2 thermostats 1 boiler ???

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Old 11-13-11, 06:30 PM
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2 thermostats 1 boiler ???

ZVC 406-EXP zone control with 4 zones currently on the small boiler. No zones/all zones running on large boiler. For all intense and purpose these are in separate buildings though they are connected. My needs are simple but I have a brain fart on how to get there.

The small boiler is being removed to allow some major plumbing to be done and I need to hook up to the large boiler but control both buildings separately. Next year when I able to do what the engineer drew up it will be simple but for now I need a simple answer. There is the correct size pipe ran to the large boiler from the small boiler.

My thoughts are to hook both pumps up so they are able to get to the boiler (one is teed in) then as they run they can support their individual buildings as needed, my concern is if both pumps come on what will happen. This is a two pipe direct return system in both buildings. The zvc 406-exp could control the boiler I think to satisfy call for heat from the separate thermostats, the pumps would be the check valves.

I just have no idea how to accomplish my needs, I specifically told the engineer that I needed a solution this year without buying new boilers; guess he did not hear me!!
 
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Old 11-13-11, 06:51 PM
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I presume that the large boiler is large enough to meet the heat loss of both buildings?

And the pump for the smaller building is running off the 406 panel?

How is the pump for the large boiler controlled? From the aquastat on that boiler?

I believe you are saying that the heating pipes for both buildings are already connected in parallel?

What are your concerns regarding both pumps coming on at the same time?
 
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Old 11-13-11, 07:21 PM
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1) yes and then some
2) currently yes
3)Honeywell relay thermostat to relay to pump/boiler
4) will be when pipe-fitter finishes, though I'm not sure parallel is correct, both buildings currently have their own piping with small boiler connecting at large boiler
5)2" pipe as supply and return (except for that old gravity pipe that needs replace in large boiler building) will they be competing!
 
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Old 11-13-11, 07:30 PM
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Just off the top of my head I would assume you add a circ in series of the big boiler to keep the flow rate but get more head???

Why the other pump in the other building???

Hmmm... OK I need to think.

Then run the endswitch wire of the 406 to the big boiler. You actually could run both circs off the 406.

But I guess as trooper stated how is the big boiler being controlled?

Mike NJ
 
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Old 11-13-11, 08:59 PM
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picture this

A boiler heating three floors and a basement with one thermostat on second floor, all radiation is CI rads. Now what I want to do is attach two pipes to this boiler so that a separate building with zone controls and different insulation needs can be controlled by a separate thermostat. Both systems are two pipe direct return, no primary secondary here.

I think the zvc 406 can control both pumps and the boiler so when thermostats call for heat the controller knows what stage the boiler is in (copper tube) currently small boiler pump runs 24/7 only because of some exposed walls and pipe and we do not want any freezing surprises this year. The zvc 406 does control the zone valves and the firing of the boiler. The large boiler is controlled by a Honeywell relay will check which one later but it controls the pump and the firing of the boiler.

We can not have 1 large zone because of the difference in radiation needs, it will be overheated or cold. (7 apts 3 commercial units)

Currently the zvc 604 end switch to pump and end switch to the boiler is used by the small boiler. If the end switch to the boiler is low voltage then I can run a wire the 100 feet to the large boiler, hook the thermostat from the large boiler to zone 6, run the zone 6 low voltage to the Honeywell relay to control large boiler pump with a jumper on zone 6 end switch.

What ya think?
 
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Old 11-13-11, 09:11 PM
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does anybody know if you can mix and match a sr 501-exp(switching relay) and a zvc 406 exp (zone valve control) if so then this just became easier if I can get it quickly unlike the 2 months it took to get the zvc 406 exp

Duh! found it.

Expansion Connections: Set the expansion switch to MASTER on
the zone valve control that has the designated priority zone or is
utilizing the PowerPort options. Set all other daisy chained controls
to SLAVE. Connect thermostat wire (18-22 gauge) between terminals
1, 2, 3, 4 on the master control to the corresponding 1, 2,
3, 4 on the SLAVE control(s). Controls may be daisy chained up to
20 zones using any combination of Switching Relay -EXP or Zone
Valve -EXP controls
.
 
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Old 11-13-11, 09:49 PM
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Aside from hooking up the controls, thats the easy part. I am thinking more on the circualator side of things.

You are running 200 ft of supply and return from the big boiler to small boiler area?

When you remove the boiler you are removing the pump?

The pump on the big boiler may not have enough head. 2" piping you say?

First off what make and model circs?

I was suggenting add a circ to the big boiler. Two in series. Keeps the same flow rate but will increase the head.

Just a thought.

Mike NJ
 
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Old 11-13-11, 09:57 PM
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Actually at this time I'm keeping both pumps, small boiler is the grundfos alph and the large boiler is an Armstrong s35. Basically other then meeting at the boiler both systems are separate(I know that is not accurate) at this time because of so close to actual winter we just want to drain once and cut in a lot of valves so we can remove sections over time. The system and pipe size has been redesigned for new boilers and new pumps just that ain't happening this year. All of this is part of a larger renovation. I want to keep it as simple as possible as long as I can heat both buildings I will be happy.
 
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Old 11-13-11, 09:59 PM
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Heelo Grumpy,
How can a pump run 24/7 on a system with zone valves?

I don't know what the SR501 would be needed for?

There are 3 available relays in the ZVC

Peter
 
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Old 11-13-11, 10:02 PM
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isn't head determined by pipe friction and height? the small boiler is on the first floor heating the first floor and 1 floor above. The large boiler is in the basement of the front building heating a total of three floors which have a bigger footprint then the back building. I'm figuring the top floor in the far corner has the most head so wouldn't it be the design head for the whole system? That being said the engineer did up the pump size and in series, but head design only went up by 2 ft, gals increased by 15
 
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Old 11-13-11, 10:05 PM
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24/7

24/7 by having 2 rads not zoned, always accepting flow this is doing two different units, the apt is zoned while the commercial area is under construction. I'm aware that there is a way to wire in another pump but I rather do low voltage for the 100 feet to the other boiler. This is temp, only for this season during some major renos.

And where the zvc is it just needs to move to the other side of the wall when the new boilers are installed.
 
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Old 11-13-11, 10:12 PM
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Sorry, i'm lost.
The existing pump need to keep running, yes?
Is not this pump in the small boiler building, with the zvc404?
Wouldn't a low voltage wire to the TT on the Aquastat on the big boiler, work when there is a heat call from the zvc404?

Peter
 
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Old 11-13-11, 10:20 PM
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not the large one, yes, and I think so, but what happens when the large building is calling for heat and the other building does not need it.

Lets assume you are heating with a boiler, you neighbor is to but the boiler is leaking like crazy. You being a nice guy dig a trench to his house and pipe his system into yours. You neighbor is 100 feet away and this is just temporary to get him through the Christmas season. (I'm guessing you had to much Christmas cheer to make such an offer) His house is zoned and yours is not, his house is poorly insulated and yours is beyond any standards. Now he is freezing because your boiler is not firing, so you open some windows to activate the thermostat on your side now he has heat and his zone valves are working. But it is like a sweat-lodge in your home where the window is not open. Solution is to allow each to control a pump and the firing of the boiler as your needs will not be the same.

Pretty well exactly what I want to do.
 
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Old 11-14-11, 02:37 PM
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I'm looking at this as if the other building was simply another 'zone' or set of zones.

So why can't you simply run an endswitch from the 406 in to the big boiler and connect it in parallel with the endswitch from the relay that runs the other pump?

The 406 will operate the zone valves and pump in it's respective area and pump through the big boiler.

The t'stat in the big building will operate the relay, which turns on the pump and fires the boiler.

The only thing I really see as a possible problem would be if there were no CHECK VALVES either in the pumps themselves, or in the piping... you don't want one pump running an pulling from the other building.

Presuming the shared piping is large enough to support the flow if BOTH buildings are calling for heat.

Isn't it that easy? or am I missing something?
 
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Old 11-14-11, 02:41 PM
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isn't head determined by pipe friction and height?
Yes, and No.

In a CLOSED heating system, where the water simply goes round and round like a ferris wheel, HEIGHT has no bearing whatever. Every foot you pump UP, you also have water pulling DOWN on the other side.

In an OPEN system, YES, height has EVERYTHING to do with head.

In a closed system, the only head you need to overcome is the friction of the pipes, gravity does the rest.
 
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Old 11-14-11, 09:35 PM
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Isn't it that easy? or am I missing something?

I think so, and that really is the game plan. A live test in the real near future will answer the question I hope.
 
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