Gas Boiler not firing

Reply

  #1  
Old 12-17-13, 06:52 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
Gas Boiler not firing

I have a old Weil Macain gas boiler. It has two zone heat - taco zone valve 571.

I have replaced one of zone valve head.

The system has a auxiliary transformer from which the load (red wire 25V) is gone to the thermostats. Both thermostats are calling for the heat. The Terminal 1 & 2 has 25 volt. Terminal 2 & 3 are common both zone valves and connected to the Honeywell T stat relay.

Honeywell T stat has 2 T terminals and 2 X terminals. The T terminals are connected to Zone valves and terminals X goes to the Burner control module. The Burner has Honeywell auto ignite.

Now when I unhook all the wires from a Zone valve and put them back, system is completely shut off of for 15 min, the boiler is firing with the first call. The heat runs for a while.

But the heat call is not satisfied.

After the the first run, the boiler does not fire again and thermostat is continuously calling for the heat. Now I do not understand the the functioning of the T stat. The T stat runs the Circulator which runs all the time.

What could be the problem? I did not notice any voltage at T or X terminals at T stat. Both has 0 volt when my multimeter is set for 20V.
 
Sponsored Links
  #2  
Old 12-17-13, 09:23 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
old Weil Macain gas boiler
How old, and what is the MODEL number of the boiler?
 
  #3  
Old 12-17-13, 11:18 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
boiler model

I don't know how old it is. It looks like it is Weil Mclain 78 gas boiler. It was running for a while but the heat used to be in 80's. Then it stopped running. Now as I explained earlier, we can fire it once and it shuts off when the water temp gets to 180 degree. Then it does not turn back on itself. We have done that few times.
 
  #4  
Old 12-17-13, 11:32 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I'm trying to determine if this boiler has a 'millivolt' gas valve.

You are saying that it has "Honeywell auto ignite"... what exactly do you mean?

If it does, it's possible that the trouble is as simple as dirty relay contacts.

By the way, that device you called a 'T stat'

Honeywell T stat has 2 T terminals and 2 X terminals
Is actually just a RELAY. Probably an R832 model.

Is it possible that you can take some pictures so we can see what you are working on rather than trying to guess ... I would like to see any and all controls on the boiler, and also a clear picture of the gas valve.
 
  #5  
Old 12-18-13, 06:01 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
Pics and last night test

When I got to the boiler, thermostat call was there, boiler hasn't fired once after the first fire. No hot water in pipes. Circulator was running.

I turned the boiler off from main switch. zone valve got opened. After 5 min, I tuned the power on, heat call was made, boiler fired normally.

Voltage for aux transformer: 25V
Voltage at each valve: varying from 24V to 26V. Responding good to the thermostat.
Voltage at R832A: no voltage at T terminals. X terminals has 6.7 or 6.8mv while boiler running.
Voltage at two terminals at the burner box: 24 to 25mv

Boiler ran until the water reached 180 degree, it got shutoff.

Did not fire again.

Voltage for aux transformer: 25V
Voltage at each valve: varying from 24V to 26V. Responding good to the thermostat.
Voltage at R832A: no voltage at T terminals. X terminals has 0, boiler not running.
Voltage at two terminals at the burner box: 0

Pictures attached.
 
Attached Images           
  #6  
Old 12-18-13, 07:39 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
It is possible from what I am reading in your description that what you are seeing MIGHT be normal operation.

Have you 'lived with' the boiler for some time and observed it's activity for past winters, and is what you are describing now something NEW that you have noticed?

The way this should function is that when the boiler water gets to the 'high limit' setting of 180, the BURNER will turn off, but the CIRCULATOR will continue to run as long as the thermostat is still calling for heat.

If the thermostat CONTINUES to call for heat, when the boiler water COOLS DOWN approximately 10-15 from the point that it turns off at 180, the burner will automatically fire again... as long as the thermostat continues to call for heat.

Your boiler appears to have been OIL FIRED at one time and the burner that is now connected to the boiler is a CONVERSION GAS burner that was added at some time after the boiler was installed.
 
  #7  
Old 12-18-13, 07:55 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
I have not noticed this before. This is started happening in last few weeks. Right I am using electrical heaters in each room.

As you stated If the thermostat CONTINUES to call for heat, when the boiler water COOLS DOWN approximately 10-15 from the point that it turns off at 180, the burner will automatically fire again... as long as the thermostat continues to call for heat.

It is not happening. The boiler does not turn on, I watched the water getting cold but boiler did not fire.

To fire the boiler again, I have shut off completely for 5 min and turn on.

Could it be aquastat? that it shuts of the boiler when the water temp gets to 180 and gets stuck there until the power is turned off.
 
  #8  
Old 12-18-13, 10:14 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
another question is: aquastat has only wire which is coming from the main switch. There is no connection to R832A or burner? How would it tell the burner to fire again when there is no connection?
 
  #9  
Old 12-18-13, 05:40 PM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
Heat is running since yesterday. But I found a new thing, one of the thermostat wire wire has short. So the zone valve is continuously running and so the circulation. Nor I have a question, Is it possible that boiler does not fire when the zone valve called heat for hours (at least 48 hours)?
 
  #10  
Old 12-18-13, 06:21 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
There is no connection to R832A or burner? How would it tell the burner to fire again when there is no connection?
Would it be possible for you to draw a diagram of the wiring and somehow post it here?

So the zone valve is continuously running and so the circulation. Nor I have a question, Is it possible that boiler does not fire when the zone valve called heat for hours (at least 48 hours)?
Not sure what you are asking... do you mean is there some kind of a 'timer' ? No, there is not.

As long as zone valve is open, it would be calling the boiler to fire.

You probably have a number of things wrong there... perhaps a bad zone valve endswitch.
 
  #11  
Old 12-18-13, 07:39 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,698
Received 11 Votes on 11 Posts
You have a Honeywell S8600 control. That's electronic and by shutting the system down and restarting you are resetting that control.
It's very possible that's where your problem is.

My guess is something is wrong internally with the electronics and that is how you reset those.
When I was servicing regular that was a commonly changed part. They were not very dependable.
 
  #12  
Old 12-18-13, 08:37 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I was thinking that too... 8600 bad... maybe flame rod dirty... bad zone valve... probably a combination of problems.
 
  #13  
Old 12-19-13, 05:34 PM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
I have attached a wiring diagram.

The boiler was not running yesterday. I turned off the heat from the thermostat. Then turned off the power at boiler. Then I turned the power on. NO heat call, all looks okay.

Then raised the temp, thermostat called for the heat and boiler fired. All well. I stood next to the boiler for next one hour. Boiler fired few times normally and the temp got the set point. Zone valve got off. Everything is good.

to rule out zone valves, I replaced both zone valves.

Then I left. Today when I checked the boiler again, thermostat called for the heat , circulator running but boiler did not fired. I turned the power off for couple min and turned one. Boiler fired normally, I waited until the boiler fired couple times.

It looks like something is getting reset after the power turn off/on.

If the S8600 is the possible cause, I have S8600H. Is there any better option? I assume this is not repairable. Also I found it to be expensive.
 
Attached Images  
  #14  
Old 12-19-13, 06:15 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
another question is: aquastat has only wire which is coming from the main switch. There is no connection to R832A or burner? How would it tell the burner to fire again when there is no connection?
I believe that you will find TWO WIRES inside that CABLE.

I also believe that if you inspected the wiring very carefully you would find that the 6006 aquastat is wired IN SERIES with the power going to the burner much as a wall light switch would control room lights.

When the 6006 reaches it's setpoint, it OPENS and the power to the burner is cut off.

Could it be aquastat? that it shuts of the boiler when the water temp gets to 180 and gets stuck there until the power is turned off.
Anything is possible.

WARNING! EXPOSED 120VAC INSIDE BOILER CONTROLS! DO NOT TOUCH EXPOSED TERMINALS! YOU CAN BE KILLED!

Slide the cover off the 6006 aquastat.

With your multimeter set to measure 120 VAC touch one meter probe to each of the terminals when the burner should NOT be firing and is NOT firing. What voltage do you read?

Repeat the above test when the burner IS firing. What voltage do you read?

Repeat the same test when the burner SHOULD BE firing but is NOT. What voltage do you read?
 
  #15  
Old 12-19-13, 07:05 PM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
I have already checked the voltage at L6006 in two cases;

When the boiler is fired: 0 V at RB

When boiler turned off: 120 V at RB

When fired again: 120V at RB
 
  #16  
Old 12-19-13, 07:37 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
When the boiler is fired: 0 V at RB

When boiler turned off: 120 V at RB

When fired again: 120V at RB
I'm afraid you are not being clear enough for me to positively understand.


Does this:

Repeat the same test when the burner SHOULD BE firing but is NOT. What voltage do you read?
mean the same thing as this?:

When fired again: 120V at RB

If you are reading 120V at RB, the boiler should NOT be firing. You said 'when fired again'.

Do you mean to say " when boiler SHOULD BE FIRING again, but is NOT " ?
 
  #17  
Old 12-19-13, 07:39 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
What are the settings of the 6006?

Tell me the temperature setting on the front dial AND ALSO the DIFFERENTIAL SETTING.
 
  #18  
Old 12-19-13, 08:00 PM
Member
Join Date: Oct 2013
Location: United States
Posts: 2,698
Received 11 Votes on 11 Posts
On a call for heat, when the boiler doesn't come on have you checked for 24v on the S8600.
There are terminals marked 24v on there. Test with meter. If you have 24v and nothing happens I believe that would eliminate the controls up to that point. If no voltage I would back tract circuit to see where it stops.
 
  #19  
Old 12-19-13, 08:10 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Spott, things could get confusing if we start going in different directions. I'm tracing forward, and you are tracing backward...

That last post where he said:

When fired again: 120V at RB
Is telling me that it might be an issue with the 6006.

Let's stay focused on that for a bit before we start looking elsewhere.

From what I can see, the only control over the burner is whether or not it gets 120VAC supply.

If he is reading 120VAC across RB in the 6006 when it SHOULD BE ZERO, that right there is the problem. Getting a good solid confirmation is going to be the hard part.
 
  #20  
Old 12-20-13, 05:10 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
Sorry NJ, I forgot to mention that I have not tested the following step in L6006,

Repeat the same test when the burner SHOULD BE firing but is NOT.

It is set at 180. The DIFF wheel is 5.

I will perform the test you have asked for in the evening.
 
  #21  
Old 12-20-13, 05:38 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I am trying to understand your system so that I can better assist...

On the burner assembly I see what appears to be a PULL CHAIN LAMP SWITCH... are my eyes deceiving me or is that what it is? Any idea the purpose of that?

Is there any manufacturer or model number information on that gas burner?

As I mentioned previously, I believe that boiler began life as an OIL fired unit and that the installed burner is a field modification / conversion.

From what I am able to determine, the only wiring to this burner is the X X wires from the 832 relay to the burner, and the 120VAC wiring which travels through the 6006 aquastat. Does that appear to be correct?
 
  #22  
Old 12-20-13, 05:40 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
It is set at 180. The DIFF wheel is 5.
We can talk more about this setting after we (hopefully) can find the trouble.

For the time being, leave setting as-is.
 
  #23  
Old 12-20-13, 06:03 AM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
the only wiring to this burner is the X X wires from the 832 relay to the burner, and the 120VAC wiring which travels through the 6006 aquastat. Does that appear to be correct?

You are correct.

On the burner assembly I see what appears to be a PULL CHAIN LAMP SWITCH... are my eyes deceiving me or is that what it is? Any idea the purpose of that?

There is no switch, It is connected to a mounting plate on the box cover. No function.
 
  #24  
Old 12-20-13, 06:57 PM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
I am back to the boiler. Same story, it did not fire. So i checked the RB voltage at 6006 when it suppose to fire but it did not, it is 0 volt which means 6006 is okay. Now i am standing here, boiler fired at least 5 times.
 
  #25  
Old 12-20-13, 08:18 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
Is there any manufacturer or model number information on that gas burner?
Asked earlier because I need to know this... can't help if I don't know what we're working on.
 
  #26  
Old 12-26-13, 02:08 PM
Member
Thread Starter
Join Date: Feb 2013
Location: USA
Posts: 21
Received 0 Votes on 0 Posts
This has gas valve vr8304m3194. Then burner is 63200-001, I could not find the brand name. It has serial #4697. Then it is connected to Honeywell 8600. The metal box on the blower has 24 volt transformer and centrifugal switch themodisc 12s20.
It has fasco 7021-9084 blower. Centrifugal runs the blower.
 
  #27  
Old 12-26-13, 03:01 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
It's probably a "Wayne Combustion Products" unit, specifically:

P265F BB 120V EPN 8.25"

The one in the middle... does this look exactly like yours?



I can't post a link direct to the manual, website doesn't allow... so go here and scroll down to download the manual for your burner:

Product Manuals - Current in English
 
  #28  
Old 12-26-13, 03:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 2 Votes on 2 Posts
I am sorry to say that I do not feel comfortable advising you to work on that burner. I don't know enough about them myself, and even so, I do not feel as if this is a DIY project.

I will tell you this: The S8600 is probably 'locking out' because it is not sensing that the pilot light has lit. This control often requires a power cycle off/on in order to reset the lockout.

I would advise that you find a technician who is familiar with these burners.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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