radiant heating actuator issue

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  #1  
Old 01-15-14, 09:55 AM
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radiant heating actuator issue

I had hydronic radiant heat set up when I added an additiotn to my house- two zones- one for the master bath and the other for the master bedroom. Here is a picture of the set up



the problem is- the actuators never have worked. when either of the two thermostats call for heat, the circulator kicks in but the actuator stays closed. Right now both zones run at the same time when either thermostat call for heat because I had to remove the actuators. the set up consists of uponer thermostats, legend m-8300 manifold, and two 2-wire legend actuators.

I cant tell if they open when powered up- should that be obvious? Any suggestions on how I can make this work? My plumber moveed and my electrician claims it is wired correctly. here are a few more pictures





 

Last edited by NJT; 01-15-14 at 03:20 PM.
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Old 01-15-14, 03:17 PM
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my electrician claims it is wired correctly
I sorta doubt it.

How can you control TWO zones with a SINGLE zone relay box?

It's impossible to follow wires in photographs so other than to see that little 'rats nest' of wiring at the top of that relay box to tell us something is wrong, we can't do much more...

Unless you can draw a clear diagram of the wiring so we can suggest what needs to be done.

From what I can see, if you replace that single zone with a 2 or 3 zone control panel, and wire it correctly, you'll be in business.

Something like this:

ZVC403-4 - Taco ZVC403-4 - 3 Zone Valve Control Module with Priority

Can we see pictures of the rest of the system please? Show us how the radiant subsystem is connected to the boiler piping.
 
  #3  
Old 01-16-14, 10:38 AM
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I thought so-

If I remember correctly, the way it is wired is each thermostat has one wire that goes to the zone relay and one that goes to the actuator. What made me hesitant to call it wrong was that there is only one circulator.

I'll double check and post again when I get home.
 
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Old 01-16-14, 03:50 PM
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What made me hesitant to call it wrong was that there is only one circulator.
The ZVC control panels are designed to run the single circulator.

If I am seeing what I think I'm seeing, the installers are 'trying' to power the zone valves from that wimpy little transformer in the relay box. That transformer MAY have enough capacity extra to power the valves, but there is no way to properly wire the thermostats to the valves that will allow the system to work properly.

Also, it doesn't appear that there is any provision made with the current wiring to actually fire the BOILER when either of those two zones calls for heat. The result is that those zones have to WAIT for the OTHER zones to call for heat before they get any hot water.

Waiting for pics to see the rest of the system.......................
 
  #5  
Old 01-17-14, 06:27 AM
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I do not believe the Radiant heat thermostats have any connection to the boiler. If you look at this picture, you'll see the bx cable on the left connects to ajunction box that connects to the shutoff:

That being said, I have never had an issue with the floor heating up- I have the mix valve set at about 120 degrees. So it goes into the floor at 120 and comes out at 90 (a pretty nice delta if I do say so myself). My floors are set at a toasty 70 and they stay close to that (except for the fact that two zones are running as one, bedroom tends to get a bit warmer). I always figured that once the radiant heat started circulating, if the water in the circulation system became too cool the boiler would kick on automatically.

Here are a few pictures of the plumbing for the radiant floor heat. The red pex you see in the picture was a bypass for the mixing valve that my plumber set up when he was first purging the system- it is now kept closed.



 
  #6  
Old 01-17-14, 10:06 AM
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it goes into the floor at 120 and comes out at 90 (a pretty nice delta if I do say so myself).
Radiant systems are usually designed with less delta, often around 10F. A delta of 30F might indicate not enough flow, too long of a loop, etc... but if it works with no complaints, then it's OK I guess.

The piping for the mixing valve is a bit unusual, but again, if it works, it works, and that's really the bottom line, isn't it?

I always figured that once the radiant heat started circulating, if the water in the circulation system became too cool the boiler would kick on automatically.
With the way your system is configured, you are correct.

Since you have a low limit of 150F on your boiler, it will always be hot. When the radiant starts circulating and the boiler loses temp, it will automatically fire up to maintain the 150... so as long as it stays running with the Low Limit the way it is now, you don't really need a connection to fire the boiler.

If you replace that single zone relay with a 2-3 zone panel, you could continue to run it the same way.

I believe that I would consider turning the LOW setting down even a bit lower to save some fuel. I would try 130F on the LOW setting for a while and see how that works out.
 
  #7  
Old 01-17-14, 11:54 AM
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Hmm- I actually had my thinking about the delta-t backwards- I purposely slowed the flow to increase the delta, figuring the less heat coming back the more was used up in the floor (made sense in in some twisted way, I guess). I am going to tweek a little and see what happens.
 
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Old 01-17-14, 02:51 PM
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figuring the less heat coming back the more was used up in the floor
Well, yes... that is true, but there's no real benefit to that, and there may be a 'downside' to it.

Water entering at 120 and exiting at 90. That's an AVERAGE water temperature of 105 in the loop.

What this means is that some of the tubing being cooler will not output as many BTUs because the 'driving force' for heat transfer (the difference between the water and the surrounding area) isn't as great. So you actually get LESS BTU output as opposed to if the entering water temp was 120 and the exiting was say 100 ( the average now is 110 ). If you are able to get entering at 120 and exiting at 110, now your average is 115.

Higher average water temp means more output.

You have flow meters on the loops I believe? How much are you flowing with the 30 DT?

1/2" PEX (looks like what you have) is good for about 1.5 GPM. If you think that the flow meters are accurate enough, I would just set them to 1.5 GPM and forget about the DT. Let it be what it will be.

I guess that the best way to state the above is to set the flow in the loop for either 1.5 GPM or 10F DT, whichever comes first. If you can't achieve a 10 DT at 1.5 GPM, so be it. If you get a 10 DT with 1 GPM (I doubt you will), so be it. When adjusting give the floor time to warm up as DT will be higher if it's cold.

Is that pump a 3 speed? What speed are you running it? Use the lowest speed that will give you 1.5 GPM in both loops running at the same time.

By the way, from the pump install instructions:

Installation

Position of terminal box: Proper installation of the pump will have the terminal box located to one side of the pump or the other, with the conduit entry down. See Figure 3A.

If the terminal box position needs to be changed, it is best to do so before installation. However, if the pump is already installed, ensure that the electrical supply is turned off and close the isolation valves before removing the Allen screws.

To change terminal box position:

1. Remove the four (4) Allen screws (4 or 5mm wrench) while supporting the stator (motor).

2. Carefully separate the stator from the pump chamber and rotate it to the correct terminal box orientation.

3. Replace the Allen screws and tighten diagonally and evenly (7 ft.-lb. torque).

4. Check that the impeller turns freely. If the impeller does not turn easily, repeat the disassembly/
reassembly process.
So you might want to plan on correcting that after the heating season is over.
 
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Old 01-17-14, 05:25 PM
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I got the flow to just over 1 gpm and the delta is just over 15 now. Couldn't get any more flow from it. The grundfos circulator has a switch on the bottom and it appears to be set to the fastest speed-Not sure if it would require to be wired differently to go faster. Should be simple enough to reposition the pump correctly.

For now, I happen to have an extra taco sr501. Is it possible to use it for the second zone on my radiant system instead of buying a multi zone one? If it's possible it will save me some money- always my preference!
I figure I'll have to use a jumper from one box to the other to power it, but I'm trying to wrap my head around how I'll wire them both together to control the single circulator.
 
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Old 01-17-14, 05:38 PM
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I think you can possibly use 2 of the 501s...

Gotta go out for a while, I'll think on it later.
 
  #11  
Old 01-17-14, 06:20 PM
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I was speaking to a Budrus boiler rep. about flow through baseboard and his explanation was that the slower the flow the greater the fuel saving . Flow should be as slow as possible as long as the room remains comfortable. It probable has to do with temperature difference and losing btu. were not wanted. I had installed a bigger pump single speed, so I changed back to a three speed and run it on the slowest setting . The system has OTR. also, can not say if there are fuel savings.
 
  #12  
Old 01-17-14, 06:30 PM
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Very simple wiring solution assuming actuators are 4wire. All you need is an inexpensive 40VA transformer. Wire the actuators as zone valves...end switch wires in parallel to "tt" on the 501...circ gets wired to N and 4NO...boiler gets wired to 5 common and 6NO...a dry contact...Troop can explain how to wire the actuators and thermostats as zone valves..cant make a diagram on my phone here..
 
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Old 01-17-14, 06:40 PM
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They are the older two wire type.
 
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Old 01-17-14, 07:51 PM
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Is there a VA rating printed on the top of the transformer in the 501?

Do you know the VA rating of the actuators?

I've got a drawing started, will finish it tomorrow.

It is possible to use two 501s as long as the transformer has a VA rating with enough to spare for the actuators.
 
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Old 01-18-14, 09:15 AM
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Here's a possible way to use your two 501s to control both zones.

Success of this approach is based on the transformer in the 501 having enough VA rating to operate the actuator.

 
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Old 01-18-14, 09:34 AM
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Awesome- that looks simple enough. I'll get that done today.
 
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Old 01-18-14, 09:38 AM
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Check the VA rating first!
/////////////////////////////
 
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Old 01-18-14, 10:03 AM
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It's says 24 volt 15 va on each. Can not locate actuator va ratings anywhere.
 

Last edited by monk25; 01-18-14 at 10:15 AM. Reason: Additional info
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Old 01-18-14, 10:18 AM
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Old 01-18-14, 10:32 AM
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Haven't found the actuators yet, but I'm close, here's the install and setup instructions for the manifolds if you don't have them:

http://www.legendhydronics.com/media...T_02.14.12.pdf
 
  #21  
Old 01-18-14, 10:36 AM
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Manifolds are all set. I am going to see if I can get one actuator working with the existing zone controller before trying for the dual set up
 
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Old 01-18-14, 10:51 AM
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I've found 2 different actuators, but the information is confusing:

One says:

Power consumption 1.8W
Supply voltage 24VAC
Max current draw 0.25A

Since VA is Volts times Amps that says 6 VA for this actuator.
But VA is the same thing (almost) as Watts and it says 1.8 Watts!

Doing the math, 1.8W equals 0.075 A at 24V

How can this be?

Perhaps the word "MAX" in the current draw means that it draws .25 A for a bit but once the valve is open is settles down to 0.075 A ?

If this is your actuator then you should be fine to hookup as shown.

The other one says (and doesn't appear to be the one you have):

Power consumption 3.5W
Supply voltage 24VAC
Max current draw 1.5A

So the VA here is THIRTY SIX!

I don't think this is your actuator, but it clearly would overload the transformer in the 501.
 
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Old 01-18-14, 10:54 AM
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I am going to see if I can get one actuator working with the existing zone controller before trying for the dual set up
That's a good plan.

Let it run for a while ... quite a while... and feel the transformer in the 501.

If it's HOT, we need to rethink the plan.

You can still use the two relays, but you would need to install a separate transformer and wire it and the actuators off of the extra set of relay contacts. Not hard to do, just a little extra work.
 
  #24  
Old 01-18-14, 10:56 AM
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Just tried to set this up as a one zone system- I thermostat one actuator. Didn't work. This particular actuator is no longer manufactured, but I have spoken to legend in the past and they are very helpful. I will give them a call Tuesday and perhaps they can give me the specs. If the va for this controller is too low, what are my options?
 
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Old 01-18-14, 10:59 AM
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The actuator didn't open when the system was on (easy enough to see with the flow indicators) I'm concerned that the actuators are faulty. If not, perhaps it's just the va rating? What would I need to get?
 
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Old 01-18-14, 11:04 AM
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The grundfos circulator has a switch on the bottom and it appears to be set to the fastest speed
After you get things wired up, I'd like you to try switching to MED and LOW ... running that pump on HIGH is probably a bit 'extreme', but if you need to do so in order to get the flow up, then that's what you need to do.

It would not surprise me to learn that you can get the same flow at lower speed setting, and save a little electricity.

Do you have an idea of how many feet of tubing are in each loop?
 
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Old 01-18-14, 11:05 AM
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Do you own a multimeter and know how to use it?
 
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Old 01-18-14, 11:13 AM
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Don't own a multimeter, but I should!

Loop lengths are probably in the vicinity of 200' and 150' each (guesstimate). Both rooms are about 35' from manifold. One is a pretty small area, bathroom and small hallway. The other is a bit larger, my bedroom and walk in closet (180 sq feet)
 
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Old 01-18-14, 11:14 AM
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perhaps it's just the va rating?
At this point, I don't think so.

The transformer in the 501 is 15 VA and the only thing that it is powering in the relay box itself is that small 'cube' relay, which is probably only about 5 VA MAX (if that).

So, presuming your actuators are drawing 6 VA MAX, that's only 11 total on a 15 VA transformer.

Also, if it WAS being overloaded, it would get hot, and the voltage would get pulled down, and the relay in the box might not even work... but apparently is IS and the pump is running, correct?
 
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Old 01-18-14, 11:16 AM
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Yes. The pump kicks on when either thermostats call for heat. I know legend makes newer 4 wire actuators. What would be the difference?
 
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Old 01-18-14, 11:18 AM
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With a multimeter you could check the resistance of the actuator coil to see if it is 'open' or not. I am not sure how those things work, but presume that there's a 'coil' inside... an electromagnet type setup.

Maybe past attempts to get it working properly by yourself and others have somehow damaged the actuators?
 
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Old 01-18-14, 11:20 AM
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Yes, that is what I am afraid of. I've never seen them in the open position. They make no noise or movement when powered.
 
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Old 01-18-14, 11:25 AM
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Is there ANY labeling on the actuator itself?
 
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Old 01-18-14, 11:33 AM
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Only 24 v 50/60hz. When the actuator is hooked up, I get an 'click' from the relay. I don't get it when it's not.
 
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Old 01-18-14, 11:40 AM
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When the actuator is hooked up, I get an 'click' from the relay. I don't get it when it's not.
More and more confusing!

You are saying that with the actuator NOT connected, when the thermostat is turned up to call for heat that you do NOT get a click from the relay in the 501?

But that the pump still turns on and runs?
 
  #36  
Old 01-18-14, 11:54 AM
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Let me restate- I made an assumption. The thermostat was calling for heat and the pump was running. In order to test actuator, I hooked it up after everything turned on. Once connection was made, zone relay clicked. Actuator did nothing.
 
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Old 01-18-14, 12:55 PM
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Once connection was made, zone relay clicked. Actuator did nothing.
Did pump shut off at that time?

Perhaps that was the actuator overloading the transformer and the voltage dropped and the relay clicked OPEN...
 
  #38  
Old 01-18-14, 01:07 PM
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It didn't shut the pump off. I'm baffled.
 
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Old 01-18-14, 01:14 PM
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Makes two of us Monk. Unless...

What I was thinking earlier about the initial 'surge' being higher... maybe momentarily dragged down the transformer and the relay clicked open and back closed again...

I'm going to do another drawing... actually modify the one I sent... that shows how to power the valves from an external transformer.

Gimmee some minutes...
 
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Old 01-18-14, 02:06 PM
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Looks more complicated than it is.

What I would do us use an AT72 Honeywell ($20 or so) (or equivalent) transformer that mounts on a cover plate for a 4" junction box.

AT72D1188 - Honeywell AT72D1188 - Plate mounted 120 Vac Transformer with 9 in. leadwires

Run the AC feed to that box and branch out from there to the two relay panels with the AC feed to them. Moves some of the bulky wiring out of the relay boxes. Use an extra deep junction box so there's plenty of room for the wiring under the transformer.

 
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