Boiler heating system


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Old 11-01-09, 10:18 AM
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Boiler heating system

I have a oil fired boiler system with both in-floor and baseboard radiating system. There a two circulating systems each with two zones. The boiler is equipted with a honeywell aquastat relay L8124L with two zone valves (V8043G) and is controlling the boiler burner and the circulating motor.
The second circulating motor operates directly off the AC line and the radiators are controlled by two zone valves.

I want to have the circulator pump to operate only when the sone valves calls for heat to avoid the motor running continuously.

I have reviewed some honeywell switching relays but they do not resolve the problem unless I install multi units. To expensive.

Help Please.
 

Last edited by Trouble1936; 11-01-09 at 11:37 AM.
  #2  
Old 11-01-09, 11:29 AM
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I don't fully understand the setup...

You have a mixed system, baseboards and radiant in-floor.

You say there are two 'circulating systems'... does one of these 'systems' (or loops) run the baseboards, and the other run the in-floor?

Do the two 'systems' run at different temperatures? I think they should... the radiant system doesn't need as high a temperature as the baseboards, so there should be some type of valve that is 'mixing' the water down to a cooler temperature for the floors.

Help us understand so we can help you...

Pictures of the entire system might help if you can take them.
Set up a free account at Image hosting, free photo sharing & video sharing at Photobucket and upload the pics there, and place a link to your album here.
 
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Old 11-01-09, 11:50 AM
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There is a mixxing system with a lower temp for the in-floor. the infloor and the baseboard has independent loops. The infloor loop in controlled by the aquastat L8124L pump control. The baseboard loop circulating pump is wired directly to the AC line and runs continuous. I know that I can control pump operations by using a switching relay, but these relays will only support one zone relay. So since I have two zone valves on that loop I would need two switching relays at about $200 each. I am wondering if there is something out there much simpler to control the pump operation
 
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Old 11-01-09, 01:31 PM
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I'm not sure what you are looking at for $200 each... but I don't think that's what you need! At least you hope not, right?

I'm thinking that you only need ONE relay for the pump, at under $50 or so... but in order to make a suggestion, I would need to know a lot more about how the whole thing is wired.

So, I'm going to need to ask more questions, and would also ask that you post some pictures if possible...

Are all four zone valves the same? (V8043G) and they all have four wires, two yellow, and two red, CORRECT?

Do the zones that control the baseboards ALSO fire up the burner? In other words, if one or both of the baseboard zones calls for heat, will the burner fire?

And, just so I'm clear, you said that the circ pump for the radiant zones is controlled by the 8124 aquastat?

One more... does your boiler also supply domestic hot water to your home?
 
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Old 11-01-09, 03:51 PM
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Because of the way the installer, long before i bought the house, configered the plumbing above the boiler it is impossible to take a picture.

This is what I have. There is a temperature control device to provide low temp for the in- floor heat and a higher temp for the baseboard radiaters.

Loop 1. The in-floor heating is one loop, divided into two zones. Those zones are connected to the L8124L honeywell aquastat.
Loop 2. The base board radiateor is another loop, divided into two zones. The low voltage transformer to supply power to the thermostat and the zone valve motor,is mounted on the wall external to the boiler. The red wires a not attached. The circulating pump is connected directly to the AC power and runs continuously.

I don't know if any wiring changes have been made to the aquastat.

Yes, the boiler does respond and fire when the any one of the thermostat for Loop 2 is adjusted.
Yes, the boiler supplies domestic hot water.
 
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Old 11-01-09, 05:02 PM
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OK, we're gettin' there!

Yes, the boiler does respond and fire when the any one of the thermostat for Loop 2 is adjusted.
Without any connection to the red wires on the associated zone valves, there's still a piece of the puzzle missing.

That is: How is the burner firing when loop 2 calls for heat if there is no connection to the end switches?

Begs yet two more questions:

When the burner fires for a loop 2 call, does the circ for the radiant ALSO run? or does it remain off?

Is there any wiring going to the ZR terminal of the aquastat, and if so, where does it go?

The red wires a not attached.
It is very possible, since these are not connected, to use them to trigger a relay to run the circ.

As long as both endswitches are functional, you can wire them in parallel, to the thermostat connections of an R8845U relay (the
 
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Old 11-01-09, 06:15 PM
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Loop 2. The red wires of zone alarms are not connected to anything. The yellow wires are connected to a 120V/24V isolated transformer. The circulator is connected to the ac line only. There is no electrical connection to the aquastat or any part of the furnace. There is no hidden relay. As far as i can see the in-floor circulator remains off and the zone valves are off. There are no wires connected to ZR. I can see no reason why ir fires unless the aquastat has been modified to fire on low temp. I spent 35 years in electronics. but I am not fimiliar with the guts of the heat probe and as of yet I am not in the mode to pull the thing apart if I can find another solutation.

Yes the could be used to run a relay. Looking at the wiring diagram for thR8845U, it is similiar to the R845 and only allows for one valve. I have two zone valves and two thermostats. So paralling two zone valves to one thermostat wont work as the valves controlss the temperature in different parts of the house ( one=Livingroom/Dining. Two=bedrooms/bath)

Zone 1, the in-floor radiation is in the basement and one zone valve and thermostat is for the family room,utility room and laundry. the second zone valve is for a bedroom, study and large bath.

The house is 1600 sq ft on each level. if I was building it I would have at least six zones.

If u have an idea, maybe u can draw me a diagram.
 
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Old 11-01-09, 08:38 PM
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Here's what I think is happening...

The boiler isn't _directly_ being fired when the baseboards call for heat. It is reacting to the cool water flowing back from the baseboards, and the LOW LIMIT is firing up the burner.

The aquastat hasn't been modified, there's no reason to 'reverse engineer' anything. This is the way a "triple" aquastat is designed to work. When the boiler cools to below the Low Limit, the burner fires to maintain that limit... if there is a contact closure at the T/TV terminals, the burner will fire up to it's HIGH limit setting.

Electronics, eh? OK then you understand what an OR gate is. You have TWO inputs, the endswitches (the endswitches are isolated dry contacts), one from each valve. When you wire the endswitches in parallel and switch a relay coil, you have created an OR gate. You have one output that goes high when EITHER of the two inputs is true. That output runs the circ. I'm not sure why you are thinking that you need two relays... you are only switching ONE circulator.

I want you to be clear that you are NOT paralleling the thermostats, OR the inputs to the zone valves. You will not touch any of the yellow wiring, or the transformer wiring. Each thermostat will still control it's own valve. You will only be using the OUTPUT from the valves, in parallel, to switch the relay to run the circulator.

There is a way to use the same relay (another set of contacts) to also DIRECTLY cause the burner to fire, but as long as the home is heating adequately with the temperature of the water they receive, there is no point in doing the extra work. If you tell me that the baseboard heated rooms are often too cool when it's really cold out, I can show you how to do that also, with more wiring from the same relay.

The reason I recommend the 8845 is because it is cheaper than the 845, which will also work, as will the Taco SR501, and others...

if I was building it I would have at least six zones.
And your boiler would probably 'short cycle' because the 'load' from each of those zones would be so small as to only require short bursts of output.

What are the settings on the HIGH, LOW, and DIFF dials inside the aquastat?

Is the hot water supply to the home adequate?
 

Last edited by NJT; 11-01-09 at 09:11 PM.
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Old 11-01-09, 09:04 PM
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Here's a diagram using the 8845 to switch one circulator from EITHER of two zone valves.

 
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Old 11-02-09, 10:30 AM
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boiler heating system

Thanks. I missread your previous msg. For som reason I could not log-on. It was late and I quit. However, I did solve the problem this AM. Thanks for your assistance.

Sometimes one gets bogged down and cannot see the woods for the trees.

tks

Trouble 1936
 
 

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