Zone Valves BANG on opening only
Recently had an IBC VX110 Boiler installed on a 3-zone baseboard system with an indirect water heater. Now that the New England extreme heating season is here we have banging in the system. And I'm talking loud enough I can hear it in the driveway. I have put an annotated drawing below. (Please note, the old system was very similar other that it had a single circulator (with NO check valve) and 4 zone valves (one being the priority IWH) and never had this type of banging)
After some long observation, Found out the banging occurs AFTER the system is at rest (no calls for heat and all 3 circulators are off). The banging only occurs when the 1st zone valve OPENS. Zone valve opens, BANG, end switch made, Zones & Primary Circulator Pumps start.
If 1 of the zones is running, there are no noises when any of the other zones start or stop (other that normal Woosh when valve closes). All 3 Circulators are Grundfos 92603107 UPSe 15-58FR High Efficiency ECM Wet Rotor Circulator Pump w/ check valve programmed at Zone Valve (constant Pressure) Setting III.
The Post Purge time for the 3 pumps are Zone Circulator - 0 sec, Primary Circulator - 300 sec, and IWH Circulator - 180 sec.
Reading some other post there may be 2 effects (but I'm not a pro). Effect 1 - Looks like the system is Circulator-Boiler-Expansion Tank and Effect 2 - all the circulators are supplied with check valves.
Don't know if these are issues, but the installer is brainstorming and I'd figured I'd ask here as well.
Comments
-
When DHW calls for heat, do all the zone valves close?
0 -
No, the Zone Circulator shuts down and the IWH circulator ramps up. Any zone valve that was open stays open unless the thermostat shuts it down.
0 -
Deleted! One day I will learn to.read more better.
0 -
the zone circ shows a check in the drawing, as does the indirect.
Are the valves flow direction sensitive? I think those are ball valve type ZVs?
I think the opening speed depends on if the capacitor is charged or not?
It is usually a fast closing valve that can start a bang or hammer?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Remove the check valve on the circulator for the zone valves.
1 -
I’m probably too late to the party. For the next opportunity, here is a piping option.
The air purger at the boiler puts it in the highest temperature zone and covers the indirect and secondary loop,best.
The indirect parallel to the boiler gets full temperature output, through the close tees it will blend some.
Officially speaking, the loop with the expansion tank is primary.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Yes, the zone valves are NOT directional and they are the capacitor type. When the thermostat closes, the light flashes until it opens. They do close fast, but they do NOT hammer on closing, just opening. The check valve is my thought as well. Even though the Zone Circulator is at a 0 (zero) second post purge, there is a couple of seconds that it is running full out. Not only is is putting pressure against the zone valves and manifold, it is also pressurizing the expansion tank between the circulator and zone valves. I'm thinking the pressure is what is causing the BANG when they open. The installer is coming back out Monday morning to do some more troubleshooting, since all Circulators are properly isolated with ball valves, I may tell him to lose the check valve(s).
0 -
I want to make a few corrections on your drawing here.
- The primary loop is the loop with the expansion tank
- In your drawing the expansion tank is located on the system side of the primary secondary piping, so the primary loop is the zone valve system.
- That would make the boiler loop the Secondary in your drawing.
- The closely spaced tees are connected in reverse. the hot water from the boiler supply is being put in just before the return piping to the boiler, So the installer got it backwards and your system is preheating the return to the boiler and the return from the system is cooling off the heated water to the radiators.
I believe that your bang may come from water expanding or contracting as a result of all three zone valves closing against the check valve in the Zone Circulator. See the Red shaded section of the diagram below
Once all the calls for heat are satisfied, the hot water in the baseboard radiators will cool off and contract however that water has no connection to the expansion tank, so Hydraulic pressure (actually Hydraulic Vacuum) is put on the circulator check valve and the zone valves. As soon as one of the zone valves opens, that Vacuum will be released rapidly and that may be your BANG.
Since you need to make the repair to the reversed supply and return from the boiler to the system anyway, you can make several other corrections at the same time.
- Move the expansion tank to the supply pipe from the boiler
- Remove the check valve from the Zone Circulator
- Put the supply from the boiler ahead of the return to the boiler in the system (ZONE) loop so you are not mixing the hotter water with the colder water.
This way the DHW circulator and the System circulator will be in the hottest portion of the system and pumping away from the point of no pressure change. (the expansion tank)
All the piping will have access to the expansion tank from one direction or the other even when all the check valves and zone valves are closed.
Leave the boiler pump on the return to increase the boiler pressure going into the boiler as many manufacturers recommend, in order to keep water in the heat exchanger from flashing and making a different noise.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
1 -
I like Ed’s drawing but would connect the expansion tank into the system on the blue return just under the boiler circ. Then the boiler circ is “pumping away”. As is the indirect circ via. Path through the closely spaced tees to the PONPC, orange dots.
The fill valve connects there also.
Expansion tanks do not need to be under air purgers. And may collect debris there as the air sep media is also a dirt sep media. The debris falls onto the diaphragm.
If you put an expansion tank under an air sep use a tee, the branch and an ell to get it out from under the sep.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
EdtheHeaterMan and Hot_Rod, thanks for all the comments and diagrams. They make perfect sense to me and support what I have been reading here in this awesome forum (especially that reversal of the primary circulator tee!). I will show the technician these drawings to "help" him troubleshoot when he comes again Monday morning. I have also attached a photo of the system. I have taken a picture of the system and I will update my Visio drawing and repost with what they can physically do with least effort. Below is my SWAG on the Vacuum pipe length on the system.
OK, the geek came out in me and I put my engineer hat on. Looking at these circulators running full out in Zone Valve Mode (constant pressure) and at Setting III, they are pumping out 13.6 GPM which equates to 0.227 GPS.
Let's say that the pump runs for 1/10 second after the valve shuts, this is 0.0227 gallon that gets forced between the pumps check valve and the closed Zone Valves. On the flip side, the pump is drawing that 0.0227 gallon from the inlet side of the pump, creating a "void".
With a 1" system, 0.0227 gal would be a void of 6.5". In a 0.75" system, this void would be 12". The way I see it, this is the void (at a lower pressure) that the higher pressure water BANGS into when a zone valve opens.
This seems to make sense to me and support the reason for taking out the check valve in that Zone circulator.
0 -
Those clacking check valves are never missed. I spent a lot of time removing two of mine. I just have the one left in the DHW loop. A monkey could design a better zone valve controller than what you can buy. A 2 second delay between pump shutoff and zone valve closing wouldn't kill them. I'd consider making those zone valves close on a dhw call and losing the checks. But having three zone valves close at tge same time presents it's own challenges. Again, gives you some idea of the thoughtfulness of zone control design. I have a set of time delay relays added into the dhw switch over so the zone pump shuts off, the dhw pump comes on, then the zone valves close.
0 -
Yeah, in this day and age. Smart ZVC with bi-direction info flow to/from the boiler should be a no-brainer.
0 -
since you cannot compress or stretch water, in a sealed pressurized system there really cannot be a void or empty spot. Where would that fluid go to? It can’t get out. Pressure can and will increase as temperature goes up
An increase in pressure can also be seen from the circ adding head.
Improper expansion tank placement can cause a negative pressure in parts if the loop, but not really a void or empty spot inside
The piping suggestion should correct multiple issues for you
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Quick question hot_rod. Since the expansion tank is between the pump and zone valves, is it possible to compress the water force the bladder into the air zone. The amount of bang I get really suggests a real pressure differential. Once again, thanks for everyone's help.
0 -
It probably varies from brand to brand, but when powered down, the end switch opens almost instantly. The Caleffi take 5-6 seconds to close completely, so there is a few 3-4 seconds of delay built in. Thermal electric and some of the ball valve type are slower to full close off.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
The bang is usually from stopping a fast moving flow. Do you need the pump at that speed setting, 13 gpm? How many gpm do you actually need. Slow down the circ see what happens.
It would be nice to know which change actually cures this.
If you make multiple changes at once, we may never know?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Yes, the pump often doesn't spin down anyways as it's shared accross zones but in my case it hammers when one particular zone closes by itself,if other zones are calling no hammer. It also sounds like the house exploding on a priority call when all the zones shut off at once, that's where the real fun would begin. So the delay I put there we see power from the boiler control that is used to start the dhw pump, I put a time delay in there so the dhw pump wouldn't come on for a 5 seconds and give the zone valves a chance to close. Seemed to solve that issue. Would like to see the zones cascade off in sequence so it's not so violent. The caleffis I have stuck with for a long time now. Slowest closing valve I know of.
0 -
We have sent these thermal actuated zone valves out to problem jobs where every spring return brand they tried banged.
These take several minutes to open and close. A 4 or 5.6 Cv version. The twistTop actuator makes it easy to manually open also.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
The comments seem to be tending to BANG on CLOSE. The system never bangs on close, only the "woosh" sound of the closing on the valve. The BANG only happens on the opening of the 1st of the 3 zone valves. If ALL 3 zones have been closed, they opening any of the 3 will create BANG. If 1 of the zones is already open, then opening another will NOT create a bang. The BANG will re-occur after all 3 zones have been closed again.
0 -
Remove the check valve on the circulator with the zone valves.
2 -
Yes, that seems to be the 1 fix that needs to be done along with the reversal at the tees for the Primary Circulator pump. I'm sure that reversal is messing with the algorithm for the burner control!!
0 -
@EdTheHeaterMan Diagnosied the issue, the current setup isolates the space heat when zone valves close so when any opens water rushes in. This causes high flow rate and the check valve slam shut once the flow settles.
Remove the check valve.
1 -
Wow, thanks for all the help. I have sent the installer a synopsis of this chat along with @EdTheHeaterMan diagram for preferred hookup so when the troubleshooter come out (for the 2nd time), it will help.
I'll let you know what they do for the solution.
1 -
HVACNUT is correct. Just remove IFC from zone valves circ. It is not needed anyway. Heating loop goes into vacuum when it cools down after heat call with zone valves closed.
0
Categories
- All Categories
- 86.6K THE MAIN WALL
- 3.1K A-C, Heat Pumps & Refrigeration
- 54 Biomass
- 423 Carbon Monoxide Awareness
- 98 Chimneys & Flues
- 2K Domestic Hot Water
- 5.5K Gas Heating
- 101 Geothermal
- 157 Indoor-Air Quality
- 3.5K Oil Heating
- 64 Pipe Deterioration
- 931 Plumbing
- 6.2K Radiant Heating
- 384 Solar
- 15.2K Strictly Steam
- 3.3K Thermostats and Controls
- 54 Water Quality
- 42 Industry Classes
- 48 Job Opportunities
- 17 Recall Announcements