# Adding a radiant heat zone -hydronic experts



## Joe F (Jan 27, 2008)

I am in the process of adding a single hydronic radiant zone to my existing hot water baseboard (boiler) system. I've done quite a bit of research, however I am not sure if my design is up to snuff and have had some difficulty in converting my plan to a parts list. Most companies I have contacted have provided minimal "tech support". So, I have a design that I think is workable, but no "shopping list".

I have attached a diagram of my system with some specific questions highlighted in blue. Any help and/or constructive criticism is greatly appreciated.


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## Clutchcargo (Mar 31, 2007)

Check out Taco's library. Under "systems" there's quite a bit on radiant systems.


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## tk03 (Sep 30, 2008)

Your basic plan is OK except for the return from the bathrooms need to be between the circulator and the boiler. You do not want the return from the bathrooms to have to push through a non-operating circulator.
To operate the pump and zone valve you will need a floor sensor or thermostat. The floor sensor is for a lightweight gypcrete pour and a thermostat is going to be affected by the humidity.
I would run the radiant pump 24/7 through the winter months and adjust the mixing valve to the proper temperature to keep the bathrooms at the temperature I desired. I did this with my kitchen and it worked well except I need to turn the circulator power switch on in fall and off in spring and also had to close/open a valve also. 
There are thermostats designed for high humidity areas. What is the part number of the Taco box? I will guess ZVC504. If you are going to use a thermostat I would change the Taco box big enough for your system (6 zone) and upgrade to an EXP version. Then you can easily add outdoor reset (plug in module) either now or at a later date.
BTW your boiler circulator is way oversized.


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## Joe F (Jan 27, 2008)

Thanks TK, this is starting to make a little more sense to me. I understand the reason for "bypassing" the main circulator. 

If I understand the rest correctly, there are two options 1. Use a floor sensor or thermostat to control the pump and zone valve (do I need a zone valve) OR 2. Run the pump 24/7 and adjust the mixing valve to the desired floor temp (if no other zone is calling for heat, cold water will circulate).

My current Taco control box is the 3 zone version. I would upgrade to a 5 or 6 zone to support the new setup. Are the Taco control boxes capable of controlling multiple pumps in different zones?

Funny you mention my circulator pump being oversized. I got a copy of Taco's pump selection chart and after doing all the math for length, number of elbows and tee's etc... I calculated that I need a 0013. My current pump is actually a 007. The chart also makes me think I need a 0014 for the radiant zone. Do I need to reread the directions and recalculate?


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## beenthere (Oct 11, 2008)

Joe F said:


> Do I need to reread the directions and recalculate?


I think so.

Not too many residential systems have a zone with 27 foot of head that the circ needs to work against to move 10 GPM.

And your radiant zone should be over 20 foot of head.


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## Joe F (Jan 27, 2008)

Bear with me, the light bulb is starting to glow (a little).
In my initial calculation, I used 3/4" for the piping (zone pipe size). When I recalculate using 1 1/4" pipe size (that's the size coming out of the boiler into the pump), I get 7 feet of head rather than 25. If I understand you correctly, the radiant zone will be pulling more head because of the smaller pipe size i.e my 0014 pump calculation might be close, but I'll recompute. How do you plumb this pump? 3/4" copper reduced to 1/2" PEX on the input and output? As a single zone, I assume I calculate based on 1/2" PEX.


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## beenthere (Oct 11, 2008)

You calculate the resistance of all the pipe the water is traveling through. Plus all fittings, including the zone valves. You calculate it for all the loops, and then size to the the longest loop.
If the shortest loop, has too little resistance, then you use balancing valves to control its flow. 


The radiant loop is calculated the same way, and you include the mixing valve in the calc. 

You can pipe 3/4 from the circ and mixing valve and then connect your pex.


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## Joe F (Jan 27, 2008)

Thanks for all the help so far :thumbup:

I did a rough recalculation on the pump size and came up with a 007 for the main system (which is what I have) and a 0011 for the radiant zone (based on an estimated 200' loop). Sounds better, right? I'll take real measurements and double check everything this weekend.

I guess the only piece I don't understand is how to control the radiant zone pump. I know a zone control box will work for the zone valve, but how do I wire in a circulator that will only be supporting the one zone? I don't see that the zone control box has provisions to do that (pump & valve).

Here's a picture of my plan based on the latest updates.


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## beenthere (Oct 11, 2008)

The easy way, is to just use a circ relay for the radiant zone, instead of going through the same zone valve control panel as the other zones.
And use a flow check instead of a zone valve on the radiant loop.

Just curious. What head pressure did you come up with for your longest regular loop, and what head pressure for your radiant loop.
How much head pressure did you allow for zone valve.


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## Joe F (Jan 27, 2008)

The flow check would go before the mixing valve? (same place I have the radiant zone valve shown) and T-stat would wire into the pump relay. How does the boiler get the heat call? Tie in with the same wires from the existing zone controller?

I came up with 6.2 for the regular loop and 23 for the radiant. Those numbers are based on system measurements from memory. I stilll need to do actual measurements and figure out which is my longest loop. I just wanted to make sure that I am doing the calculations correctly. 

The chart I have lists a head of 10 for a 1/2 inch zone valve and 20 for a 3/4 zone valve. It doesn't give a number for a mixing valve, so I used the zone valve number. FYI the flow check will add 143. For the fittings and valves, the Taco chart uses effective length in feet vice pressure.


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## beenthere (Oct 11, 2008)

The flow check would be installed after the mixing valve.
Thats 20 foot at 6 gallons a minute.

You shouldn't have a ¾" loop moving 6 gallons a minute.

What GPM did the flow check list.


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## Joe F (Jan 27, 2008)

beenthere said:


> The flow check would be installed after the mixing valve.
> Thats 20 foot at 6 gallons a minute.
> 
> You shouldn't have a ¾" loop moving 6 gallons a minute.
> ...


You're starting to go over my head a bit, but the chart only gave a single number for each component. Flow chek was 143. I couldn't find a GPM for the Flow check on Taco's site. 

6 gpm is way too much, right.


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## beenthere (Oct 11, 2008)

Joe F said:


> You're starting to go over my head a bit, but the chart only gave a single number for each component. Flow chek was 143. I couldn't find a GPM for the Flow check on Taco's site.
> 
> 6 gpm is way too much, right.


For 3/4" it is.

The flow check should have had a Cv listing.
With that, and knowing the GPM of the loop, the PD/foot of head of the flow check can be found.

This is the knowledge, that contracting companies don't provide. Because they don't get paid for their training, and time then.


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## Joe F (Jan 27, 2008)

Taco lists the Equivalent feet/Cv as:

143/2.5 for part #219 3/4 (bronze)

35.8/5 for part #218 3/4 (cast)

Seems like an awfully big difference.


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## beenthere (Oct 11, 2008)

The cast iron models have a larger internal opening then the sweat models do.

So they have less resistance.


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## beenthere (Oct 11, 2008)

The cast iron will flow 5GPM at the same PD that the sweat flows 2.5 GPM.

Vertical flow checks are worst yet.


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## Joe F (Jan 27, 2008)

I called Taco to see what they recommended. The tech rep suggested using a ZVC-405 Zone Control box and SR-501 pump relay for the radiant zone circulator. I'm supposed to connect terminal #2 on the zone valve (or ZVC) to "T" terminal on the SR 501 and terminal #3 on the zone valve to the other "T" terminal on the SR 501.


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## beenthere (Oct 11, 2008)

Yea.

2 and 3 of the zone valve go to the circ relay(501).

Where are you getting power from to operate the zone valve?


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## Joe F (Jan 27, 2008)

I plan on wiring the zone valve from the ZVC (3 wires). I assume one of those is power (24v?)


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## beenthere (Oct 11, 2008)

Don't think you want to connect terminal 3 of the ZVC to the zone valve, and also to the 501.

You'll have transformers bucking each other.

And, the ZVC will turn on its circulator when the zone valve opens.


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## beenthere (Oct 11, 2008)

As I recall, the Sr501 can use an external 24volt input.
But no the way you were told by tech support.

You can't use both of the TT terminals if you want to use an external 24 volts.

You have to use the W terminal, and the 24 volt Com terminal.

Then you can wire the zone valves 2 and 3 to the 501 and ZVC.

But, the ZVC will still run its circulator that way.

Your better off wiring the 1 an 2 of the zone valve to the ZVC.
And then 2 and 3 to the 501 TT terminals. As long as the ZVC doesn't receive a signal back to its 3 terminal, it won't run its circulator.


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## Joe F (Jan 27, 2008)

I printed out the ZVC and SR501 Instructions and re-read my notes from the Taco call. Tech said to jumper 3 and 4 on the ZVC, then connect ZVC term #2 to #2 on the zone valve or TT on the SR501 (same with term #3 to #3 or TT on the SR501). Looking at the schematic, I can't tell what that does. I would have thought that the SR501 provided 24vac for the T-stat, I guess that's not the case. Does the SR501 need a 24v transformer in all applications?


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## beenthere (Oct 11, 2008)

The 501 has its own transformer.

It generally isn't enough VA to open a Taco zone valve though.

Personally, I would use a flow check and no zone valve and make things simple.


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## Joe F (Jan 27, 2008)

I'm with you now on the flow check, the simpler solution makes more sense. In this arrangement, how does the call for heat get to the boiler? Is there a way to send the signal from the 501 thru the ZVC to the boiler or do I run the TT wires from the 501 to the TT lugs on the boiler?

My latest plan:


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## beenthere (Oct 11, 2008)

Either wire the 501's end switch terminals parallel to the end switch terminals at the ZVC, or at the boiler with the ZVC wires.

Either way will work. And either one can call for the boiler to run.


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## Joe F (Jan 27, 2008)

Sorry if I'm oversimplifying, but looking at the schematics, there is no terminal labeled "end switch" on the 501. I believe terminals 6 n/o and 5 are the ones I want. Also, the ZVC has terminals labeled "extra end switch. I think that connecting 6 n/o and 5 on the SR501 to "extra end switch" on the ZVC will give me the desired result.


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## beenthere (Oct 11, 2008)

The N.O. 6 and 5 of the 501 are correct.

But on the ZVC, you connect to the end switch that the boiler is connected to.

An end switch is just a set of contacts. If you connect the 501's 6 and 5 to the extra, nothing will happen unless the boiler or some other device is also connected. 

It would be like wiring 2 light switches to each other without any lights or power.


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## Joe F (Jan 27, 2008)

beenthere,

I think I have everything I need. Thank you very much for taking me by the hand thru this plan. I know I owe you an adult beverage (probably two or three), but it might be a bit tough for me to deliver. Rest assured that I'll raise my glass to you when I sit down to enjoy a cold one tonight. Thanks :thumbsup:


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## beenthere (Oct 11, 2008)

Your welcome.


PS:

I still think, a 0011 is over kill for a circ for your radiant loop.

How many GPM did you use to calc the head loss.

That loop shouldn't need 1 GPM.


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## Joe F (Jan 27, 2008)

I forget what I used, so I just recalculated using 1 GPM. I cross reference to a 005 or 006. Does that sound more like what you'd expect?


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## beenthere (Oct 11, 2008)

I would think a 6 or an 8.


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## cudafish61 (Jan 12, 2010)

Hi Joe F I know this post is kind of old. I am looking to do the same thing you want to do. Add a low temp radiant zone to my existing boiler. My boiler has one main pump, I have 3 high temp zones using zone valves and a zone valve controller. I was wondering how you made out ? Maybe you can post a final sketch of you system. Any info would be great.

Thanks


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## Joe F (Jan 27, 2008)

cudafish - Happy to help! Give me a few days to sketch out my final layout. If you send me a PM with your email address, I can shoot you some pictures, some documents for determinining the correct pump and system head etc... Mechanically, this wasn't that difficult however I can't overstate the importance of doing your homework. If you have a good understanding of your current hydronic system, you're probably 70% of the way there. I couldn't have completed this project without this site, namely a regular poster called Beenthere. He had "the answer" everytime I started to scratch my head. Where in NY are you?


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## cudafish61 (Jan 12, 2010)

Thanks for the reply Joe F. I am not sure how to send you a PM I thought I read PMs are not allowed because of spam threat. If _I read wrong please let me know how to PM you._

_Thanks for the reply._


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## YerDugliness (Jun 2, 2008)

cudafish61 said:


> I am not sure how to send you a PM I thought I read PMs are not allowed because of spam threat. If _I read wrong please let me know how to PM you._


Cuda, it's just too quick, so to speak. You will be able to send PM's to members as soon as you have the required minimum number of posts......not sure what that number is, perhaps 10 or so. But you are probably correct, the spammers would just PM everyone soon as they signed up, this keeps the jerks away!

Dugly


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## Scuba_Dave (Jan 16, 2009)

Yes, you need 10 posts before you can send a PM
Its automatic & might take a day to turn on after the 10th post

It is to keep spammers from signing up & spam PM'ing people


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## cudafish61 (Jan 12, 2010)

Just a follow up about my system. I do have a good understanding about my system I installed the boiler (with the help of a friend) and converted from steam heat to hot water. Like I said in my first post I have a main pump (taco011) on my boiler and three zones, using zone valves. I want to add a low temp radiant manifold with 2 zones, using zone valves. I am pretty sure I would need to add a second circ pump for my radiant setup. I am pretty sure the additional plumbing I need to do is not to difficult. Though I still can use help plumbing . The additional wiring has me stumped. How do I wire the radiant pump so it does not turn on when my high temp zones call for heat ? Can I wire my 2 radiant zones using my existing 6 zone controller ?

Thanks again for the reply Joe F. and everyone else.


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## beenthere (Oct 11, 2008)

No. You need another zone control panel.


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## cudafish61 (Jan 12, 2010)

Thanks for the reply. I read through some of the older post on this topic. I think I know what I have to do. Like you said I need another zone controller (ZVC404 Zone Valve Control). I also need (SR501 Switching Relay). I need to wire (thermostats & zone valves) from my two new radiant zones into the ZVC404. The next few steps I am not so sure. I should next wire the TT out on the ZVC404 to the thermostat in on the SR501 and the TT out from the SR501 to ??

Thanks for taking the time answering my ??


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## beenthere (Oct 11, 2008)

Don't need to add a SR.

The zone valve panels both have their own dry contacts. Your current one is using its to bring on the boiler(or should be).
You just parallel wire the new zone panels dry contacts to the old ones. And everything will work as it should.

The install manual will refer to the dry contacts as an "end switch". 

Dry contacts. Are just a switch. Has no power itself. The device its controlling provides the power.


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## cudafish61 (Jan 12, 2010)

I understand I do not need the SR I just wire the new zone panels dry contacts to my existing zone valve controller so the boiler will fire when a radiant zone calls for heat. One question about the radiant plumbing, looking a Joe F drawing he is showing a separate circ pimp for the radiant loop is this correct, If yes how do I have the pump come on only when the radiant loop call for heat. 



Thanks again for all the help.


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## cudafish61 (Jan 12, 2010)

One question about the radiant plumbing, looking a Joe F drawing he is showing a separate circ pimp for the radiant loop is this correct, If yes how do I have the pump come on only when the radiant loop call for heat. That's where I thought the SR controller would be used for.



Thanks again for all the help.


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## beenthere (Oct 11, 2008)

The new zone panel(ZVR) will have a control circuit that runs that circ.


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## cudafish61 (Jan 12, 2010)

I understand.

Thanks a lot.


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## cudafish61 (Jan 12, 2010)

Hi Joe F. It seems I can not pm you because I do not have enough post. I was wondering if you can post a sketch of you final setup.
Rob New Hyde Park NY
Thanks


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## sarlaud (Jan 24, 2010)

I like the basic plan but, why another pump for the bathroom zone? If you add a new connection to existing piping after the existing flow control valve and then a new taco zone valve and then pipe to the mixing valve and on to your radiant loop.... You dont need another pump!!! Get a zone control that will meet your number of zones you need now and at least one spare for future connection! Your home free!


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## cudafish61 (Jan 12, 2010)

I am adding a two zone manifold with zone valves on the manifold. Also a mixing valve for the radiant side.


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## beenthere (Oct 11, 2008)

cudafish61 said:


> I am adding a two zone manifold with zone valves on the manifold. Also a mixing valve for the radiant side.


He may be looking at Joe F's diagram and think its yours.


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## cudafish61 (Jan 12, 2010)

Hi Beenthere I am a little confused. Do I need to add a second pump just for the radiant add on ? Or can my 011 system pump which is in use now, be used for both high temp and low temp. 

Thanks for the help


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## beenthere (Oct 11, 2008)

Post a pic or drawing of your current piping configuration.

You probably need another circ. A 0011 is a lot of circ for a radiant loop.


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## sarlaud (Jan 24, 2010)

I have a question for "beenthere". I was thinking of doing the radiant zone also or maybe 2. I was going to use my main system pump Taco 007 and add zone valves for radiant zones and then go to a multiple brass manifold that has intregal balancing valves and optional flow meters to adjust my flows to different radiant zones. What do think of this approach?


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## sarlaud (Jan 24, 2010)

*shematic*

what program did you use for drawing your program?


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## beenthere (Oct 11, 2008)

sarlaud said:


> what program did you use for drawing your program?



I use Tinycad. Its a free program. Its actually for electronics. But I find it works great for quick drawings of any kind.

Generally. The mixing valve has to be before the circ. So it can work right.

If you put it after the circ. Then it simply shuts off water flow to the radiant loop when it tries to add more cold/cool water from the loop back to the loop.


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## sarlaud (Jan 24, 2010)

Ok I see. Thanks for the input! I may get that cad program also for my quick sketches! Thanks!!!!!


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## cudafish61 (Jan 12, 2010)

Current system. It's been working great for the past 5 years.

Thanks for your help.


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## beenthere (Oct 11, 2008)

Your air scoop is on the return?
Your circ is pumping into the boiler?


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## beenthere (Oct 11, 2008)

You will probably end up with something like this.


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## cudafish61 (Jan 12, 2010)

Thanks for the reply and thanks for the sketch. I know you asked Your air scoop is on the return?
Your circ is pumping into the boiler?
The attached PDF is from Manufacture Instruction Manual. I know it shows circ pumps for zone control, they show the same layout for zone valve installation. 

Thanks again


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## beenthere (Oct 11, 2008)

Its not a problem.
it was more so I knew for sure that I was drawing what I though I was drawing.

I'm use to old style systems where they are on the supply. So I asked to be sure.


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## cudafish61 (Jan 12, 2010)

Hi Beenthere thanks for the sketch. I have a question about supply and return connections. Could I use my spare supply and return on my manifold now? I would like to try and avoid cutting into my 1 1/4" supply and return pipes off the boiler. Also I know I need a check valve I just don't under stand why.

Thanks again


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## beenthere (Oct 11, 2008)

The flow check prevents the loop from heating when the circ for the rest of the house runs.

Piping into your existing header. Will allow the 0011 to over power the radiant loops circ. And stop water flow through the loop. Because the 0011 will decrease the return water flow from the loop to the mixing valve.


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## beenthere (Oct 11, 2008)

You can. But. If you do it something like this.

If you have a zone valve on the unused branch. or add one. Then you don't need to add a flow check in between the tee's from the mixing valve.

If you don't have or use a zone valve on that branch. Then you need to add a flow check between those tee's.

Additional control work required depends on how you pipe it.


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## cudafish61 (Jan 12, 2010)

Hi Beenthere thanks for the latest sketch. As you can see from picture this is why I did not want to add radiant supply and return on output side of pump. Not much room between bottom of pump and Boiler. The last sketch is the way I would like to go. I do have a zone valve installed already so I can use the valve. Now what I hope is my last question so I do not bother you much longer. How do I use the zone valve for the radiant. How do I open the zone valve, run the radiant circulator and fire the boiler.

Thanks again for taking the time with my ??


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## beenthere (Oct 11, 2008)

Post pick of zone valves, or post their brand and model number. So I know the type.
And also what brand and model number is your zone control panel.


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## cudafish61 (Jan 12, 2010)

My current system setup:
Argo AZ-6p
Honeywell V8043E1012 3/4"

Thermostatic two wire actuator for radiant zones

I have a Taco ZVC 403 that I was going to use just for the radiant.


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## beenthere (Oct 11, 2008)

Check you end switch amp ratings.
Might be high enough to run the circ for the radiant.

If not, you can use the other zone panel for the radiant loops zone valve and circ.


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## cudafish61 (Jan 12, 2010)

Thanks for the reply Beenthere. If I use the Taco zone control for the radiant setup or if my current controller contacts are ok(amps). If I use a existing zone valve on the supply side I am not sure how to wire zone valve so it opens when radiant calls for heat ? or should I just use a check valve. 


Thanks


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## beenthere (Oct 11, 2008)

Using your existing panel. Just hook the stat wires like they are for the other zones.

Then if the end switch can handle the amp of the radiant loop circ. Run a 120 volt line through the end switch.

If it can handler the amp draw. Get a taco circ with built in low voltage transformer and relay. And the end switch can control that circ through its relay system.


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## cudafish61 (Jan 12, 2010)

I understand your last reply how to wire radiant zones using my existing Argo controller. I am just not clear if I use a zone valve on the supply to the radiant manifold how do I wire the valve to open when a radiant zone calls for heat. I guess what I am saying how do I open 2 zone valves to open at the same time. Your question in an earlier reply (If you have a zone valve on the unused branch. or add one. Then you don't need to add a flow check in between the tee's from the mixing valve.) This is what I am not certain about.


Thanks again


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## beenthere (Oct 11, 2008)

The thermostat will go to the stat connection in teh zone controller, lets say zone 4.Directly below that connection. Will be the wire terminals that you use to connect the wires from the zone valve to the zone controller. The panel will open the zone valve.

Your won't be opening 2 zone valves at the same time for the radiant loop.

Your drawing only shows zone valves on the supply. So not sure what second zone valve your referring to.

I'm a little slower some days then others.


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## cudafish61 (Jan 12, 2010)

The pdf will explain. Maybe I am really confused.
Thanks


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## beenthere (Oct 11, 2008)

Ah.

I would either eliminate the zone valve on the on the high temp manifold, or the radiant loop.

I didn't realize you had zone valves on the radiant loop manifold. Since you do. If you keep them in the circuit. You don't need a flow check in the return line from the radiant loop.

How many zone valves are on the radiant manifold.


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## cudafish61 (Jan 12, 2010)

2 zone valves(2wire) on the radiant manifold. I would like to use a zove valve on the radiant manifold supply side if possible, so when only my high temp zones call for heat I am not pushing water through the mixing valve all the time. If this is not a concern then the latest sketch looks great.


Thanks


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## beenthere (Oct 11, 2008)

The water won't go through the mixing valve per say.

1. Keep the t's that tap into the cross over 12" or less apart.
2. Pipe a thermal trap in before the mixing valve.


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## cudafish61 (Jan 12, 2010)

Thanks I understand now, except what is a thermal trap?

Thanks again


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## beenthere (Oct 11, 2008)

Basically. just the pipes running down 6 to 12", and then turning back up to connect to the mixing valve pipes/connections.
Hot water doesn't like to flow down. And cold water doesn't like to flow up.


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## cudafish61 (Jan 12, 2010)

got it thanks for all your help.


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