Loud Whoosh and Bang When Zone Valve Opens (not closes)

SDJ88

I've tried searching for what seems like a pretty common topic but 90% of the results have to do with the zone valves closing too quick and creating a water hammer. My issue is when the zone valves open

Issue
When a zone valves open, I get a loud whoosh followed by a substantial bang/shake in the pipes. If just one zone valve operating and goes to close, there is no issue. If two or more are running, and one tries to close, I do get a whoosh sound but no bang/shake in the pipes. This happens more when the zones haven't called for heat in a little bit - almost as if some extra pressure is building up. If I manually open one of the zones very slowly - like, turn it 1/4 of the way I can hear the water rushing out. But, by controlling it so slowly, the noise isn't pronouced and I avoid the bang/hammer issue. Finally, if I leave the zone manually open, then crank the thermostat up so that it starts the circulator, there are zero issues until the next cycle.

Maybe helpful background?:
The bang part is pretty new (within the past week), but I can't associate it with any change other than it's been much colder out lately. The loud whoosh has always been there for the 2 months I've had this house. When I bought the hosue this fall, I had all three zone valves replaced. The prior owners installed a new boiler this summer. The circulator looks original. The expansion tank doesn't seem waterlogged and the spirovent was replaced when I bought the house. The boiler pressure runs at about 20 PSI.

The Setup:
3 zones, each with a Taco Z075P2 zone valve
Taco Cartridge Circulator - Model 007-F5-8IFC

http://i64.tinypic.com/35cqvdg.jpg

http://i67.tinypic.com/21evsxs.jpg

MikeL_2

SD,
I experienced a similar issue and had the Taco rep and a Taco tech support specialist visit my install. They agreed that I had the correct pump and near boiler piping, and they witnessed the noise you are describing. The Taco support specialist said it was some type of flow velocity anomaly and gave me Taco 570 valves to replace the zo75's; I installed them and no more whooshing.......

STEVEusaPA

Could also be air

SDJ88

I don't think it's air, I've tried bleeding the system and didn't notice much.

Mike - I'll give Taco a call and see what they say. Glad to hear it fixed your similar issue.

Harvey Ramer

Here is a quick little test you should do before doing anything else. Turn on all zones and let them run till all the return pipes from the zones are hot and the boiler is hot. Then turn off all zones so they don't run for at least an hour or so. Make sure all the baseboards are cooled off. Then turn on one zone. Listen. If you hear a bang at that point, you have a flow check in the pump and it will have to be removed.

What happens is this. When all zones are on, the whole system is filled with hot water. When all zones turn off, the water in the zones cools off and becomes denser. In layman's terms, it shrinks. Since all zones valves are closed and a check valve in the pump, the baseboard side of the system can't be replenished with water from the expansion tank. So it falls into a vacuum. As soon as the first zone valves opens again, bang! You get water Hammer as the system pressures equalize all in one second.

I copied this from this thread. http://forum.heatinghelp.com/discussion/160068/nighttime-banging-pipes-waking-up-the-house#latest

This is your most likely cause. If you have a check in the pump, you will have to remove it.

Ironman

I totally agree with Harvey.

Take the flow check out of the circulator and your problem will go away.

SDJ88

So I tried the test mentioned above and got the hammer noise when opening the zone valve at normal speed. I see both of you guys recommended removing the IFC from the Taco circulator. Are there any potential drawbacks to that? I was looking up instructions on how to do that and it references potential overpumping / unsafe operating:

http://www.gothotwater.com/sites/default/files/Removal and Replacement of IFC.pdf

Anyways, assuming it's not a big deal, I assume I can just close the valves before the circulator, drain the water/relieve the pressure, and then pop open that round housing secured with 4 small bolts?

Pic for reference:
http://i67.tinypic.com/sy5qip.jpg


The PDF I linked to made it seem like a pretty simple job and the IFC itself is just a small plastic piece that pops out. If its that straight forward, I'll give it a shot. If there's more to it than those instructions let on, please let me know. New homeowner and slowly learning how to be handy. Thanks!

Ironman

It's that simple.

lchmb

and it's not needed...your zone valves control flow out to the system

hot_rod

Looks like the expansion tank to pump relationship is wrong?

Do you know if the pump start when the zone valve opens, via the end switch?

When you pump away from the expansion tank the pump pressure increase (head) show up as a positive pressure increase in the system.

When you pump at the expansion tank, the opposite happens and pressure is lowered in the system.

If the fill pressure is low, the pressure differential developed by the circulator can pull a negative sub atmospheric condition.

It would be interesting to see if the problem could be eliminated by changing the expansion tank connection to the pump location?
Moving the tank connection to the inlet of the circulator would keep it in the system without the check and zone valves isolating it. It should prevent possible system depressurization caused by the fluid cooling?

Although you may not want to do a piping change.

SDJ88

Sounds like I'll be removing the IFC tomorrow. Rather not do it tonight night with the temp dropping in case I royally muck something up.

hot rod - When the zone valve fully clicks open, the circulator starts to pump. If I'm understanding your post and diagram, are you suggesting the better setup would be that the circulator comes after the expansion tank on the supply/hot side of the line? I'm going to try the IFC fix first, but I'll keep this in mind if it doesn't work.

Appreciate all the help guys. I'll post an update either way for future reference.

hot_rod

SDJ88 said:

Sounds like I'll be removing the IFC tomorrow. Rather not do it tonight night with the temp dropping in case I royally muck something up.

hot rod - When the zone valve fully clicks open, the circulator starts to pump. If I'm understanding your post and diagram, are you suggesting the better setup would be that the circulator comes after the expansion tank on the supply/hot side of the line? I'm going to try the IFC fix first, but I'll keep this in mind if it doesn't work.

Appreciate all the help guys. I'll post an update either way for future reference.

Yeah, if you ever want to get into it that deep. Either the tank moves down by the inlet of the pump, or the pump moves up downstream of the Spirovent and tank.

The check removal may fix the bang, changing the PONPC will prevent air, noise another issues related to pumping towards the tank.

Here is a good read on the concept, available in the bookstore.

SDJ88

Just wanted to post an update that removing the flow check solved the issue. Thanks guys!

Mark Eatherton

Congratulations. Buy a book on your way out to support the community.

ME

jewashko55

Sdj88, I had an old burnham unit replaced and the old unit would do the same as your issue described. I recently had it replaced with a combination unit but using the old heat pipes and the issue still occurred with the new unit. I had the installer back out scratching his head not able find a cause or solution. 

I have searched just as you have and came across the same issue of only finding solutions for when the issue occurs as the zones close, not open. Literally thanks you you, Harvey and HotRod I gained the Knopf what is causing the issue, why it exists, and how to fix it. One I removed the check from the pump which was just as easy as you guys said bam, problem solved. Thank you guys so much, it gets -20 where I live in the model of nowhere so a pipe break or leak would be a big big deal for me and you guys not only gave me the info to correct the issue but the confidence to fix it myself for free and eliminating the possibility on me wasting money having other professionals coming out here providing no solutions.
only advice I would add is be sure to have the pipes supported when removing the heat pump as that factor caught me off guard.
Just wanted to say thanks guys, you cured a lengthy headache of mine as I’ve spent multiple months with each unit installed trying to fight what the heck was going on and how to fix it.
Sincerely,
Jason

ps- No Mark I’m not buying any book so don’t try to make me feel obligated like you did to SDJ88.