Boiler TT terminals

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Voyager1947

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Your new boiler Honeywell control is a more sophisticated smart control and aquastat combined into one unit, it supplies its own 24v internally from the TT terminals and performs logic contol of the circulator.

The installer must have put a relay to isolate the two transformers so when either Tstat called a "dry contact" was made with the relay, basiclly to short the TT terminals, hence turning on the boiler.

You said you "removed this relay", what did you put in its place?

Are you sure you have the same type of zone vales as shown in that diagram?

Not sure I have the same type of zone valves, but every schematic I saw looked just like this one, so that's how I wired it after I removed the relay, I put nothing in place of the relay. I'm fairly confident the installer didn't put the relay in for any "electric" reason. At first he wired it without the relay, but couldn't make it work. He was trying all kinds of combinations of connecting the zone valve wires, does this go to terminal 1, lets try it on 2, no lets try it here, etc. I didn't have much confidence. Why he put the relay in, I don't know, but there was no discussion about isolating anything, or anything like that. All I know is that once he got it working, it was very loud when it operated, and being right under my bedroom, I had to do something. When I saw nothing about including a relay on anything that I researched, I removed it and wired as in the earlier post. As I say, it's been working fine since October and still works fine, it's just that occasional circulator run problem. Lately, I've been running one zone to see if it's zone valve related, but too early to tell
 

Houptee

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Oh ok i thought you meant this problem started after you removed the relay.

I would test it by removing the wires at TT and put your meter leads on the wires that were connected to TT, but set meter to Ohms setting to test for continuity, not Voltage setting.

Turn Tstats #1 and #2 down to lowest temp setting so they will not call for heat, you should now have both zone valves closed, and measure infinite resistance on the meter (an open circuit).

Now turn Tstat #1 up to 90 deg, zone valve 1 should open, and you should measure 0 ohms on meter (a closed circuit).

Now turn Tstat #1 back to low so zone vale 1 closes again and measure infinite on meter again (a open circuit)

Now turn Tstat #2 up to 90 deg, zone vale 2 should open, and you should measure 0 ohms on meter (a closed circuit).

If all that checks out then your Tstats and zone valves are wired correctly.

The problem with circulator running without a call for heat must be in the Honeywell unit.
Read the manual and try disabling the Anti Short Cycling, Thermal Purge, and Pump cycling features.
With all those disabled nothing other than the Tstats calling for heat should turn on the boiler and circ pump
 

Tom Sawyer

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Oh ok i thought you meant this problem started after you removed the relay.

I would test it by removing the wires at TT and put your meter leads on the wires that were connected to TT, but set meter to Ohms setting to test for continuity, not Voltage setting.

Turn Tstats #1 and #2 down to lowest temp setting so they will not call for heat, you should now have both zone valves closed, and measure infinite resistance on the meter (an open circuit).

Now turn Tstat #1 up to 90 deg, zone valve 1 should open, and you should measure 0 ohms on meter (a closed circuit).

Now turn Tstat #1 back to low so zone vale 1 closes again and measure infinite on meter again (a open circuit)

Now turn Tstat #2 up to 90 deg, zone vale 2 should open, and you should measure 0 ohms on meter (a closed circuit).

If all that checks out then your Tstats and zone valves are wired correctly.

The problem with circulator running without a call for heat must be in the Honeywell unit.
Read the manual and try disabling the Anti Short Cycling, Thermal Purge, and Pump cycling features.
With all those disabled nothing other than the Tstats calling for heat should turn on the boiler and circ pump


The problem is a sticking end switch on one of the zone valves.
 

Houptee

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Yes it could be bad end switch on a zone valve and all the more reason to put a Taco or equivalent type zone control on the system.

Then the end switches on the valves are not used any more since the zone control provides power to the valve coil to open and close valves and has separate XX contacts to trigger the TT circuit.

The cost of purchasing a replacement zone valve head is actually the same as the cost of a Taco ZVC403 control, and the advantage of the control is it cleans up and simplifies the system wiring and provides easy diagnostic visibility using the LEDs.

And in future you can use less expensive 2 wire zone valves since you don't need the 3 wire end switch type any more.

http://www.pexsupply.com/Taco-ZVC403-4-3-Zone-Valve-Control-Module-with-Priority
 

Voyager1947

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Oh ok i thought you meant this problem started after you removed the relay.

I would test it by removing the wires at TT and put your meter leads on the wires that were connected to TT, but set meter to Ohms setting to test for continuity, not Voltage setting.

Turn Tstats #1 and #2 down to lowest temp setting so they will not call for heat, you should now have both zone valves closed, and measure infinite resistance on the meter (an open circuit).

Now turn Tstat #1 up to 90 deg, zone valve 1 should open, and you should measure 0 ohms on meter (a closed circuit).

Now turn Tstat #1 back to low so zone vale 1 closes again and measure infinite on meter again (a open circuit)

Now turn Tstat #2 up to 90 deg, zone vale 2 should open, and you should measure 0 ohms on meter (a closed circuit).

If all that checks out then your Tstats and zone valves are wired correctly.




The problem with circulator running without a call for heat must be in the Honeywell unit.
Read the manual and try disabling the Anti Short Cycling, Thermal Purge, and Pump cycling features.
With all those disabled nothing other than the Tstats calling for heat should turn on the boiler and circ pump

The readings are exactly as you describe, the only thing is it takes a minute or so to go from open to close and back, but I think I've read where that's normal with these Taco valves, as some wax has to melt or some such. Also, these are Taco 571s and they have a small schematic on them showing the wiring, also showing a transformer, and it's wired just like that.

Also, the purge settings and such are all set to 0. I've read about this short cycling stuff, and supposedly it's a thermostat setting, but mine are digital and I don't find anything about that. There are settings for the type of system, oil, heat pump, etc., but those all look ok.
 

Tom Sawyer

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Yes it could be bad end switch on a zone valve and all the more reason to put a Taco or equivalent type zone control on the system.

Then the end switches on the valves are not used any more since the zone control provides power to the valve coil to open and close valves and has separate XX contacts to trigger the TT circuit.

The cost of purchasing a replacement zone valve head is actually the same as the cost of a Taco ZVC403 control, and the advantage of the control is it cleans up and simplifies the system wiring and provides easy diagnostic visibility using the LEDs.

And in future you can use less expensive 2 wire zone valves since you don't need the 3 wire end switch type any more.

http://www.pexsupply.com/Taco-ZVC403-4-3-Zone-Valve-Control-Module-with-Priority

No it doesn't. The ZVC controllers use all three terminals on the 504 zone heads. The XX terminals are dry contacts
A 504 head is about 70 bucks, the whole controller is over a hundred.
 
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Houptee

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Tom Sawyer

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The readings are exactly as you describe, the only thing is it takes a minute or so to go from open to close and back, but I think I've read where that's normal with these Taco valves, as some wax has to melt or some such. Also, these are Taco 571s and they have a small schematic on them showing the wiring, also showing a transformer, and it's wired just like that.

Also, the purge settings and such are all set to 0. I've read about this short cycling stuff, and supposedly it's a thermostat setting, but mine are digital and I don't find anything about that. There are settings for the type of system, oil, heat pump, etc., but those all look ok.

The amp setting on the thermostats needs to be set to .9 amps. There's probably a dip switch in the thermostat.
Taco 571's use terminals 2 & 3 (middle and bottom) to switch. The 504 controller has no way of knowing if the valve is open or closed if you only use two wires. Who's thermostats are you using?
 

Voyager1947

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The amp setting on the thermostats needs to be set to .9 amps. There's probably a dip switch in the thermostat.
Taco 571's use terminals 2 & 3 (middle and bottom) to switch. The 504 controller has no way of knowing if the valve is open or closed if you only use two wires. Who's thermostats are you using?

Honeywell RTH221. The L7248 and the manual says the same, set heat anticipator to .9 amps. From what I read, if that setting was wrong I would be short cycling, but that don't seem to be happening. I also can't find a way to adjust that anyway with the thermostat manual that I have. A google search shows that it mainly applies to mercury type thermostats.
 

DonL

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I don't think that T-stat will have a heat anticipator. Not current driven. That was Old School.

It calculates the setting and the adjusts to the environment.

The current that the system uses does not mater, as long as it can carry the load.

The T-Stat most likely will not measure current, it goes by Temp rise and fall. Then it stores that info into memory and uses it.


Have fun.
 
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Tom Sawyer

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It did apply mostly to mercury thermostats but some of the early digitalis have dip switches to set heat anticipation. I'm betting on a sticking zone valve end switch. You can try taking it off and spraying the insides down with contact cleaner.
 

Houptee

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Another option you could do is get rid of the zone valve system and have 2 circulators, one for each zone.

I just got an email today from Taco about a free webinar next week Feb 27 and 28, 2014

"Zone Valves or Circulators? The Ultimate Debate"

It's a question asked all the time. Both have advantages, both have drawbacks, but in our latest FloPro webinar, we'll separate fact from opinion and give you the straight scoop, so you can make the best choice for your customers.
There IS an answer to this question. Find out what it is in this fast-paced, fact-filled one-hour online webinar.
 

Voyager1947

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Another option you could do is get rid of the zone valve system and have 2 circulators, one for each zone.

I just got an email today from Taco about a free webinar next week Feb 27 and 28, 2014

"Zone Valves or Circulators? The Ultimate Debate"

It's a question asked all the time. Both have advantages, both have drawbacks, but in our latest FloPro webinar, we'll separate fact from opinion and give you the straight scoop, so you can make the best choice for your customers.
There IS an answer to this question. Find out what it is in this fast-paced, fact-filled one-hour online webinar.

Getting rid of the valves and putting in another circulator would be out of the question for me, I don't have the skills and it would be cost prohibitive to hire someone. So far, with the one zone that I am running, I have had no failures, I wan't to give it a few more days before I switch zones to see how the other one reacts. However it turns out, I surely appreciate everyone's input on this.
 

Tom Sawyer

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Getting rid of the valves and putting in another circulator would be out of the question for me, I don't have the skills and it would be cost prohibitive to hire someone. So far, with the one zone that I am running, I have had no failures, I wan't to give it a few more days before I switch zones to see how the other one reacts. However it turns out, I surely appreciate everyone's input on this.

Here's a sure fire way to tell if its the zone valve end switch.

Turn a thermostat down and thE other one up. The circulator should be running. Wait two minutes and pull the wire that is closest to the valve body of the off zone. If the circulator stops, that valve head is bad. If the circulator keeps running turn the other thermostat down, wait two minutes and pull the wire. If the circulator stops it's that valve head.
 

Voyager1947

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Here's a sure fire way to tell if its the zone valve end switch.

Turn a thermostat down and thE other one up. The circulator should be running. Wait two minutes and pull the wire that is closest to the valve body of the off zone. If the circulator stops, that valve head is bad. If the circulator keeps running turn the other thermostat down, wait two minutes and pull the wire. If the circulator stops it's that valve head.

Tom, not sure I understand what you mean when you say "pull the wire that is closest to the valve body of the off zone". Terminal 3 would make sense, is that what you mean. That's the one that is closest to the actual water line. I think I've seen it referred to as the end switch.
 

Tom Sawyer

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Yep, terminal 3. I was trying to keep it simple for those that don't know which is terminal 3 but you get the idea.
 
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