Hello,
I have 3 Taco zone valves that appear to be properly functioning. When The thermostat calls for heat the valves open and thus the pipes on both sides of the valves get hot. The boiler comes on when the temperature drops in the boiler.
A Couple of months ago I replaced the Honeywell L8148A1017 Aquastat Relay with a new one. The boiler was not firing previously. After the new Relay was installed all worked properly.
At this point in time the circulator only comes on when the boiler calls for heat. So even though the zones are calling for heat and have approx. 24 volts and have hot pipe on both sides of the zone valves the circulator does not come on unless the temperature in the boiler drops and the boiler comes on. As soon as the boiler calls for heat the circulator comes on but shuts off as soon as the boiler turns off. So I only get hot water circulating when the boiler is running resulting with a cold house and heat only when the boiler is actively running.

 

Hi Schiff, welcome to the forum and Happy New Year!

By "... boiler comes on ..." , do you mean ' BURNER FIRES ' ?

So when a heat call occurs, the burner fires, and the pump comes on.

As the heat call continues, the water in the boiler gets hot, hits the high limit setting (which should be around 180F or so), and the burner cuts off.

Are you saying that the PUMP ALSO CUTS OFF at this time? How do you know the pump cuts off?

You say the pipes are hot both sides of the zone valve... are the zone valves on the SUPPLY, or the RETURN side of the boiler?

This is a strange one because if the aquastat is wired properly, what you are saying is basically not possible.

 

While you are poking around at the boiler, please read the PRESSURE and TEMPERATURE gauge and report the readings.

Do you have a multimeter and know how to use it?

 

Valves on supply side. Pump on return side. Circulator Pump shuts off when boiler hits high limit. I removed Aquastat board to check for bad or cracked solder. None found.
I only have warm heat when boiler running. The boiler feeds air handlers and domestic hot water tank. When burner on hot air and return pipe gets very hot. When boiler not running, return pipe is only warm. Can verify circulator running when boiler running because can feel vibration and return pipes are very hot & air felt of handlers is warm. When boiler not running return pipes are much cooler, no vibration from circulator, and air not warm off handlers.

I am going to put Aquastat back in. Please verify connections for me.
From 24 VAC transformer to Taco Zone valves
Load goes to #2 on all Taco Zone valves
#1 is a wire from each individual thermostat to each zone valve
#3 is the end switch

Coming off the Taco zone valves does the load wire connect to the left or right T screw on the Aquastat?

L1 hot or common? or should it not be used and L3 have Hot or common?
L2 hot or common?

C1 Should that be hot or common
C2 hot or common?

As mentioned was working fine a few days ago but not now.

Thanks

PS I have a multimeter am very handy but have little experience with the meter. I can easily check continuity and voltage.

boiler shut off at this minute Aquastat out for inspection

 

Please answer all questions............... even if the boiler is cool... I want to know the pressure and temperature.

 

You should have labeled the wires before you removed. AND taken digital photos.

One 'leg' of transformer to #2 on all zone valves.

Other 'leg' of transformer to one side of all thermostats.

Other side of each thermostat to respective zone valve #1

Wires from #2 and #3 on zone valves to the T T terminals on aquastat, polarity does not matter.

 

Temperature looks to be around 110* pressure around 10 hard to tell exact (gauges do not appear to be marked for exact precision).

 

L1 is 120VAC HOT (BLACK).

L2 is 120VAC NEUTRAL (WHITE).

C1 is HOT to circulator pump.

C2 is NEUTRAL to circulator pump.

B1 is HOT to BURNER.

B2 is NEUTRAL to BURNER.

There is no " L 3 " .... There IS a " 3 " (no L). There should be a metal jumper between 3 and L1.

 

I believe that your problem is NOT electrical.

Your pressure is probably LOW and you now have an AIR BLOCKAGE in the pipes to the air handlers.

When the aquastat is reinstalled and the boiler is HOT please report the pressure reading and temperature again.

Where is the boiler in relation to the air handlers?

In other words, how far above in feet are the air handlers from the boiler?

Is this a 2 story home? Air handler in attic and boiler in basement?

 

Yes that is the way I had it wired. Thanks for verifying. You had mentioned in the first reply that maybe I had wired something incorrectly so I wanted to verify prior to putting the Aquastat back in.

I visually inspected all sodler with a loop and did not see anything that caused alarm. I also checked continuity where it appeared it should be and everything seemed to be correct. Is there anything you can suggest I check on the Aquastat before I put it back in? I have it right here and have a meter.

Thanks

 

Boiler on ground level in garage. First floor is up 5 steps. Second floor up 13 more main floor and air handler in attic 8 feet above second floor. Air handler one in lower level/walkout basement.First thing I did was purge all the zones. No air. I understand that air can create a block and so that was the first thing I did. Even did it twice. To verify that all was good I had hose going into 5 gallon pail to check for air bubbles. No air bubbles. Purged until cold cold water from my well was circulating through each zone. Purged one zone at a time have ball valve shut offs on each zone.

 

No, not with aquastat out... sounds like you have done a thorough examination.

Go ahead and reinstall and when you are done, set your multimeter to read AC VOLTS (120) and connect to the C1 and C2 terminals.

Turn boiler on and call for heat (push thermostat all the way up so boiler goes to high limit and burner shuts off)

You should have 120VAC on C1 and C2 as long as there is a continuing heat call.

 

Let us check that this was done properly because if the valves are not correctly manipulated you will not push water through the zone, but only through the boiler because water will take the path of least resistance.

Can you take and post a picture of the valves around the boiler please?

In the meantime I will try to explain...

There should be 'purge stations' on each zone. A purge station is a STOP or SHUTOFF valve, and next to it will be a DRAIN valve.

If this is what you have, the STOP valve should be CLOSED, and the drain valve OPEN. This prevents the water from coming straight through the boiler and instead up into and through the zone.

Is this what you did?

I also still want to know the pressure and temperature when the boiler is HOT.

IF your gauge is accurate, the 10 PSI you stated is on the LOW side. You should have 12-15 PSI in the boiler when it is COLD, and this will rise to perhaps 20 PSI when the boiler is HOT.

Please read this:

http://www.doityourself.com/forum/bo...ure-gauge.html

and since it is good information to know even if this is not presently the problem, this also:

http://www.doityourself.com/forum/bo...sion-tank.html

I've got some work to do... I will be in and out during the day... if I don't answer immediately you should check back time to time for answers.

 

Hydro air if that is the correct name for it seems like it takes a simple concept and make it more complicated than it needs to be.

I am still at a loss. A bigger one in fact.

When I put the Aquastat back in I decided to not hook up the burner to verify whether or not the thermostat solenoid actually was working without the burner or not. What I determined is that it does work properly for the basement and domestic hot Water but does not work properly for the third zone. I hooked everything up Burner shuts off temperature 180 pressure 12psi.

I proceed to remove the thermostat that controls the third zone. It is a bryant evolution. It is held in a series of pins and controls 2 zones first floor and second floor. One zone off the boiler goes to this handler and then an airduct system with diverters deciphers which zones need heat.

Anyway I remove that thermostat and try jumping the thermostat to try to get results at the boiler for that zone. No luck. Then when we put the thermostat back in we have no power to the once powered thermostat. No voltage anywhere. We take our meter to the attic and there is a circuit board that looks like it could run the city of Chicago. That appears to have no power anywhere. We pull off the cover to the blower area and there is another circuit board of almost the same character. We trace some wires and find 240 volts that go to a connector with about 8 or 10 colored wires and find a 24-26 volt pair of wires held together with wire nuts that proceed to go to a little black block that has some sort of diode or resistor board on it. Power on one side of this block has the 24-26 volts mentioned the other side has zero volts. These diodes/resistors or whatever the correct term is has zero continuity if you go across each one of them (there are 4).

I have to go to work in a few minutes I work 11p-7a. I have no idea what the block or resistor is. We looked it up and found the block and board both sold separately online for about $15 each. Was not able to find any info on how to test either or what their actual purpose is. I would imagine it is some sort of protector for the circuit board.

I will bring these with me to work and maybe able to do a little research tonight on them. I would not think the block would have gone bad probably just that little resistor board but I don't know.

So before I had power to the thermostat and the fan would run and I would manually open the zone valve if I wanted to and heat the main house. Now I get no response. We shut off the power to the transformer at the boiler and determined that the 24-26 volts in the attic is from the transformer that works the zone valves and boiler but as I mentioned is stops at that block and neither circuit board gets any power.

I am grateful for your input to this point and will need to rectify this problem. My guess is that something in the air handler in the attic is the original culprit but am skeptical that the original issue has anything to do with the current problem. I can only hope and pray that when I tried to jump the thermostat to get it to work the burner and circulator that I did not ruin one or both of those boards.

It seems like the circuitry in the bryant air handler is more complex than it would need to be.

Please continue to add input because I need it and will need to solve this issue myself.
Thanks again.

 

The part I explained prior to work is a Carrier Rectifier
HK61EA003-Carrier-Rectifier-Control

That clips onto the block I described which is a
Potter & Brumfield Relay Model T92S7D22-22

As mentioned there was 24-26 volts from the transformer that runs the zone valves and connects to the Thermostat on the Aquastat that powered 2 of the connectors but no power coming off the Rectifier at the top and there is no continuity between the diodes or resistors or whatever the proper technnological term is.

I am hoping if I replace one or both of them my thermostat will once again work and power will hopefully go back to the circuit boards on the air handler.

It sure would be nice if I could purchase those pieces locally Friday buy I am guessing they will be hard to find in my area 06010.


Thanks again for any and all input.

 

Supposedly there is a low voltage fuse that is generally the culprit when the thermostat goes blank. We looked for a fuse yesterday but one did not seem apparant. When I get home from work I will look more closely.

 

Regardless of anything else (I haven't yet read all your messages) this pressure is too low and will cause problems with air blockages in the air handlers.


image courtesy supplyhouse.com

That is a 'bridge rectifier'. Those are diodes.

Now that I look at that part closer, it's not being used as a bridge rectifier because there are only two connections, but they are diodes.

Set your multimeter to the DIODE test position if it has one. You should read OPEN if you test in one direction, and about 0.6 if you read in the opposite direction.

It's purpose is to convert the 24VAC to DC.

I'm sure that the DC it produces is being used to power the control boards.

You may in fact have shorted something out when you were fooling with the thermostat control.

 

You say that diode assembly clips onto the relay?

I highly doubt that the relay is bad... but you need to properly test those diodes.

If you google "How to test a diode" you will learn what to do to test them.

 

OK here is the update.

I found the fuse on the air handler 3amp. Replaced it and thermostat and circuit boards are working again.

Boiler was cold had not been running. Turned it on. It ran continuously to 180* then shut off. Pressure is very close but under the 20 PSI on the gauge. Boiler came back on a couple minutes later and shut off around 190* Pressure still close but under 20psi.

Zone 1 domestic hot water calling for heat and 24-26 volts at zone valve.
Zone 2 (problem zone) calling for heat at zone valve 24-26 volts.

Burner shuts down circulator stays on.

Burner came back on a couple minutes later and shut off around 190* Pressure still close but under 20psi.
Zone 1 satisfied and zone valve shut off 0 volts at zone valve.
Zone 2 still calling for heat and circulator still on.

20 minutes later Zone 2 still calling for heat and circulator still running whether burner on or not.

As of this minute it appears that the entire system is functioning as it is supposed to.

I will update if further issues.

Thanks

 

20 PSI at 180F is not a problem.

Why is zone 2 taking so long to satisfy thermostat? Are all radiators warm/hot ?

It's still possible that you've got an air issue...