Post Purge with Zone Valves

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  #1  
Old 12-30-11, 05:45 PM
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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
 
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  #2  
Old 12-30-11, 06:01 PM
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I'm not even gonna try tonight! Sam Adams says not to...

How about a 'theory of operation' ?
 
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Old 12-30-11, 06:03 PM
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OK,
But i thought you wanted to decipher it.

give me a few..

Peter
 
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Old 12-30-11, 07:02 PM
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Well... I do... but Sam won't let me!
 
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Old 12-30-11, 07:22 PM
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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
 
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Old 12-30-11, 07:30 PM
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Well... I do... but Sam won't let me!
LOLOLOLOL
Been there done that
too many times,
 
  #7  
Old 12-30-11, 08:24 PM
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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
 
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Old 12-30-11, 08:41 PM
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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
 
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Old 12-31-11, 07:13 AM
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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?
 
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Old 12-31-11, 07:28 AM
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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
 
  #11  
Old 12-31-11, 07:31 AM
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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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Old 12-31-11, 07:36 AM
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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
 
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Old 12-31-11, 11:06 AM
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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?
 
  #14  
Old 12-31-11, 12:19 PM
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OK I see it now. That is a coil babove the two parallel lines. I did not realize at first this was a relay coil.
Sorry.
 
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Old 12-31-11, 01:48 PM
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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]
 

Last edited by NJT; 01-02-12 at 05:59 PM.
  #16  
Old 12-31-11, 01:53 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
 
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Old 12-31-11, 01:57 PM
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Thanks RBeck, because you made me realize there is an error in the design.

Peter
 
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Old 12-31-11, 02:03 PM
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Hello NJT,

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 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.

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.
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.

The core of the logic here seems to be the use of the 3PDT switching to 'transfer' zone valve control to the PP mode.
Yes, plus the relay to allow the zone thermostat to take back control. is also key.

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?
Yes, exactly.

Peter
 
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Old 12-31-11, 02:13 PM
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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
 
  #20  
Old 12-31-11, 02:50 PM
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What are you using to draw with???
PaintShop Pro... older version. PhotoShop would work too...

All that needs to be done would be to draw the 24v hot connection to the realy for the zone valve.
Yeah, that's why I labeled the 24V as com and hot...

However, i don't know any easy way to tell if a different zone is calling without using the ZVC.
I've got an idea for yet another relay... jeeze! Will the cost be worth the end result?
 
  #21  
Old 12-31-11, 03:55 PM
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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.



jeeze! Will the cost be worth the end result?
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
 
  #22  
Old 12-31-11, 05:45 PM
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The label on the 24v transformer is 15va.
I'm sure there's enough there to run a few relays at a couple hundred milliamps each.

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 08:34 PM.
  #23  
Old 01-01-12, 08:39 PM
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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]
 

Last edited by NJT; 01-02-12 at 06:00 PM.
  #24  
Old 01-01-12, 09:07 PM
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Yes, I believe it can...

[no, it can't... drawing deleted, revised version later in thread]

Somebody check my brain...
 

Last edited by NJT; 01-02-12 at 06:01 PM.
  #25  
Old 01-01-12, 09:11 PM
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And lastly, if there is no zone panel, discrete wiring:

[drawing deleted, this won't work either, revised version later in thread]
 

Last edited by NJT; 01-02-12 at 06:02 PM.
  #26  
Old 01-01-12, 09:14 PM
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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...
 
  #27  
Old 01-01-12, 10:47 PM
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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
 

Last edited by PeterNH; 01-01-12 at 11:25 PM.
  #28  
Old 01-01-12, 11:08 PM
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#27
What keeps the circulator off until the valve opens?


Peter
 
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Old 01-01-12, 11:22 PM
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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]
 

Last edited by NJT; 01-02-12 at 06:03 PM.
  #30  
Old 01-01-12, 11:25 PM
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If you use the existing control, for the circulator...
What keeps the burner from firing....????
The absence of a heat call...

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.
 
  #31  
Old 01-01-12, 11:27 PM
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#27 What keeps the circulator off until the valve opens?
Darn you!

hmmmm... nothing.

So THAT's what that other relay is for!

Back to the drawing board!
 
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Old 01-01-12, 11:34 PM
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Darn you!

hmmmm... nothing.

Back to the drawing board!
It a great thing to clean up my crappy drawing,
but another thing all together
to start messin' w'it my design


lol

P
 
  #33  
Old 01-01-12, 11:38 PM
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It a great thing to clean up my crappy drawing,
but another thing all together
to start messin' w'it my design
Ya know, I looked at that third relay... and looked at it ... and looked at it ... and thought "what the heck that's there for? Just add another pole to the relay!" ....

EHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

Wrong!

I'll put it back tomorrow.

night.
 
  #34  
Old 01-01-12, 11:39 PM
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re #31
i have to scroll, over and over to see it, on this little net book
so i need some time.

I'll sle ep on it and i'll get back to you in the morning.

Peter
 
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Old 01-02-12, 12:16 AM
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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
 
  #36  
Old 01-02-12, 03:47 AM
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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.
 
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Old 01-02-12, 05:39 AM
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Hi GO,
Glad for the input.
A timer would cost more than the original plan.
Thanks anyway,

Peter
 
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Old 01-02-12, 11:05 AM
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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..."
 
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Old 01-02-12, 11:25 AM
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icm,202 delay on make, 6.25 dollars,pex supply.com don't know the shipping cost though.
 
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Old 01-02-12, 11:37 AM
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deleted... mistake in drawing...
 

Last edited by NJT; 01-02-12 at 05:55 PM.
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