Proposed system design

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Old 03-29-13, 10:56 AM
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Proposed system design

Below is a diagram of a system that I think I'm going to go with when my existing 32 yo boiler goes. I hope it never goes, but if it does, I want to be ready.

Some background info can be found here.

Can knowledgeable folks here take a look and let me know if this makes sense or if I'm missing something? I appreciate all the opinions and comments!

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Old 04-01-13, 06:44 AM
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i guess i did it right, since i got no comment/objections.

i'm going to ask this question - is it ok to reverse the flow in the zones that had particular flow direction for 32 years? from piping prospective and for better room heat balancing it would make sense for me to reverse the flow, but i'm wondering if anyone knows any downsides to that?
 
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Old 04-01-13, 06:58 AM
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is it ok to reverse the flow in the zones that had particular flow direction for 32 years?
I dont see anything wrong with it...

When I re-piped the baseboard in my crawl I changed the direction. I have a dinette area that has less baseboard then required and was last on the line. It is now first on the line so it receive the higher temps. My bedrooms are now last, which are over radiated.....

Drawing looks good. I guess your going with pumps for the zones?
 
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Old 04-01-13, 07:04 AM
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I did the exact thing with my upstairs loop when I replaced the boiler as well, for much the same reason as Mike did.

The only possible down side would be the location of any manual bleeder valves. If they were installed at a downstream elbow before going down into the floor (allegedly the correct application), then when the flow is reversed, they will be at the 'wrong end' of the radiator... but probably not a problem, just something to consider. Mine were, and are, but I never need to use them anyway.
 
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Old 04-01-13, 07:07 AM
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By the way...

Is this a new thread? Didn't you have another of the same question?

What do you mean
i guess i did it right, since i got no comment/objections
.
Several ppl commented on the other thread as I recall...
I'll look later, I will probably merge the two threads.
 
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Old 04-01-13, 09:14 AM
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i did have another thread and i was asked to create a new one since the old one drifter into too many details. so i did.

i did decide to go with the recircs for the zones - simpler piping installation, wiring, fewer moving parts to break/maintain/replace.

i wouldn't mind having this merged back to original topic.
 
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Old 04-01-13, 04:54 PM
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Yeah, I see the other thread... it kind of 'morphed' into this one... so, it's OK with me if you keep just this one going. Let's leave it be for now and trudge forward.

Don't know if you've see these or not... (pexsupply.com search for "Webstone")

Eliminates a few solder joints:



The neat thing about this valve is that by removing and reversing the handle, the 'drain' can be from EITHER SIDE. I used these on my recent install... very handy for use as 'purge stations'.



This is a Watts RBFF. A bit more pricey than the Webstone, but more features.



images courtesy pexsupply.com

Just some ideas for you...
 
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Old 04-02-13, 06:42 AM
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NJ Tropper,

I'm definitely incorporating these into my new system. very handy!
 
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Old 04-02-13, 08:47 AM
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If you like fancy stuff, HG Spec has a neat little system to hold the expansion tank,
http://www.hgspec.com/PDF_english/No...on-tanks_2.pdf
Look towards the middle of the page, under service centers.

There can be a few problems when reversing flow directions, the first has been covered already i.e. rad sizing based on a perimeter loop of rads.
The second, you might get some noise / close off issues if you have thermostatic rad valves on your system.
If you have copper BB rads then you should be ok, but those people with parrallel piped rads with TRV heads might run into problems.

I personally disagree with zoning with circulators, that was something we did 10 to 15 years ago. Electricity was cheap then , and zone valves where not as reliable. It's your system, if you are more comfortable with circs, who am I to agrue :-)

Edit: How do you intend (or do you intend) to handle DHW production priority ?
I understand the purefire will be a "if / when" deal, so you will not be able to count on the electronics in that to prioritize the demands
 
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Old 04-02-13, 09:28 AM
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TOHeating, I value everyone’s input, so please do argue.

I don’t necessarily like fancy stuff, but if there is a contraption that makes installation/maintenance simpler, I would definitely consider it.

I personally disagree with zoning with circulators, that was something we did 10 to 15 years ago. Electricity was cheap then , and zone valves where not as reliable. It's your system, if you are more comfortable with circs, who am I to agrue :-)
Besides the increased electricity usage (this will only be encountered when 2 zones call for heat at the same time), what are the disadvantages of zoning with circulators? Peerless installation documentation revised in 2013 seems to favor that approach. The first piping diagram in the doc shows zoning with circulators and it’s labeled “recommended piping”. I really like the simplicity of zoning with circulators and lack of need for extra wiring for valves.

Edit: How do you intend (or do you intend) to handle DHW production priority ?
I understand the purefire will be a "if / when" deal, so you will not be able to count on the electronics in that to prioritize the demands
It looks like PF handles the DHW priority and I could rely on it. Please let me know if it’s reading it wrong:

DHW Priority:

The PUREFIRE® boiler control provides limited
domestic hot water priority with an installer selectable
maximum time limit.

The CH/DHW Switch Time indicates the maximum
amount of time that the boiler should operate to
satisfy a CH demand or a DHW demand.

If there is a domestic hot water demand during a call
for central heating, the control will immediately shut
down the CH pump, start the DHW pump and target
the DHW setpoint.

The control will continue to target the DHW setpoint
until the time limit is reached or the demand is
satisfied. Then, if there is still a CH demand, it will
shut down the DHW pump, start the CH pump and
target the required CH temperature.

If there is a central heating demand during a DHW
call, the boiler will continue targeting the DHW
setpoint with the DHW pump operating and the CH
pump idle until the time limit is reached.

For example, if the CH/DHW Switch Time is set for
30 minutes, and a CH demand is activated after 6
minutes of a DHW call the following will occur. The
boiler will continue to target the DHW setpoint and
the DHW pump will continue to run for the remaining
24 minutes. After which time, the control will shut
down the DHW pump, start the CH pump and target
the required CH temperature.
 
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Old 04-02-13, 10:11 AM
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Expansion Tank

That HG Spec Service Center looks pretty useful, cantilevered designs always scare me though and its not clear how it attaches to the wall---I'm assuming typical mounting bolts like something you would use for cabinets but heavy-duty. But I've been wondering how to position my expansion tank, I was thinking of making my own mounting bracket with two steel pegs to support the tank from below that hook upwards and provide a point to cup the tank to the wall. In case you're wondering why this is a concern for me, most of my tubing is going to be pex, so there isn't a rigid structure in place to hold the weight of the tank.

I did find this:
QS-12 - Holdrite QS-12 - QuickStrap Expansion Tank Mounting Bracket (5 Gal. Capacity)

I just think that it needs a bottom strap ... gravity is always exerting its force and I just think the tank is bound to drop at any point.
 
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Old 04-02-13, 11:08 AM
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NJ Trooper,

I like the expansion tank valve and I will use it in my new system. My current system doesn’t have fresh water intake piped to expansion tank junction, so I can’t use this particular valve since It has an extra port for water intake.

I will likely be servicing my expansion tank soon and I’m wondering if I could use a simple ball valve with a weep waste port to equalize the pressure before removing the tank. That should work, right?
 
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Old 04-02-13, 12:54 PM
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That should work, right?
Yes, as long as the weeper is on the tank side. It's going to take some time perhaps to drain the pressure off the tank, and those little weepers have about as good an 'aim' as a two year old... water will squirt all over as you open it...
 
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Old 04-03-13, 05:19 PM
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Besides the increased electricity usage (this will only be encountered when 2 zones call for heat at the same time), what are the disadvantages of zoning with circulators? Peerless installation documentation revised in 2013 seems to favor that approach. The first piping diagram in the doc shows zoning with circulators and it’s labeled “recommended piping”. I really like the simplicity of zoning with circulators and lack of need for extra wiring for valves.
Well,
There is the extra power usage, but if your not careful it can yield quite large flow rates thru the loop piping. This will reduce your delta T, and affect your boiler efficiency. It also makes it hard to deal with DHW priority, as now you have to do some fancy wiring inside a switching relay box. As it stands now in order to get priority u have to shut down both circs, since as you have it piped you cannot turn off the boiler pump.
Typically I would pipe the indirect off the injection piping as it was drawn before, that will allow you to control the system loop with the boiler pump.
There really is nothing inherently wrong with zoning with circs, but to me for a residential load (even big homes) one circ (often a 007 if the system was thoughtfully designed) can do the entire load with out breaking a sweat.
 
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Old 04-04-13, 07:00 AM
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It also makes it hard to deal with DHW priority, as now you have to do some fancy wiring inside a switching relay box. As it stands now in order to get priority u have to shut down both circs, since as you have it piped you cannot turn off the boiler pump.
TOHeating,

I don't understand why having zones with recirs are harder from IHW prospective.

With zone valves when there is IHW call, the boiler would have to make sure that zone valves are closed and primary loop recirc is not running. it will have to have boiler recirc running and IHW recir running.

With recirc zoning, when there is IHW call, the boiler would have to make sure that 2 zone recircs are not running. it will have to have boiler recirc running and IHW recir running.

so the difference is boiler would have to take care of 2 zone recircs instead of one. are you saying that this is not supported out of box?

if anything zoning with valves would have fancier wiring since there will be valves to wire.
 
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Old 04-05-13, 01:39 PM
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there is a T/P gauge on boiler supply outlet as suggested in the manual. I think it would be beneficial to have one on the return side. This way a delta T can be monitored and there will be redundancy with a second pressure gauge since they have a tendency to go out.

but i wonder if it makes sense to have it installed on supply/return of the zone loop? or would using IR thermometer be more practical?
 
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Old 04-05-13, 01:48 PM
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TOHeating,

I think I understand now where I was confused. I was under impression that the boiler control panel would be able to control multiple circulator zones, but it looks from wiring diagram that it would only control 3 recircs: boiler, CH and DHW. So a zone relay like taco SR 503-4 would be required. is that what you meant by fancy wiring?

and if one goes with zone valves, the boiler has a capability to control the CH recirc and the zone valves would be controlled by thermostat.

did i get it right?
 
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Old 04-05-13, 02:07 PM
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but it looks from wiring diagram that it would only control 3 recircs: boiler, CH and DHW.
Correct but you can control additional circs, or zones with a taco zone control or relay control box....

and if one goes with zone valves, the boiler has a capability to control the CH recirc and the zone valves would be controlled by thermostat.
The t stats would go to the taco control box. Then the control box gets wired to the boiler with simple t stat wiring to TT.

The problem if you use circs is the taco controller would go to TT to activate the boiler on a call for heat, but there will be no connection to the CH terminals in the boiler.
I would have to look at the purefire manual again.

See what I mean? The boiler will not be controlling the ch circs per se'. Thats why TO said fancy wiring is needed to get it to work properly.

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Old 04-05-13, 02:38 PM
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is there a need for a separate control board like taco in the system with one CH recirculator and 2 zone valves? my understanding there isn't. the thermostat start the boiler and opens one of the zone valves. and the boiler runs the CH recirc. right?

i'll need to look more into wiring a bit more to educate myself on this subject.
 
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Old 04-08-13, 06:32 PM
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Lawrosa nailed it.

Typically, i would pipe the indirect off the boiler, and kill the boiler pump, and start the indirect pump.
This would allow your zones to keep circulating, but would not get any heat, because the boiler pump is off.

If you use the boiler pump, indirect and system pump output with zones valves you can kill the system pump which would stop flow thru the zones.

In order to do it your way, you'll need an sr 503, and you will need to bring the system pump power to the correct terminals in the sr box in order for the pumps to lose power when the DHW calls and the boiler control drop the system pump off.

I know my writing isn't as fancy as many others, and I wonder sometimes how much sense it is making to other who read it... I think this will be one of those times. LOL
 
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Old 04-09-13, 07:56 AM
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TOHeating,

In my original thread on this subject, rbeck mentioned that the required flow for the IHW would result in 23 feet of head it piped directly thru the boiler (from here):

To get the 8gpm flow required for the tank piped through the boiler the boiler will need to operate at a 10f delta-t. That puts the pressure drop at 23 ft head, table 4.4 in their I&O manual. Some of this is due to the high resistance through the boiler. You'll have to pipe it like figure 5 to keep the circulator smaller and allows you to use a larger boiler delta-t or choose a tank with lower flow rate.
so i think for this specific boiler/IHW combo it's better to pipe it off the primary system loop.

let me ask you this:

let's say i have a system like the first post depicts but with zone valves for individual zones. basically primary zone loop with a system recir and 2 zone valves, boiler piped as a secondary with a boiler recirc, IHW piped off the primary loop with a DHW recir.

would that require any additional control board or would it be supported out of the box by PF-50 with this customer connection:

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my understanding is it would work. matter of fact it works on my ancient system right now.

but i'm not sure i get the whole sequence though.

does tstat opens the zone valve directly when it calls for heat? or does it do it via boiler controls?

what is tstat connections on the boiler (terminals 1&2) for?

there should be delay between when call for heat is initiated and recirc is starting to allow for the zone valve to fully open. how is that implemented?
 
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Old 04-09-13, 08:08 AM
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Diver... If you use zones the boiler is set up to kill the CH or indirect pump. They will not run at the same time....

If you pipe off the boiler for the indirect then pump sizing is critical. I would come off the system as it was discussed in another post with the indirect.

You dont need a taco control if your doing zone valves. You run the end switch from the zone valves to CH t stat as in your pic.

The taco, ( 502 is all you need) makes it cleaner because the transformer to power the zones is contained in the taco. Additionally the wiring of the zones is so simplified. I see no reason to not use a taco controller.
 
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Old 04-09-13, 08:30 AM
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Oh i am sorry... They dont make a 2 zone control. You would get the 403 as seen in this pic. Use only two of the three.

Simply wire the t stats to the control, wire your valves to the control ( probably a 4 wire), wire 120v to the transformer, and wire the end switch to the CH t stat in the boiler....Done!!!!!
 
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Old 04-09-13, 08:34 AM
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Without a controller you could end up with a wiring nightmare like this.....


 
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Old 04-09-13, 01:46 PM
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Did some studying... Here it is... Simple if you want to use cics for CH....
 
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Old 04-09-13, 02:04 PM
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lawrosa, thanks for your time looking into this.

i looked at the same diagram, which confirmed that i would need a switching relay board like taco sr503 if i want to zone with recircs. it was mentioning before that the need for this kind of board is one of the disadvantages of zoning with recirc.

but you also mentioned that a controller board (zone valve control module) is also recommended to simplify wiring for zoning with the valves. which makes zoning with either equally the same as it comes to wiring. for recircs you'd have relay switching board and for zone valves - zone valve control board.

on other hand you mentioned that wiring with valves without a board can be done but is somewhat nightmarish. i think this is how my current system is wired and it looks very clean.

i want to take some pictures tonight of what i have and post them here to make sure it is what it is.

since PF has DHW priority connection to begin with, i would assume a relay switching board without priority (SR502-4) would be more suitable for my purpose and IHW would be controlled by boiler. does that make sense?
 
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Old 04-09-13, 03:25 PM
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The 502-4 has priority also but you just leave it off....

My preference is for the price I like to have one extra potential zone avalible. Never know if you add an addition at some point... heat that garage...add a 4 season room.... etc....

If you cant put the controller close to the valves then you need to extend then. Like I did hear on this install. It would be the same concept without the controller.

Wrap the excess wire with a pencil, take your time, and make it look neat.
( I'm not the neatest guy, but do my best)
 
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Old 04-09-13, 05:49 PM
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lawrosa,

here are the pics of my system wiring. the wires from room thermostats come done from the top of the picture along the side of the 120V conduit.

the wires go down to what appears a 24V transformer, then further to boiler control box and gas valve. some of the wires go to the zone valves (horizontal set of wires in the mid of the pics).

i believe it's wired without any control board, using end zone switch as you mentioned before.

pics got resized a bit, but hopefully you can still make out the details.

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Old 04-17-13, 11:53 AM
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so if i were to zone my system with zone valves instead of individual recirculators as it was suggested here ... and use full port zone valves so i could use zone valve for IHW as well...

would it make sense to use an ECM variable speed recirculator (taco bumble bee?) as a system recirculator?

i would use constant speed recirc for boiler loop to maintain proper flow thru the boiler and i would set the system recirc for a specific delta T to provide proper flow thru:

- 1st zone
- 2nd zone
- 1st + 2nd zone
- IHW loop.

i know that each of my zones and 2 of them together are handled by my taco 007 right now without any problem. i know that IHW tank that i would go with (thanks lawrosa!) has pressure drop/flow requirement that is also compatible with taco 007. so i could simply use taco 007 for all of it, but wouldn't VS recir be suited better for this purpose?

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Old 04-17-13, 03:35 PM
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but wouldn't VS recir be suited better for this purpose?
I assume you would use the zone controller taco and set priority so the heat zones do not come on same time...

I dont think you need VS.......

would it make sense to use an ECM variable speed recirculate (taco bumble bee?) as a system recirculator?
I would stay away from that pump. I have read its plagued with problems....

Just my opinion.
 
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Old 04-17-13, 04:35 PM
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I kinda agree with Mike... I don't think the VS pump is needed. Extra cost for little or no advantage.

The 007 with it's 'flat' curve isn't going to care much if one or two zones are open at the same time, so no need for a pressure diff valve, and with the 1" piping to the IHW the 007 will be up to that task as well.
 
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