Boiler system won't send hot water to 1 part of the house?

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Old 01-22-11, 12:29 PM
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Boiler system won't send hot water to 1 part of the house?

Hello,

Thanks in advance!

I have a boiler system with 4 Honeywell V8043E1012 zones valves. 3 of them work perfect and heat their respective parts of the house. The trouble valve or section of piping was working fine until the other night when it got down to -25 here in MN. We had a major fireplace fire going and topped out at 79 degrees on this day so we accidentally turned the thermostat down to like 40, I know mistake. We went to bed and woke up the next morning and I noticed the mistake and immediately turned up the heat. Now there is no heat to this part of the house. I am guessing there is an ice blockage so no water can go and return. I have already replaced the zone valve and that didn't fix the problem. Glad I did to as the old zone valve was a rusty old looking mess. When you turn up the heat on the thermostat my new zone valve opens but no water goes up the pipe. Is there anything I can other than take a hair dryer to every part of the pipe? Or could this be another problem?

Thanks,

ASMcNeill1970
 
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Old 01-22-11, 12:37 PM
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Welcome,

What part of the zone valve did you replace???? Did you try bleeding the zone first to see if that is your issue?? You may just be air bound. Where are your pipes located that would lead you to belive they are frozen?

What is the make and model of your boiler?
What does the pressure and temp say on the boiler gauge?
4 zones 4 t stats? Or does one zone heat your hot water?

We can start there and help you further with this info.

Mike NJ
 
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Old 01-22-11, 12:50 PM
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Well, I think it's frozen since it was working perfectly before our first -25 night this season. When I cam down stairs the next morning it was so cold, probably the coldest I had every felt in my living room.
The boiler is a Utica with 25 pressure and 30 is the max before the gauge turns red.

I replaced the the whole zone valve except for the copper part that is soldered to the rest of the pipe. So the zone head, motor and black rubber stopper/valve ball are brand new.

4 Zones for 4 stats.

On the boiler, it sends hot water to a T. At the end of each part of the T is one of the zone valves. One side of the T is for the basement which works great. The other side of the T is for the living room which isn't getting heat. I have temp gauges on the pipes. The basement is 150 and the living room pipe is 100 even though they are getting hot water from the same pipe. I am new at this but doesn't the water go up the pipe into the registers and the come back through the return? If there is a blockage no new hot water will make it through the cycle. I just want to make sure that it isn't anything other than ice.

Thanks for the reply
 
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Old 01-22-11, 12:54 PM
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Also, I took the cap off my air purger that has a tank expansion connected to it and pressed the little pin valve button and a tiny negligible amount of air popped out and then steady water. Pipes up in the living room is still cold though.

Thanks
 
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Old 01-22-11, 01:05 PM
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Turn all other t stats down so the boiler does no kick on. Then turn up the t stat in the living room. Does the zone valve oprn and boiler kick on? If yes and still no heat then turn that t stat down and lets try to bleed the zone. There should be a hose bib and a valve on the return side piping. There should be 4 of each. Can you identify which one is for the living room?

Leave the cap on the air bleeded loose and dont touch.

Let me know I will be here a while.

Mike NJ
 
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Old 01-22-11, 01:46 PM
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Thanks for the help, I did what you said and turned off all tstats and the boiler stopped firing. I then turned on the LR tstat and there was a click and the zone valve opened but the boiler didn't fire. I am bleeding the living room return now, unfortunately there are 2 separate zone that come in on the same return. So the whole main floor comes back on the LR return so it's taking a while to bleed as air fights its way to the top. I will keep bleeding and once the water stops I will fill it back up and try again. I did close the valve below the return valve so gravity wouldn't bring the upstairs return water out the LR return valve.
 
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Old 01-22-11, 01:54 PM
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I did not tell you to start bleeding. You dont bleed until the water stops. As your bleeding you need to raise the pressure in the boiler to push the air out. But you were supposed to wait until the boiler cools. Hot boiler and cold water equals cracked cast iron heat exchanger!!!!!

OK let me know how it goes then!!!

Mike NJ
 
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Old 01-22-11, 02:06 PM
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Oh, my bad.......uhhggg. I haven't refilled the boiler with water yet. I will wait for the whole system to cool down first. Thanks for the info. So why didn't the boiler fire? Because there is air in the pipes?

Thanks
 
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Old 01-22-11, 02:26 PM
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No it should of fired. Unless it was up to temp, then the circ would just run until it cooled down enough for the burner to kick on. As long as the t stat is calling for heat.

My next question would have been is the circ on? Did the zone valve open? If not , the zone valve may be wired incorrectly. Plus the boiler fills itself with water up to 12 PSI. And you need to isolate the loop before you bleed.

OK Lets slow down. Let start with, you post on where you are at now, and explain everything you see and here?? Plus you never said the make and model of your boiler.

Mike NJ
 
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Old 01-22-11, 02:41 PM
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Ok, right now I stopped the bleeding and I am waiting for the boiler to cool down. The boiler is a Utica and the model is PGB125. Right now everything is like room temp. I can touch everything and it's not hot.
When we turned on the LR tstat there was a click and the new zone valve instantly opened so I know that is working. The only thing it didn't do is fire. I then turned on the basement tstat and the boiler didn't fire so it must have been at the right temp and didn't need to fire. I also wired it the exact same as the old one because I taped and numbered the electrical connections. I have 3 others just like it to reference. I was able to isolate the loop thankfully.
So, at this point, the bleeding was going slow trickling water out with gulps of air going up to the top of the pipe loop. Now that the boiler is cooled down do you want me to start filling the boiler to get the pressure up and then start bleeding again? What pressure does the boiler need to be at for me to start bleeding?

Thanks again
 
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Old 01-22-11, 03:25 PM
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Make sure all t satas are down or turn off electric to boiler.

OK where you bled the water out, is there a valve under it? If yes close it. Hook up a hose to the hose bib.
You boiler should have 12 psi in it now. Find the fill vave tha feeds water into the boiler. Looks like this.



Yours may be different but if you lift the top it fills the boiler.

Open the hose bib and bleed the zone but at the same time fill the boiler and watch the pressue. Keep pressure in the boiler but stop filling when it gets up around 25 psi.

This is a give and take until you get constant water out and no air.

When you feel the water went all the way around the loop, and you got all the air out, stop filling and close the hose bib. The pressure should stabilize to around 12 psi.

Open the valve under the zonevalve and call for heat at the living room t stat.

If you got water out while bleeding I guess you did not have frozen pipes.

What happens....

Mike NJ
 
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Old 01-22-11, 03:51 PM
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Ok, I did exactly what you said and I got water coming out but no air! So that is good. I am now at about 15psi in the boiler. When I turn on the LR tstat I get a click but no water movement. When I turn on the other tstat on the same floor as the LR I hear a click but water immediately rises in the pipe and goes to that side of the house. It looks like the pump is not pumping the water when the LR tstat is calling for heat. I had steady water coming out after the bleeding. I opened up the isolated LR return too. What else can I check?
So when the LR tstat calls for heat the aquastat checks the temp of the water in the boiler. If it's to low it fires to heat the water. Once it reaches a certain temp the aquastat then turns on the pump which pumps the water to the zone that is calling for water. What would stop a aquastat from not pumping water that is the correct temp to a zone that is calling?

Thanks
 
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Old 01-22-11, 05:07 PM
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So your living room t stat does not open the zone vave?? Or does it??? I know from what you state its not turning on the circ. If the zone valve is opening and the circ is not coming on your zone valve is wired wrong or the new zone valve end switch is bad. Your t stat is good if the t stat makes the zone valve open... But the end switch in the zone valve is not starting the circ or burner....

Mike Nj

Mike NJ
 
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Old 01-22-11, 05:48 PM
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The LR tstat opens as soon as my wife turns the tstat to 80 or whatever is higher than room temp. I can actually see the zone valve open. I am going to swap out a working zone valve for the zone that is not working and see if that works.
After things cooled down I turned on the tstat in the LR and the boiler fired. The fire stays on until the required temp is achieved. But that is where it ends, with no water being pumped. I had to get heat going in the rest of the house because it's now cold and my 3 yr old is going to bed. So, I may have to do this tomorrow because I would have to shut down the power to the system to swap out those zone valves. Thanks for your help and I will report back tomorrow.
 
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Old 01-22-11, 08:43 PM
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Its hard because I am not there. If the zone is opening, and the boiler is firing, and the circ is circulating then the problem is air. It could be frozen but I dont know what or where your pipes are connected to or what areas are prone to freezing.

I dont know if I can help anymore because of lack of pics and I am not sure of your skill set. Please call a professional.

Mike NJ
 
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Old 01-22-11, 11:17 PM
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Hi Mr. McNeill:

I'm no more familiar with your heating system than Mike was, but I'm intimately familiar with Honeywell V8043 series zone valves.

I've skimmed this thread so far, and gathered that:
1. You've been able to flush your living room loop so there's no air in that loop.
(I doubt you did any harm to your boiler by the way. Boilers are cast iron, and they're very strong.)
2. That initially the boiler wouldn't fire and the circ pump wouldn't turn on when you raised the living room thermostat, but later you said the boiler would fire, but the circ pump wouldn't turn on.

Honeywell 8043 series zone valves will typically have either two or four wires or 5 screw terminals for connections on the back of them. If you have wires coming out of the valve then typically, there'll be two yellow wires. If you have and end switch in your zone valve, you'll also typically have two red wires coming out of the valve as well. The two yellow wires go to the zone valve's motor, and it doesn't matter if you mix up the yellow wire connections. Essentially, the living room thermostat, the 24 volt transformer (probably located in your boiler) and the motor in your zone valve are all wired in a series loop so that the thermostat simply completes a 24 VAC circuit from the transformer to your zone valve's motor, causing that motor to open the zone valve. That's why it doesn't matter if you reverse the yellow wires; 1/120th of a second later the alternating voltage and current will reverse your connections anyway. Ditto for the two red wires. They go to the end switch, and you can mix them up too.

Basically, the way your system PROBABLY works is that each of your zone valve end switches are connected in PARALLEL with a relay in your boiler so that if ANY end switch closes then a 120 VAC or 24 VAC circuit is completed to that relay.

The electromagnet in that relay then snaps shut to complete TWO circuits simultaneously; a 24 VAC circuit through all the boiler's safety controls to the boiler's gas valve to open the gas valve to fire-up the boiler (or if it's an electronic boiler, a 24VAC circuit to the boiler control that then fires up the boiler) AND a 120 VAC circuit to your circulating pump.

So, the sequence of events is that when the LR thermostat calls for heat, then the LR zone valve opens. At the end of that zone valve's travel the end switch completes a circuit to the relay inside the boiler causing both the boiler to fire up and the circ pump to come on. And, since all 4 of your thermostats and zone valves will be wired the same way, the boiler and circ pump will remain on as long as any thermostat is calling for heat.

From what I can see, I suspect that either your new zone valve's end switch isn't completing the circuit to the relay, or that the relay isn't turning on the circ pump. You may have had a faulty relay for years, but it's just now that you're testing your heating system that it's coming to light.

If you have a multimeter, could you first find out if the power going to the end switch is 120 VAC or 24 VAC. Then, if it's 24 VAC, or you know how to shut off the 120 VAC power to the zone valve end switches, disconnect the red wires to the LR zone valve, turn the LR thermostat all the way up, and check for continuity between the red wires going to the zone valve's end switch. You should have continuity. I'm just wanting to confirm that the zone valve end switch is working as it should.

PS: 25 PSI is actually way too high to operate your heating system at. You typically need about 12 psi to prevent cavitation of the impeller in your circulating pump, but anything higher than that is unnecessary. The way you use the pressure gauge on your boiler is to guestimate the elevation difference between the highest radiator in your heating system and your boiler's pressure gauge in feet. Multiply that elevation difference in feet by the pressure gradient of water, which is 0.43333 psi per foot, and that will give you the pressure you need to fill your system to the top radiator. You need to operate your heating system at that pressure, or 12 psi, whichever is higher.

PS2: You calculate the pressure gradient of water by knowing that water weighs 62.4 pounds per cubic foot at sea level. Since a cubic foot is 144 square inches to a side, the pressure at the bottom of a cubic foot of water will be 62.4 pounds / 144 square inches, or 0.43333 pounds per square inch. And, since water is essentially incompressible, the pressure gradient will be the same in a column of water 144 square inches in area, namely 0.43333 psi per foot of change in elevation.

PS3: Most likely there was nothing wrong with your old LR zone valve that a shot of WD40 to the motor rotor wouldn't have fixed. But, that's all water under the bridge now that you've got a new valve in place. I have 21 Honeywell V8043C zone valves in my apartment block, and it's common for the tiny motors in them to get stuck. Common, at least, as women wearing hats in Bolivia. Every autumn I have to give one or two of them a shot of WD40, and they're good for another 5 years.
 

Last edited by Nestor; 01-22-11 at 11:50 PM.
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