Boiler goes on when no heat is needed

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Old 02-14-11, 01:36 PM
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Boiler goes on when no heat is needed

I recently purchased a house with a Hydrotherm boiler feeding hot water baseboard radiators. The boiler goes on for a minute and a few seconds periodically, even if there is no heat demand in the house. The boiler gas flowing makes a mid-high pitched sound so I can hear it run. Keeping the water hot when there is no need for heat in the house seems like a big waste. I need a better solution than just unplugging the boiler on warmer days.

I have simple analog round thermostats on 3 zones that trigger hot water flow, but the boiler seems to only be concerned with keeping the water hot 24/7. I know for certain that the boiler runs when no water has been circulating all day.
 
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Old 02-14-11, 01:53 PM
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How do you heat your domestic hot water? Is there a separate water heater?

Some boilers also provide domestic hot water, so if yours does, this explains why it runs when it apparently should not.

What is the full model number of the boiler?
 
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Old 02-14-11, 02:18 PM
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No, I have a separate hot water heater. I will have to get the model number when I get home.
 
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Old 12-12-11, 09:15 PM
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Winter is back, problem is still around

The cold season is back and I'm regularly using the boiler again. As I mentioned before, the boiler always tries to keep the water hot as long as it is plugged in. It doesn't matter if any heat is required. It acts like a storage water heater, but does not provide tap water.

On top of this, I believe the system is over-sized. It's input is about 125k BTUs and something like 101k BTU output for an insulated 932 sq. ft. bungalow! And that's in California where it rarely freezes.

So I think I am wasting gas!

I want to know how this boiler should run and how to reduce gas usage. I just unplug the thing from the electrical outlet on warmer days now.

I have photos of the Boiler labels and wiring here: https://picasaweb.google.com/bnh142/...eat=directlink

Any advice would be appreciated. This system was installed DIY by a previous owner and has probably never been seen by an expert.
 
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Old 12-13-11, 11:08 AM
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What is the model # of the aquastat (the Honeywell control w/gray cover in pic #6)? If you could take the cover off and snap a pic of the wiring, that might help too.
 
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Old 12-13-11, 02:57 PM
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I believe this is the manual for your boiler:

hydrotherm.com/modules/lit_lib/download.asp?litFileID=1549

Based on what I can see so far in the pictures, your wiring diagram is most likely fig 1.21

Given that, I believe you will find that the gray Honeywell box is an L4081A.

If it is maintaining temp in the boiler, then there is a wiring snafu.

So as Rock has suggested, tell us what that control is, and show us pictures which will allow us to trace the wiring.
 
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Old 12-13-11, 03:23 PM
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No... something has been buggered... the schematic attached to the boiler is not the one that I thought it was in the manual... there has been a control added...
 
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Old 12-21-11, 07:59 PM
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Thanks, I added 4 new photos of the thermostat with the cover off to the album below. Any help would be appreciated.

Also, if it makes any difference, there are 3 zones controlled by those classic round heat-only Honeywell thermostats.... very basic.

https://picasaweb.google.com/bnh142/...eat=directlink
 
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Old 12-21-11, 08:48 PM
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They help... but I still can't get a mental picture of how this is wired... it's DEFINITELY been modified from the original schematic on the unit, but I can't follow the wires... i can't really tie all the individual pics together in my mind.

The part that's shown in pics 3 and 4 called 'left wiring'... that part has been added... that's a modification. When you say 'left wiring', where is that part in relation to the other pics?

Can you get a picture of that part straight on so that I can see the terminal numbers/letters and follow the wiring to where it goes?

Is it possible to step back and take some pics at a wider angle so that I can trace out the wiring?

Where does that wire coming out of the top of the box in the new pics go? Those two blue wires... from where?

Find the wires from the thermostats... what are they connected to? Are there motorized valves? Can you show us those?

The more pics you take the better. We need to see ALL the wiring and be able to piece it together from the various pics.
 
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Old 12-21-11, 09:17 PM
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That box connects to the circulator pump. There is wiring coming from the zone controls to that box as well, but there appears to be no connection to the wiring on the other side of the boiler. I have added some more photos that should make this more clear.

I'll try to answer your questions a bit later.
 
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Old 12-21-11, 09:25 PM
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Trooper you cant see that #???

Its the relay for the circ.......

American HVAC Parts Honeywell Transformer Relay Controller 24 Volt # R8239A1052

Yes on no call for heat the unit should not kick on.

Have you noticed at what temp the boiler is at when it kicks on? Is it consistant?

Mike NJ
 
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Old 12-21-11, 09:47 PM
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Sure I can see the number... it's the wiring I can't make out... and since that relay was added later, we need to figure out what was done that is causing this to run 24/7...

Sorry Brian, can't help... in order to tell you how to fix the wiring, we need to know how it's currently wired. This unit has been modified so we can't go by the drawing ...

Unless you can get pictures in which I can trace the wiring, or you are able to draw a diagram of the wiring, nothing more I can do for ya.
 
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Old 12-21-11, 09:58 PM
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The boiler gas flowing makes a mid-high pitched sound so I can hear it run.

Sounds like the gas valve selonioid is shot. I see no drip tee on that gas valve and wonder if sediment got in there.

I would try to describe more on whats happening. How long does it kick on for? Is it sporatic?

You may have a dangerous situation but the main problem I have is its electric ignition. Plus the vent damper needs to open before it even fires.

So its going through an ignition sequence. I am thinking faulty zone valve!!!!

Mike NJ
 
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Old 12-22-11, 01:10 PM
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So its going through an ignition sequence. I am thinking faulty zone valve!!!!
I thought that too at first but then dismissed it for some reason... but maybe...

Brian, does the pump run when the boiler fires all on it's lonesome?

Since it was said that this was a DIY by previous HO, and it's obvious that the wiring has been buggered, my belief is that it's wired wrong... but ya nevah know.
 
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Old 12-23-11, 07:33 PM
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Alright, I hope this helps, but please let me know what else you would like to know if you need more info:


1. What is the model # of the aquastat: L4080B-1212

2. Can you get a picture of that part straight on so that I can see the terminal numbers/letters and follow the wiring to where it goes?

A: I took a video and uploaded it to YouTube: Troubleshooting boiler wiring - YouTube Sorry my camera skills and narration aren't that great...

3. Have you noticed at what temp the boiler is at when it kicks on? Is it consistent?

A: I made the boiler cycle a few times by turning the thermostats up until the boiler fired and then Immediately turned the thermostat off once the boiler turned on. The visible thermostat needle moves very slowly so the temperature still drops after the boiler turns on and continues to rise after it shuts off. The needle stops moving at 180 degrees on the high side and about 145 degrees on the low side. I think the boiler may trigger at 140 since the burners have been on a while by the time the needle catches up.

4. Brian, does the pump run when the boiler fires all on it's lonesome?

A: No, the pump only runs when a zone calls for heat. It never circulates water unless heat is called for. The boiler burner on the other hand, does not care if the pump is on or not. The burners seem to be triggered by the boiler water temperature exclusively. When the circulator comes on, the boiler will not go on until the water temperature drops to the trigger point.

Also, I stopped the whistling burner sound by partially closing the valve on the gas line supplying the furnace. The flames have much less yellow visible now as well. As the water gets hotter, the boiler does make an odd but not very loud sound like air escaping from a kettle somewhere, but there are no apparent leaks. It gets higher pitched in a warbling uneven way as temperature rises and stops once the burners shut off. Then I can hear what sounds like water boiling for a little while before that dies down.
 
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Old 12-23-11, 07:43 PM
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Also, I stopped the whistling burner sound by partially closing the valve on the gas line supplying the furnace.

Umm, I probably would not do that. Open it up. You may get draft and CO issues.

You have CO detectors in the home?

Additioally Trooper will give his wiring advice after he sees the vid.

Here is the aquastat manual.

http://customer.honeywell.com/techli...0s/60-2101.pdf

Control manual. I believe this is the universal control.

http://customer.honeywell.com/techli...0s/60-2101.pdf

Heres the relay.

http://customer.honeywell.com/techli...it/60-1190.pdf

Mike NJ
 
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Old 12-23-11, 07:49 PM
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Hi Brian, I need to spend some time with your video and the pause control... I might be able to figure something out with this... at least now I have an idea where the wires are going from / to on each of the individual pics... that's what was missing.

I'll be kinda busy tomorrow, but I'll get back to ya on this.

In the meantime...

Also, I stopped the whistling burner sound by partially closing the valve on the gas line supplying the furnace.
This is really NOT a good idea at all.

It sounds to me as if the gas pressure is incorrect... I highly urge you to have that checked out by a professional! SOON. It's not something for DIY.

Happy Holidays!
 
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Old 12-23-11, 10:21 PM
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Thanks for your help. I really appreciate it! Don't go crazy with the video. I can go down there and try to make a wiring diagram if needed.

As for the gas pressure... is that something I should call my utility (PG&E) for or a HVAC repair person? I had the home warranty guy look at the system when the water pump went bad, but obviously he didn't care about anything else. It's been set like that for months and my nearby CO sensor has not gone off, but I'll go open it back up.

The flames had a lot of yellow before the adjustment even though the air intake covers on the burners were fully open. The pressure was reduced just a little so that it looks more like the "proper gas flame" photos I found. This also happened to stop the whistling. Anyhow I had a friend almost die from CO so I won't ignore the issue!
 
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Old 12-24-11, 10:17 AM
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Brian, I would like to recommend that you get them paint cans and stuff away from the boiler if possible. Even if it's not flammable oil type paints... just don't seem like a good idea. Just sayin'...

On your zone valves, the two top terminals on each are wired in parallel from one to the other, then they go back to the relay box on the side... trace those wires out and tell me to which terminals they go.

Then, there appears to be a third wire, probably the green one... tell me which terminal that is on, and where that goes on the zone valves.

Here is a diagram that shows how two zone valves would be wired... you have three, but no matter, it gives the basic idea.



Those two wires from the endswitch, probably the red and white ones, the drawing says they go to the 'aquastat on the boiler', but in your case they go to the two terminals on that relay...

The 'xfmr' in this drawing is in that box on the side... and I believe that the green wire is supplying the power to the zone valves.

What SHOULD be happening here is that when any thermostat calls for heat, the zone valve motor gets energized and opens that valve. When the valve opens, the ENDSWITCH makes contact and sends a signal to the boiler to turn on... so we need to start here at the zone valves and work our way through.
 
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Old 02-06-12, 10:38 PM
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Figured it out!

The aquastat was wired to the constant 24V current rather than the switch activated current on the transformer. Three wires were connected with the same wingnut. The boiler now only turns on when there is a call for heat.

I wonder why it was wired to always on before. Perhaps it heats the house a little faster that way?

Anyway thanks all for your help!
 
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Old 02-07-12, 02:08 PM
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I wonder why it was wired to always on before. Perhaps it heats the house a little faster that way?
I wonder too... yeah, the house would heat a bit faster, but probably not enough to make the extra fuel expense worthwhile...

Have you seen your fuel costs drop?
 
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