Newbie here :Peeping On U2:

I would like to issue kudo's in advance to everyone

Hopefully I'll control my ranting..

Last season, Local "technicians" (I use this term grimmacing and grinding my teeth because their $700 SCREW JOB was evaluated and said to have been a

 

With your voltmeter, you need to find out why 24V isn't getting to the gas valve during a call for heat. Troubleshoot in a systematic manner using the boiler wiring diagram: Series MMW

The Peerless wiring diagram doesn't show it, but the end switches on the zone valves, a low-water cutoff, or flue damper OPEN contacts might be in the control circuit for the gas valve. Since the circulator runs, you only need to concern yourself with the portion of the 24-V circuit that controls the gas valve.

 

Thanx for your reply!

Checked for voltage at the gas valve which equaled 0.
Checking B1 and B2 (burner) terminals on the board of the L8148J returned 0 volts also.
I think we already knew that no voltage from the aquastat to the valve was already evident.

I noticed that there is a High Limit (temperature) dial in the same area as the burner terminals on the L8148J.
Does this act like a relay and control power to these terminals if the readings became to hot?
I am wondering if during the night the unit shut itself down because of ????
I searched BOTH diagrams for my boiler and didn't find a high temp limit.
Where does one find this and once known, should I check this dial and see if it is at that limit?


Will download the diagram for the "end" switches on the zone valves, but if the signal was cut from the thermostats and they shut off, can these be ruled out?

Searching also for the low water cut off and flue damper control locations..
all GREEK to me..

When testing the system is shut down, but I will leave it running as water can circulate through both zone areas.
It gets below freezing here at night, barely above at day and I don't want to burst any pipes.

Back to the drawing board..

Apologies for the stupidity, this is all new to me.

 

... that your boiler might have a millivolt gas valve.

I can't seem to determine from your model number whether it does, or does not... so we will need some more information.

You said that there is an 'auto/man' switch on the unit? This isn't 100% conclusive that you DO have millivolt valve, but it does make it POSSIBLE that you do...

Can you take pics of the gas valve? If not, tell us if there is any numbers on the valve? The type of valve you have will make a big difference in the troubleshooting steps.

If you can take pics, set up a free account at Image hosting, free photo sharing & video sharing at Photobucket and upload them there. Come back here and post a link to your album so we can view. If you post the pics, you won't have to learn Greek!

 

That temp dial in the 8148 is the high limit control, and will shut down the burners when the temp reaches that setpoint. When the water cools to appx 10° less than the setpoint, if there is still a call for heat, the burners should fire again. All this time the circulator should run as long as the heat call continues.

You WILL see durn near zero volts at B1 B2 if you have a millivolt valve...

 

OK, if you have an 8148J aquastat, AND your gas valve is wired to B1 and B2, THEN you DO have a millivolt valve.

There should be no wire on B3 in the aquastat. Is this true?

 

There will be two wires coming from a device near the pilot flame, and they will run to the gas valve. Depending on which gas valve you have, the terminals that these two wires go to may be labeled either ' PP ' or ' PG ' ... what is the voltage on these terminals? (hint: it will be low, but need to know how much?)

 

OK, I didn't scroll far enough among the Peerless MMW wiring diagrams: Series MMW

The last one has a a White-Rodgers 750-mV system.

 

AWWWWW.... but I wanna learn Greek! to be multi-lingual..

B3 and B1 connected, no connect on B2.

What should the millivolts readings be?
Shouldn't there be 24v at these points, apologies for redundancy..

OK, signed up with the bucket and here are ALL the Boilers pics;

Pictures by freezerburn2 - Photobucket

Order got lost in posting though..

Went back and looked for any other switches or wires near the burner, pilot, flue and pipe..
didn't see anything.

Basically, what you see in the pics is all I have to deal with.

Please notice the full pic of the inside of the boiler and the beautiful wires from the thermos, valves..
and the big hole cut then peeled by the PRO'S (toothless folk) to get to the pump..

I know it's coming..
"don't even waste your time, buy a new unit.."

Thanks again to ALL for replying!

going to grab dinner and come back and finish reading your replies...

half baked and getting frozen..

 

I didn't re-check the voltages as B3 and B1 were used and not B2.
I will wait for your answer(s) after seeing all the pics.

Pictures by freezerburn2 - Photobucket

Dial was set at around 180 as it looks.
But system is still up, water flowing, housings on valves still warm and thermos in the house still set at 70.
Water is definately cooled in all the pipes surrounding the unit.

I keep running in circles waving my wand and chanting.. to no avail..drats!
I'll behave and wait for further instructions before something gets hurled in my direction..

have a great evening, sir!

 

Love it! great writing...

I've gotta grab some food myself...

If you are wired to B1 and B3 then you DO have a 24VAC gas valve, and when the heat is calling, there should be 24VAC between B1 and B3 ...

So check that, and I'll be back in a bit.

 

Thanx for the kudo's..

I checked at B3 and B1, 0 readings. Meter set at 40V.

Was wondering, does the wheel have any priority with causing the boiler not to fire?
Pin points and voltages or other suggestions?
I've been pouring over the L8's diagrams.. trying to see if testing can be done on the relay other than just pressing it down.
And when this is performed, why does it shut everything off?
I'm trying thinking (look out world) :Peeping On U2: on finding 24V and directing it towards the gas switch to see if she'll fire..

Look West and if you see a mushroom cloud lighting the Purple Mountains Majestry.. you know I failed..

Heading for the couch with my grilled Tapia fillets and Asparagus.. piling on the cats and dogs for warmth... balmy 59 degrees inside.. warm glow of the electric heaters bringing visions of my wallet struggling from my pants and running off into the darkness...

will continue with you tomorrow morn.. give me a while to let the digits warm first...

 

You mean the 'High Limit' temp dial wheel? (yes) OK, it should only prevent the burner from firing if the water temp in the boiler rises to it's setpoint.

We'll get to this, below.

Hopefully you are looking at the same diagram that I am, and the following will make sense:

First, some explains of the components inside...

The two squiggly lines with the straight lines in between is a 120 to 24 VAC transformer. measure between ( TP or Z or W ) to ( TV or B3 ) and you should see the secondary voltage of that transformer; 24 VAC NOMINAL (as high as maybe 27, but not much lower than 24)

When the thermostat connection is made between T and TV, power will be applied to the ELECTROMAGNETIC COIL of the relay (which is the diagonal line thingy between T and W on the diagram).

When that coil is energized, the coil pulls the relay in and CONTACT SETS 1K1, 1K2, and 1K3 are 'made'.

1K1 sends 120VAC to the circulator.

1K2 would be used to close the circuit for the gas valve ONLY IF it were a millivolt gas valve, and it's not, so ignore this part of the diagram.

1K3 sends 24VAC to the LIMIT SWITCH (the part with the B and R on it, and that B and R indicates the color of the wires... this is the physical object inside the aquastat with the two screws on top with the BLUE and RED wires on it), and from there to B1 and on to the gas valve.

Since you know that the circulator is running, you also know that the transformer is good, the relay coil is good, the relay is 'pulling in', and that contacts 1K1 are good.

You don't know, or care, about contacts 1K2. (not used)

I believe that from your description of no voltage at B1 and B3 that EITHER 1K3 contacts, OR the limit switch contacts are bad, OR that there is a bad solder connection on the circuit board.

We'll get back to this in a sec... first an answer to another question:

Because when you press it down, you are turning it OFF. If the circulator is running, the electromagnet coil is pulling the contacts CLOSED. By pressing on that part, you are pulling it away from the coil, and returning the relay switch to the OFF position. If you turn all the thermostats down, you will see this relay turn off. If you then press it in the other direction, it will turn ON.

Now, more on the troubleshooting...

You probably already are aware that there is exposed 120VAC wiring inside this aquastat, so caution should be taken! YOU CAN BE KILLED! Do not accidentally touch any terminals that shouldn't be touched! Understand what you are doing before you do it! If you have any doubt about this, STOP! and consult a professional!

With your meter still set for AC volts ( 24VAC ), and the thermostats calling for heat (circulator running), measure between ( TP or Z or W ) and B . You should see ZERO volts. If you see appx 24VAC, you know that contact 1K3 is not 'making' and not sending the voltage to the gas valve.

If you see ZERO between the previous points, measure between B and R. You should see ZERO volts. If you see appx 24VAC, you know that the limit switch is not 'making' and not sending the voltage to the gas valve.

more...

 

If you find that either of the contacts 1K3 or the LIMIT SWITCH are not 'making', you can do some testing with a short jumper wire.

NOTE: These tests are for DIAGNOSTIC PURPOSES ONLY. Do NOT leave test jumper wires permanently attached. You WILL be BYPASSING important SAFETY CIRCUITS if you do. REMOVE JUMPERS immediately after testing! If you have ANY doubt about your own ability to perform these tests SAFELY, STOP! :NO NO NO: and consult a professional!

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TURN POWER TO BOILER OFF

To verify 1K3 fault:

Place a jumper wire from ( TP or W or Z ) to B.

Turn up thermostat to call for heat.

Turn power to boiler ON.

BURNER SHOULD FIRE if diagnosis is correct that 1K3 contact is bad.

TURN POWER TO BOILER OFF

Remove jumper wire from previous step.

=======================================

TURN POWER TO BOILER OFF

To verify LIMIT SWITCH problem:

TEMPORARILY! place a jumper from B to R SAFETY BYPASS! for DIAGNOSTIC ONLY!

Turn up thermostat to call for heat.

Turn power to boiler ON.

BURNER SHOULD FIRE if diagnosis is correct that LIMIT SWITCH contact is bad.

TURN POWER TO BOILER OFF

Remove jumper wire from previous step.

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Check your Private Messages...

 

If these tests indicate a defective aquastat, then that is the part that should be replaced. Did you say that Bozo and ClaraBelle already replaced that one time?