Whine but no grapes

Mike Dressler

One zone whines, two are ok.

Mike Dressler

We have a customer that about four years ago had a Tetedyne Laars mod JVT225NDIS boiler installed by another contractor. In Nov of 2001 that same contractor came back and installed 2 zone valves splitting the first and second floors. After the valves were installed for a couple of months, this time last year, the customer started to notice a whining noise. I got the call yeaterday as poor second floor heat and whining. They couldn't solve the problem which is how we got involved. The poor heat problem was air in the second floor rads and I found a water logged exp tank. With that corrected, the whine which had been there before I started, seemed to have gotten slightly worse. The noise starts up at about 155deg 21#.It only occurs when one zone is calling. It is slightly worse when the calling zone is the first floor. Once the whining starts if you open the other zone or shut down the burner it stops instantly. The system is a single pipe with two loops(1st and 2nd floor). The boiler piping and the loops are 1 1/4", the zone valves are 1". The circ pump is on the return side. It is a B&G series 100. There are valves on the returns of each loop. If you close the return valve on the non-calling side the noise stays the same. I had persued the idea that the noise might be forced flow across the closed zone valve, but this seems to rule that out. With only one zone calling the supply temp of the boiler climbs at a normal rate. The previous contractor had blamed the noise on steam pockets. His solution was to lower the set point of the boiler to 160 and reduce the firing rate by setting the manifold pressure to 1.6"WC. That did reduce the noise, but didn't eliminate it. If I turn the temp up and the pressure to say 3.0"WC the whine gets louder but I don't hear any pinging or noise that I've noticed on boilers that were steaming and my supply temp and pressure climb at a steady normal rate. The other contractor recomended they either plug some of the burner orifices or install a two stage gas valve. Considering that at 1.6" the burner is way throttled down, and I'm not convinced the thing is steaming,I don't believe this is the way to go. I've thought that perhaps smaller pumps on the supplies of each zone or even putting in bigger zone valves might help, but since I can't ID the problem that may be wasting the customers money. I throw myself at the mercy of the internet gods and beg for assistance. Any help would be greatly appreciated. Thanks!

Mark J Strawcutter

cavitation

My guess is that you're seeing/hearing cavitation which in turn sets up harmonics in the piping.

Pumping toward PONPC means circ differential is all negative on the circ input side. With only one zone calling the pressure drop across the system is such that when reduced by the pump differential it causes cavitation.

Best solution is to re-pipe to pumping away.

Could also try different pump that better matches system head loss(es)

Increasing static pressure may help, as would (did) keeping the temps as low as you can.

Mark

Mark Hunt

Ghostly noises!!


The Teledyne boilers REALLY need to be piped Primary/Secondary or at least have a by-paas installed.

Once the delta T across the system gets too high, the T/L units will whine or even howl.

Hope this helps!

Mark H

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hot_rod

Not nearly enough pump

in my opinion. Need lots of flow through copper tube boilers. Find the manual and see what pump you need for adequate flow through that 225. That 100 sounds a little small to me. You may need a pressure activated bypass, also.

Primary secondary is the best way to pipe these, I feel.

hot rod

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Mike Dressler

All good ideas. I've already got the manual on order. The other guys probably through it out with the box! They certainly didn't read it.

Steamhead

You might also

want to ditch the zone valves and install a properly sized circulator on each zone. This would work better especially with primary-secondary pumping.

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Dan Law

Whineing

I agree with Mark. These low mass boilers are very sensitive in terms of flow rate. We do considerable work with Raypak boilers, another low mass manufactuer. Nearly every boiler requires a by pass around the boiler. Too much flow can cause a harmonic that can be described as moaning or possiblly whining. You may have even noticed the moan can be tuned out by adjusting the gas pressure (NOT recommended) The harmonics are a relationship of the burner firing over and the flow of water through, the heat exchanger. Raypak recommends adjusting the by pass to achieve a 20F delta T (temperature rise)through the boiler.
Somewhere in your installation manual you'll find Teledyne's recomendations. I'll see if I can locate the same info in my manuals and post it here.
Regards,
Temptrol

Dan Law

PS

I suspect the problem began with the installation of the zone valves, due to the increase in velocity through the boiler when only one zone is calling. Does the moan correlate to only one zone? In other words, is there no moan with both zones calling simultaneously?

Buffalo Bill

Been there, done that !

Mike, I had the same problem several years ago, did all the same things to stop the noise, nothing seemed to work, I talked to the factory service rep. and found that the heat exchanger had been damaged from lack of water flow thru one zone, end solution, heat exchanger had to be replaced, also added bypass loop to lower delta tee thru boiler.

Dan Law

whine relates to zoning

It adds up in my way of thinking. As one zone closes, the velocity through the heat exchanger increases, setting up the resonance. I'll bet it doesn't whine when the burner cycles off, but the pump is still running, right?

Unknown

I have a Manual

on JV 225. It is equipped with what is called Flo-Guard control, its purpose is to sense overheating conditions caused by low water flow. If you e-mail me your fax number I will send you some info.

They recommend a by-pass where there is high water volume or low operating temoerature.

System pumps should be selected to provide a water temperature rise of 20 degrees.

For the 225 at 15 degrees temp rise 24 GPM 5 foot pressure drop through boiler.

20 degree TR 18 GPM 3.1 ft pressure drop

25 degrees TR 12.4 GPM 1.9 Ft pressure drop.

These will tend to whine with low flow and a harmonic is set up with gas flow. When you lowered gas pressure it stopped but that is not the solution. Lowereing gas pressure can cause Carbon Monoxide not a good idea to do that.

There have also been problems with the thermister used on the Flo-Guard control.

Mike Dressler

Got the install book today and talked to one of Teledyne's engineers yesterday. For this app it needs to be repiped primary-secondary. We figure the flow was down to about 8gpm. Mfr recommends 18. According to teledyne, the noise is caused by water gassing-off at the top of the inside of the tube. They said they used to put a turbulator in their tubes and now they don't. Guess when they noticed the problem? That still isn't an excuse for the sorry waste-of-space that piped it wrong. I think there should be a license required to even buy tools.

Mike Dressler

Thanks again for responding. I've read through some of the threads for sometime now and this is the first time I've needed some input on an issue.