Adding zone to hot water heating system


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Old 02-12-13, 06:32 PM
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Adding zone to hot water heating system

I read this thread with interest, but it is a bit stale so I'm stariting a new one.

http://www.doityourself.com/forum/bo...ic-heat-2.html


I have hot water radiator heart. The old system dates to 1927. I recently dug my basement deeper and installed pex tubing in the slab. I purchased a kit from an online company that includes a single zone switching relay and a circulator pump for the slab system. I hooked the new system to the old system with two T connections, one for the supply and one for the return. I think the system is not correctly hooked up. I have shut the valves between the two systems and am running my primary system only. I have not tested the new system.

I have posted info about my system and my questions here:

http://www.randallmariger.com/heat_s...nfo_master.pdf

Thanks in advance for your help.

Randy
 

Last edited by NJT; 02-12-13 at 08:20 PM.
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Old 02-12-13, 08:25 PM
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Hi Randy,

I briefed over your PDF and will spend more time with it when I have more time...

I don't think you have a MIXING VALVE on the floor tubing... you need one. You can't feed the 180 degree water from the boiler into the floor, you'll crack the new concrete slab. You need to limit the temperature to around 120° or so.

I really hope that you insulated UNDER the new slab. Did you?

How deep in the slab is the tubing?

More tomorrow.
 
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Old 02-12-13, 09:05 PM
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Yes, there is a mixing valve. I'ts a Honeywell AM1 series. Best seen in the thirdto last photo. Honeywell doc here:

https://customer.honeywell.com/resou...0s/62-3098.pdf

I did insulate under the slab-- 1" of XPS. The insulation is on 4" of gravel and there is 4" of concrete over the tubing. I followed the instructions of ths company. Radiant Heat From Radiant Floor Company - DIY Radiant Floor Heating. I was told that 1" of insulation is sufficient in Virginia. The slab is 6' below grade.
 
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Old 02-13-13, 05:21 AM
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OK, good... I did see the mixing valve in the pictures after I replied.

I'll review your PDF file again sometime today...
 
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Old 02-13-13, 03:17 PM
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I looked at my boiler manual (there is a link to it in the pdf document I posted) and think maybe all I need is one zone valve. If I understand the working of my primary system correctly, my boiler is set up so that the primary thermostat starts the pump and the movement of water then triggers the boiler on. If that is the case, my secondary thermostat can trigger my secondary circulation pump and the movement of water would then trigger the boiler without triggering the primary pump. This would require that water can move through my primary pump without the pump being on. Is that the case?

If my understanding is correct, and water can move through the primary pump when it is not on, then I think I would need only one zone valve at the return side of the secondary system. That zone valve would ensure that the primary pump does not force water through the secondary system. (The company I purchased the secondary circulation pump from says water can pass through the pump when the pump is not on.) I don't think I need a zone valve on the primary system because the secondary circulation pump sucks water through the secondary loop; I don't think it would cause water to circulate through the primary system.


Thoughts?

Thanks, Randy


 
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Old 02-13-13, 05:10 PM
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Hi Randy,

No, I don't think so. I believe that you have some conceptions of how the system operates a little wrong.

The flow of the pump does not trigger the boiler to fire. Or at least not normally... it would be a very rare bird if your system did so. Flow switches are not normally used on boiler systems.

If you are set up with individual pumps on the two 'zones', you don't need zone valves.

I'll be back with more after I sort it out... it's a little inconvenient having to go the PDF and back again, it would have been better if you included the links in the body of your post.
 
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Old 02-13-13, 05:19 PM
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Randy, can you create a more detailed drawing of your piping?

You need to show the mixing valve, the pumps involved with the radiant, and the location of the pump on the boiler.

In order to do what you want to do, you are going to need to do some re-piping, and some work on the controls.

Once I have a very clear picture of how your system is built, I can help further...
 
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Old 02-13-13, 05:46 PM
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I’ve copied my pdf document below with all the links.

My system is apparently a rare bird. See “sequence of operation” on page12 of my boiler manual (link below). To paraphrase, the sequence is:

1. Thermostat closes and circulator is activated
2. When adequate draft is proven by the pressure switch, the 30 second pre-purge timer starts
3. After 30 second delay, 24 VAC is provided to terminals, relite control starts spark, pilot valve is opened,
4. Pilot ignites

Copy of PDF



Hot Water Heating System

I have hot water radiator heart. The old system dates to 1927. I recently dug my basement deeper and installed pex tubing in the slab. I purchased a kit from an online company that includes a single zone switching relay and a circulator pump for the slab system. I hooked the new system to the old system with two T connections, one for the supply and one for the return. I think the system is not correctly hooked up. I have shut the valves between the two systems and am running my primary system only. I have not tested the new system.

Schematic and photos are at the links below. Below that I ask my questions, and document certain features of my system.

Schematic of system as currently hooked up is here
http://www.randallmariger.com/heat_system_schematic.pdf

System Photos are here
Collection - heat

Questions

1. I want to be able to run the primary and secondary systems independently. To do that as the system is currently configured, the secondary system thermostat must be able to turn on the boiler and the secondary circulator, but not the primary pump. I’m not sure that is possible. Currently, the primary pump and boiler always go on simultaneously.

2. One possibility would be to remove the secondary circulator and install two zone valves that isolate the two systems. If I did that, would the primary pump be too powerful for the secondary system when only the secondary system is on? Pump specs are below. The primary pump is 1/12 HP, and the secondary circulator is 1/25 HP.

Boiler

Weil McLain
Model HE-5
Series No. 2
133,000 BTU/hour
Max water pressure 150 PSI
Manual is at http://www.randallmariger.com/weil_mclain_boiler_he2manual.pdf

Primary Pump affixed to Boiler

Bell & Gossett Motor
Model MO9181 4-82
1/12 HP
1725 RPM
1.75 amps
Phase 1
115 volt

Primary Radiator System (1927, except three radiators have been replaced)




Slab System (New)

Currently plumbed, but I think incorrectly. It has not been tested.

Four (4) 250’ loops of 7/8” pex tubing
Each loop served in parallel by the slab manifold

Azel i-Link SP-81 Universal Single Zone Switching Relay
Manual is at http://www.randallmariger.com/azel_sp81manual.pdf

Circulator Pump
Grundfos No. 59896341 P1
[TABLE="class: MsoNormalTable, width: 3"]
[TR]
[TD]Application:
[/TD]
[TD="width: 155"]Zoning
[/TD]
[/TR]
[TR]
[TD]Material:
[/TD]
[TD="width: 155"]Cast Iron
[/TD]
[/TR]
[TR]
[TD]Voltage:
?
[/TD]
[TD="width: 155"]115v
[/TD]
[/TR]
[TR]
[TD]Max Pressure (PSI):
[/TD]
[TD="width: 155"]145 psi
[/TD]
[/TR]
[TR]
[TD]Type:
[/TD]
[TD="width: 155"]3-Speed Pump
[/TD]
[/TR]
[TR]
[TD]Horse Power:
?
[/TD]
[TD="width: 155"]1/25
[/TD]
[/TR]
[TR]
[TD]Max Flow (GPM):
[/TD]
[TD="width: 155"]17
[/TD]
[/TR]
[TR]
[TD]FlowRange (GPM):
[/TD]
[TD="width: 155"]0-17
[/TD]
[/TR]
[TR]
[TD]HeadRange (ft.):
[/TD]
[TD="width: 155"]0-19.5
[/TD]
[/TR]
[TR]
[TD]Max Head (Ft):
[/TD]
[TD="width: 155"]19.5
[/TD]
[/TR]
[TR]
[TD]Hertz:
[/TD]
[TD="width: 155"]60
[/TD]
[/TR]
[TR]
[TD]Phase:
[/TD]
[TD="width: 155"]1
[/TD]
[/TR]
[TR]
[TD]RPM:
[/TD]
[TD="width: 155"]2450
[/TD]
[/TR]
[TR]
[TD]TemperatureRange (F):
[/TD]
[TD="width: 155"]36°-230°F
[/TD]
[/TR]
[TR]
[TD]Connection Size:
[/TD]
[TD="width: 155"]3/4"
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD="width: 155"]1-1/4"
[/TD]
[/TR]
[TR]
[TD][/TD]
[TD="width: 155"]1-1/2"
[/TD]
[/TR]
[TR]
[TD]Connection Type:
[/TD]
[TD="width: 155"]Flanged
[/TD]
[/TR]
[/TABLE]




 

Last edited by NJT; 02-14-13 at 07:42 AM. Reason: removed size tags...
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Old 02-13-13, 06:34 PM
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My system is apparently a rare bird.
Nope... that 'pressure switch' reference has nothing at all to do with the water flow.

That switch is only 'proving' that the induced draft FAN on the boiler exhaust is running up to speed before any fire is allowed to be lit.

NOT a water flow switch.

I still need an accurate system diagram.
 
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Old 02-14-13, 06:47 AM
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Thanks for setting me straight. I've revised the schematic to show the primary pump and have added an annotated photo showing the piping of the secondary system zone manifold board. The revised schematic is here:


http://www.randallmariger.com/heat_system_schematic.pdf

A direct link to the annotated photo is here:

http://www.randallmariger.com/heat_s...mageFull15.htm

Ignore the question posed in the photo, those are fill spigots. (I prepared this photo to check my understanding with the company that supplied the board, and to ask questions.)

My post that copied the pdf somehow got corrupted and the link to the full set of photos is wrong. I can’t figure out how to edit the post. Please advise.

The correct link to the full set of photos is here:

Collection - heat

I really appreciate the time you have put into this.

Randy
 

Last edited by NJT; 02-14-13 at 07:37 AM.
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Old 02-14-13, 07:53 AM
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OK...good... I have a fairly clear understanding now. This evening I'll work something up to suggest the changes you can (and should) make to the system.

I've edited your orignal post to correct the link to the picture page.

Ignore the question posed in the photo, those are fill spigots
Well... I wouldn't exactly call them 'fill spigots'. Is this the explanation that you got from the company that provided the module?

Their PURPOSE in this case is for initially filling, and purging air from the system after installation. Did they explain how to do that? If not, we can help...
 
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Old 02-14-13, 08:17 AM
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Thanks.

No, I did not inquire about filling the system, so advice is welcomed.

My primary system fills automatically--water is added to the system I assume based on pressure. I imagined I'd open the gates between the two systems and let it fill automatically, opening up the return side "spigot" on the new system to let it bleed air.
 
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Old 02-14-13, 03:08 PM
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Before I get started on your drawing... I wanted to point out a few things.

The white PVC from the pressure relief valves is probably not a good thing. It's not rated for the extreme temperatures that it could be subject to in the event that the relief valve opened.

Also, where does it go? That looks to be 3/4" tubing? How long it it?

I don't think there's any way that setup will pass code inspection.

Is the water heater relief valve also connected to that line?
 
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Old 02-14-13, 04:32 PM
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As built ...

You asked, so I'm going to tell... you might not like what you hear, I'm sorry about that, nothing personal ya know.

Here's what you have now:

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Problems that I see with it...

Even before adding the radiant, forget it's there for a moment, there should have been some 'boiler protection' built in. The potential for this system to return cold water to the boiler for a LONG time is quite high. High volume of cold return water to boiler for extended time is really bad for boiler...

When only the radiant is calling for heat, you probably won't have adequate flow through the boiler. It may 'short cycle'.

Water will have to flow through a turned off (main) pump. It's true that it will flow through the pump when off, but it really ain't 'right'.

Water will ALSO be pulled through the system radiators to some extent, how much depends on how much resistance to flow (also called 'head') that the boiler has, compared to how much resistance to flow the system has. There needs to be a check valve to prevent this.

The reverse is true when only the main system is calling for heat and NOT the radiant. There will be flow induced in the radiant in this condition... again, check valves.
 
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Old 02-14-13, 05:10 PM
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Thanks for being so generous with your time and knowledge.

1. The relief pipe is special ¾” pvc (CPVC). Here (http://www.ehow.com/about_5092663_types-pvc-pipes.html) it says:

CPVC
Chlorinated polyvinyl chloride pipe (CPVC) is the newest version of PVC pipe. It can withstand heat up to 180 degrees Fahrenheit, so it is suitable for domestic hot water systems and is available in the same schedules and uses the same color schemes.

The hot water heater relief is also connected to the pipe. The length is about 7’ to the corner, then another 30’ to a sump pump.


2. Sounds like you don’t think this system can work with only the secondary system on no matter how it is plumbed due to too little flow through the boiler. That seems odd, as the secondary system includes 1000’ for pex tubing, which I would think is not an unusually small sized zone. Don’t all multi-zone systems need to work with only one zone on?

3. Do the two symbols above the boiler indicate your suggested check valve locations?

4. What is your bottom-line suggestion? That is, what would you do if this was your system?
 
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Old 02-14-13, 05:21 PM
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1. Even CPVC can be subject to higher than spec temps. The water from a relief valve can be 212, or even STEAM under some conditions. Remember those relief valves only open when there's a PROBLEM, so the discharge system should be designed for absolute worst case.

Relief valves also need to be allowed to discharge the proper FLOW, and it's possible that the long lengths of CPVC with the elbows and all will present significant resistance to high temperature, high volume flow.

Connecting the hot water heater relief to the same pipe constitutes a 'cross connection' of sorts between your domestic and your boiler. Not that it is likely that your domestic can be contaminated, but it is very remotely possible... and this is why the plumbing codes won't allow that connection.

2. No, it CAN work... I'll be doing more drawing in the coming days... in fact, I've started already.

3. No, those are the ball valves that you've got on the lines already.

4. You'll see! it could take a while to put it all together though... and explain it all... if you'll hang, so will I! Don't disappear on me! I'll be an unhappy camper if I do all the drawings and design and you disappear...
 
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Old 02-14-13, 06:02 PM
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Thanks so much. I'm very much interested in your recommendations, and will not dissappear. Your drawings don't need to be pretty, just readable.
 
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Old 02-15-13, 03:13 PM
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While this drawing does not show a lot of the details, this would be the way I would approach this type of installation.

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I will show how I might control this next...
 
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Old 02-15-13, 03:48 PM
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Here's one possible way to control.

You will need another pump, and another relay. It doesn't have to be an Azel, a Taco SR501, Honeywell 8845, and several others will all work the same.

Since you already have the one Azel panel, you might as well use it, but you could also use a single Taco SR-5xx panel to which the two zone pumps would connect along with the both thermostats.

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Ask questions...
 
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Old 02-16-13, 09:06 AM
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Thanks! This is certainly more than I expected. A few questions before I ask about simpler options. (I understand I asked for the first-best system a professional designer could be proud of.)

1. For this to work, it appears that Pump P1 in the pic below must be on when either system is on, and that both thermostats must therefore connect to the boiler as does my primary thermostat now.

2. I assume pump P1 is my current primary pump moved up and on the supply side rather than the return side.

3. If both systems are on, it appears that supply water will meet return water at A, but supply water will be forced up and return water forced down.

4. If only the secondary system is on, supply water will meet return water at B, but supply water will be forced right and return water will be forced down. No supply water goes above A.

5. If both systems are on, it appears supply water to secondary system at B will be a combination of water passing horizontally through A (and hence recently warmed) and return water from the primary system. (and hence less warm). This would seem to be a problem.
 
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Old 02-16-13, 09:34 AM
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1. For this to work, it appears that Pump P1 in the pic below must be on when either system is on, and that both thermostats must therefore connect to the boiler as does my primary thermostat now.
Yes, correct. Pump P1 is in fact wired to the boiler control so that when EITHER thermostat calls for heat, that pump will run. Note that the thermostats are not DIRECTLY connected to the boiler, they are connected to the zone control relays which pass the heat demand call on to the boiler.

2. I assume pump P1 is my current primary pump moved up and on the supply side rather than the return side.
Yes and no...

Yes, the 'preferred' location of the boiler loop pump would be as shown, pumping AWAY FROM the connection point of the expansion tank at the boiler. This is an 'ideal' to strive for, but you could in fact leave that pump at it's current location and probably not notice much difference in performance.

No, I would move your existing pump to location P2 and fit a Taco 007 in place of the existing pump.

3. If both systems are on, it appears that supply water will meet return water at A, but supply water will be forced up and return water forced down.
Correct. The pairs of closely spaced tees provide 'hydraulic separation'.

4. If only the secondary system is on, supply water will meet return water at B, but supply water will be forced right and return water will be forced down. No supply water goes above A.
Correct, ditto.

5. If both systems are on, it appears supply water to secondary system at B will be a combination of water passing horizontally through A (and hence recently warmed) and return water from the primary system. (and hence less warm). This would seem to be a problem.
Also correct, but not a problem because the water to the radiant slab should not be allowed by the mixing valve to go above about 120° anyway.

If the return water from the primary system is consistently below say 130° then there's something else wrong... one example might be not enough flow in the main system allowing the water to cool too much before returning.
 
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Old 02-16-13, 09:45 AM
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This design addresses a couple problems that I see.

The first existed BEFORE the addition of the radiant, all along.

You said you have cast iron radiators. This means that you have a large volume of water in your system. It also means that there will be large volumes of cool water returning to the boiler for extended periods of time.

I mentioned earlier that this can damage the boiler, flue pipes, and chimney due to a condition called "flue gas condensation" ... Google that term for more information.

By placing the existing system on a "Primary/Secondary" setup, you are limiting the exposure to the boiler of that large mass of cool water continuously.

It may in fact NOT BE ENOUGH protection though.

Without more data, such as long term temperature measurements of the supply and return water, we can't know for sure.

It may turn out that you also require some form of BYPASS, either manual or thermostatically controlled to fully protect the boiler from this problem.

The second, mentioned earlier, of 'short cycling' the boiler due to not enough flow when only the radiant zone is running... is addressed by also putting the radiant on a set of closely spaced tees. The boiler flow will always remain constant because of the closed loop and the pump on that loop.

The radiant system will draw only what it needs in order to maintain the temperature of the water at the outlet of the mixing valve.

The boiler may STILL 'short cycle', but not because of insufficient flow... only because of a very light 'load'.

The IDEAL setup is even MORE complicated than this... and more expensive!

(see this thread if you dare!):

http://www.doityourself.com/forum/bo...y-new-one.html
 
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Old 02-16-13, 11:20 AM
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I haven’t rejected your design, but would like to investigate options. How about putting two zone valves in as in the pic below?

When I considered this option I was worried that when only the secondary system is on, there would be two pumps going in series and that may be too much pressure. But your suggestion has this feature too.

Another possibility would be this zone valve configuration without the secondary pump.
 
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Old 02-16-13, 12:53 PM
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I understand, and even if you did, I would be OK with me! After all, it's your system and your choice! I have no reason to impose my will on you! ($$$)

I already knew where we would be going with this...

Understand that none of the alternate options will protect your boiler from the cool return water...

How about putting two zone valves in as in the pic below?
You could...

What size is the big ole pipe on supply and return of the boiler, the original stuff?

You NEED a zone valve at least as large as that piping. You can't use 'adapters' to use a smaller valve. You don't want to limit the flow to the radiators by doing that.

When I considered this option I was worried that when only the secondary system is on, there would be two pumps going in series and that may be too much pressure. But your suggestion has this feature too.
The radiant pump isn't technically entirely in series with the main pump in any case.

In most cases, with the way it is piped now, only PARTIALLY in series.

Remember that since the mixing valve will be constantly adjusting to maintain setpoint of 120-ish, that a majority of the flow will be 'recirculating' through the floor, back through the mixing valve, and right back to the floor. The mixing valve will only allow enough of the HOT boiler water in to allow keeping the water in the floor at 120.

This presents the other problem of not enough flow in the boiler because as that mixing valve closes the HOT port IN, it will effectively be 'choking' the main pump.

Piped as per my diagram, this would not be true. Anything not going through the mixing valve into the floor would go right around and back into the boiler.

Here's what I meant earlier when I mentioned 'hydraulic separation'... the flow in the loop around the boiler would NOT be affected by the flow in either loop. The boiler loop flows the same all the time. The main loop would flow the same all the time. The flow in the floor loop would on the DOWNSTREAM side of the mixer would flow the same all the time. The flow in the loop between the boiler loop and the mixer would vary depending on how much hot water was needed to maintain the mixing valve setpoint.

Another possibility would be this zone valve configuration without the secondary pump.
No, not a possibility at all. You absolutely MUST have that pump there. You can't use the boiler pump to 'ram' water through the mixing valve. It just won't work properly at all.
 
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Old 02-16-13, 02:00 PM
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To use zone valves, you would need to still use a pair of closely spaced tees as shown here:

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The globe valve shown must be used to restrict the flow somewhat through the radiant loop in order that it doesn't 'hog' the flow from the main system when both are calling for heat. You would close that valve until you had a 30-40 degree difference between the supply and the return from the radiant loop.
 

Last edited by NJT; 02-16-13 at 03:06 PM.
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Old 02-16-13, 03:52 PM
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And this is how you might control it:

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I've shown both types of Honeywell valves for illustration purposes, the 'E' model with leadwires and the 'F' model with terminal strip. You would of course use one or the other, or another brand altogether with appropriate wiring changes if needed.

The radiant thermostat would open it's zone valve first, then the zone valve would signal the Azel panel to start the pump, and signal the boiler for heat demand.

The main thermostat only needs to signal the boiler through it's own zone valve.

You will need to add a 40VA control transformer to power the zone valves.



AT72D1006 - Honeywell AT72D1006 - Plate mounted 120 Vac Transformer with 9 in. leadwires
 

Last edited by NJT; 02-09-14 at 02:17 PM.
  #27  
Old 02-16-13, 05:47 PM
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I must say I am amazed at how unselfish you are with your time. Thank you so much.

Your configuration of the zone valves seems to achieve the same thing as your preferred system with respect to “anything not going through the mixing valve into the floor would go right around and back into the boiler.” Is that right?

This feature of both designs ensures sufficient flow through the boiler but, to the extent that little water is returning to the boiler from the floor system, it would seem that the water circulating in the small loop would get extremely hot. Might that be a problem?

I take it the other problem that your preferred design addresses (the possibility of lots of cold water reaching the boiler) is not addressed by the zone valve system. On this score, I note that my existing system has been working fine since at least 1990. I did have a condensation problem on the inside of the chimney during my first year in the house, but that problem was solved by installing a chimney liner.

On your control plan, what controls the globe valve?

I don’t think my system works at 180 degrees. When sizing radiators a couple of years ago, I taped a meat thermometer to the copper supply pipe coming out of the boiler (wrapped in a rag) and kept the system on over an hour. My recollection is the temperature peaked at about 165 degrees.

Thanks,
Randy
 
  #28  
Old 02-16-13, 06:44 PM
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I'm 'paying forward' for all the ppl that have given me a 'leg up' over the past 50 years... I've got some catching up to do!

Your configuration of the zone valves seems to achieve the same thing as your preferred system with respect to “anything not going through the mixing valve into the floor would go right around and back into the boiler.” Is that right?
Yes, pretty much the idea. It also lets the mixing valve operate without being 'force fed' by the boiler circulator. It can now draw only what it needs.

it would seem that the water circulating in the small loop would get extremely hot. Might that be a problem?
It would never get hotter than the high limit setting on the boiler aquastat which typically would be 180°... no, not a problem.

your preferred design addresses (the possibility of lots of cold water reaching the boiler) is not addressed by the zone valve system.
Correct, same as it ever was.

I did have a condensation problem on the inside of the chimney during my first year in the house, but that problem was solved by installing a chimney liner.
Yeah, you might be OK...

Just curious if you ever taped the meat thermometer to the return leg back to the boiler to get an idea of what a typical long term temp profile exists there.

On your control plan, what controls the globe valve?
Your hand! Set it up once and fuggeddaboudit.

My recollection is the temperature peaked at about 165 degrees.
Very possible. This could be because of all that cast iron out there too... and possibly a 'lazy flow' through the system. The possible problem of "...lots of cold water reaching the boiler..." probably comes into play here also. This would prevent the boiler from ever getting up to temperature.

Depending on how much heat emitter ( BTU output ) you have in the home, it's also possible that the heat calls are ending long before the boiler comes up to temp. In other words, you might have enough emitters that the system doesn't NEED 180 water to satisfy the thermostat.

My system is that way (fin-tube baseboard). There's so much installed that even when it's 10° outdoors, the thermostat satisfies by the time the water reaches about 150°.
 
  #29  
Old 02-17-13, 12:08 PM
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I’m inclined to go with the zone valve system given that my boiler has been working fine for the past 20 years.

My primary thermostat is 2-wire, and the pipe is 1-1/4”. Must I restrict myself to a 2-wire zone valve on the primary system? How about the zone valve for my radiant system?

How does this look for the globe valve?

3/4" Two Way Cartridge Globe Valve (4.9 Cv) (sweat connection)
SKU:V5852A2072Brand: Honeywell
http://www.pexsupply.com/Honeywell-V5852A2072-3-4-Two-Way-Cartridge-Globe-Valve-4-9-Cv

On a different but related matter, I’m planning to restore a radiator in the 2[SUP]nd[/SUP] floor bath that was converted to electric in the 1970s. That radiator is on the side of the house opposite the boiler, and it’s possible it was replaced because it didn’t function well. (More likely, I think, is that it was replaced to get more room when the bath was remodeled.) On this score, my radiators, their size, which main loop they are on (left from the boiler, or right from the boiler), and distance from the boiler are given in the attached table. After I install the new radiator in the 2[SUP]nd[/SUP] floor bath, the left loop will have 36,536 BTUs and the average horizontal pipe distance to the boiler is 16.8 feet (a BTU weighted average). The right loop is further away and has more BTUs—52,503 BTUs and an average horizontal pipe distance to the boiler of 33.7 feet. Do you see anything I should be concerned about?

When I re-pipe the system, I’m wondering if I should replace my flow balancing valves. The existing valves are like the one in the photo below. They don’t seem to give me much control. I’m not sure if they are just on-off or give me gradations of water flow. Would a modern ones make balancing easier? The pipes are 1” at the radiators, so this might be a possibility.

http://www.pexsupply.com/Taco-ACUF-1...-1-Sweat-ACCU-FLO-Balancing-Valve
 
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  #30  
Old 02-17-13, 02:21 PM
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You don't need to spend that much... this will do just fine:


image courtesy amazon.com

Amazon.com: Webstone Valve 10403 N/A 3/4" Brass Globe Valve with Hard Seat - IPS 10403: Home Improvement
 
  #31  
Old 02-17-13, 02:49 PM
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My primary thermostat is 2-wire, and the pipe is 1-1/4”. Must I restrict myself to a 2-wire zone valve on the primary system? How about the zone valve for my radiant system?
I don't think the Honeywell 8043 series valves are available in 1-1/4"... you can get this type:

MZV527E - Honeywell-Sparco MZV527E - 1-1/4" Sweat Motorized Zone Valve, w/ auxiliary switch

Taco has:

573-2 - Taco 573-2 - 1-1/4" 573 Sweat Zone Valve

Any zone valve you install is going to restrict the flow to the main system somewhat.

I'm not sure what you mean by a '2 wire zone valve' ? Please explain.
 
  #32  
Old 02-17-13, 02:50 PM
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radiator in the 2nd floor bath that was converted to electric in the 1970s
How did they do that?

Oh wait... they didn't convert the radiator to electric... they removed the radiator and installed electric heat in it's place?

I think that's what you meant?
 
  #33  
Old 02-17-13, 03:01 PM
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I’m wondering if I should replace my flow balancing valves. The existing valves are like the one in the photo below. They don’t seem to give me much control. I’m not sure if they are just on-off or give me gradations of water flow.
Forget about trying to balance heat output with the valves. It's a futile effort. Consider those valves to be on/off and fuggedabowdit.
 
  #34  
Old 02-17-13, 03:07 PM
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different but related matter, I’m planning to restore a radiator...
The only thing you really need to be concerned with is that you have enough flow... it's a tough call to make without being there.

This is one of the reasons that I initially recommended a separate pump for the main system, that and the cool return issue...
 
  #35  
Old 02-17-13, 03:07 PM
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1. Conversion wasn't a good word. They installed an electric baseboard unit (not hydronic). I was able to find the old pipes under the subfloor.

2. Not sure how 2-wire and 3-wire valves work, but I was considering these two white rodgers units, one 2-wire and the other 3-wire.

1-1/4" Sweat Zone Valve (Two Wire)
SKU:1361-104Brand: White Rodgers
1361-104 - White Rodgers 1361-104 - 1-1/4" Sweat Zone Valve (Two Wire)

1-1/4" Sweat Zone Valve (Three Wire)
SKU:1311-104Brand: White Rodgers
1311-104 - White Rodgers 1311-104 - 1-1/4" Sweat Zone Valve (Three Wire)


Do you prefer Honeywell to White Rodgers and Taco?
 
  #36  
Old 02-17-13, 03:37 PM
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You found the one I was looking for! Good on ya mate!

Look at the Cv rating of that valve... 42.2

What this means is that valve will flow 42.2 GPM with ONE PSI of pressure drop! The restriction of this valve is almost negligible.

The other valves, Taco, Honeywell, etc have Cv ratings of around 7-8 ... meaning that they are MUCH more restrictive.

You do NOT want the 3-wire model, you need special thermostats with those.
 
  #37  
Old 02-17-13, 03:45 PM
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This response concerns your post #34

Might it make sense to install a globe valve to restrict flow to the "left loop" so as to balance with the needs of the "right loop"?
 
  #38  
Old 02-17-13, 06:52 PM
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Might it make sense to install a globe valve to restrict flow to the "left loop" so as to balance with the needs of the "right loop"?
I don't think it will be worth the trouble... as mentioned previously, trying to balance heat output with a valve is a worthless pursuit.

You can 'balance flow', but it will not do a whole lot to balance heat output.

This is in fact the main reason for ODR an 'modulating boilers'. The heat output relationship between TEMPERATURE and BTU OUTPUT is SO much easier to control. It's a 'fairly' linear relationship. Not so with FLOW and BTU OUTPUT.

Take a look sometime at the output charts for fin-tube baseboard. You will see that there really isn't a heckuva lot of difference between the output between 1 GPM and 4 GPM. Hardly even noticeable in practice.

What cutting the flow WILL do is 'unbalance' the system. Since slower moving water has more 'dwell time' in the system in order to give up it's heat, what happens is that the return water comes back too cool. The rooms at the end of series piped systems get too little heat. With your rads which are probably piped in parallel not so much of an issue there, but the return water is still coming back cooler, and that's not good... especially since you have no boiler protection to speak of.

[ LATE EDIT - fast forward almost exactly one year... today is 2/9/2014 ]

I've just re-read the entire thread to reacquaint myself with the details.

I think I might have misunderstood the question of the added valve to balance the flows between the 'left and right loops'.

If you only have one rad on one of the loops, then YES, I believe that I WOULD add a valve on the SMALLER of the two loops so as to restrict the flow to that loop.

Otherwise, there might be TOO MUCH flow to the one rad and NOT ENOUGH flow to the others.
 

Last edited by NJT; 02-09-14 at 02:32 PM.
  #39  
Old 02-17-13, 08:06 PM
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Makes sense. Will consider your preferred system fresh tomorrow. Thanks.
 
  #40  
Old 02-19-13, 06:39 PM
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I ordered the zone valves but am having second thoughts and think I’ll try to cancel the order in the morning.

I’m thinking about the space requirements for your preferred plan. The sketch below shows a mirror image of the preferred plan appropriate for my setup. As you can see, I’m working in restricted space.

1. Can Pump P2 be directly above P1 on a straight line? Likewise, can the return line opposite P2 be on a straight line? (In this case, there would be two parallel lines with a “ladder rung” in between.)

2. You are suggesting my current primary pump be in position P2. That would put it about 18” below my living room floor. I think it would be noisy. Also, its looks to be a fairly heavy pump. Do I need the full 1/12 HP?

Thanks,
Randy
 
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