Hydrostat - SR504 wiring error?

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Old 09-19-12, 04:20 PM
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Hydrostat - SR504 wiring error?

As I mentioned in http://www.doityourself.com/forum/bo...83-update.html, I expected that, with the HydroStat set for cold start, the economy setting on, and the indirect water heater priority switch on, upon a call from a thermostat the boiler would come on, heat up to 120, and then the respective zone circulator would come on.

Well, thats not happening. Instead the circulator comes on and circulates whatever temperature water happens to be in the boiler, usually around room temperature, until the indirect's thermostat gooses the boiler into action. At that point the zone circulator switches off, as it's supposed to, and comes back on again as soon as the indirects circulator cuts out, now pushing nice hot water, at least, for a while.

My guess is that Ive made some stupid mistake in the wiring, but Ive checked and re-checked all the connections in the HydroStat and the RS504 and read and re-read the wiring instructions for both and cant find my error.

The HydroStat instructions for my sort of setup (Three heating zone circulators plus indirect.) read, To use a multi-zone panel for both heating and indirect zone connections, connect the zone panel end switch to T-T and install a wire from ZR to the hot terminal of the indirect circulator in the multi-zone box.
I assume that means that the ZC terminal in the HydroStat stays empty, and that the jumper between ZC an ZR on the 504 stays in place, and thats how I have it.

In winter when there are frequent calls for heat from the zones and the indirect, all this is no great problem: Ill set the low limit for 140, or so, and the mixing valve for around 115, and with a 10-15 loss in the loops, all should be fine. In summer, with only the indirect going, no problem either because Ill reset for cold start. The fuel consumption penalty in winter would, probably, not be particularly high.

Still, it bugs me that I screwed up, and I would like to get the thing to work the way the book says it is supposed to.

Any ideas as to how I could track down the problem?
 
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Old 09-19-12, 10:12 PM
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I expected that, with the HydroStat set for cold start, the economy setting on, and the indirect water heater priority switch on, upon a call from a thermostat the boiler would come on, heat up to 120, and then the respective zone circulator would come on.
I don't think you made a mistake... that's the way a cold start boiler works!

Why did you expect that the zone circs would be delayed?
 
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Old 09-20-12, 06:29 AM
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Why did you expect that the zone circs would be delayed?
Because on the cover page of the Model 3250 it says, Reduces Condensation - Holds circulator off until boiler reaches 120F and on page 7, NOTE: To reduce the potential for condensing, the control will allow the boiler to heat to 120F prior to energizing the circulator.

Here's a link to the manual, http://www.hydrolevel.com/pages/pdf_...structions.pdf
 

Last edited by Vander; 09-20-12 at 06:50 AM.
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Old 09-20-12, 10:14 AM
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I still don't think you've "made a mistake", but there may be some misunderstanding...

The only circulator that the 3250 can control is one which is wired to the C1 and C2 terminals on itself.

Circs that are wired to the 504 panel are only controlled by the 504 and the 3250 has no way to influence their operation.

The only thing that the connection to the ZR terminal does is to inform the 3250 that this particular heat call is from the indirect and thus overrides any temp limits that may be in place.

There MAY be a way to work around this though... I need to think on it for a bit.
 
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Old 09-20-12, 12:08 PM
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Circs that are wired to the 504 panel are only controlled by the 504 and the 3250 has no way to influence their operation.
OK, that makes sense. Thanks!

There MAY be a way to work around this though... I need to think on it for a bit.
As I said, it won't be a great burden to get along without the circulator delay feature, but if there is a solution that doesn't challenge my limited technical abilities too much, that would be icing on my cake.
 
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Old 09-20-12, 03:41 PM
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Before suggesting my idea, I need to determine how the circ outputs on the 504 are powered. That ZC / ZR jumper may in fact carry the power to the circs. If so, it may be possible to remove that jumper and power the correct terminal ( I think the ZC on the 504, not certain yet ) from C1 on the 3250.

Another point which needs to be determined is whether or not the C1 terminal is capable of supporting ALL of the circs running at the same time. It may turn out that yet another relay will be required. In this case, that other relay would have the coil wired to C1/C2 and the switch contacts wired to the 504 (ZC I think) .

Last, it would need to be considered what happens when the indirect calls. It could turn out that after making this change the indirect circ won't run...

I don't understand why Taco doesn't make the schematics of their controls available. I guess I need to 'reverse engineer' a few of them and draw my own!

Bottom line is that it might be more trouble than it's worth (your decision), and in fact may not even be necessary.

You have a multimeter and know how to check AC Volts?

Kill power to system, remove ZC / ZR jumper in 504.

You don't need to run the boiler for this testing, so you could disconnect one of the T T wires, and the ZR wire on the 3250 from the 504 indirect circ output. Make sure to put a wire nut on that wire because it will be AC HOT when the testing below is done! Or, just leave the wires on there and be aware that the boiler will fire during these tests. Be brief ...

Remember there will be 120VAC present during the following tests! YOU CAN BE KILLED! Make sure you fully understand what you are doing before starting! If you have ANY doubt about your ability, do NOT PROCEED!

Restore power and measure from AC NEUTRAL in the 504 to both ZC and ZR terminals. Let me know if either or both have AC power on them. I believe that you will only see 120 VAC on the ZR terminal.

Force a heat call from the indirect and measure both again. I believe you will see NO power on either. Note whether or not the indirect circulator runs.

Force a heat call from one of the zone thermostats. Note that none of the zone circs run.

Replace jumper and restore power.

Let me know results...

A little explanation about how I think the 504 works.

When the indirect priority is ON, the 504 will power the ZR terminal only when the indirect is NOT calling.

The circs are powered from the ZC terminal and this terminal gets it's power from the ZR when the jumper is installed.

If this is true, then theroetically you could remove that jumper and power the ZC in the 504 from the C1 in the 3250 and restore the 120F circ delay function.
 
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Old 09-20-12, 05:03 PM
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Old 09-20-12, 05:46 PM
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Here's how my SR504 is wired, I too have a Hydrostat 3250

the RED wire on Zone 4 goes to the HYDROSTATE ZR point.

i have a jumper between SR504's ZC&ZR[SUP][/SUP]


just out of curiosity, if your SR504 has the dip switches, what are your current settings for those?
 
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Old 09-20-12, 08:43 PM
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I think that's exactly what Vander has wired... but not sure if he's got the 'EXP' version which is what yours looks to be.
 
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Old 09-20-12, 08:53 PM
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The way may system has been functioning:
1. heating zone circ pumps will operate when the t-stat calls for heat, whether it's 1, 2, or 3 pumps running.
2. if IWH needs heat, the SR504 will shut off any of the zone circ pumps 1-3, start zone 4 pump (priority) and send a signal to Hydrostat to start burner and fire to 190F (which is my HL setting). once the hot water temp is reached, the circ pump shuts off, this is usually happening after the boiler has stopped firing.
3. if IWH is calling for heat for more than 1 hour, then zone 4 will stop and zone 1-3 will operate. this is the Priority Protection dip switch.
4. The Hydrostat Low Limit is set to 120F, I believe it can be set lower, but the Boiler mfr suggested this minimum set point. I have 3 zones in the house and the Hydrostat economy feature dial D is set to 3. When the IWH is not calling for heat, the Thermal Targeting has been calling for 145F and have seen the boiler fire when the water temp drops to 120F and shut off when it reaches 145F.

In Hydrostat
1. Check if the Jumper B is on (100% certain it is not)
2. check the Z/I switch setting, should be set to I
3. Thermal pre-purge On or Off? (mine is on)

In SR504
1. jumper between ZR & ZC
2. your dip switch settings are?
3. are you wired to the MAIN or PRIORITY end switch contact points?

Trooper,
dont think EXP version makes a difference from non-expandable model as far as basic function is concerned, however, i think there is an updated design of the SR units that have dip switches which provide for some additional functions/settings. don't know which one Vander has, previous model or latest/greatest gadget.
 
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Old 09-21-12, 07:14 AM
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Mine is the regular 504, not the EXP with the plug in cards, the switch below them, and the "slave" switch in the upper left hand corner. I believe I may have an older version because the instruction sheet that came with it says "Effective: June 1, 2006. And, yes, mine is wired like Thors Twins' and behaves pretty much the same way, except that, after my first post in this thread, I set the low limit to 140F.

The reason I did that was because, with the low limit off, the circulators just kept on pumping ambient temperature water through the system and the boiler didn't fire even though the
temperature in it had dropped to around 60F. The target temperature was somewhere around 150F at that point. IOW, the differential thing wasn't performing its act, and I'd like to find out why before I do anything else.

Through this conversation I think I've gained a somewhat better understanding of how the 3250 - 504 combo is supposed to be working. Maybe I'm deluding myself, but I'm going to experiment some more with different settings to see if I can overcome the behavior the above paragraph refers to.

I have some outside chores to take care of first though, so it may be a while before I come back with a report.
 
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Old 09-21-12, 07:28 AM
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Thanks, TT.

No, mine is definitely an older, simpler version and does not have the dip switches. I guess I now know why I got it for such a "good" price.

And, yes, I also have the jumper between ZC & ZR.
 
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Old 09-21-12, 07:45 AM
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Trooper, I really appreciate all the thought you have put into this, and I believe I'll be able to follow your instructions without letting too much smoke out of the electronic gadgets. Considering the effort you've put into this, I'd feel guilty if I chickened out now.

Before I do, however, as I mentioned in my other response, I want to fiddle around some more with the settings to see if I can get the thing to behave more like it's supposed to in cold start. I may also come back later with some more questions to make sure I have understood your instructions correctly.

Thanks again.
 
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Old 09-21-12, 08:00 AM
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Thanks, Rockledge.

I believe that, if I add a switching relay, like Trooper tentatively suggested, I could probably use one of the old Honeywell 842s, of which I have a surplus after I installed the SR504. I'll ask him if and when the time comes to make that decision.
 
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Old 09-21-12, 03:18 PM
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I may also come back later with some more questions to make sure I have understood your instructions correctly.
No problem there... and don't feel guilty if you bail!

I would still like you to take those voltage readings if you get a chance and feel able to do so. It would give me some reassurance that I understand the internal circuitry of the 504 and that the plan will work.

I could probably use one of the old Honeywell 842s
842 ? Do you mean 832 ? Yes, that would work.

I would feel much better about you using a relay because if all the circs called at once for some reason it might trigger the smoke release function by overloading the 3250 circuit.

What I would like to do if you decide to go forward and try it is to draw and post a diagram for you to follow.

Also, this is the type of thing that you could 'jury rig' in order to test it before installing permanently.
 
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Old 09-21-12, 06:47 PM
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842 ? Do you mean 832 ? Yes, that would work.
Sorry, I get confused with all those magic numbers floating around: I meant to say, R845. That's what I now have a small stack of.

I would still like you to take those voltage readings if you get a chance and feel able to do so. It would give me some reassurance that I understand the internal circuitry of the 504 and that the plan will work.
Will do, or, at least, will give it my best shot.

Spent most of the afternoon, including my nap time , watching the boiler go through its paces with different settings and taking notes. One more setting to try tomorrow, and then I'll try to put an intelligible report together.
 
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Old 09-21-12, 07:39 PM
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Wire C1 on the hydrostat to ZC on the Taco relay. Remove the jumper between ZR & ZC

Here are the specs on the hydrostat control.
Circulator Contacts 5.8 FLA, 34.8 [email protected]
 
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Old 09-22-12, 06:53 AM
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Thanks rbeck, I thought it would work but didn't look at the specs on the 3250...

Vander, what pumps are you using? is the total of the three running at the same time within the 5.8 Amp rating of the 3250 ?

If so it's a simple fix!
 
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Old 09-22-12, 08:30 AM
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Trooper, they're all Taco 007s, rated at 0.71 Amps. So, three of them simultaneously would be within the limit. You guys seem reasonably sure I won't fry anything vital if I make the change, that is, unless I do something totally idiotic, so I'll give it a try.

First, though, I want run through a few more control setting combinations to see if the differential is functioning the way it is supposed to.

This morning, with the low limit at 140, the Economy feature set for 3 zones, and one thermostat set so it would call for heat a few times during the night, I found the temperature at 180 and both the target and the high limit yellow LEDs on: something I wasn't able to make happen yesterday.
 
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Old 09-23-12, 12:24 PM
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If so it's a simple fix!
That's what I thought, but alas, no dice, folks.

I connected C1 on the 3250 to ZC on the 504 and removed the ZC-ZR jumper. With power back on, boiler temperature at 166 (the indirect had called for heat shortly before), and the thermostat cranked up to 80 on a 68 room-temperature day, the circulator for that zone would not start up.

Next I did the test you, Trooper, prescribed, and got the following results:

With a TT wire to the 3250, and the wire from 3250 ZR to H 120VAC on the 504 disconnected, the jumper between ZC & ZR still removed, and the power restored, there was no power from AC neutral to either ZC or ZR.

On a forced heat call from the indirect, there was power to ZR but not to ZC and the indirect WH circulator didnt run.

After reconnecting the TT wire, a forced heat call from the zone thermostat did not start the corresponding circulator.

So, Ill just settle for running the system with the low limit activated during the heating season. At the moment, 130 seems to be about right for my setup, but that may change after some more adjusting to the mixing valve. Ill leave that till when the cold weather hits. During the summer Ill switch back to cold start.

Ive also come to the conclusion that the Economy feature isnt really of much use when you have a large volume, low temperature, under-floor radiant heat set up because with the low limit set at, for example, 130 the burner cycles between 120 and 130, while the target temperature stays at around 150. Only latent heat and, of course, the indirect WHs calling for heat makes the boiler temperature rise above that point. A buffer tank might be good for this sort of system, but space and financial limitations, not to mention a distinct reluctance to get into more pipe soldering and joint twisting, keeps me from going down that road. (I read about the fun youve been having with that, Trooper, in your MPO installation thread. Nice job, BTW, at least, to my laymans eye.)
 
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Old 09-23-12, 05:55 PM
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I connected C1 on the 3250 to ZC on the 504 and removed the ZC-ZR jumper. With power back on, boiler temperature at 166 (the indirect had called for heat shortly before), and the thermostat cranked up to 80 on a 68 room-temperature day, the circulator for that zone would not start up.
Did you measure the voltage on C1 at this time?

This is actually a very key piece of data. I'm sorry that I didn't think to ask for it!

If C1 had been powered, the circ should have run.

Are there any settings on the 3250 which govern the behavior of the C1 output?

Was ZR on the 504 powered at this time?


On a forced heat call from the indirect, there was power to ZR but not to ZC and the indirect WH circulator didnt run.
Is the switch on the 504 set to 'Priority' during this test?

If not, it would explain why the indirect pump did not run.


==========================================

This CAN be done, once the logic in the 504 is fully understood.

I'll understand if you want to 'settle', but I'm game if you are!

==========================================


As I understand it at this time:

1. There must be power to ZC on the 504 in order for any of the circs to run.

2. ZR provides that power via the ZR/ZC jumper when either a) the indirect calls (but unknown yet if it does so when in priority mode) or b) any zone calls.

3. Removing the jumper and providing power to the ZC terminal in the 504 from an alternate source will allow power to the circs.

4. The man in the green house owns the Zebra.
 
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Old 09-23-12, 06:38 PM
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I'll understand if you want to 'settle', but I'm game if you are!
Mmmmm, that sounds like a challenge to me. Tomorrow morning I'll go back into the dungeon, take a print of your post #6 and this one down there with me + the handwritten instructions to myself I used today, and give the whole routine another run-through, including taking careful note of the actual voltage at C1.

Are there any settings on the 3250 which govern the behavior of the C1 output?
Search me! PDF available at: Hydrolevel.com

Is the switch on the 504 set to 'Priority' during this test?
They were on, both on the 3250 and the 504.

The man in the green house owns the Zebra.
Absolutely, and the alarming part of that is that no Zebra has exactly the same stripes.
 
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Old 09-23-12, 07:13 PM
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They were on, both on the 3250 and the 504.
I'll read through the HL manual later, the Admiral wants me to watch TV with her...

I don't think that you need BOTH priorities on. Just the one on the 504. In fact this may account for the fact that the C1 terminal power was not raised.

I didn't know that about Zebra! I once saw one that had my FINGERPRINTS on it! The FBI was tailing it!
 

Last edited by NJT; 09-23-12 at 08:56 PM.
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Old 09-23-12, 09:02 PM
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When you say priority is ON at the 3250, do you mean the " Zone / Indirect " switch?

If so, that's not exactly a 'priority' switch, and should be set to ' Indirect '

You said you were wired per Figure 5 in the manual, correct?
 
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Old 09-23-12, 09:21 PM
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You understand that the " Low Limit " is something different from the circulators not running until 120, correct?

Since you do not have a " Thankless Coil " in the boiler for domestic hot water, the Low Limit should be set to OFF. Is it ?
 
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Old 09-24-12, 05:47 AM
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When you say priority is ON at the 3250, do you mean the " Zone / Indirect " switch?
Yes. IOW, switched to "I".

You said you were wired per Figure 5 in the manual, correct?
Yes.
 
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Old 09-24-12, 06:46 AM
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You understand that the " Low Limit " is something different from the circulators not running until 120, correct?
Correct.

Since you do not have a " Thankless Coil " in the boiler for domestic hot water, the Low Limit should be set to OFF. Is it ?
I know, and that's how my first cry for help came about. With the Low Limit off, the circulators just keep on running and the burner never fires till the indirect WH calls, even though the boiler has dropped to ambient temperature.

I believe the low limit was OFF when I did the tests, but I have changed back and forth between low limit OFF and low limit ON so many times during the past three days that I won't swear to it. I'll make doubly sure it is off for the next round.

From your post #23:
I don't think that you need BOTH priorities on. Just the one on the 504. In fact this may account for the fact that the C1 terminal power was not raised.
I'll run both, the experiment with C1 on the 3250 wired to ZC on the 504, jumper removed, and the tests you prescribed with the 3250's Zone/ Indirect switch on Z and on I.

One more: when in your post #21 you say,
Did you measure the voltage on C1 at this time?
You mean, test it between C1 and ground, right? and even if the circulator is not responding, right?
 
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Old 09-24-12, 09:38 AM
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You mean, test it between C1 and ground, right? and even if the circulator is not responding, right?
You could read to ground but technically Neutral is correct. C2 is neutral.

I know, and that's how my first cry for help came about. With the Low Limit off, the circulators just keep on running and the burner never fires till the indirect WH calls, even though the boiler has dropped to ambient temperature.
I'll have to go back and re-read the thread. I don't remember that part...

In any case, that behavior is not correct!
 
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Old 09-24-12, 10:27 AM
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Here are today's (Sept. 24) test results.

First, when I follow rbeck's recommendation: C1 on 3250 to ZC on 504 and the jumper removed, with the low limit off, there is no zone circulator response and, of course, no current at C1 on the 3250. Same as with the low limit activated.

On to your tests: with the jumper in the 504 still removed, one TT wire in the 3250 disconnected and the wire from ZR to the hot side of the indirect WH terminals on the 504 also disconnected, and the low temperature limit OFF, there is 120VAC at ZR and no current on ZC and no current on C1. The position of the 3205's Z/I switch makes no difference and neither does setting the low temperature limit to 130.

Upon heat call from indirect: same results. Indirect circulator does not come on.

Upon forced heat call from thermostat: same story. Zone circulator does not come on.

So, it looks like we're back to square one.
 

Last edited by NJT; 09-24-12 at 07:00 PM.
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Old 09-24-12, 12:02 PM
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So, it looks like we're back to square one.
I don't know square one... maybe two!

First, when I follow rbeck's recommendation: C1 on 3250 to ZC on 504 and the jumper removed, with the low limit off, there is no zone circulator response and, of course, no current at C1 on the 3250. Same as with the low limit activated.
I believe that there may be a problem with the 3250... maybe...

When the TT on the 3250 is closed, as with a heat call from the 504 panel, the burner should fire and when the boiler water reaches 120F you should see 120VAC between C1 and C2.

If this were happening properly, the plan would work.
 
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Old 09-24-12, 02:23 PM
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Vander

Have you called Hydrolevel yet? The tech guys there are a great help over the phone & located in New Haven CT. They could help in the troubleshooting process of determining if it is or isn't a control issue with the Hydrostat.
 
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Old 09-24-12, 02:36 PM
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When the TT on the 3250 is closed, as with a heat call from the 504 panel, the burner should fire and when the boiler water reaches 120F you should see 120VAC between C1 and C2.
I'll check that, but are you sure that shouldn't be "B1 and B2" which is what I think the troubleshooting flow chart (page 10) is telling me. Think because I'm not 100% sure what they mean by, "Is the External Zone (ZC-ZR) calling for heat?"

Anyway, I know the Thermostat is working, because the circulator does come on, both, with the low limit on and off, but the burner fires only when the low limit is on. So, following the troubleshooting chart's instructions, I'll check for 120VAC between B1 and B2 as well when the yellow LEDs are off, the zone thermostat is calling for heat and the burner isn't firing. I suspect I won't find any, which would mean that the HydroStat is defective.
 
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Old 09-24-12, 04:23 PM
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Trooper,

With boiler temperature down to 100, low limit off, the thermostats calling, and the circulators running, there is no current between B1 & B2, nor between C1 & C2. With low limit on, my multimeter shows 120VAC between B1 & B2 and zilch between C1 & C2. So, it appears that the 3250 is defective.

I'll follow Thors Twins' advice and give Hydrolevel a call to see what they have to say, and I'll pay a visit to my supplier (20 minutes driving from here) to see what they can do to get me a replacement.

Am I right in assuming that, even if I get a new 3250, I would still have to make the rbeck wiring change, or will we only know that when we find out if the new gadget does or does not do its delayed circulator act?

BTW, where in my post #29 I said "there is 60VAC at ZR", I should have said "120VAC". I was reading the 500 ACV scale. [edit: NJT - that did have me scratching my haid... I fixed]
 

Last edited by NJT; 09-24-12 at 07:00 PM.
  #34  
Old 09-24-12, 07:14 PM
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are you sure that shouldn't be "B1 and B2"
Yes. B1 and B2 are the burner power terminals. It's the circulator terminals C1 and C2 that don't appear to be getting any power.

I'm not 100% sure what they mean by, "Is the External Zone (ZC-ZR) calling for heat?"
Take a look at the other wiring diagrams also. In some cases you will see a relay contact across them. The 3250 (as well as other modern aquastats) can use these terminals for dual zone, OR indirect water heater triggers. (The Honeywell in the MPO works the same way). In your case, the 'External Zone' is your indirect.

You don't need to bother with the flow chart. I had looked it over and didn't see anything there that applied to the C1/C2 terminals.

With boiler temperature down to 100, low limit off, the thermostats calling, and the circulators running, there is no current between B1 & B2, nor between C1 & C2. With low limit on, my multimeter shows 120VAC between B1 & B2 and zilch between C1 & C2. So, it appears that the 3250 is defective.
This must be the other problem which you mentioned...

There could also be a problem with the 504 though.

The END SWITCH on the 504 specifically. It must make contact in order for the 3250 to know that there is a heat call and energize the burner and circs.

Set your meter up for 24VAC measurement. With NO heat call, you should see 24VAC nominal across T-T in the 3250, or X-X in the 504.

With a thermostat forcing heat call, you should see this voltage drop to ZERO (or very close to).

Check both ends of wiring. T-T then X-X . This will learn us if the 504 is calling and the wiring is kaput, or if the 3250 is getting the signal but not working, or if the 504 is not calling.

You DID reconnect them from previous tests, correct?

Another test you can try: SHORT the T-T connections at the 3250. Does the burner fire for a heat call? If so, almost certainly the 504 or the wiring is defective.

The LOW LIMIT works because it does not depend on any external signals.
 
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Old 09-25-12, 09:59 AM
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Preliminary report:

Set your meter up for 24VAC measurement. With NO heat call, you should see 24VAC nominal across T-T in the 3250, or X-X in the 504. With a thermostat forcing heat call, you should see this voltage drop to ZERO (or very close to).
When this test didn't produce the desired results, I checked continuity between T-T an X-X, and that led me to a disconnect in the DPDT switch that connects X-X to either T-T on the old boiler or on the new one.

I jumped that switch, making a direct connection between the 3250"s T-T and X-X, and now, with the low limit off, the burner fires simultaneously with the activated circulators and there is current across C1 & C2. So, we're making progress.

What I haven't been able to determine yet is if the circulator delay feature now functions, and I'm waiting for the boiler to cool down to find out. I expect that it won't, and if that is so, I'll make the "rbeck connection" again to see if that will do the trick
 
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Old 09-25-12, 04:16 PM
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The rest of the story.

I forced a heat call with the boiler cooled down to 100, and the burner and the circulators came on simultaneously, i.e., no circulator delay. I then connected the HydroStat's C1 to the CZ on the 504, the CR-CZ jumper removed. That resulted in no response from either the burner or the circulator, which may well have been a consequence of latent heat having raised the boiler temperature to above both the target temperature and the high limit. More importantly, however, there was no response to a forced call from the indirect WH, not with the priority switch ON, nor with it OFF.

Since the WH is crucial and circulator delay is not, I decided not to wait the several hours it takes the boiler to cool down from 190 to below 120 (70 ambient temperature today) and restored the normal connections.

When I restored power again, I did notice that the Purge feature was working: something I hadn't noticed it do it before. That was good news.

As things now stand, unless someone comes up with a different way of restoring the circulator delay without cancelling out the indirect WH, I'm just going to live with what I have now. Through this exercise I've become a lot more familiar with how this thing operates, and just that has made it worth my while, and I would, most likely, never have found the disconnect inside that switch junction box.

Having watched how long it takes the boiler to cool down when there's no call for heat, I figure that between the indirect WH causing the boiler to fire up at least six times per 24 hours, and the zones calling for heat regularly, boiler temperature is hardly ever going to drop below 110 during the heating season, and in summer when it only supplies the indirect, zone circulator delay wouldn't have brought any benefit anyway.

Thanks, Trooper, rbeck, Thors Twins, and everyone else who piped up, for your help and your patience.
 
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Old 09-25-12, 04:20 PM
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I checked continuity between T-T an X-X,
I had a hunch... not sure if you had mentioned the 'transfer switch'... you should have! :bad poster:

What I haven't been able to determine yet is if the circulator delay feature now functions, and I'm waiting for the boiler to cool down to find out. I expect that it won't,
I too expect that it won't, in fact can't.

I'm quite certain that the zone pumps will run with the delay when the 3250-C1 is wired to 504-ZC.

What I'm still uncertain about is whether or not the indirect pump will run, so make sure to check that carefully.
 
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Old 09-25-12, 07:34 PM
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I had a hunch... not sure if you had mentioned the 'transfer switch'... you should have!
You're right, I should have. You would have had to track back through the links to when I first started asking questions about how to run two boilers on one heating system, way back on March 16th, and I realize that's too much to ask: mea culpa, mea maxima culpa.

I'm quite certain that the zone pumps will run with the delay when the 3250-C1 is wired to 504-ZC.
What I'm still uncertain about is whether or not the indirect pump will run, so make sure to check that carefully.
Maybe they would for a smarter, or more persuasive, guy than I, but for me they won't, not even after two Hail Marys and a Pater Noster, but maybe that's because I'm not of The Faith, although I'm not above shamelessly looking for help in the unlikeliest places.
 
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