Honeywell L8148A, Aquastat Relay and Carrier Boiler

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Old 11-15-12, 10:05 PM
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Honeywell L8148A, Aquastat Relay and Carrier Boiler

Hi,
My first post......pardon me as I try this....
I have a Carrier Hot Water gas fired boiler with a Honeywell L8148A, Aquastat.
The house has 4 zones.
Here is my problem...The 4 Taco zone motors are running all the time.
The thermostats are all "off" and not calling for heat. The boiler fires, heats to 140f and shuts off as it is set to do. The Taco motors continue to run and feed the house until the boiler temp drops, calling for the boiler to fire and reheat.

So my stupid question is...is the aquastat bad (a component in the aquastat), do I have a crossed wire, etc....
I I feel it must be a simple problem..... What should I be testing....
Thanks for your time.....
 
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Old 11-16-12, 06:46 AM
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gas fired boiler with a Honeywell L8148A
More likely an "E" model if it's a gas fired system, i.e. L8148E , but that's sort of irrelevent because it doesn't sound as if the aquastat is the problem here... or is it?

You also said:

The boiler fires, heats to 140f and shuts off as it is set to do.
What 'setting' are you referring to? If you have an L8148E aquastat, there will be only ONE temperature dial and it should NOT be set as low as 140

Perhaps you have an L8124x Aquastat with THREE DIALS ?

Further you stated:

The 4 Taco zone motors are running all the time
I would like to clarify that you are talking about the CIRCULATOR PUMPS... OR, are you referring to the ZONE VALVES?

If you are referring to PUMPS:
Are you SURE that the pumps are in fact running? How do you know?

How are the pumps being controlled? To what are they wired?

If ZONE VALVES, same basic questions.

If you can supply some photos of the system it would help us determine some of the unknowns and be better able to assist.
 
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Old 11-16-12, 09:28 PM
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Hi NJ Trooper,
Thanks for the reply, I will take a few pictures tomorrow of the system. Can I attach them here or do I send them to you?
I see after rereading, that I did not say what I ment to say.... I am trying to help an older relative correct what I hope is a simple problem, thus saving a service call, but maybe that is what the next step will be...
The house was built circa 1969. The present "Carrier" boiler was installed in 1997.

Here is what I can diagnose so far...The circulator pump runs continually.... I can hear it running and also feel it running when a screw driver it place on the pump motor housing. I will check the Taco Zone Valves tomorrow more in depth....

Their is only ONE tempature setting and the setting is set at 140 on the Aquastat and the inside of the cover says that it is a L8148,E Aquastat....

What should this setting be at?

I will get those pictures and send them. But just to clarify where should I send them? attach them here on the posting?
Thanks for your time so far!!!
 
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Old 11-17-12, 08:11 AM
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Hi MN,

It is possible to attach pics directly from your computer to the forum, but the forum will resize them and we may not be able to see needed details.

I feel a better choice is to set up a FREE account at Image hosting, free photo sharing & video sharing at Photobucket and upload the pics to a PUBLIC album there. Come back here and post a link to the album so we can view the pics. Please make sure the pics are in focus, well lighted, and large enough to see details. Especially in the case of wiring issues it is important to take pics of the same thing from at least two angles so we can try and visually follow the wiring.

OK, I have a bit better understanding now... the system has a single pump with zone valves.

The pump should be wired to the C1 and C2 terminals inside the 8148E aquastat.

There should be two wires on the T and TV terminals that may be coming from a "rat's nest" of wires around the zone valves, or if there is a zone control panel those two wires will be coming from there.

BE CAREFUL! THERE IS 120VAC EXPOSED VOLTAGE INSIDE THE AQUASTAT! YOU CAN BE KILLED! BE CERTAIN THAT POWER IS TURNED OFF BEFORE WORKING INSIDE THE AQUASTAT!

What I would like you to do first is remove EITHER of the T or TV wires from the terminal, make sure it isn't touching anything else (maybe a spot of tape?) and turn the boiler back on to see if it now does NOT run. It should NOT.

This will tell us if the problem is at one of the zone valves or wiring, or if it is at the aquastat.

Do you own and know how to use a multimeter?
 
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Old 11-17-12, 08:16 AM
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The 140F setting on that aquastat will lead to problems with the flue gas condensing inside the boiler, flue pipes, and chimney. This condensate will be acidic and will in time (often quite quickly) cause corrosion and destruction of anything in contact with it, including the chimney itself.

Any idea how long the system has been operating at this temperature?

Is there any evidence of condensation? Usually the first thing one might see would be 'whitish streaking' starting at the joints in the flue pipe.

After the problem of the boiler continuing to run on is cured, my recommendation would be to turn it back up to the 'standard' of 180F and make sure that it stays there... (i.e. elderly relatives possibly turning it back down thinking they will save some money that way...)
 
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Old 11-17-12, 08:53 AM
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Thank you again for your reply.
The whole electrical system can be easily turned off by a switch right at the boiler. I am very safe when it comes to electricity. I own a multimeter and know how to use it as well...

I will get photos, try what you have suggested to test and reply back.

Thanks again for your help!
 
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Old 11-17-12, 09:08 AM
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OK, good on the multimeter.

Let me give you some more testing then...

After you remove the wire from either the T or TV terminal, use the meter in the OHMS position and check for CONTINUITY between the two wires. ( leave the one DISconnected, you don't want the control influencing your reading, you only want to check the wiring).

If you DO have continuity on those two wires with all the thermostats turned all the way down, then there is either a short circuit or a bad zone valve head.

You said these were TACO zone valves? probably 571 series?
 
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Old 11-17-12, 09:10 AM
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Standby for a sec, I'm going to post a graphic of taco zone valve wiring...
 
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Old 11-17-12, 09:20 AM
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The actual routing of the wiring may differ, but the actual connections should end up the same...

Perform following tests with power OFF.

Note that terminal 1 of each zone valve comes from a thermostat. When thermostat calls, the 24VAC powers and opens the zone valve.

When the zone valve OPENS, this will cause an ENDSWITCH inside the valve to make contact between terminals 2 and 3 of the valve.

This endswitch closing is the signal to the boiler to fire.

Note that they are all in parallel, meaning any ONE valve or more will cause the boiler to fire.

Check each valve and make sure that none of the 'manual override' has been moved to manual mode.

After this, IF you find continuity on the previous test, you need to check each valve to determine if the valve itself is at fault, or if the problem is in the wiring.

Place one meter lead on terminal 2 of any valve (they are all connected together).

Remove the wire from terminal 3 of each valve, one at a time and test from terminal 2 to 3 of each valve in turn.

If you find one that is making contact when the thermostat is all the way down and power to boiler OFF, you have found the culprit.

There's more... but do this first.
 

Last edited by NJT; 11-18-12 at 09:03 AM.
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Old 11-17-12, 09:23 AM
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Will you have connection to internet at relative's home?

If so, I'll check time to time for replies while I'm about today...
 
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Old 11-18-12, 06:41 AM
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Hi NJ Trooper,

Sorry I did not see your last message. I will not have internet at the relative home, but am hoping I will be able to connect via a smart phone. I am planning on testing this today.

Thanks again.
 
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Old 11-18-12, 09:06 AM
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OK, no problem, I'll be watching during the day for updates...

One more thing... If you find a bad power head, the power heads of the Taco valves are easily swapped out. Push and turn the head and it pops off. Reverse to install new one. TAG THE WIRES FIRST!
 
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Old 11-18-12, 07:47 PM
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Hi NJ Trooper,

Well I think with your help I have found a few of the problems......ugh....

The system is divided into four zones, with four Taco Valves. Downstairs, Garage, Bedrooms, Living Room-Kitchen.

I did everything you said for a test and believe I can rule out the aquastat as the problem.......

I took off each of the power heads and blew out the dirt....

The "Bedroom" head upon inspection had the "contacts" in the "on" position, calling for heat....
I slightly bend it back to be in the off position but when the valve opens to be in the on position...

So here is a quick run down..
The "Downstairs" valve - when tripped by the thermostat has 24.6. volts warms up, opens valve, and starts boiler....

The "Garage" valve - when tripped by the thermostat has 24.4 volts........ but after 5 minutes still does not open valve, no response.

The "Bedroom" valve, when tripped by the thermostat has 24 volts, warms up, opens valve, and starts boiler

The "Living-Kitchen" valve has 23.1 volts, after 5 minutes, nothing.......

After I did this and had everything done, I suppose I should have tried a good head on a bad head spot....

I did on the two valves that did not activate, after 5 minutes try and open the valve manually... they both had resistance, which if I have this correct means that the head did not open the valve but I opened it manually, meaning the head is bad, correct?

I don't know why the bedroom valve contact was on.......... I wonder if someone had tried to adjust before?

So what else should I do.... get two new Taco heads? How about the valve body itself?

Thanks once again for your time....
I will try and send a few photos.....
 
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Old 11-19-12, 10:49 AM
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The Taco valves are a 'heat motor' design. Inside the head there is a sealed 'bellows' that has a wax substance inside. There is a heating coil around this assembly. When the wax inside is heated it expands and pushes the valve open.

It sounds as if the two that aren't doing anything have developed 'leaks' (you said that they do get warm, right?) that is preventing the expansion of the wax to open the valve.

I would replace at least two of them... and possibly the one for the bedrooms also. You should not have had to bend anything... unless as you say someone was 'monkeying' with it to try and get something to work.

I wouldn't think that there's a problem with the valve body itself.

Check prices... you might find that the complete valve is not much more money than the head itself, in which case maybe purchase the whole valve, try the new head alone first. If that doesn't fix the problem, then proceed to the next step of replacing the body. If it DOES work, then you have a spare body or two on the shelf for future use.

Did you pop a head off one of the non-working ones and see if it was possible to push the actuator pin down? Not that it's much of a diagnostic, but if you are unable to push the actuator down it might tell you something.

On-line sellers that I've used, and who stock the Taco parts at good prices and fast delivery are:

Patriot Supply - Industrial, Commercial & Residential HVAC Parts & Equipment

PEX - Radiant Heat - Radiant Heating - Plumbing Supplies - PexSupply.com
 
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Old 11-19-12, 11:46 AM
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Thanks NJ trooper,

Ok, another question.... until I get the new Taco valves.....
Should the boiler be heating to 140 and holding at 140 even when their is not call for heat? Or does it just fire and heat when their is a call for heat from a zone?
(I will correct to 180? once things are straightened out)....Is that the ideal temp 180?

If a valve needs to be repaired... can a change out be made with the valve body thru the four screws or does the whole valve needs to be replaced?

What else should I be checking at this point?

Thank you, Thank you for your help!
 
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Old 11-19-12, 12:28 PM
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Should the boiler be heating to 140 and holding at 140 even when their is not call for heat? Or does it just fire and heat when their is a call for heat from a zone?
It will only heat and hold if there is a constant heat call, for example, you said you found that the valve for the bedroom showed continuity with no thermostat calling for heat.

If everything is working properly, it should only heat up when there is a call for heat and any one or more of the valves open.

Is that the ideal temp 180?
"Ideal" may not be the correct word. But "standard" design temperature for a hydronic system is in general 180F.

If a valve needs to be repaired... can a change out be made with the valve body thru the four screws or does the whole valve needs to be replaced?
Maybe... but I can't say for sure. What you are asking is can you remove the 'guts' from a new valve and install them in the existing valve body to save the work of having to cut out the old body and sweat in a new one, right?

It's been long time I've seen Taco valve, and know that I have never 'rebuilt' one.

Perhaps one of the other members would be able to answer that... or, ask Taco!

I doubt that you will need to change the valve body though.
 
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Old 11-20-12, 03:47 PM
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Hi NJ Trooper,

Well I have 3 new Taco Zone Motors on order from Pex. What else should I be checking at this point?

Thanks for all your help.
 
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Old 11-20-12, 05:29 PM
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What else should I be checking at this point?
I'm hoping nothing... that the new heads will solve the problem.

I am reasonably confident (as I think you are) that the problem has been narrowed to that bedroom valve that was still calling for heat when the thermostat was not.

The other two that did not open, well, those simply were not calling for heat at all.
 
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Old 11-20-12, 08:24 PM
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Ok, one last thing....
Should I set the aquastat at 180? or what temp should it be set at...

Thanks,
 
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Old 11-20-12, 08:32 PM
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Yes, 180 should be the max needed to heat the home...

You CAN turn it down SOME... I don't think I would go below say 160 or so... depending on how close the system is designed to the actual heat loss, when it gets real cold it may become necessary to turn it back up though.

Of course, don't do it until you are sure the system is fixed and not continuously running as it had been.

Ya know, maybe that's the reason it was turned down to 140 ? Did you ask if they had turned it down? I bet they were getting roasted out and turned it down...

Please when you get the new valves installed let us know if all is well!
 
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Old 12-03-12, 09:44 AM
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HI,
Well the Taco Valves are installed and the system seems to be operating correctly. I also replaced one thermostat for the living room area of the home. Nice to have the system so it turns on each zone on its own and runs the circulator, only firing the boiler when the temp drops below the set temp.

OK, here is another question..... Can the aquastat be tweaked? What I mean is that the aquastat temp is not very accurate compared to what the actual boiler temp is. And in adjusting the temp wheel a very small adjustment makes a big difference in the shut off temp of the boiler. Anything i should do or just leave it be as it works?

Thanks
 
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Old 12-03-12, 04:18 PM
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What I mean is that the aquastat temp is not very accurate compared to what the actual boiler temp is.
They really never are. The big thing is REPEATABILITY though, not the absolute accuracy. You don't really care if it's 175 or 185, as long as it hits the same mark every time.

Also, the aquastat and the temp gauge being in different areas of the boiler means that they might actually be seeing different temperatures. There's a lot of turbulence and mixing of the return water with the hot inside the boiler. So don't be alarmed if they read differently.

adjusting the temp wheel a very small adjustment makes a big difference in the shut off temp of the boiler.
Shouldn't be THAT sensitive... so make a small adjustment and observe for MORE THAN ONE CYCLE... SEVERAL cycles...

Your temperature gauge isn't all that accurate anyway, trust me. So you don't really know what the ACTUAL temperature is.

"A man with a watch knows what time it is. A man with TWO watches is never sure."

You've got two 'watches' on the boiler, the temp gauge and the a'stat dial.

As long as you are in the 'ballpark' of 170 to 180 degrees, you'll be fine.

Anything i should do or just leave it be as it works?
You already turned the a'stat back up to 180 right? And it shuts off at the same temp, and it's in the ballpark, then leave it be.

Ya done good!
 
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Old 12-03-12, 08:32 PM
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Thank You, Thank You, Thank You.....I think things are working better than they have for several years....Now on to the next project......Do you know anything about Universal Rundle Toilets that were sold by Sears some 40 years ago...one piece, low profile.....Thanks again...
 
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Old 12-03-12, 08:46 PM
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Do you know anything about Universal Rundle Toilets that were sold by Sears some 40 years ago
No, can't say that I do! But of course that's a question for a different forum!

Toilets, Sinks, Showers, Tubs and Garbage Disposals - DoItYourself.com Community Forums
 
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