Post Purge with Zone Valves
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Post Purge with Zone Valves
Hello Friends,
Well here it is, Alpha verison 1.
I'm sure there are more than a few different ways to do this.
Here is one try. I think it will work.
http://home.comcast.net/~k16862/hsym2.bmp
Good sized download please be calm.
Givens:
The purge can only work on a specific zone(s)
A Taco ZVC is needed, as an easy way to signal if another zone is calling for heat, in order to terminate the purge.
Based on NJT's Post Purge method with circulator pumps.
Fire away, ask questions, tell me why it won't work,
offer improvements and simplifications, etc.
Happy New Year,
Peter
Well here it is, Alpha verison 1.
I'm sure there are more than a few different ways to do this.
Here is one try. I think it will work.
http://home.comcast.net/~k16862/hsym2.bmp
Good sized download please be calm.
Givens:
The purge can only work on a specific zone(s)
A Taco ZVC is needed, as an easy way to signal if another zone is calling for heat, in order to terminate the purge.
Based on NJT's Post Purge method with circulator pumps.
Fire away, ask questions, tell me why it won't work,
offer improvements and simplifications, etc.
Happy New Year,
Peter
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How it works.
(hopefully)
Pick a zone to purge to.
When the thermostat for this zone calls for heat, the call closes a set of contacts on a double pole, double throw, 24v, relay,(R1) and is passed on to the ZVC in a normal manner.
At the same time another set of contacts is opened on this same relay and turns off everything pertaining to the post purge. Thus allowing the zone to make a normal call for heat as needed.
The Z1 heat call ends, there is excess heat in the boiler:
The aquastat (A1,) tied to the supply pipe of the boiler, closes as the temp is above (? 90). Relay R1 above, turns off and the normally closed set of contacts, closes. 24V power flows thru R1, thru the a'stat, thru the Normally Closed end Switch on the ZVC, and energizes relay R2.
*If, any time, during this post purge process, another zone calls for heat, the end switch, on the ZVC opens and stops the post purge process.*
Relay R2, when it is Off, shunts the connections from the ZVC to the Zone valve in a normal fashion.
When R2 turns on:
24v power to the zone valve heater, is shunted from the ZVC, to open the valve. When the valve opens, the end switch on the valve is wired thru R2 and 24v power to relay R3.
This closes realy R3 and sends 120 volt power to the Circulator pump. Thus finally, sending the remaining heat out of the boiler and into zone 1.
Whenever the water finally cools off, A1 opens and the post purge process shuts down.
Again, at any time, a call for heat from Zone 1 stops the process, as does a call from any other zone connected to the ZVC.
Also of note, the circulator can not run until the zone valve opens.
And of course, any other zone that finsihes a heat call, and leaves hot water in the suppy pipe, will also initiate the process, not just zone 1.
Peter
(hopefully)
Pick a zone to purge to.
When the thermostat for this zone calls for heat, the call closes a set of contacts on a double pole, double throw, 24v, relay,(R1) and is passed on to the ZVC in a normal manner.
At the same time another set of contacts is opened on this same relay and turns off everything pertaining to the post purge. Thus allowing the zone to make a normal call for heat as needed.
The Z1 heat call ends, there is excess heat in the boiler:
The aquastat (A1,) tied to the supply pipe of the boiler, closes as the temp is above (? 90). Relay R1 above, turns off and the normally closed set of contacts, closes. 24V power flows thru R1, thru the a'stat, thru the Normally Closed end Switch on the ZVC, and energizes relay R2.
*If, any time, during this post purge process, another zone calls for heat, the end switch, on the ZVC opens and stops the post purge process.*
Relay R2, when it is Off, shunts the connections from the ZVC to the Zone valve in a normal fashion.
When R2 turns on:
24v power to the zone valve heater, is shunted from the ZVC, to open the valve. When the valve opens, the end switch on the valve is wired thru R2 and 24v power to relay R3.
This closes realy R3 and sends 120 volt power to the Circulator pump. Thus finally, sending the remaining heat out of the boiler and into zone 1.
Whenever the water finally cools off, A1 opens and the post purge process shuts down.
Again, at any time, a call for heat from Zone 1 stops the process, as does a call from any other zone connected to the ZVC.
Also of note, the circulator can not run until the zone valve opens.
And of course, any other zone that finsihes a heat call, and leaves hot water in the suppy pipe, will also initiate the process, not just zone 1.
Peter
#7
Peter what happens if I set this up and because of temp overshoot I assume, as an example, set my t stat to say 67f to get a nice 70f in the home.
But now the t stat will not kick back on until the home cools 3f. This will be uncomfortable.
Mike NJ
But now the t stat will not kick back on until the home cools 3f. This will be uncomfortable.
Mike NJ
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Hello Mike,
Could happen. You think there is that much heat left over?
Shame to waste it, if there is.
How about dumping it upstairs?
Using a second R2 relay, you could dump it to both zones at once, if you think that might help?
Otherwise NJT says his smart thermostat "learned" the overshoot and mostly comensates for it.
Wish that Indoor reset guy would answer you.
That might be the best plan.
Peter
Could happen. You think there is that much heat left over?
Shame to waste it, if there is.
How about dumping it upstairs?
Using a second R2 relay, you could dump it to both zones at once, if you think that might help?
Otherwise NJT says his smart thermostat "learned" the overshoot and mostly comensates for it.
Wish that Indoor reset guy would answer you.
That might be the best plan.
Peter
#9
Am I missing something or will the transformer have a direct short when the end switch closes? Wouldn't you have to have the common side go directly to terminal 2 on the zone valve and not trough the end switch. You would not have to switch a neutral.
Thoughts?
Thoughts?
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Hello RBeck,
I'm not sure i understand your question. But it might depending on the polarity, i think...
But i do think it was a mistake to try and use the internal 24v on the ZVC to open the valve.
I think a better solution would be to totally isolate the valve from the ZVC and then supply the needed power.
Perhaps you could reframe your comments as your thoughts are ahead of my understanding.
Peter
I'm not sure i understand your question. But it might depending on the polarity, i think...
But i do think it was a mistake to try and use the internal 24v on the ZVC to open the valve.
I think a better solution would be to totally isolate the valve from the ZVC and then supply the needed power.
Perhaps you could reframe your comments as your thoughts are ahead of my understanding.
Peter
#11
I was referring to the external transformer. I believe then the end switch closes the transformer is a dead short between the transformer and the end switch on the zvc,
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No, it goess thru(turns on) the relay that runs the ciirculator.
But you comments, have me thinking, that i might not have the power to the valve heater set up -correctly..
Peter
But you comments, have me thinking, that i might not have the power to the valve heater set up -correctly..
Peter
#13
Peter, I've studied it... and think the logic is all good... but I'm going to re-draw with some different symbols that I'm more used to, and in so doing will understand it even better.
I'm not sure either about robbing the power from the ZVC panel in that fashion is a good idea... Don't they all have terminals for the purpose these days? I know the older ones did not, but I believe the newer ones do.
I'm also going to look at your ideas in terms of a system with no ZVC and discrete wiring, and also applications for the Honeywell valve.
The core of the logic here seems to be the use of the 3PDT switching to 'transfer' zone valve control to the PP mode.
One question... The circulator relay shown... I presume the intent is for that relay to shunt the normal circulator relay and is only drawn that way for clarity, correct?
I'm not sure either about robbing the power from the ZVC panel in that fashion is a good idea... Don't they all have terminals for the purpose these days? I know the older ones did not, but I believe the newer ones do.
I'm also going to look at your ideas in terms of a system with no ZVC and discrete wiring, and also applications for the Honeywell valve.
The core of the logic here seems to be the use of the 3PDT switching to 'transfer' zone valve control to the PP mode.
One question... The circulator relay shown... I presume the intent is for that relay to shunt the normal circulator relay and is only drawn that way for clarity, correct?
#15
Here's a preliminary stab at my redraw, which I can follow a little better... (no offense Peter, but I just don't like that style of showing relay contacts... even if Honeywell does... it's that old school EE ejumication ya know)]
[drawing removed, final version later in thread]
[drawing removed, final version later in thread]
Last edited by NJT; 01-02-12 at 04:59 PM.
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I'm with you all the way NJT.
Especially on the symbols.
What are you using to draw with???
Long ago, i knew how to use Visio, now i'm lost and forgotten it.
I did what i did with MS Paint and it was painful.
I'll answer you other thoughts in a few.
Peterr
Especially on the symbols.
What are you using to draw with???
Long ago, i knew how to use Visio, now i'm lost and forgotten it.
I did what i did with MS Paint and it was painful.
I'll answer you other thoughts in a few.
Peterr
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Hello NJT,
I'm not so sure either. Plus there is an error in the design, when the 3 pole closes, the power to the heat the zone valve is lost... Needs a little work in this area.
That's good 'cause i know a lot of folks will be looking for it.
However, i don't know any easy way to tell if a different zone is calling without using the ZVC.
Yes, plus the relay to allow the zone thermostat to take back control. is also key.
Yes, exactly.
Peter
I'm not sure either about robbing the power from the ZVC panel in that fashion is a good idea... Don't they all have terminals for the purpose these days? I know the older ones did not, but I believe the newer ones do.
I'm also going to look at your ideas in terms of a system with no ZVC and discrete wiring, and also applications for the Honeywell valve.
However, i don't know any easy way to tell if a different zone is calling without using the ZVC.
The core of the logic here seems to be the use of the 3PDT switching to 'transfer' zone valve control to the PP mode.
One question... The circulator relay shown... I presume the intent is for that relay to shunt the normal circulator relay and is only drawn that way for clarity, correct?
Peter
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You got it perfect NJT, first ry, i knew you would audit my work and help fi it.
Thanks.
All that needs to be done would be to draw the 24v hot connection to the realy for the zone valve.
I managed to leave mom alone for a few hours today and wen to the electronics surpuls store in
Manchester today.
Got a whole bag full of 2, 3 and 4 pole DT relays plus sockets and a rail for 40 bucks.
I'm going to build it next week, time permitting.
In a few minute, i'm going down the cellar and look under the cover of the ZVC 6 and 3 that are down there, for 24v availability..
Peter
Thanks.
All that needs to be done would be to draw the 24v hot connection to the realy for the zone valve.
I managed to leave mom alone for a few hours today and wen to the electronics surpuls store in
Manchester today.
Got a whole bag full of 2, 3 and 4 pole DT relays plus sockets and a rail for 40 bucks.
I'm going to build it next week, time permitting.
In a few minute, i'm going down the cellar and look under the cover of the ZVC 6 and 3 that are down there, for 24v availability..
Peter
#20
What are you using to draw with???
All that needs to be done would be to draw the 24v hot connection to the realy for the zone valve.
However, i don't know any easy way to tell if a different zone is calling without using the ZVC.
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Hello NJT,
On both ZVC's i have, there is no provision for 24v power anywhere.
The SR501 i have has an extra 24v common up by the T'stat connection for power to "some progamable thermostats" there is no indication of how much current is available. The label on the 24v transformer is 15va.
Dunno', i gotta' make one and find out.
The relays are not that bad, but they get ya' on the sockets.
A budget install, i guess we could solder the 24v wires directly to the relays to save $$$.
I'm using the sockets.
3a 24v 4pdt new NTE, $11.00 ea, socket 8.00
2-10a 24v dpdt new NTE, $8.00 ea, sockets, 7.50 ea
:
A question for the august NJT,
I'm sure it is not kosher, to have the screw terminal on the 120v relay socket for the circulator, out in the open on a din rail.
What method would you reccomend for mounting this relay.
(tape over the screws?) or?
I'm sure putting the 24v wires in a 120v handy box, is not too kosher either...
Peter
On both ZVC's i have, there is no provision for 24v power anywhere.
The SR501 i have has an extra 24v common up by the T'stat connection for power to "some progamable thermostats" there is no indication of how much current is available. The label on the 24v transformer is 15va.
jeeze! Will the cost be worth the end result?
The relays are not that bad, but they get ya' on the sockets.
A budget install, i guess we could solder the 24v wires directly to the relays to save $$$.
I'm using the sockets.
3a 24v 4pdt new NTE, $11.00 ea, socket 8.00
2-10a 24v dpdt new NTE, $8.00 ea, sockets, 7.50 ea
:
A question for the august NJT,
I'm sure it is not kosher, to have the screw terminal on the 120v relay socket for the circulator, out in the open on a din rail.
What method would you reccomend for mounting this relay.
(tape over the screws?) or?
I'm sure putting the 24v wires in a 120v handy box, is not too kosher either...
Peter
#22
The label on the 24v transformer is 15va.
15VA on a 24V transformer is about 1.6 A [ooops... no it's not, more like] 0.625 A or so... thereabouts anyway.
I'm headin' out ... goin' to the neighbors for a few yards of ale...
HAPPY NEW YEAR!
Last edited by NJT; 01-01-12 at 07:34 PM.
#23
How about this for a Honeywell valve?
Note that a relay has been removed... not needed. I think this relay can also be removed from the Taco design.
[drawing deleted, revised version later in thread]
Note that a relay has been removed... not needed. I think this relay can also be removed from the Taco design.
[drawing deleted, revised version later in thread]
Last edited by NJT; 01-02-12 at 05:00 PM.
#26
And this last drawing made me realize that the ones with the zone panels can be changed around too... instead of using a single thermostat to trigger the post purge, the ENDSWITCH on the zone panel can be used, as in the discrete model...
more to come...
more to come...
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--Brain check--
If you use the existing control, for the circulator...
What keeps the burner from firing....????
ok, i guess you could mix nasty 120v to a set of the relay contacts and wire around 1k2, directly to zc and c1.
but there still remains one other..., see the next post....
Peter
If you use the existing control, for the circulator...
What keeps the burner from firing....????
ok, i guess you could mix nasty 120v to a set of the relay contacts and wire around 1k2, directly to zc and c1.
but there still remains one other..., see the next post....
Peter
Last edited by PeterNH; 01-01-12 at 10:25 PM.
#29
What are you still doing up? I'll peruse your questions in a minnit... look at this one in the meantime and tell me if you think it will work...
Here's my last stab... this is the original Taco and ZVC with only 2 relays, a single pole and a 4 pole.
[drawing deleted, revised version later in thread]
Here's my last stab... this is the original Taco and ZVC with only 2 relays, a single pole and a 4 pole.
[drawing deleted, revised version later in thread]
Last edited by NJT; 01-02-12 at 05:03 PM.
#30
If you use the existing control, for the circulator...
What keeps the burner from firing....????
What keeps the burner from firing....????
The 4th pole of the relay is wired from L1 to C1 in the aquastat, it will only run the circ... it's not wired to the T T ... that comes from the endswitch of the Taco panel as usual.
#32
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Darn you!
hmmmm... nothing.
Back to the drawing board!
hmmmm... nothing.
Back to the drawing board!
but another thing all together
to start messin' w'it my design
lol
P
#33
It a great thing to clean up my crappy drawing,
but another thing all together
to start messin' w'it my design
but another thing all together
to start messin' w'it my design
EHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
Wrong!
I'll put it back tomorrow.
night.
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re re#31
ok NJT, here's my 2 cents:
The ZVC doesn't close it's end switches until and end switch on a zone valve closes. If there was a way to just sense a thermostat call, this would be easier.
However. Since the "purging" zone's valve is "relayed" out of the normal circuit, there is no way to re-trigger a call from the purging zone. A heat call would have to wait for the A'stat to cool down and open, to break the cycle.
Now, maybe this doesn't matter... ?
And can actually help the typical short-cycle situation.
But, if the door is open and a lot of cold air is pouring in, and a lot of heat is needed, right now, it might not be the best set-up.
On the other hand, this purge zone my be a bit overheated already and it might not ever matter.
Otherwise i like it!
Of course it's a given the circulator relay is put back.
Peter
ok NJT, here's my 2 cents:
The ZVC doesn't close it's end switches until and end switch on a zone valve closes. If there was a way to just sense a thermostat call, this would be easier.
However. Since the "purging" zone's valve is "relayed" out of the normal circuit, there is no way to re-trigger a call from the purging zone. A heat call would have to wait for the A'stat to cool down and open, to break the cycle.
Now, maybe this doesn't matter... ?
And can actually help the typical short-cycle situation.
But, if the door is open and a lot of cold air is pouring in, and a lot of heat is needed, right now, it might not be the best set-up.
On the other hand, this purge zone my be a bit overheated already and it might not ever matter.
Otherwise i like it!
Of course it's a given the circulator relay is put back.
Peter
#36
sorry to intrude, haven't really read or studied you thread or diagram but there is a simple timer used in ac,adj. from about 2sec to about 10 minutes low or high voltage should not be more then about 20.00 dolllars you might find usefull somewhere.it just breaks one leg and there is a knob to adj.
#38
A simple timer has been brought up as an alternative a few times. It could cost more, depends on how much of the work was DIY, and how carefully one shopped for parts.
Peter, I'll be posting a new diagram a bit later... it's a complete re-write... "I had a dream..."
Peter, I'll be posting a new diagram a bit later... it's a complete re-write... "I had a dream..."