Adding a zone/circulator to honeywell aquastat L8148A

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Old 11-16-13, 02:31 PM
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Adding a zone/circulator to honeywell aquastat L8148A

I have a forced hot water system (Pensotti boiler, Riello burner). One zone, controlled by an Honeywell Aquastat L8148A.

I'm adding a new zone and I have a question about powering the relay for the second zone. Based on the schematic I see in the manual for the L8148A, It would seem that I simply jump the L1 and L2 terminals (hot and neutral) to the relay for new zone.

Is this correct? It would seem that this would bypass the the Aquastat, allowing the second zone circulator to move cold water through the system.

Any advice would be appreciated!
 
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Old 11-16-13, 03:14 PM
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You will need a Honeywell R845 or Taco equivalent.(501 I believe)
8148....................R845
1...........................1
2...........................2
Jumper across 1&3 on 845
Circulator.............2&4 on 845
TT.........................5&6
1 to 1
2 to 2
Jump 1&3 on relay
Circ. goes to 2&4 on relay
5&6 on relay goes to TT on 8148 aquastat.
I hope I explained it so you can understand it.
Good Luck.
 
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Old 11-16-13, 04:09 PM
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Ummmm... Spott, what is going to stop the first zone circ from running when there is a heat call on added zone 2 ?

That's not what you want to do.............................................

Me personally would use the SR-503 Taco panel.

SR503-4 - Taco SR503-4 - 3 Zone Switching Relay

Put BOTH pumps on the panel, run endswitch from panel to T T terminals in 8148.

Done...
 
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Old 11-16-13, 04:15 PM
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The 1st zone is run off the 8148, the c1&c2 terminals. The 2nd zone is run off the 845.
Am I missing something?
You can use the taco panel but is it cost effective for just one more zone. The first zone is already wired in to the circuit. All he needs is one more relay. Just my opinion.
I believe either one will work.
 
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Old 11-16-13, 04:20 PM
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Am I missing something?
I think maybe...

The first pump will run when you close T T on the 8148 with the wiring to 5 & 6 on the 845. The 8148 has no way to know WHICH zone is calling.

That's the problem with zoning and the 8148, you need to remove the pump from C1 and C2 and provide it's own relay. If you don't then the zone 1 pump will run when ANY zone calls for heat.
 
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Old 11-16-13, 04:44 PM
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Trooper
I stand corrected. I was thinking of the 8124. I think it's time for a break.
 
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Old 11-16-13, 05:36 PM
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With the 8124A or C yes (but NOT the E), you can use it for the first zone pump, but you would then interface to the ZR and ZC terminals for the additional zones.

You still can't go to the T T terminals for the added zones because they would run pump on C1 - C2 just like with the 8148.

Using ZR and ZC bypasses the pump relay in the 8124 and allows burner firing only.
 
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Old 11-16-13, 05:43 PM
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is it cost effective [to use a Taco panel] for just one more zone
I think so. Two relays are gonna cost about $100 or so. The Taco panel is about $25 more.

It takes a lot less time to wire... just one 120VAC run to the panel, thermostats under terminals, pump wires under terminals, endswitch to aquastat. No fussing with jumpers and daisy chaining the AC, etc.

And, it looks better IMHO...

Time is money! I think it's worth the extra $25.
 
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Old 11-18-13, 08:37 AM
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I liked Spott's first answer because
1) It matched what I was seeing in the user manual;
2) I have a free R845 at my disposal

But it also left open the question of how the aquastat (L8148A) would keep the second zone from running if the boiler wasn't hot enough.

So do I need to buy a different aquastat that will control more than 1 circulator? I hate to spend the extra money, but if I have to, I will.

And just to clarify -- I'm the homeowner with some spare time, so I don't mind spending a bit of that over the green variety.
 
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Old 11-18-13, 08:49 AM
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OK -- I read through this a little more carefully and I think I understand the thread. It would seem that the best option is to buy the Taco panel, run the two circulators off that and control it via the existing L8148A aquastat -- do I understand that corrrectly?

One question -- you make a reference about "endswitch to aquastat" -- can you expand on that a bit for someone who isn't familar with the shorthand terminology?

Thank you!
 
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Old 11-18-13, 09:36 AM
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run the two circulators off that and control it via the existing L8148A aquastat -- do I understand that corrrectly?
Close I think... The Taco panel would actually control the 8148... vice versa what you said.

you make a reference about "endswitch to aquastat" -- can you expand on that a bit for someone who isn't familar with the shorthand terminology?
Sure...

To fire the boiler, the thermostat has to make contact across the T T terminals in the 8148 aquastat.

If you do choose to go with the Taco panel, you will be removing that thermostat from the 8148 and rewiring it to the Taco panel.

The Taco panel has a set of terminals on it that are called the "Endswitch" which is basically a set of contacts that close when ANY zone calls for heat.

You would wire these contacts to the T T in the 8148 in place of the thermostat wiring that you moved.

If you've already got ONE 845 relay, then in lieu of the Taco panel you could get ANOTHER 845 relay and wire them both up instead.
 
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Old 11-18-13, 02:46 PM
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Ah, thanks -- I understand now how the taco panel will work with my existing aquastat.

And I think I understand how the two 845s will work (one for each circulator). And from what you said and the manual I saw, they connect with the thermostat terminals on the aquastat via the 5 and 6 terminals -- correct?

If so, then a practical question -- I'm assuming that the 5 and 6 terminals are low voltage? Do I run the wires from each 845 box and double up the wires on the aquastat thermostat terminals?

Thanks!
 
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Old 11-18-13, 03:13 PM
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they connect with the thermostat terminals on the aquastat via the 5 and 6 terminals -- correct?
Yes.

I'm assuming that the 5 and 6 terminals are low voltage?
They can be either, depending on what function they will provide. In this case, yes, low voltage.

Do I run the wires from each 845 box and double up the wires on the aquastat thermostat terminals?
You could. You could also jump from one 845 to the next, and then on to the aquastat if it makes sense from a wiring layout standpoint. The two relays are likely to be mounted next to each other and the aquastat at a further distance. So jumping from 5&6 in one to 5&6 in the next, then to the aquastat might make more sense.
 
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Old 11-18-13, 05:25 PM
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Another way I do it is bring everything to a common point and wire nut so you only have one set of wires on each terminal.
Mount a small box, bring 5&6 from the two 845's and from TT on aquastat and connect there.
 
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Old 11-18-13, 06:21 PM
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That's just 18ga thermostat wire, should be no problem tightly twisting those and putting under screw... but even if you did go with the "1 wire / 1 screw" idea, why mount another box? There's plenty of room for a few small wirenuts inside the 845 box.
 
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Old 11-18-13, 06:30 PM
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Thank you very much -- I greatly appreciate the assistance (and patience!).
 
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Old 11-18-13, 07:12 PM
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You're welcome, and no problem...

Let us know how it works out!
 
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