Issues with & Replacement of Honeywell L8148E Aquastat

pfarq

We have a Honeywell L8148 that has started to act up and in

lieu of spending $450 to have a technician replace it, I’m interested in

swapping it out myself.

This will be the third time within 6 years of ownership that

the aquastat will have to be replaced.

To give some background of the problem, the burner will

sometimes fail to ignite. The “solution” to the problem is giving a slight

jiggle to the plug and wire shown in the red box of the attached image. The

burner ignites and heat is restored.

Then the same problem will happen again, usually at 3 in the

morning of if we’re away for the weekend only to return to a house with an

internal temperature in the 50s.



So, I assume it’s not possible to replace the suspect plug

or circuit board and a total replacement is in order. It seems like a

straightforward r&r, though I’m a bit uncertain about the physical

connection of the aquastat to the boiler (see attached image).

Do I need to drain the boiler prior to unscrewing this nut?

Do I unscrew the aquastat off this stem?



Any .02, thoughts and advice would be very welcome.

Regards,

PF

Tim McElwain

The plug you are

"jiggling" is the place that a vent damper if one were used could be plugged in. If you are going to have your contractor replace the relay then install a Universal Replacement L8148J, the plug will be eliminated and that is not a problem as you do not have a vent damper anyway.

pfarq

Hmm...

Hi Tim,

Thanks for your thoughts. Interesting tidbit about the damper in that last year, the technician that installed this current aquastat unplugged the damper for some reason; if I recall correctly, he said it wasn't working and that we were just wasting energy by keeping it in the open position, so he must have placed that plug in place of the damper plug. Interesting in that the tech that visited 2 years prior said it was no problem to leave it open. (Which train of thought is the right one? I'm still trying to get up to speed on boilers, relays and dampers.)



Nevertheless, I plugged the damper back in and the boiler has now come back to life (it shut off again about half an hour ago, as you might notice in the pics, the temp had dropped down to 120.)

Do you think this is the cause for the recent failures of the boiler to remain on and hold temperature or does the aquastat need to be replaced?

furnacefigher15

Damper

With the damper functional, you save about 2% on overall fuel consumption.



But, those dampers are fairly expensive, so for some the payback is not there.

Plumdog_2

damper danger

Try this: get the damper to actuate one more time by turning the power off and back on. With the blade in the OPEN position (the flat shaft will be vertical, look up inside the draft hood with a flashlight to verify) find the little switch on the side of the vent damper motor and place it in Man. Hold Open position. The unit should work with the damper open all the time. Your damper jumper plug is probably loose.

pfarq

Update

I removed the jumper plug and plugged the damper back in. The boiler has been performing perfectly ever since. Can't believe I had been dealing with the jiggling issue for nearly 3 months! Thank everyone for your help.



PF

Eric_32

Keep an eye..

It could be that the end switch in the damper has sporadic issues and will work sometimes and not another.

I have done 50/50 on removal or replacement, but was up to the customer.

Tim Potter

Replace your own... if yours starts giving trouble again

http://www.beckettcorp.com/Product2/productdetail.asp?detailid=35



When my Honeywell failed, (intermittent Bad solder connection,) I replaced it myself with this Aquasmart, reasonably priced, easy to program, it works great, has an option for built in LWCO, was easy to install, has smart control for fuel savings, & I was able to wire up my existing SlantFin specific 4 wire plug Damper Harness.



PS, they are a site sponsor, look to the right on the main page





Tim

Gregpa

Have a Q

A have exactly the same problem as pfarq had but my aquastat is L8148B. If I manually connect contacts B1 and B2 (Burner) I'm able to ignite the burner. What could be a problem here?

Tim McElwain

Your problem is not the same I

would say. The relay you have the L814B has an isolated burner circuit typically used with powerpile systems.You probably have a powerpile (self generating) gas valve, is that correct? If so is the pilot lit? If it is then you need a professional to come in and take some millivolt readings on your system. It can sometimes be that the pilot needs cleaned and a new generator installed. I have a section here at Heating help called Tim's Closet, go to resources above and click then library and look for that section it outlines how to take readings on these systems.

Gregpa

Thank you Tim

I'm reading your troubleshooting doc. Just want to let you know that the pilot stays lit all the time and  the burner sometimes ignites (can take hours calling for heat).

 

Tim McElwain

That is typical of

powerpile systems. You have a very simple circuit just the hi-limit in the relay and the wire from B1 - B2 to the gas valve not a lot can go wrong there. In addition to the troubleshooting procedure the gas pressure needs to be checked before the gas valve and at the outlet when it is running.

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

rocky22

similar issues

I have a slant fin c90.  It has L 8148E 1273 aquastat.  Can it be replaced with L8148J 1009?  I also replaced the damper and intermittent pilot control without success. could it be a bad wire . With the power on the only thing that will run is the pump. Was told the J should work. 

Tim Potter

c-90?

Rocky22,

I Cant find any reference to the c-90, possibly a v-90???

Anyway your description of the symptoms sounds remarkably similar to my problems with my slantFin SX-150. It used the same control (L8148E) and it drove me & my boiler man mad trying to find out why the boiler would intermittently not fire. It was suggested to replace the vent damper & gas control too, but I resisted until the failure was confirmed. Good call on my part, because it was a cold solder joint on the L8148E control relay. Its a DP relay, and the burner contacts were the problem, so the circulator would work ok. I chose to replace with the Becket Aquasmart (similar pricing, but features are included to save$$$) check it out,

http://www.beckettcorp.com/Product2/productdetail.asp?detailid=35

its a nice unit



Tim

p00

Similar problem

I have L8148E, 2 zones with 1 Circulator.  I have 2 zones, which are downstair, upstair.   Downstair is working fine and Upstair is not.  Both zone valves are working properly and switches in the zone valve are also working properly (I heard the sound on/off, measured the voltage, 24V or 0 V).  But the Upstair's control could not fire the Burner.  I could not understand.  Any idea ?



Thanks,

Tim McElwain

What make

zone valves do you have?



Try jumping out the end switch on the zone not working and see what happens?



The relay is obviously okay as zone 1 brings every thing on.

p00

Honeywell

These are Honeywell  V8043 E 1042 Motorized Valve.



Each of the out from the Valve has 24V or 0V depending on the Thermostat temperature setting.   Out from the valve are parallel and these go to TV and T in L8148E.



If there is a heat demand from  Th1 (thermostat 1),  voltage between TV and T goes to 0V from 24V, then the furnace starts to burn.



If there is a heat demand from  Th2 (thermostat 2),  voltage between TV

and T goes to 0V from 24V,  the furnace does not start to burn. --- I do not understand.



If making a jump between TV and T (short circuit), it would not fire either -- I do not understand.

honeowner

more problems with Honeywell L8148E

I have a similar problem to many here.  I have a Slant Fin S-120-DP with a Honeywell Aquastat relay L8148E.  It has a motorized damper vent control.

I started to have the intermitent problem a year ago (once), but this year has become a regular occurance. stat signal is confrimed, zone controllers (I have 3 zones) open, pump starts, but no fire.  For a while I would shut off power and back on, and the vent woudl open, fuel control woudl make and it woudl fire.  I tried cleaning the contacts on the realy w/ emery cloth (man, it is hard to get in there) and thought that worked, but then it happened again.  I finally have figured that I need only "tap" the top of the L8148E box, and "click!"  But...****? Easy to do when I am home, but not when I am out of town on a -20F MN day.

It SEEMS to me like there is not enough current (sometimes) to pull in the contact, but why would this work sometimes and not others?  No rhyme or reason.  I have jiggled for other loose connections but found none.  Any help woudl be appreciated.

stumped in winter,

Bob Gagnon plumbing and heating

We Had About

4 of these problems last season, my electrician solved the problem quickly by soldering the back of the board, behind where the vent damper plugs in, we haven't had one come back yet.



Thanks, Bob Gagnon

BobC

cracked solder joints

Molex board connectors are known for developing cracked solder joints, it's often because of a small solder pad that does not allow everything to heat up properly in the soldering process. If you look closely you might see a faint black ring around the joint, cleaning and resoldering the joint usually works.



Manufacturers often use the cheap tin contacts in them and they are prone to corrosion and loosening up with vibration and thermal cycling. For a dime they could have used a decent bronze phosphor contact but the bean counters are adamantly against that.



Bob



Bob

unclejohn

I didn't Read

Every post but no you do not have to drain the boiler to replace the control. You may try using a plastic wire tie through the loop of the jumper wire on the plug to add some tension that will hold the plug down and that will usually work until you get a replacement control. I would also contact Honeywell customer service and let them know your issues with their controls.

Tim Potter

Bad solder Joints on Honeywell control

Ditto on the bad solder joints on the Honeywell control on my slant fin SX-150.

Same symptoms, intermittent no heat, not a good thing on a vacation home on the Colo Mtns when you are not there to know....

I replaced the control with a Beckett AquaSmart. There is some wiring needed to operate the vent damper, but otherwise a nice control.



If you need more info, let me know



Tim

soeasytobefake

Solder points

Found the problem. Apparently its a common one. The solder points on the back side of the circuit board are junk. the amount of force required to install or remove the cable gives these solder points no chance to survive even with the two heavy screws holding the plug to the board. Im going to attempt to resolder these points. Wish me luck.

PeteCal

I have the "J" version

I am not trying to hijack this thread but it is so close to my problem I can't resist.

I have the L8148J version. 

It has been having relay contact problems for years.

I have cleaned the contacts many times, usually the first time it doesn't come on in the fall.  And it usually lasts most of the winter.  But today (May 16) I needed heat and the contacts didn't close.  I just joggled the top of the relay and the flame came on.

I sure wish I could find the model number of the relay.

Sometimes relays are only a few dollars each.

Any ideas?



Pete

Tim McElwain

Is your gas valve

24 volts or Powerpile (millivolts)?



The "J" version is the L8148J Universal replacement relay. If you have a millivolt system sometimes it will act erratic due to loose wires or poor connections at the relay.



The full model number for the "J" is L8148J-1009.



The procedure for troubleshooting powerpile is located on this site at resources-library-Tims Closet.

PeteCal

Inside My Aquastat

Thanks.

I am actually looking for the relay inside the RELAY.  That is the actual three poll Normally Open relay.   



I attached a picture.  The relay I am talking about has a gray metal plate on the top.  It is shown in the middle of the picture with the word Honeywell embossed on it.  Looking at the preview picture I see that the word Honeywell doesn't show.  But I scribbled "PUSH" on top of Honeywell and that is slightly visible in the picture.



Because it is a low voltage system, even the slightest accumulation of dust or dirt on the contacts will inhibit current flow.  When the contacts don't make contact I just push on the word Honeywell a few times and the gas will come on.  That is usually good for many months.  Sometimes it has become stubborn and needs to be pushed each time the furnace needs to come on. 



Then I kill the power and take a relay file to the contacts (behind the plate) and clean them.  Then I'm good to go.



I am hoping someone knows the model number for this inside relay.  Sometimes they are really cheap.  Like just  a few dollars.



Pete

Robert O'Brien

The number 7744

is the date code. It was made October 1977. Buy a Beckett Aquasmart or a Hydrostat 3250 and solve the problem while upgrading to an energy saving control for very little $$

Tim McElwain

That relay is not

replaceable you need to replace the entire L8148J. Are you a homeowner or a technician?



I would suggest having a professional check this system before you spend money and find out you have a millivolt problem.

icesailor

Contacted:

The contacts on the relay, are silver coated. The same as the ignition points on old cars. It is a very thin coating, but silver just the same. When you "file the contacts", you file away all of the silver, causing arcing. And once carbon/burning builds up, you lose contact.



You can have an old car with ignition points. Drive it for 5,000 miles and start having ignition problems. You need to change the points & Condenser. Quality contacts determine the quality of charge going in and out of the condenser coil. You can file the points, but it won't go 5,000 miles again. You're lucky if it goes 50 miles. The silver is gone.

Your symptoms are classic bad contacts from the silver either being burned off or filed off.

Some Neanderthal I know used to say that you could keep a 1950 Chevy or Ford running forever with a screwdriver, a pair of pliers and a roll of tar tape. That was in 1960. He doesn't drive a 1950 Chevy anymore. He complains bitterly that he can't fix his 2010 Chevy truck with a screwdriver, a pair of pliers and a roll of tar tape. He has to take it to a garage.

This isn't 1960. You need to replace the control. What you are doing may be an acceptable repair for you. For most any professional here, it would not. The customer would be calling someone else. When potential customers call, they usually want to spend money. If I answer, I want them to keep calling.

Unknown

I Understand

I'm sorry for the delayed response.  I was having password problems and

they have not been resolved.  I had to create a new identity to reply.  I'll try

to cover all comments here.

 

Date code of 1977 sounds right.  I contracted to have the house built in

November of 1977 and moved in in March of 1978.

 

I am a homeowner.  But I am also a 66 year old retired electrical engineer

that spent his entire career in the thick of real hardware and little

time behind a desk.

 

If I saved all the relays that I have had technicians replace over the

years they wouldn't fit in a large garbage tote.  From the top this looks like a

common type relay.  But there are thousands of them listed on Digikey for

example.  Some are top of the line brand name and priced at less then $10.  I

was hoping someone had a bad one and could read the part number.  If not I'll

have to take the Aquastat apart and hopefully find the relay part number on the

other side.

 

And, yes I know I might have rubbed some of the plating off the contacts. 

But I have been nursing this thing along for 10 years.  Not that I need to but

it always fails to fire at the most inappropriate times.  So I bump the top and

away it goes.  Maybe for months, maybe for the rest of the season.  A few times

it I have had to bump it every few days.  Then I spend 10 minutes cleaning the

contacts and I'm good to go for a long time.

 

And I certainly agree that for a professional, the customer wants you in

once, fix it and out. 

 

And for you buddy repairing his Chevy, tell him to get a good scantool.  I

have a few and they make trouble shooting easier then the "old days"   ;-)



 

Thanks Guys,

 

Pete

SWEI

If you're an EE

You're certainly capable of measuring the output of your generator.  TIm McElwain has graciously provided some resources right here on the site

http://www.heatinghelp.com/article/338/Boilers/2737/Thermocouple-Testing-Procedure

http://www.heatinghelp.com/files/articles/1975/Charts%20for%20troubleshooting%20thermocouples%20and%20powerpile%20systems.pdf

http://www.heatinghelp.com/files/articles/1976/Procedures%20for%20Troubleshooting%20Powerpile%20Systems.pdf

Tim McElwain

I am not an engineer

but have many years experience (74 years old) and due to liability I would never attempt what you are trying to do. Replace the entire relay or upgrade as Robert O'Brien suggested.



I would however caution you that if your gas valve is Powerpile it could simply be the powerpile circuit and polishing up those relay contacts only gave it the little umph it needed. Take some readings before you replace an entire relay. I say that but the contacts are probably shot already. The L8148J allows you by the way operation with the powerpile system operation in a power failure by placing the system on gravity feed and switching the switch on the side of the relay to manual.