Boiler will fire without TH


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Old 09-21-08, 09:31 AM
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Boiler will fire without TH

I have a Pennco boiler with a Honeywell aqua stat. I have checked the wiring from pump and blower and all is correct. However, have only the 110 connected and no thermostat connected, the system will fire. Without the thermostat connected the system cannot be calling for heat. I cannot understand what is going on. This hot water system heats only the home not domestic water.
 
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Old 09-21-08, 09:39 AM
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Sounds like a wiring problem, but will need more info to help you.

Control models and manufactures.

Pictures of the wiring if possible
 
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Old 09-21-08, 10:23 AM
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Controls

Some controls are made to keep the boiler hot all the time with the thermostat essentually controling only the circulator. Make & model of the aquastat will help. There's usually a label on the inside of the aquastat cover.
 
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Old 09-21-08, 11:56 AM
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Thanks for the help. The system is a Pennco with a Honeywell aquastat. I checked the wiring using the diagram at the Pennco website http://www.ecrinternational.com/secu...ument/1402.pdf and found that it is as it should be. The system is about 6 years old and we never really had a reduction in usage from the antiquated system that it replaced. We had to move the system to a new location in the basement and once I began doing the work myself things didnít seem to make sense to me, although I will admit that I am no professionalÖnor was the company that put it in originally.

I want to confirm that the boiler should not run it the thermostat isnít calling for heat. Next question is will the system run automatically if a thermostat is not connected?
 
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Old 09-21-08, 01:39 PM
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A HoneyWell L8184 aquastat includes a high limit cutout and a circ. relay, with a transformer to supply 24v to the Thermostat. Without a connection across T-T the burner and circ. should not operate.
If it does, there's a stuck relay in the aquastat. Welded points.
 
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Old 09-21-08, 02:07 PM
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You mean L8148 , correct ?

If it actually IS an 8148 ... if that boiler has a 'triple' aquastat installed, the burner will run without a t'stat connected.

Take a look at the aquastat (gray box) and see if you can find a model number on that. If there are 3 temp settings inside that gray box, it's a triple.
 
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Old 09-21-08, 03:22 PM
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The Aquastate is L8148A. It has a dial wheel to set temperature.
 
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Old 09-21-08, 03:26 PM
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"L8148A Comb Hi Limit & Relay Control"
This is copied from the .pdf supplied.

There would be no low limit with this cntrl, looking at the ladder diagram shown. Just an adjustable High limit, with a built in differential.
However, this is a high efficiency boiler and if the return is below 120* there will be serious condensation and corrosion issues.
In that case, the manual recommends a bypass from the supply to the return to maintain 120* or above to avoid this.
Maybe the plumber put a triple aquastat in place to get around doing the bypass piping.
In that case it would fire to the low limit (circ) setting, without a wall thermostat even installed.
So, if it is an L8148A cntrl, then there is a short in the cntrl or a stuck relay.
I would tilt the guts out of the aquastat housing and look for shorts/burnt spots. I think the relay housing may be clear plastic so get a strong light and see if points are burnt together.
Of course, with an ohmeter it would be easy to check. With the power off, check for continuity from L1>B1, L2>B2. Shouldn't be any.
We need the actual model number off the aquastat to be sure.
 
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Old 09-21-08, 04:24 PM
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That's what I was thinkin' that someone swapped 'em out to a triple... but not ...

I think there will be continuity from L2 to B2 and C2 ... the relay only switches the HOT, the Neutral goes straight through.
 
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Old 09-21-08, 04:30 PM
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Absolutely! What was I thinking?
 
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Old 09-21-08, 04:54 PM
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L8148a

As Trooper said, there should NOT be continuity between L1 & B1. There will be continuity from L2 to B2.

Please confirm the boiler is wired correctly & there is no short between the terminals labeled T & T.
 
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Old 09-22-08, 03:03 PM
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Ok, I have nothing between T&T. I checked the wiring using the diagram at the Pennco website http://www.ecrinternational.com/secu...ument/1402.pdf and found that it is as it should be. The only thing that the diagram does not show is the blower that is currently connected to B1 – B2 along with the circulator. Without the blower the system has a safety feature not allowing the system to fire.
 

Last edited by NJT; 09-22-08 at 03:53 PM. Reason: fixed link
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Old 09-22-08, 03:50 PM
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The circulator is on B1 B2 ?

What's on C1 C2 then ?

When you say 'blower' I believe you are referring to the 'draft inducer', which IS shown on the schematic diagram.
 
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Old 09-22-08, 04:24 PM
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Is this a gas or oil boiler? They have a L8148J that has a manual override switch on the side for gas boilers with standing pilot. I ran across one once and was dumbfounded. Power was off and burner still ran

Auto-Manual Switch
The AUTO-MANUAL switch (only L8148J millivolt
models) makes it possible to operate the burner (in a
system with a millivoltage gas valve) during an electrical
power failure. With switch at MANUAL, the burner
operates continuously until either the high limit setting is
reached or the switch is reset to AUTO. The circulator,
requiring line voltage, is inoperative. When power is
restored, the switch must be set to AUTO to resume
automatic burner operation.

http://customer.honeywell.com/techli...it/95-6940.pdf
 
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Old 09-22-08, 05:24 PM
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Correction, the blower that is currently connected to B1 Ė B2 along with the low voltage relay.

Iím not really sure what a 'draft inducer' is in reference to a blower. This unit blows that carbon monoxide through the vent pipe. Again, I am not familiar with the terminology but learning quickly. Thanks to all for the help this far.
 
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Old 09-22-08, 06:08 PM
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Blower/Draft Inducer

The blower & draft inducer are one & the same. Pennco refers to it as an "induced draft blower".
 
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Old 09-23-08, 11:47 AM
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Getting worse?

There is no visible sign of burnt spots on the aquastat. At this point the system will not fire at all now. I have power coming in at L1 L2. The low limit controller that is on the diagram I do not see on my system. Unless it is the device connected to B1 & B2 that runs to the blower.

Below T T I have a switch that has HONEYWELL stamped on it. When it was firing, that switch would click and the system would turn on even though no thermostat was connected. Now that is not happening even when I connect the thermostat and it calls for heat. If I manually push this switch the stem will fire with or without the thermostat connected. Again I see no sign of burnt spots on the face or back of the aquastat.

Thanks again to all for the help!
 
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Old 09-23-08, 01:52 PM
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http://customer.honeywell.com/honeyw...spx/L8148A1017

The thing you push in manually to start the burner is the built-in relay. The limit is usually a brown control with a wheel to set the cutout temp.
The limit opens the circuit between the t-stat, transformer, & relay coil and will prevent the relay from pulling in. No burner, no circulator.
If the relay won't pull in, then there's a problem in the series circuit or the transformer has burnt.
Honeywell doesn't even list the L8184A anymore. Just the L8148A, which goes for just under $300. This info is right from the Honeywell website.
I don't know what more to suggest without actually seeing the setup.
Goodbye.
 
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Old 09-23-08, 02:46 PM
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Thermostat Connected

When you connected the thermostat & set it well above room temperature, did you actually get circulation?
 
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Old 09-24-08, 05:15 AM
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No circulation when connected to the thermostat.

I have photes at http://pagregg2.spaces.live.com/photos/
 
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Old 09-24-08, 05:27 AM
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If I need a new aquastate how do I know that this model is correct for my system? I am thinking that it ran all the time as we had questioned this in the past but dismissed it due to lack of knowledge
 
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Old 09-24-08, 04:30 PM
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I just glanced quickly at the photos...

One thing you need to do right off the bat...

See that uninsulated copper wire (ground) coming from the cable that feeds 120VAC power to the aquastat ? That wire is dangerously CLOSE to the terminals on the top of the LIMIT SWITCH (the brown thing with the blue and red wires on it).

You will have fireworks, probably a fried aquastat (if it's not already broken), and most likely a tripped breaker.

That wire needs to be insulated, or better yet, moved to a better location near where the cable enters the aquastat.

If you were to put the cover on that, and push that wire down and it hits either of those terminals, and the aquastat kicks on ... BZZZTTTT BANG !
 
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Old 09-24-08, 04:48 PM
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Another thing about that wire ... it's not the right kind of wire, it should be that metal covered stuff as the other wires are. Also, it appears that the locknut for the cable clamp is not even installed ... that needs some attention ...
 
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Old 09-24-08, 07:25 PM
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No Circulation, etc.

If the boiler was hot & you had no circulation, that could be why the boiler didn't fire. With the thermostat calling for heat, do you get 120v between C1 & B2/C2?

I agree with Trooper about the wiring. Replace that romex with MC cable.

If the aquastat needs to be replaced, Pennco specs an L8148A. You will have to either transfer the external transformer to the new aquastat or replace it too.
 

Last edited by Grady; 09-24-08 at 07:32 PM. Reason: added more information
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Old 09-27-08, 08:02 AM
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I have no power when thermostat calls for heat other than L1 L2 unless I manually pull on the built-in relay then it fires and I have power to C1/B2 and C2/B1.
 
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Old 09-27-08, 08:09 AM
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Also If I take a wire an jump T-T nothing.
 
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Old 09-27-08, 08:15 AM
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That does make is sound as though the aquastat is fried...

You have a multimeter I presume ?

Set it for AC VOLTS, a range that will allow you to measure 24VAC,
and with the TT terminals OPEN, measure across them.

You should see 24 VAC there ...

if not, the internal transformer or the relay coil are toasted.
 
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Old 09-27-08, 08:20 AM
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Should I have power at the high limit control? B-R no power.
 
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Old 09-27-08, 08:29 AM
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No power to the high limit control until the relay pulls in.

There will be 120VAC on both of those wires when the relay is pulled in, but NOT between them.

If the relay is pulled in, you will measure 120VAC from L2 to EITHER of those Blue or Red wires, UNLESS the boiler is above the high limit ... then you will only have 120VAC to ONE of them (don't remember which one, but only one).

What do you have across the OPEN T T terminals ?
 
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Old 09-27-08, 08:49 AM
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Ok, I took the aquastat board out of the box and pulled the heat sensor out of the system and checked the circuit board again and could see no sign of burnt marks. I put everything back together and at first had no power between T/T using the meterÖbut after wiggling it I had 24v. I connected the thermostat and it FIRED! It shut down accordingly! What is going on?
 
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Old 09-27-08, 08:55 AM
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No Power

There could have been a loose connection, possibly a bad solder joint.
 
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Old 09-27-08, 09:56 AM
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What I am now seeing is that if I bump the aquastat when the thermostat is calling or heat it will turn on and off. Bad connection on circuit board?? Is this anything that I can fix?? It would have to be at T/T correct? That is were the power is being cut right? As I didnít have power at times (on and off) at T/T.
 
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Old 09-27-08, 10:19 AM
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Loose Connection

Most likely it's a bad solder joint but finding it is the real trick. Another possibility is a weak relay but if you loose the 24 volts at T-T the problem is not the relay.
 
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Old 09-27-08, 10:29 AM
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If you just installed this control, look for a loose or BROKEN wire around the screws. This is common and sounds like what is happening here.
 
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Old 09-27-08, 12:15 PM
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Whatever is happening with it _now_ does NOT explain why it was firing ALL ON ITS OWN previously though...

My recommendation would be to replace the control.

http://www.patriot-supply.com/produc...witem.cfm/8084
 
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Old 09-27-08, 12:37 PM
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I agree that the original problem has not been solved yet.

I was just pointing out a possible reason why you can tap the control and it goes on and off.
A loose screw in the wiring, or during all this troubleshooting and possibly moving wires around, one could have been broken off and not noticeable.
 
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Old 09-28-08, 05:53 AM
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If relay is pulling in with wires removed from T-T and burner and circ wiring are correct then replace control. This control is for heat only not domestic hot water so nothing should happen if T-T is not made if all works with T-T wiring removed (jumped burner comes on not jumped shuts down) check for short between T-T somewhere in wire between control and t stat. Also if your tapping control and it is coming on and off and your sure all wires are tight replace control.
 
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Old 09-28-08, 10:48 AM
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Ok, I was given a Honeywell aquastat today. The original is an L8148A and the one that was given to me is an L8148B. The only difference appears to be an option on the side of the unit for auto / manual. I am unsure of what this is for.
 
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Old 09-28-08, 11:19 AM
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That's not the only difference.

The B model is obsolete and replaced by the J model.

These models have a LOW VOLTAGE output.

If you didn't have the draft inducer on your boiler, you _might_ be able to use it, but as it stands, you can not use that one.
 
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Old 09-28-08, 12:35 PM
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The reason for the switch is to allow a pilot style boiler to operate in millivolts and turn on the burner during a power outage. Of coarse you would still need to manually open your flow check or zone valves to get gravity heat in the house. And if you have the switch in the wrong position, this will allow the burner to run with the power switch off.

Ask me how I found out about these controls
 
 

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