Zone valve failure

Gardyloo

Jamie Hall said:

Depends on what is in the water vs. what the balls are made of. Anywhere from a few hours to a few weeks -- and it is a time, not flow, based problem.

Good point, do you think the water could deteriorate the zone valves in less than a minute?

Its the body of the valve that's damaged, the metal seat is cut away from water flow, the damage to the balls is likely secondary after the valve got eaten away.

Alan Welch

It's hard to tell from the pictures of the new valves, might be a stupid question, but were the valve bodies replaced as well, or just the ball assembly and powerhead ? I would isolate and drain one of the zones, and remove the ball assembly to see if there is a piece of solder inside, or too much heat melted the ball.

Gardyloo

Alan Welch said:

It's hard to tell from the pictures of the new valves, might be a stupid question, but were the valve bodies replaced as well, or just the ball assembly and powerhead ? I would isolate and drain one of the zones, and remove the ball assembly to see if there is a piece of solder inside, or too much heat melted the ball.

All new valves, I removed the ball when I sweated them in and wiped out the flux residue. Typically I would not disassemble the valve, but did in this case. System has been flushed at the bottom of the boiler, system was pretty clean.

Robert_25

Gardyloo said:

hot_rod said:

Any response from HW or Resido?
Ill bet their first request is a fluid sample😉

I spoke to a rep in Minnesota, he tried to be helpful, but his firewall would not allow him to see the pics. I described it, but not much help w/o seeing it. Not much was said about the water, I did mention it was treated.. believe me its not the water. I had it tested when we completed the house, as I said before some minerals, some iron, no red flags, treated with a softener. No arsenic or anything odd. None of the techs I have talked to have mentioned seeing that from the local well water.

The valve is scoured from aggressive water flow, the new valve immediately started bleeding water past the ball. Water did not and could not deteriorate the valve body within minutes of bringing the system on line....

It is not the water or the 8-way.

You will probably need to talk to someone in technical support at the corp. level to get anywhere.

https://www.resideo.com/us/en/pro/HVAC/

Your equipment is a proven design, so it is logical to think there is something amiss with either one or more components, or the water chemistry.

Please return and let post whatever you figure out.

Gardyloo

I received a call from Honeywell today, they were reviewing the photos I sent them and do not have a explanation. They asked that I hang onto the valves in case they want to inspect them. They did not have any similar issues with these valves and I have to assume if it was a manufacturing problem that I wouldn't be the only person to have had this problem.

I did check the voltage at the zone valves this weekend and O volts present when closed. Furthermore the bleed by appears to have subsided. I have no explanation as nothing has changed since last week when I swapped them out. I have no explanation for this.

I do have the pressure in the system higher than what I have kept it in the past, close to 30 PSI when hot, the pop off is holding.

In the past I have kept the pressure close to 20 when hot and when the system is cold it would go down close to 0, which I would expect is OK.

I have several vents to remove air from the system, however I am wondering if latent air in the system could have percolated the valve and caused it to open slightly, if this persisted over time it could create a path for water flow and once the seal was compromised and allowed water to flow it simply eroded the valve over time...?

I will continue to monitor.

mattmia2

If the expansion tank is sized properly and charged properly and the gauge is reasonably accurate the pressure shouldn't change that much between hot and cold.

hot_rod

I think a pressure relief valve is designed to seep at the rated pressure, say 30 psi, and full discharge at 5 psi above that.

30 psi would be a risky pressure to run.

The pressure increase has to do with the pre-charge psi, static fill cold, volume of the system and the temperature rise. Some systems move only a few lbs, others can move 8, 10 or more psi. There are not that many different expansion tank sizes, so it depends if you are close to the expansion acceptance.
A #30 tank on a system of 30 gallons would show a small pressure increase. On a system with 100 gallons a higher pressure increase.

Table 5 in the Amtrol engineering guide shows Net Expansion of Water if you know the systems volume.
Table 6 you chose the minimum operating pressure, say 12 psi, and the max pressure, maybe 25 psi this gives you the acceptance factor. Divide those to get tank volume.
This is the critical sizing used mostly on larger systems, it does show how the tank size and pressure are related.

For residential work the quick sizer is adequate. Larger residential and commercial work it is better to use the calculator with more input options.

HomerJSmith

I have had several communications from Roger (thank you, Roger). The problem with Taco Sentry ZVs is the charging time which is so long that the boiler reaches Hi Limit before the valve opens. Once the capacitor is charged the valve fully opens in 5 sec.

hot_rod , I did read John's post and Roger's letter to me on Energy Kinetics recommendation on the use of Sentry ZVs. (Don't use them because of the charging time.)
I replied to Roger with the following solution. I hope it is workable.It would depend on what resistor value would be needed to charge the capacitor without turning the motor. I don't have a Sentry on the shelf to experiment with.
Roger, this is how I would do it. Taco used a 920 ohm thin film 1/4 watt bleed resistor to keep the ESP zone valves charged. I drew in a 1K ohm bleed resistor. I recommend a 1/2 watt carbon resistor. My drawing shows a 2pole/Double throw relay with a 24V coil. This should keep the capacitor charged.
You only need one transformer and all ZVs would be wired in parallel with one thermostat off the manager. If you have more than one thermostat controlling a ZV, you would need a relay for each ZV.

Let me know what you guys think.

mattmia2

There is no need to switch the pre-charge resistor, you can just put it right across the contacts of the relay that control the zone valve.

HomerJSmith

mattmia2, I don't see it. I'm probably not understanding your meaning.

hot_rod

HomerJSmith said:

I have had several communications from Roger (thank you, Roger). The problem with Taco Sentry ZVs is the charging time which is so long that the boiler reaches Hi Limit before the valve opens. Once the capacitor is charged the valve fully opens in 5 sec.

hot_rod , I did read John's post and Roger's letter to me on Energy Kinetics recommendation on the use of Sentry ZVs. (Don't use them because of the charging time.)
I replied to Roger with the following solution. I hope it is workable.It would depend on what resistor value would be needed to charge the capacitor without turning the motor. I don't have a Sentry on the shelf to experiment with.
Roger, this is how I would do it. Taco used a 920 ohm thin film 1/4 watt bleed resistor to keep the ESP zone valves charged. I drew in a 1K ohm bleed resistor. I recommend a 1/2 watt carbon resistor. My drawing shows a 2pole/Double throw relay with a 24V coil. This should keep the capacitor charged.
You only need one transformer and all ZVs would be wired in parallel with one thermostat off the manager. If you have more than one thermostat controlling a ZV, you would need a relay for each ZV.

Let me know what you guys think.

It could be the close off is too fast for the application also. I think that valve is a 5 second close off. It really comes down tom the application and the testing that EK has done.

hot_rod

There are other cases of the "rubber" components failing in ZVs due to water quality.

HomerJSmith

I never thought of close-off.

Rubber deterioration, could it be caused by stray current in the water? Auto radiator hoses show marked interior deterioration because of stray currents in the circulating radiator water. Is any of the hydronic piping being used as a ground connection.

Gardyloo

I was at the house last week and created a call for domestic hot water and watched the boiler cycle several times to satisfy the call/s. The unit heater and the buffer tank did not call during that time and I did not see any bleed by at the zone valves. This is contrary to what I saw after flushing the system, replacing the valves and restarting the system.

I will continue to monitor and I have no explanation other than the possibility of some air left in the system after flushing/startup?

I did hear back from Honeywell (Resideo) and they claimed the balls in the original vales were damaged during soldering. I am pretty careful about this when I installed them originally, however I did not disassemble them when I sweated them in 7 years ago....

When I replaced them recently I removed the ball and back plate.

At this point its a wait and see as it appears to be functioning normally, Will post if that changes.

Thanks for all the help here...

Gardyloo

The replacement zone valves are starting to let fluid flow, its been less than a year. I have arranged to meet a tech to take a look as maybe there is something I am missing.

I am looking again at motorized ball valve type ZV's, I understand the issue with the Taco sentry and it sounds like a resistor is a possible workaround but am not thrilled with adding another device and complexity to trouble shoot.

I am also looking at CALEFFI (6442) 40 seconds to open. Is this short enough duration to prevent the boiler from short cycling?

Or a 638, 50 seconds

They also make a Z series ZV that apparently has a torsion spring that perhaps is higher pressure than the Honeywell?

hot_rod

The fastest opening and closing zone valves will be the spring return. If that is critical to the boiler operation, I don’t see any of the ball valve type being fast enough?

The challenge with a fast closing zv is water hammer potential. So there is that trade off.

The Caleffi 644 is a slow open and close due to the gear ratio. It is also a4 wire power open, power close valve. So it needs a double throw relay

The Caleffi z one is available with a 20, 35, 50, or 75 osi shutoff. The flow rate drops off with higher close off valves, as the opening gets smaller

You want the Cv of the valve to be close to the gpm you want to flow through it

mattmia2

Adding a resistor across some contacts to bypass some current across the open contacts is a minute amount of additional complexity.

Gardyloo

Thanks for the replies…..

I am a bit outside my wheelhouse on this issue. I am hoping my local tech can steer me in the right direction.

If using a ball valve type ZV, any particulars regarding a resistor?

hot_rod

are you wiring the zone valves through a relay box? Depending on which relay box, how many thermostat wires, and what thermostat you use, a resistor may not be required.

Some of the power stealing thermostats need some resistance added so they charge properly.

Gardyloo

https://forum.heatinghelp.com/discussion/comment/1806581#Comment_1806581

The zone valves are controlled by the energy manager (System 2000)