Intermittant problem....

J.C.A._3

With a Vallant boiler, that is using a Vaughn, Hot Stow for HW.. The thing keeps "not firing", according to the homeowner. She says all she does is turn it off, then back on and it fires.

History, I serviced and checked the system , week before last, after the original call. Boiler and all controls performed flawlessly. After 3 days, callback. Owner had "re-set" the system before I got there.

4 days later, callback, same problem, no hot water. Boiler and water heater functioning when I got there. Maybe a fussy vent damper end switch? Tested out fine, replaced it anyway.(remember, it's an intermittant problem, and Ive seen them fail a time or 2!)

6 days later, same callback, no hot water. Luckily, no re-setting this time! Upon walking in, I notice that the circulator isn't running, so I pull the cover from the 8148, and notice that the clapper ISN'T pulled out. Continuity test on the end switch of the zone valve, (Honeywell V8043F-1036) , switch open, zone valve arm in the open position.

Turn off boiler and turn back on, sure enough, it fires right up!
Replace zone valve head. Problem solved right? NOT!!! Got a callback this P.M. and all is well, but she had no H.W. 2 times over the weekend. Tested all again, and all is working fine (again).

My feeling is that I've gotten another bad end switch on the replacement head. Voltage from both transformers, (5 zone valves for total system)is between 26.5-27.5 V
All other readings seem to be in line. Any suggestions? Chris

ScottMP

One of us has stop the post

Sorry Chris,

You said you did'nt have the time in your note, so I posted.

Please feel free to answer Chris's question as mine is just a repeat. We're both scratching our heads.

Scott

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Ken_8

I must assume...

You meant the control was a cad cell model 8184 - not 8148?

You also state the zone valve end switch was "open" and the lever was too? If so, that's the problem. If the end switch is not closed (made) the lever should not infer by freely opening - that the zone was opened by the stat.

I'm sure something is wrong in your model/symptom narrative.

If however you did mean an L8148 combination aquastat, then I'd check the anticipator on the stat. A break in the anticipator winding may not be visible and it may be intermittent on that part of the stat. If you see any soot or burn evidenc e on tne stat, try a jumper and see if it starts or even tap the wall where the stat sits. If it stutters when running - or starts when in apparent "lock out" - it's the stat. If not that, carefully examine the contacts on the L8148. Wouldn't be the first time I saw schmootz on a low or high voltage clapper contact - when everything else in the box looked new.

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Dingo

Sorry....

I responded to the other question.... but in short I think those Valliants DO have an ECO on the aquastat probe... sounds like its failing

Peace bro

Dingo

Unknown

Chris, I sent Scott an e-mail

with some possible theories and also some questions. I will be in class all day tomorrow but if you want call me tonight at home. 401-437-0557

Robert O'Connor_7

How many VAC

Are you sure the transformers big enough? It could be droping as the others call. So far the other posters are on the mark as well....Good luck..Robert O'Connor/NJ

S Davis

Transformer

I believe that control has a max power output of 1.2 amps and that includes your control circut, those valves draw about .4 amps each so if you have two or more zone valves on your auquastat control and all the valves call at once you might not have enough power to pull in the relay.

S Davis


Apex Radiant Heating

Unknown

L-8148E has a

50 VA transformer. The V8043 uses only 7.7 watts (VA) so you can run 5 Honeywell Zone Valves off that 50 VA transformer. The coil in the relay draws .2 of an amp. The 50 VA transformer should handle the load with no problem at all.

In Scotts other post he stated that there are two transformers. Even if they are only 20 VA they should be able to handle the split load of three and two zone valves.

Unknown

The L8148E does not

have an ECO. Some versions of Vaillant did have an White Rodgers 8D42A-704 with a "Pepi Switch" which was designed to shutoff the pilot in the event temps got above 233 degrees (F).

Honeywell had similar controls the L-8148L, M or N.

All of those controls had a seperate regular Hi- Limit which should be set for 180 Degrees.

ScottMP

And

This ran all winter ( six or seven years now ) with no problem.

Its has just happened a week ago, so we are only having the domestic zone valve calling. It has to be a control problem, some end switch is not making. Chris thought he had it with the zone valve.

It could be a bad zone valve right out of the box.

How about crud ont he ball of the Honeywell zone valve and not opening all the way every time ?? Is that possible ??

Thanks guys

Yinglings for all my friends !

Scott

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ScottMP

How to check the

Aquastat ???

Ohms ??

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BillW@honeywell

I just saw this...

Thanks to Tim & Ken for jumping in. Ken's anticipator answer is worth checking out, maybe replace the stat with a T8700, T8400 or VisionPro, and set it for 3 cycles per hour. Are your transformers NEMA rated? I know the book says you can put 5 V8043's on a 40 va transformer, but I'd rather see only 4. Non NEMA transformers are erratic in the voltage they put out. The on-board transformer in the Aquastat only will operate 2 valves. The ball inside the zone valve rotates and never seals in the same place twice, so I doubt that is a problem, although they sometimes get melted or damaged when the valve is sweated in, and while a bad end switch is possible, it's not real likely.

You can check the control by simulating a call for heat, and watching it run thru the sequence of operation, and observing where it fails. Just be sure you don't jumper or short the B1,B2,B3 terminals, this will let the magic smoke out of the control, and it will no longer function. If you think it will help, you can download a tech sheet off http://hbctechlit.honeywell.com.

ScottMP

Thanks Bill

SInce this is a call for domestic and the room Thermostat would not be invloved can it Still be a problem ?

This has gone several heating seasons with out issuie and know has been happening on calls for domestic.

Chris did find the domestic zone valve not making on the end switch and so replaced the head.

Scott

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BillW@honeywell

Hi Scott & JCA...

Can you get me the datecode off that ZV that the end switch was bad on? It's a 4 digit number stamped on the wire end of the motor housing, and would read something like "9904". If it was in place for less than 1 year, take it back for warranty. It doesn't seem too likely that the t'stat would effect a call for domestic water. In many other intermittent problem cases, the usual suspect is a wiring glitch, that's where I'd start to look.

Unknown

no hot water

Scott,

If the call is a DHW call then it IS NOT THE ANTICIPATOR on the thermostat.

I have however had a few bad aquastats on DHW tanks this year. One of my leading "ghosts" when it comes to intermittent problems with the NO HOT WATER calls.

wheels

ScottMP

Wheels and Bill

All this stuff has been in for about four years now with no glitch.

I am back to AARRRGGGGHHHH.

Scott

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Glenn Harrison_2

Scott, by chance does this system...

have a zone valve control panel with domestic water heating priority. The reason I ask is I had a customer that had a system that started locking out. Finally found out the zone panel was locking out the domestic hot water due to it taking over an hour to heat the water due to a plugged HX in the indirect. Just a thought.

ScottMP

Glenn

Thanks for the thought.

No zone control panel, all zone valves have individual relays.

You are on the right track as the originall call was on a Sunday and after she had restarted the boiler it took allmost an hour and half to come up to temp. The first thing Chris did was service the boiler and shock and flush the coil. Chris had the HO watch as he flushed the crud from the coil.

Scott

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Glenn Harrison_2

Is this unit Gas, or Oil,...

and if it's gas, what kind of ignition system does it have? I ask as I'm thinking this unit may be locking out for more than one reason. Probably going to have to catch the thing in "lockout" again before you will know for sure. Man I hate calls like these. They make you age way before your time!

J.C.A._3

Glenn, It's gas

Unit is standing pilot. Like I stated in the initial querry.... I found the zone valve OPEN, and the "clapper" on the 8148E control in the "not calling" position. That's when I cheked the end switch on the zone valve and found IT open.(like the arm didn't move far enough OR the switch didn't quite make all the way)

Homeowner has been away for a couple days, but I haven't had the time to go back and check it out again. I think that the end switch on the newly installed "head" is doing the same thing, and not making contact "all the way" through the end switch.

The "anticipator setting" is a nil, null and void thing. This beast is being controled by a Honeywell 8040B aquastat, and it checks out to acurrate within about 10 °.

Like I said , the call was made, but the end switch just didn't make contact. I'm wondering if I got a bad one right out of the box. (I'll go back to get the date code next week, Thanks Bill W.) Chris

Glenn Harrison_2

O.K. with those answers,

It would realy only make sense that it's something with the zone valve, although a bad indirect aquastat, L8148, or other wiring problem is not out of the question.

Now that I think about it, I had one time where I replaced a Honeywell powerhead, and had to go back a little time later and found the gears would slip right before the end switch was closed. Only happened once in a while. Changed the powerhead again and all is fine.

marco_4

I've run into a few zone valves that would not open far enough to activate the end switch (intermittently) even after the power head was replaced. One time it was due to the H.O. getting a job at radio shack and replacing his 24v transformer with a lower voltage one thinking it was for his doorbell. The other times it was due to the shaft of the zone valve having some stiffness to it. Replacing the zone valve body is the answer, although one night after a brutal 16 hour day of A/C calls I got a no H/W call at 11PM. Our other techs had been there and most recently had replaced the power head. All I could think about was my pillow so I lubricated the shaft with a spray lubricant and operated it with pliers until I could turn it freely by hand. That was 2 years ago, and it's still OK.