Do I have a short cycle problem..?


  #1  
Old 05-11-08, 05:52 AM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
Do I have a short cycle problem..?

Sometimes my burner runs for only 2 minutes..this seems to be a pretty short run time, to me it does not seem efficient and it seems that I would have more expansion/contraction cycles on the boiler..do I have a short cycle problem?

Here are the particulars..

Oil/hot water system installed summer of 2007
Peerless hot water boiler WBV-03
Carlin EZ-1HP Burner
Honeywell Aquastat L8124A
settings:
Hi 180
Lo 160
Diff 10

I have 3 heat zones and 1 domestic hot water zone..indirect tank..(Amitrol)

I never noticed the short cycle with my old system.I started noticing it this winter (CT). Called my oil company and they came out, at the time they felt Aquastat was bad..you could hear it's relay click on-off when you pressed on the Aquastat housing..(they felt it had an intermittent open).

Still have this 2 minute cycle issue. I can see that the boiler water temp will rise by 10 degress (from 150 to 160) in 2 minutes.

Thanks for the help
Ken
 
  #2  
Old 05-11-08, 08:20 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I think the first question is why are you not running the boiler as a 'cold start' if you have an indirect water heater ?

If you've got three dials on your aquastat, that means that the boiler is going to stay warm all the time, between 150 and 160, with the ten degree diff setting.

Is there an unused tankless coil installed in the boiler ?

I would start by turning the low setting down to 120, and the diff to 25 ...

the boiler won't stay as hot, and the run cycle will be longer but less frequent.

But still... why not run it cold start ? (change aquastat to proper model for application)
 

Last edited by NJT; 05-11-08 at 09:02 AM.
  #3  
Old 05-11-08, 09:33 AM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
Maybe I am using the wrong term....

by indirect I mean that my domestic hot water is a tank that is heated by a zone off the boiler.
I do not have a coil for domestic hot water in my boiler.

Last summer the boiler and burner were replaced. From a design stand point the entire system is essenitally the same as the previous.

As far as a cold start..I don't think the boiler I have is meant to be run as a cold start.

These short cycles seem to occur in relation to the low control setting..occuring @ 150 degrees and running until about 160 degrees. If I increase the differential would'nt the burner run longer in these situations?

I'm curious is a short burn cycle is good for the chamber, flue, etc.
It would seem to me that a longer burn is better.

Ken
 
  #4  
Old 05-11-08, 10:11 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Right... the Amtrol is an indirect water heater. Piped as a separate 'zone' off the boiler. In contrast to a 'tankless' which is a coil immersed in the boiler water (that round black plate that the aquastat is mounted on is where the coil would be if you had one.)

I don't see any reason why not to run it cold start. The newer models of your boiler use a 7224 aquastat, which is the electronic version. The LOW limit setting can be disabled on those, and would be if you didn't opt for the tankless coil.

The previous versions came with the 8124 or, I believe, the 8148 aquastat, depending on whether or not you had the tankless... the 8148 is a 'single' aquastat, meaning only a high limit... no low limit setting.

If there is no tankless coil, I don't understand why you have the triple aquastat installed...

Yes, when you increase the diff, the burner will run longer. But, there is no reason to keep the low setting at 160... you don't need to keep the boiler hot. When the aquastat on the Amtrol calls for heat, the boiler will fire and run until the indirect is satisfied, regardless of the LOW setting...

My suggestion to turn it down to 120 with max diff will allow the boiler to standby cooler, and when it does cycle, it will run longer... but LESS FREQUENTLY.

If you've got an indirect, there's no reason to keep that boiler hot... yer wasting fuel $$$ ...
 
  #5  
Old 05-12-08, 03:35 PM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
follow-ups

NJ Tropper,
Mine boiler came with the 8124.
I see what your saying about cold start but I guess I don't undertand a few things...
There has got to be a downside to cold start..
With a cold start or lower low set...domestic hot water and zone heat must take longer to recover..correct?
I see concerns mentioned in other posts over expansion cycles on the boiler..with a cold start or lower low set it would seem the boiler would have larger range of expansion/contraction..I thought that was a bad thing..what kind of issues can be expected from running as a cold start or with a lower set temp?

I've been trying to understand the relationship of the water tank t-stat to burner operation. I think you may heading me towards solving that question. On my boiler aquastat I think the ZR terminal is connected to the water tank t-stat.
So whenever the water t-stat calls for heat..the tank circ runs and the burner fires (regardless of boiler temp, assuming the boiler temp is not at the high set temp)..is that correct? Is that what happens on the ZR term..it enables a make on the oiler burner circuit?

On a related question..while the burner fires should the circ pumps for the heat zones shut off?

This short cycle scenario just happened...
I heard the burner fire..went downstairs to check..one heat zone's pipe were hot...others and hot water zone not hot. Burner runs nearly 2 minutes shuts off..boiler temp about 170 degrees. Almost 10 minutes later burner fires again...runs about 1 minute. Same Zone as earlier has hot pipes..circ pump is running and boiler temp is about 170 degrees.

Does that cycle scenario seem to be normal?

Thanks for the education in this!
Ken
 
  #6  
Old 05-12-08, 04:10 PM
plumbingods's Avatar
Member
Join Date: Apr 2008
Location: Manch-vegas, New Hampshire
Posts: 1,985
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hello,


Sorry trooper but,
I am one that disagrees with cold start. I used to install them until we started finding more problems from expansion / contraction. So the co. I worked for at the time stopped using cold start and so did I.

I also don't think you should turn the boiler down to 120 as you will not have hot enough water for your domestic hot water, unless I am reading this wrong.

How many heat zones?
How many circulators?
Are there any zone valves? How many?
Is the zone for the hot water zone valve or circulator?
Do you have a multiple zone control for running the circulators or zone valves?

Can you post a picture?

let us know
 
  #7  
Old 05-12-08, 04:42 PM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
plumbinggods..

3 heat zones
1 DHW zone..Amtrol tank
All zones and Amtrol have circulators
I see 4 flow valves..
http://i275.photobucket.com/albums/j...e/IMG_0146.jpg

Not sure I understand your question about multiple zone control..I have Honeywell aquatstat L8124A


Under what condition will burner run until boiler temp reaches Hi Control temp of 180 degrees?

Thanks
 
  #8  
Old 05-12-08, 05:44 PM
plumbingods's Avatar
Member
Join Date: Apr 2008
Location: Manch-vegas, New Hampshire
Posts: 1,985
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hello again,
I would have replied sooner but I was in the middle of some really awesome steak tips.

OK Let me try to explain what I am thinking, I may or may not be right but I am in NH and you are in CT. But hear me out. It might be quite simple.

On a call for heat or hot water, assuming you have a single circulator relay control for all zones, a circulator will start. At the same time the burner will start. Both will continue to run until the call is interrupted, or if the burner reaches high limit it will stop while the circulator continues running. The burner will come on and off as needed until the call is interrupted.
Now, let's say that the burner was off but there was still a call for heat or hot water, this would mean the circulator is still on. During this time the water in the boiler cools down enough to turn the burner on while the circulator is still running creating heat or hot water. The call for heat was almost completed, lets say 2 minutes away.
The call is disrupted and the circulator and burner shut off because the zone or H/W is satisfied. Hence the short cycle of 2 mins.

The old boiler may have been a different size, wired differently, or the burner was firing at a different firing rate so it just didn't seem to happen as often. Also, when you purchase a new system you will have a tendency to pay attention to all the noises because it is new.

If you have seperate controls it still could happen similarly.

I could be way off but I think you should look into this before changing any expensive controls.

Let me know what you find please.
 
  #9  
Old 05-12-08, 06:10 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I dunno... seems to me there's millions of cold-start boilers out there that have been running like that for how long ?

I also don't think you should turn the boiler down to 120 as you will not have hot enough water for your domestic hot water, unless I am reading this wrong.
Keep in mind that he's running an indirect, not a coil... when the indirect calls for heat, it will allow the boiler to fire right on up to high limit. I agree that if it was a tankless coil, 120* ain't hot enough.

With a cold start or lower low set...domestic hot water and zone heat must take longer to recover..correct?
Yes, to an extent... but at what price impatience ? It's costing a lot to keep that boiler warm (hot) 24/7.

Going to look at the pics now...
 
  #10  
Old 05-12-08, 06:56 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Ken, there's gotta be some relays around there running those circulators. The aquastat on the boiler all by itself is capable of running only one zone. In order to have multiple zones, there have to be relays, or a 'zone control' box ...

The ZR terminal on the 8124 is used to fire the burner when a zone (or the indirect) is calling for heat. I'm betting you've got a wire on the ZC terminal also, yes ?

You probably have one room thermostat connected to the TT terminals on the 8124, and the associated zone pump wired to C1 and C2.

There should be three other relays that run the other three circs, and room thermosats, or the indirect aquastat will be wired to the TT terminals of those.

If you've got a circulator running, that SHOULD mean that one of the thermostats, or the indirect are calling for heat.

With a warm start boiler, on a triple aquastat, there will be times when the boiler will fire with NO circulator running. This is when the boiler cools and fires up to keep warm.

In no event should ANY circulator run unless the low limit is satisfied, meaning that if the boiler cools to 150 and no zones are calling for heat, the circs will be disabled. The boiler will fire to 160, the burner will shut down, and the circs will be re-enabled.

By the way, the LOW should never be set closer than 20* to the HIGH setting. If you do set them closer, it can happen that none of the circs will ever turn on.

If you've got a circulator that runs with the boiler firing, and there is no thermostat (or indirect) calling for heat, then there's a problem with the way it's wired.
 
  #11  
Old 05-12-08, 06:56 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 38 Upvotes on 30 Posts
If the orientation of that picture is displaying correctly then that air eliminator and float vent are totally useless and the expansion tank is going to tear itself from its threaded connection.
 
  #12  
Old 05-12-08, 07:00 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I thought the same thing at first! Then, I 'backed into' Ken's photobucket site and saw the other three pics... they're all sideways. The right side of the pic is the ceiling.

Ken, can you rotate them right side up ? (you can do that right on the photo site... there is an editor) My neck hurts.
 

Last edited by NJT; 05-12-08 at 07:28 PM.
  #13  
Old 05-12-08, 07:07 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Under what condition will burner run until boiler temp reaches Hi Control temp of 180 degrees?
The burner will fire up to high limit any time one of the zones, or the indirect, call for heat, and that heat call is not satisfied before the boiler hits the high limit.

If you went and pushed a thermostat up to 90* you would no doubt see this happen.

So whenever the water t-stat calls for heat..the tank circ runs and the burner fires (regardless of boiler temp, assuming the boiler temp is not at the high set temp)..is that correct? Is that what happens on the ZR term..it enables a make on the oiler burner circuit?
When your indirect (or one of the two zones _not_ connected to the 8124) call for heat, they supply 120 VAC to the ZR terminal to fire the burner.
 
  #14  
Old 05-13-08, 08:39 PM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
answers to answers and questions !

Thanks for all the responses..I've been learning a lot..
Sorry about the pics..these should be better:
http://i275.photobucket.com/albums/j...r/IMG_0143.jpg
http://i275.photobucket.com/albums/j...r/IMG_0144.jpg
http://i275.photobucket.com/albums/j...r/IMG_0145.jpg
http://i275.photobucket.com/albums/j...r/IMG_0146.jpg


Now to catch up..

Aquastat is connected to 2nd floor T-Stat and Circ for 2nd floor Zone.

I have 2 more heat zones;
1st floor..t-stat connected to Honeywell R845A which controls a circ for that zone

Basement..t-stat connected to Honeywell R845A which controls a circ for that zone

Amtrol has Circ and T-Stat on tank unit..as mentioned before ZR terminal on 8124A is connected to Amtrol.

NJ Tropper wrote:
The ZR terminal on the 8124 is used to fire the burner when a zone (or the indirect) is calling for heat. I'm betting you've got a wire on the ZC terminal also, yes ?
I just finished checking the connections...I have nothing connected on the ZC terminal on the 8124A.

First Floor and Basement Relays have power all the time (terms 1-2), as long as boiler safety switch and low water cut-off switch are closed.

NJ Trooper wrote:
The burner will fire up to high limit any time one of the zones, or the indirect, call for heat, and that heat call is not satisfied before the boiler hits the high limit.
I don't understand how this is possible for the 1st floor and basement heat zones. I'm looking at the schematic of the 8124A and the way I read it ZC is hot only when R-W is closed which occurs only when low limit differental is satisfied. Am I missing something?

I can see how it would run to high limit if my Zone one t-stat (connected to 8124A) would called for heat. As a matter of fact it looks like the burner will always fire (assuming boiler temp is below high limit) when the t-stat connected the 8124A calls for heat. Am I correct on that?

NJ Tropper wrote:
In no event should ANY circulator run unless the low limit is satisfied, meaning that if the boiler cools to 150 and no zones are calling for heat, the circs will be disabled. The boiler will fire to 160, the burner will shut down, and the circs will be re-enabled.
So it seems in my case it is possible for 2 of my zone circs to run regardless of the boiler temp since they are not controlled by the ZC terminal.

So I have to ask...should I have these 2 zones connected to the ZC terminal? Is there a good reason why I should not connect to ZC? Pros/Cons?

Also is there logic to connecting the 2nd floor t-stat (bedrooms) and associated circ to C1/C2 to the Aquastat as opposed to say the 1st floor (Main living area)?

Let me clarify that I have never seen a situation on my system where a circ is running and the associated zone t-stat is not calling for heat.

Thanks for all the help...I look forward to the next responses

Ken
 
  #15  
Old 05-14-08, 03:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
OK, the 845's are kinda what I expected you would say.

You didn't say if there was another 845 on the indirect though... or maybe there's a different relay at the idirect, perhaps inside that box I see in the pic ?

Somehow, the other 845's have to communicate to the boiler that there's a heat call from one of the associated thermostats.

Are there wires running _between_ the 845's and the indirect controls ? and then on to the boiler ZR terminal ?

The 845 is a double pole relay. One pole is wired to run the circulator, and the other would fire the boiler. There would be terminals 'daisy-chained' together perhaps... Take a look at the way they are wired in the 8124 I&O ... see where it says "to other relays" ?

more later...
 
  #16  
Old 05-14-08, 04:33 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
So it seems in my case it is possible for 2 of my zone circs to run regardless of the boiler temp since they are not controlled by the ZC terminal.
Correct. Possibly the indirect also.

Not really a big deal though... I wouldn't bother rewiring for something like that.

On the other hand, one thing you want to make sure of is that the _source_ of the power to the relays AND the boiler is one and the same. In other words, on the same circuit, and turned off by a single 'service switch'.

If there is more than one source of power, a person might not realize that, go to work on the burner, only to have a t'stat call for heat and have an unexpected firing event... THAT would NOT make their day !
 
  #17  
Old 05-14-08, 04:43 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I don't understand how this is possible for the 1st floor and basement heat zones. I'm looking at the schematic of the 8124A and the way I read it ZC is hot only when R-W is closed which occurs only when low limit differental is satisfied. Am I missing something?
I dunno... you are correct that ZC is hot only after the LL is happy. That's the power only for that one circ though... and the burner firing is controlled by either 1K1, OR power applied to the ZR terminal from the zone relays. (I'm betting that the other relays are all wired together to the ZR terminal along with the indirect). So, theoretically, ANY zone could run the burner to high limit.

I can see how it would run to high limit if my Zone one t-stat (connected to 8124A) would called for heat. As a matter of fact it looks like the burner will always fire (assuming boiler temp is below high limit) when the t-stat connected the 8124A calls for heat. Am I correct on that?
Yes, correct. When that t'stat calls, the burner will fire, because 1K1 will override the R-B contacts on the LL switch. (which by the way will also happen if the ZR terminal is powered)
 
  #18  
Old 05-14-08, 04:49 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Let's take another scenario:

Boiler cools to 150, R-W breaks, and R-B makes.

Burner fires, circ not running, and while the burner is firing, before the boiler hits 160, the t'stat calls for heat.

The burner will continue to fire, the circulator on that zone will stay off, but when the LL is satisfied, the burner will continue to burn, and that circulator will start up.

(I'm using the settings you have set as examples, but I still recommend lowering to 120... it absolutely WILL save you money on oil, with no downside, particularly in the summer months)
 
  #19  
Old 05-14-08, 04:54 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
So I have to ask...should I have these 2 zones connected to the ZC terminal? Is there a good reason why I should not connect to ZC? Pros/Cons?
I wouldn't bother... I actually think in your case you are better off having them run as soon as the t'stat calls. I mean, how much time difference are we talking anyway ? 1 minute ?

Also is there logic to connecting the 2nd floor t-stat (bedrooms) and associated circ to C1/C2 to the Aquastat as opposed to say the 1st floor (Main living area)?
No logic at all. Doesn't matter. Any one of your zones (including the indirect) could be connected to the aquastat. It's just another zone relay when operated in that fashion.
 
  #20  
Old 05-14-08, 07:22 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Ken, early on you said this:

I heard the burner fire..went downstairs to check..one heat zone's pipe were hot...others and hot water zone not hot. Burner runs nearly 2 minutes shuts off..boiler temp about 170 degrees. Almost 10 minutes later burner fires again...runs about 1 minute. Same Zone as earlier has hot pipes..circ pump is running and boiler temp is about 170 degrees.
and then in your last post, this:

Let me clarify that I have never seen a situation on my system where a circ is running and the associated zone t-stat is not calling for heat.
What this is telling me is that the zone with the hot pipes, and the circ running, was calling for heat. In this moderate weather, it's very possible that a 2 minute burn was enough to satisfy that heat call... the burner probably went off on high limit, continued to pump heat into the zone, then fired again. With only one zone calling for heat, it's very conceivable that you would get a short cycle.

What thermostats are you running ?

When you hear the boiler fire with NO circs running, that would be a firing to satisfy the LL alone...
 
  #21  
Old 05-14-08, 11:51 PM
plumbingods's Avatar
Member
Join Date: Apr 2008
Location: Manch-vegas, New Hampshire
Posts: 1,985
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hi KenRo

Notice that NJ Trooper has just said the same thing I said many posts ago. K.I.S.S.
 
  #22  
Old 05-15-08, 02:33 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Yep... I wanted to re-state it since we seem to have strayed pretty far off the course of the original post !

Ken, the bottom line here is that you _probably_ don't have an actual 'problem' at all. It sounds to me as if what you are observing is normal operation of a good-sized boiler in response to only one zone calling for heat, or, a firing with the diff set to 10* ... and too high to boot.

Cut that low back to 120, with a diff of 20-25 and you will have less frequent runs, which will last longer. You won't lose heat from the boiler (standby losses) _nearly_ as much as maintaining it at 160, and you will save $$$ ...

try it as an experiment... you can always set it back if I'm wrong ... give the experiment a week or two ... see if you notice a loss of hot water capacity ... of course it's not heating season, so you can't evaluate that aspect, but why not save some bucks over the summer ? (Spend it on beer or wristwatches ! )
 
  #23  
Old 05-15-08, 06:17 PM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
To finish this off, I think!

After all the responses I think I have a pretty good understanding of how all the pieces fit together with the exception of the ZC connection for zones. At some point somebody @ Honeywell thought it was needed to make sure Zone 2 and up circs don't run while the boiler is running.

For anybody following the thread I will answer the remaining questions that NJ Trooper asked;

For the indirect controls..it's t-stat and relay are original from Amtrol and mounted on the tank. The circ for the indirect is mounted right at the bottom of the tank. ZR feed to 8124 Aquastat runs direct from Amtrol controls..it does not go to 845s.

Both my 845s are only using one pole..to power the circ for their zone..other pole (terms 3-4) are not used.

For Zone t-stats all 3 are digital..one is Honeywell and the other 2 are the same...not branded but marked "Ultra-1000"

For the summer I'm thinking I might lower the low limit and increase the diff setting.

Thanks for all the responses. It's been a learning experience.

Ken
 
  #24  
Old 05-16-08, 12:09 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Originally Posted by KenRo
At some point somebody @ Honeywell thought it was needed to make sure Zone 2 and up circs don't run while the boiler is running.
The main reasoning behind that is IF you were using a tankless DHW setup (obviously you are not), you would have a 'priority' setup for the DHW. i.e. let's say all your zones called for heat at once, and you were in the middle of a hot shower. Boiler temp might dip below the LL ... DHW might get cool ... so the circs would shut off to allow the boiler to maintain the minimum temp to produce your hot water. And remember also that the circs would not be disabled until the boiler dipped BELOW 150*. If the boiler has enough capacity to run the heat zones AND stay above 150, the circs would continue to operate. Since you are running the indirect, it's not an issue.

Both my 845s are only using one pole..to power the circ for their zone..other pole (terms 3-4) are not used.
This piece of info explains why your LL setting is so high!

If either or both of those zone were to call for heat, and the others not, the boiler would not fire in response to that heat call. With the LL setting up high like you have it, the boiler would fire when it went below 150* and provide heat to the zone.

IMO, it ain't the right way to do things. Those zones should be able to also fire the boiler. Keeping the boiler that hot with the LL setting is a big waste of $$$ ... I would seriously look into rewiring that part. All it might take would be a couple jumpers on the relays, and another wire to the ZR terminal.

Now I understand why you were questioning how those zones could fire the boiler to high limit if needed. Wired like that, you are correct that they can't. Also, with only 150-160* water in those loops, you won't get full output from your baseboard (I think you said baseboard early on?) units.

Going back to your earlier question about whether there was any logic to wiring a particluar zone to the 8124 : I'm changing my answer a bit. There might have been. Is that zone the largest zone ? The thermostat that would logically call for heat most often ? If so, it would then make logical sense that it is wired to the 8124, versus the two that are not.

Is the relay on the Amtrol a double pole also ? If it is NOT, they might be running the ZR terminal from the same source that powers the circulator. If that's the case, then you can't just add wires to the ZR circuit from the second pole on the other relays. If you _did_, the Amtrol circ would run in response to a heat call from either of those other two zones. You would need to add or change a relay on the Amtrol if this were the case.
 
  #25  
Old 05-16-08, 12:29 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
[I edited this post, because I realized it was all wrong!, it was early AM and I was half asleep, sorry...]

Also, in my previous post, I thought it might be possible that the Amtrol has a Single pole relay... that's not likely either.

I believe you can simply extend the ZR wiring to the other relays.
 

Last edited by NJT; 05-16-08 at 09:36 AM.
  #26  
Old 05-16-08, 06:46 PM
K
Member
Thread Starter
Join Date: Jun 2007
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
More..info..

Hi NJ Trooper,

Your last posts have added even more info and understanding for me thanks. The Amtrol schematic shows a dbl pole relay. The Circ is wired to one pole and the ZR output to the other pole. So they will both be hot when the Amtrol T-Stat closes.

Zone 1; controlled by Aquastat is the second floor...4 bedrooms 2 baths.
Zone 2; is the first floor..kitch/LR/dining room/parlor.
I usually run zone 1 and 2 T-stats about 64 degrees from 11:30 pm to 6am then they go to 67 degrees for teh rst of the day. Sometimes I might go to 70 degrees.
Zone 3; is the finished basement..I keep that T-stat @ 62 degrees since it's not used much. If we use it I'll bring it up to 67/68. That zone seems to not run very often even in the dead of winter @ the 62 degree setting.

Zone 1 and 2 floor space is the same. Zone 3 is about 2/3rd the size.

Yes I said baseboard and I had not considered the importance of the water temp running to the Zones until you mentioned it.

I just realized that my Zone 2..could be calling for heat and never see water much over 165 (assuming it was the only zone calling) in the radiators since that zone cannot fire the boiler directly it relies on the LL setting.

So how much more heat could that zone put out if I was running 180 degree water..by means of the zone firing the boiler?

Zone 3..the basement..I'm not sure it would really need to ever fire the boiler directly given how we use it.

Is there a general rule for boilers..you should be able to heat your house to x degrees when it's y degrees outside?

So I can add more hot feeds back to ZR on the aquastat from Zone relays to fire the boiler? I think I can see that by looking at the schematic for the 8124.

If I bring the other zones back to ZR I guess I would leave HL @ 180 and set the LL to ?? and the LL diff to ??.

It's becomming clear now..Thanks !!

Ken
 
  #27  
Old 05-17-08, 09:51 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
So how much more heat could that zone put out if I was running 180 degree water..by means of the zone firing the boiler?
Fin-tube baseboard is rated in BTU output per foot, at a specified flow (GPM). Using Slant Fin Fine-Line 30 as an example, your output at 160 is probably around 450 BTU/F, while at 180 it would be around 600 BTU/F.

Is there a general rule for boilers..you should be able to heat your house to x degrees when it's y degrees outside?
Boilers are sized to the heatloss of the home. The heatloss is determined by type of construction, area of exterior walls, amount of insulation, area of doors/windows, etc.. basically all the ways heat can escape from the home. This is determined for a 'design temperature' for your area, which is the coldest typical days of the winter. If you are running an indirect water heater (you are), the ratings of that heater _may_ override the boiler size needed for heat only. (Boiler may be spec'd somewhat larger than for heat only)

So, the answer is yes. A calculation is done for a specified indoor temp, versus a specified outdoor temp, and the boiler sized accordingly.

Thing is, that 99% of the winter, the boiler is over-sized, since the outdoor design temp probably occurs less than 1% of the days.

If I bring the other zones back to ZR I guess I would leave HL @ 180 and set the LL to ?? and the LL diff to ??.
Yes, HL keep at 180. I still advocate that if you have the resources to do so, change the system to cold start... there would be no reason to keep the boiler warm 24/7.

If you _did_ do this, and used the 8148 a'stat, there is no ZR terminal, so you would have to change the control scheme around and add another relay... $$$ ... (see 8148 I&O PDF)

An alternative would be to turn the LL all the way down, with the Diff at 20-25 (max).

Grady, you reading this thread ? Any input ? (or anyone else ?)
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: