He have a new boiler installed with indirect water heater. The house has only one zone and the indirect water heater is another zone. There is this Taco 'swet check 241' valve between the heating return and IWH return. My plumber told me that the valve is there to isolate IWH circulation from heating system.

Everything seems to work well except that when the boiler is working for heating( in which case the return water flows through the valve I think), it has rattling noise from the valve. It sounds like some piece of metal hitting the pipe. It's not that loud but when everything's quite in the bedroom I can hear it from the radiator and it gets me. My plumber told me that's the way it is but I have some doubts. Is it really normal to have that kind of noise or a sign of something wrong?

I tried opening up the valve partially and the noise goes away. But then it won't separate the IWH zone from heating zone right?

Thanks advance for your insights!

 

The rattling noise may be from air in the system. If everything is working properly (you have hot water & heat) the airscoop should take care of it with time.

 

You mean the air in the system can cause the check valve to turn on and off rapidly? The source sound is in the check valve.

 

Your plumber says "that's the way it is." You should call Taco and ask them. I've have had four B&G flo-control valves, and none has chattered.

Here is a theory. If your circulator is putting out too little flow, the valve, which is a lift-check valve, might not be staying completely open. That conceivably could be caused by a pump that is too small or air somewhere in the system (probably not the flo-control valve) restricting flow. Are you getting heat in all the heat emitters?

Your Taco valve is 1" - shouldn't take much of a pump to keep it open, I wouldn't think.

 

Air in the system could possibly be the problem. When the bubbles go by the valve, they might 'wiggle' the guts and cause some noise, but chances are you would also hear this in the piping.

Is this valve installed very close to an elbow on either side?

 

And this is what Taco has to say:

Q:
Why is my Flo-Chek or MPV noisy?

Normally a check valve is noisy if the valve is oversized for the flow going through the valve. The flow cannot lift or swing the disk all the way open so the disk bangs back and forth within the body of the valve.

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This is quite close to Mike's idea... if for some reason the flow is low, the thing can rattle

 

If the chattering doesn't clear up, here is one idea: replace the 1" valve with a 3/4" valve (e.g, Taco 219-4). You'll, of course, need reducers on either side of the smaller valve.

 

I changed the flow rate from 7-12 gpm but the noise actually got a little worse so I'm ruling out the low flow rate cause.

Only other thing is the fact that intake of the valve is close to an 90 elbow- 2" or so. Could that create turbulance? The pipe is 1" thick.

 

Yes, it could... that's why I asked the question earlier.

What surprises me about that though is that if you look at the literature that they have on the website, there is no mention of maintaining a certain stretch of straight pipe ahead of the valve...

 

Is it after the elbow or before. If after you are in a turbulent area and should be in a laminar flow area.

 

The pump is sitting 2-3" after the elbow and than runs 12" or so before another elbow. So if I move, should I move it in the middle of the pipe (16" or so total) or at the end near the other elbow?

 

You mean the check valve?

 

Yes, the check valve. Sorry about that.

I made another call to Taco tech support and they recommend a check valve being 18" away from an elbow due to the turbulence. But he doesn't know whether that applies to the intake side only or both intake and exit side. I have only 16" or so of horizontal run so I will have to decide on putting it in the middle or giving more horizontal run to the intake side.

 

Two week ago I have problem with my Taco Check Valve Taco Flo-Check Valves, Taco 218, 219, 220, 221, 241. Problem is some vessel sound from valve. What is that?