and how it actually is. Therefore, you can't see the problem that is there because it is hidden by the drawing you made. Been there, done that.

I call those Taco SR and ZVC controllers "Magic Boxes" or Voodoo Boxes. Because they seem to work by magic or voodoo and some of us and them out there haven't figured out exactly how they work internally. Your drawing might be correct if there wasn't a Voodoo Box there. Because, it has put some sort of an angry spell on the system. Consider the system without that additional 24 volt transformer. The power should be coming from the SR/ZVC box. But I think it is also the wrong Voodoo box. It should be a ZVC/Zone Valve Controller.

Time to get out the digital multi-meter and go play with wires.

IMO

Zman

Magic

You actually have 3 different low voltage power supplies and circuits in your system. That is not the problem.

First you have the transformer in your drawing. It should be connected to a switch (t-stat) and a load ( zone valve). As J Star suggested, you should check that this is working correctly first.



Second, you have a power supply in the zone controller. It has a coil inside which closes the pump switch and the boiler switch once The end switches on the zone valves complete the circuit.



The boiler has a similar arrangement which tells it to fire once the terminals in the zone controller close.



As Carol Fey would say, it's just power supplies,switches and loads.



Start from the beginning and sort it out.



Carl

Paulypfunk

...

I see how the ZVC would simplify my life.  But if I understand correctly I would need to put in two ZVC's, one at each manifold station.  I also have three different circulators.  The diagrams on the Taco ZVC only show terminals for one pump.  How do I interface the pumps with the ZVC?

Zman

Sr 504

I see what you have (I think). The sr 504 is controlling your 3 circulators, but not using the individual t-stats. It is using groups of end switches instead.

What you have will work just fine if you wire it right.

Do you have 3 manifolds with zone valves? Does each manifold have it's own circ? Are the circs in the mechanical room? How many wires are running to the manifold from the mechanical? Is the transformer in the mechanical?

Carl

Paulypfunk

Four circulators

four circs



Pump one.   ID HW controlled by the TT solo 110 boiler.

Pump two.  Garage with hanging fan coil heater, circulator wired in series with the fan motor.  Tstat in the garage is easy to get to so I have the 504 relay wired as it should be, with the tstat out the top and the circ/fan out the bottom.

Pump 3.   One pump controlling all floor heat, two manifold stations, one in the same mechanical room, the other one far, far away. 

     A  maniflold.  3 loops, 3 actuators, two existing thermostats.  I have 4 wires total back to the mechanical room that also houses this maniflold.  There is a 24vac transformer next to the manifold and this is the setup described in my picture.

   B manifold.  6 loops, six actuators, three existing thermostats with two wires each presenting themselves in the remote manifold closet.  This manifold closet has its own 24vac.  I have a two wire traveler coming back to the mechanical room from this closet.



Just trying to button this one up without having to replace thermostats or pull new wire.  There was the suggestion of placing a 1K ohm resistor between the outgoing Tstat wire and back to the 24 vac transformer.   Opinion on that idea?

Zman

OK

The strange thing about your drawing is that, with it wired that way,if either t-stat calls, all 3 zone valves will open. I guess it has always been like that.

I assume you have disconnected the end switch wires from the zone controller and determined that a valve is still calling. Therefore the problem is in the valves. I also assume that none of the valves are open and that the problem exists even if the transformer is disconnected. Now you can go through them one at a time with either an Ohmmeter or by trial and error and see which one is giving you trouble.You may just have a bad end switch.

With the wirsbo zone valves there can be a problem where the taco controller "overpowers" the end switch in the zone valve. This is corrected by putting a resistor in the end switch circuit. My understanding is that it damages the switch and it must be replaced.

Carl

Rich_49

Rocket Science ?

Please look at the link . This guy needs help and this is not that difficult .

   The SR relay for the circs is fine , If you use the end switches from Uponor zone control modules as if they were the t stats , they only complete a circuit .  These boxes are not magic and they are not that smart , they receive information from another source and open or close a circuit , period . Just use the right stuff . 

    Like I said above ,  Power a UPONOR zone control module with the 24v transformer , wire the t stats to the inputs on said zcm , wire the actuators to the proper terminals on the zcm , wire end switch from UPONOR zcm to SR relay and go home knowing the job works and is correct .  The only thing different about the manifold station picture is that all the pumps are at the manifolds and not in the boiler room so a single pump rlay was used , if they had all been in the boiler room an SR 505 would have been used . This happens to be a 6 zone manifold , All the connections are inside the wire raceway for the actuators . The picture shows before wiring , the link is the completed assembly

http://mechanical-hub.com/new_site/wp-content/uploads/2014/03/IMG_20140308_130607_712.jpg

icesailor

Basic Rocket Science:

Has anyone suggested pulling wires until the circulator stops? Or am  I misunderstanding the problem?

I have seen Taco 572's with sticking plungers that didn't travel all the way down and held the end switches closed. Easily spotted if you have a ZVC box and the yellow light comes on but the red one never comes on. End switches are always wired in series so any one or all will close the circuit.

I still think you have too many transformers where one might do. I am not there in person but I think you need some isolation device like a 501 relay to be starting the pump. I'd be pulling wires until it stopped doing bad things. Until you figure out where the bad things are coming from, you'll just be speculating on the cause.

You have to think like electricity. If you are looking for a cross connection with a piping array, and you can find it, think of electricity in the same way. You have a cross connection. In piping, we have check valves to make the water go where we want it. Electricity uses diodes for check valves. If electricity wants to go backwards, its a short. It can only add to itself.

What do you do when the electrician can't figure it out? YOU figure it out. I always said to electricians on complex control issues. "You wire it. If it doesn't work right, I'll figure it out and fix it."

Paulypfunk

follow up

Thanks for your help guys.  We ended up with one bad thermostat and three jankey zone actuators causing our ghost calls for heat.  Drove us nuts for a while till we pulled wires and isolated everything.  We ended up replacing all the old wirsbo motor actuated zone valves with the thermal units.  Kind of a pain trying to trouble shoot when you need to wait six minutes for a zone to activate.  How does one work around that problem?

Rich_49

One

charges for the amount of time required to do the job properly .  The Uponor zone control module I mentioned earlier will let you know that an actuator is opening with a red flashing light until the time when the valve fully opens and the light is solid .