Aquastat L8124C not engaging circulator with relay

Colin Brodsky

Regarding Aquastat L8124C used on a hot-water-baseboard central boiler with tankless water heater coil:

Problem description - no/intermittent heat with clattering/chatter from relay switching on and off inconsistently

Thanks to one of these message boards, I was told that the way to verify functionality in the aquastat is to touch a wire to short across the "T" terminals in the upper left of the box and the furnace works, then your aquastat is OK. This takes out any uncertainty about the thermostat performing properly - effecively, if the thermostat demands heat, it should short/close these terminals. If the aquastat still doesn't turn on the circulator or burner, then it is likely your problem part.

Mine would work only if I pressed hard on the T terminals during this step - I discovered that simply pushing that side of the board was enough to make it work, so I wedged something in for a while to hold that strain on the board, which made it work normally. Eventually, the problem came back. (I hoped to make it last through winter and pull apart this summer!) I suspected a bad contact somewhere on the board - front side was OK. So, I pulled the whole thing off (not too hard to do) and unwired it to remove the circuit board. All you have to do is disconnect 9 wires, and unscrew a screw on the bottom that holds it to the well where the heat sensor goes. You also need to disconnect/unsnap the wiring conduits attached to the sides of the aquastat box.

Using a continuity tester, I just systematically checked for continuity along the printed circuit runs, and also between the circuit board and the pins sticking through from the devices that were mounted. Sure enough, there was a bad solder joint on one of the wire coil terminals. The solder attached to the pin had just cracked free of the circuit board, leaving a small air gap. If I touched the center pin and the circuit board around it, I only got continuity if I pressed it together. (same motion as bending the board) I resoldered this terminal and it's working great now - did a few other suspect looking joints in the process!

By the way, I had purchased a returnable backup Aquastat in case I couldn't find the problem over the weekend - cost was $112. I was told list is $195 on it; install probably adds at least $100 to that price. It's a very easy thing for a moderately skilled homeowner to do if you already have one installed - just carefully note which wire goes where (sketch a diagram to be safe) and TURN OFF POWER to this unit. There are line voltage connections all over this unit - ours had a switch installed right before the aquastat to serve this purpose.

I must say that a bad solder joint is disappointing on a unit not even 2 years old... now I have no faith leaving this system on vacation without a backup heat system.

Hope this helps someone else,
Colin

Colin Brodsky

Aquastat L8124C not engaging circulator consistently - no heat!

Hi -

Briefly, we have a 3-zone oil fired HW baseboard system 2 yrs old new construction near Poughkeepsie, NY. (typical of most systems I've seen)

Our heater is not turning on the circulator when demanded by the thermostat. I have traced the problem to the Honeywell L8124C Aquastat relay. There is a silver spring-loaded rocker which when I pull it back, engages the relay to start the circulator, and shortly thereafter, starts the oil burner. (learned this trick watching a service guy) In this situation, it is working normally. The zone valves are all being held open by the thermostats as they normally are when heat is demanded, so as long as I hold that out, heat comes through. However, it rarely seems to work on its own - sudden problem in past few days.

I noticed yesterday when I got home the heat hadn't recovered from the setback, and wasn't even running. When I switched the relay manually, it started to run, and was able to do so on its own well enough through last night and this morning. However, it was clicking on and off rapidly a lot, as if it was borderline failing. Today, it doesn't seem to do anything unless I move it myself.

Is this a problem seen by others, and what is the fix? Contact or corrosion problem somewhere? Having read some other threads, sounds like these units are full of QC problems...

Thanks for any help,
Colin

techheat_2

Assuming

The end switches are good on all the zone valves and no loose wiring the control sounds bad

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Colin Brodsky

We have 3 zones - all behave the same way - that is demand coming from thermostat, but no action on Aquastat.

Any particular connections I should look at?

I'm guessing this fine product isn't going to be under warranty either (just over a year old) - what is a reasonable cost to have it replaced?

Mark Hunt

Warranty


Look closely at the Warranty on the unit, you may be suprised.

Most folks assume that ALL warranties other than major equipment end after one year, but quite often the parts are warranteed past that.

As for pricing, we try not to discuss that here on The Wall. There are SO many people from SO many different places and each company has it's own pricing.

I hope everything works out well for you.

Mark H

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Steve Eayrs

What is the call for heat on your aquastat?? Or do you just have the "T T" connections on the aquastat jumpered?
What kind of zone valves? Do they possibly have end switches, which whenever a thermostat/zone calls for heat, would close the end switch and then activate the aquastat, via the "TT" connections???
If wired correctly the pump will not run at all, unless the "TT" connection is closed, and the burner will not operate (off the high setting), unless the "TT" connection is closed.


I would put a jumper between the "TT" connection, and if everything operates correctly when you do this, then its a good chance the aquastat is not the problem but whatever is operatingthe aquastat.


Would advise you not "make" the relays in the aquastat work manually, since this may also be the only thing in your system to shut the burner off, and it could overheat, and blow up. Have you ever seen the power of steam, out of control?

Steve

Colin Brodsky

Hi -

Good suggestion - I tried the TT jumper, and sure enough, it then worked properly. So, maybe that's a clue...

We have three zone valves - Honeywell V8043E1012. They are all open because all three thermostats are asking for heat. I don't know too much about these, but above them, there is a junction box where all the thermostat wiring comes in. Also connected to this are the three zone valves and the wire running to the TT connection. How can I tell if I have end switches, and is there any reason why all three suddenly stopped working? Perhaps I'll dig into the junction box wiring to see if something is loose in there.

I did think about the overheating issue - holding the relay open with a clothespin, I watched it to make sure the high temp cutoff worked, and sure enough at 190 it stopped firing the boiler. (circulation continued) I have the temp setpoint high to make sure it doesn't close the zone valves with the circulator running - hopefully that is OK. Pretty darn cold here tonight!

Thanks for the help,
Colin

Steve Eayrs

If it worked right with the TT connection jumpered, then the problem is the zone vlave end switches or the wring between them and the TT connections. No problem leaving the jumper on the TT for now, and let the aquastat operate the boiler according to the setting on it.

Your zone vlaves are not opening enough to activate the end switch. The heads will need replaced, or you don't have enough 24v to open them all at the same time?? You may need to call someone to check this for you, before you just start replacing parts. Let them know the zone valves you have to make sure they have them on their truck.

Steve

Colin Brodsky

Problem further isolated... something loose on aquastat board?

Thanks to the help from Steve, I've gotten a lot closer to figuring this out. I downloaded the info on my zone valves to learn how they work - turns out they have end switches; all wired in parallel, per one of the examples in the product literature, and I verified the connections and continuity to the TT terminals on the Aquastat.

In doing so, I found that slight pressure on either terminal engaged the relay to start the circulator! So, my previous work seeing that it worked when I jumped the TT terminal really happened to be due to me pressing a jumper wire against the board!

So, at this point there must be something that has worked loose on the aquastat such that when I push the corner of the board by the TT terminals very slightly, it then works. The answer for tonight is to just wedge something in there - but I'd like to take a look at it behind the board. Is there an easy way to get at this without disassembling all the wiring? Looks like I'd have to pull off the wire conduits to remove the box enclosure. Only other option I can see is to bend up the top panel to see what is going on.

Nonetheless, a workable temporary solution has been found, and I learned a heck of a lot about how this whole system works in the process!

Thanks,
Colin

BillW@honeywell

L8124 Aquastat

I'm sorry you had a problem with one of our controls, and it sounds like you found the problem with a broken solder joint. Honeywell's warranty on our Trade products is 1 year from the date of installation. However, it sounds like this was a new install, and the Aquastat was part of the boiler, installed by the boiler manufacturer. They may have a different warranty. Its sounds like you have some technical background, but I strongly do not recommend that homeowners start dismantling these controls in an attempt to troubleshoot them! These are safety related limit controls, and switch line voltage also. An untrained person could very easily cause a fire, steam explosion or electrocute themselves. Also, attempted repairs by anyone other than a trained technician usually voids the manufacturer's warranty. I would have a pro look over the system, just to make sure everything is ok. If you are concerned about the system while you are traveling, most security systems have a low temperature alarm feature that can be added, also your oil company or heating contractor may offer that service.

Steve Ebels

It does

Make you nervous doesn't it Bill? On virtually any piece of safety related equipment I've ever seen there will be some kind of notice that says "not field repairable" or "do not repair, replace only if failure occurs". Does Honeywell have a statement like that on their controls?

BillW@honeywell

Yes, Steve, It's there...

It's printed on the installation instruction sheets of our Trade model controls. It scares me to know that people will endanger themselves and their families and their property attempting repairs that they are not qualified to do.

Colin Brodsky

Followup comments...

Agreed on the comments about line voltage - TURN OFF THE POWER! Can't be stressed enough - tried to in the last note! (I made an assumption that people who seek this board out are relatively handy with such things)

To be fair, I am a chemical engineer, and that makes the control systems fairly intuitive to me, but that's clearly not necessary to fix a bad solder joint... good safety sense and experience working around line voltage is far more valuable.

As for the warranty, I think 1 year is grossly inadequate for such a key component - especially if so many safety risks are tied to it as you suggest - the real way to avoid this is to improve reliability, rather than setup alarm companies to watch for the failures! Even if the part was replaced under warranty, most cases you're still out a big labor bill.

Again, to be fair, nobody should attempt doing this work, replacing a light fixture, rewiring an outlet, or nearly any other home improvement project involving electricity unless you know how to turn off power at your circuit box and work safely!

-Colin

Colin Brodsky

and if you think that's bad...

... think about all those guys out there replacing brake pads on their own cars! Or putting up ceiling fans that could kill someone. (I've done both and lived to tell about it...)

Just depends on your experience and common sense to know your limits. When our service guy did the annual, I asked questions. I learned as much as possible about how the system worked, and watched what he did. Some stuff I still wouldn't touch, like the flame settings, etc... where it's not so intuitive or special equipment is needed that I don't have, but this isn't all rocket science. That being said, if you don't like this sort of thing, and aren't comfortable around it, you probably shouldn't be on this board asking questions.

Again, I would also stress that the way to not have homeowners mucking around with these systems in the first place is to not manufacture garbage that fails. Manufacturing poor quality junk electronics and then getting on a high horse about safety is a pretty weak argument. The real hazzard that "endangered my family" in this was all the electrical arcing on the crap solder joint in the circuit board as the connection came in and out randomly while rattling the relay. That was FAR more likely to start a fire or burn up the safety controls than me fixing the problem!

I also think that rather than instill fear and keep people in the dark, it is more useful to provide good instructions with appropriate warnings/disclaimers on these would likely ensure people do things safely, rather than hiding that kind of detail from consumers. I'm glad to see these boards break the mentality that we're all too stupid to do anything for ourselves. Honeywell has actually put some decent, helpful documentation on the web that helped me understand the zone valves better, and that is a good step. (although I'm sure they would not like to know ignorant homeowners are accessing it and learning something useful...)

-Colin

Unknown

Colin others here have been kind to you

but I will tell you that you are an accident waiting to happen. I do not know what you do for a livng but tampering with that control is just plain stupid. I have been in the gas heating industry for over 40 years and I have never soldered a relay and left it in a customers home ever. That control should be replaced thats all there is too it. I assume you are a homeowner and want to save some money, but that is not the way things should be done. This is why I sometimes do not give information to homeowners as they can be damngerous. A little knowledge can be dangerous. A drop of solder in the wrong place and you have a run away control and then it goes BOOM!!!!

Steve Ebels

Colin

My remarks were not meant to disparage your skills or resourcefulness in any way. I have run across absolutely horrid "fixes" that were done by homeowners and "pros" alike. The caveat here, as always, is that it's not what you know, but instead what you don't know, about that control or any other, that will kill you. I'll also be the first to admit that I don't know every last detail about all the equipment that I work on. I do however have enough experience to know when I'm over my head and to know when there are unseen things that can jump out and bite me.

The other factor that I have to deal with and you don't is liability. If I were to do what you did and 2 years later your house burned down, the mere fact that I was there and tinkered with the control would tie me up in court for a long time. If you however, don't share that concern, be my guest. It's your house and your family.

BillW@honeywell

I did not mean to insult you...

but what you are doing is the equivalent to me walking into your lab and starting to mix chemicals. I would know enough to be dangerous in your lab, but I'd never do that. There have been no recalls or notices on that control. It could have been damaged during transit, installation or by something that happened after it was installed. As I mentioned, the 1 year warranty applies to our Trade controls, and yours was installed by the boiler manufacturer, who may well have a different warranty. Check it out with whoever installed the boiler, or the manufacturer. I don't know what website you visited, but the technical literature is available at http://hbctechlit.honeywell.com

I'm not trying to keep anyone in the dark or prevent them from learning about their systems, we here at the "Wall" are all for educated homeowners. Note all the free advice and educational items for sale here. I promise to stay out of your lab if you promise to let a pro handle your control work! Peace!