Teledyne Laars jvt 125 noise problem

J_W_P

I have a customer with a Teledyne Laars JVT 125 (mini therm) that is very noisy.  When a call for heat is initiated the boiler fires right up and runs fine, after about a minute a loud low pitch whistle starts to build and sounds like it is coming from around the burner/heat exchanger.  The noise gets louder as the boiler heats and stops once the burner stops.  I believe it is due to  build up on the heat exchanger (any thoughts).



Thanks,



Jim

Unknown

Teledyne Laars jvt 125

This is a great boiler! Unfortunately the price-tag led to some interesting installations.



I have seen many of them in my area with no-protection  whatsoever(ramming cold return water through), so its very likely possible to the inexperienced!  :-)

ScottMP

Harmonics

Could be a poorly sized circulator or it could have gotten over heated and distorted the HX.

We have had to open them up and installed turbulatros that spun the water thought the HX.

Call Teledyne and give them the model and serial number.

Scott



 

Mark Eatherton

Two things....

If there is a stainless steel flex connector on the gas supply to the burner, it CAN cause a distorted harmonics that emminates from the burner assembly. Get rid of the flex connector and the noise will go away, if that is the cause. If you can grab the flex, and bend it around, and the noise abates, that is the problem.



The other thing I have seen cause a howling, is a minor accumulation of sludge on the inside of the heat exchanger. It retards heat transfer, and causes a micr bubble steam flash where the fluid interfaces with the inside of the copper heat exchanger. This boiling can be suppressed in some cases by raising the operating pressure of the system (stay below 25 PSI...). In some cases, if the pump is pumping towards the PONPC, but away from the boiler, it can compound steam flash due to lower pressure.



Generally speaking, this water side howling has been limited to boilers with glycol in them, which also retards heat transfer. Never seen a non glycoled boiler howl.



Try raising the pressure first. If that works, you're done. If not, consider inducing chelates into the system which will clean the copper surface.



If that doesn't work, you MAY have a lime scale accumulation occurring on the heat exchanger surface. Follow the manufacturers instructions for deliming the coil.



ME

hot_rod

taking on make up water?

adding water, due to a small leak somewhere will cause them to get a build up inside the coils. Usually a de-scaler chemical will solve the problem, worse case they need to be disassembled and rodded out.



Chemical Specialties in Denver has a product that I have used with good results. Hercules Sizzle works well, but check with the manufacturer as mark mentioned.



Depending on the age.... A HX replacement or boiler upgrade might be a better fix.



hr

Alan (California Radiant) Forbes

Laars

I've seen (heard) this a lot on Laars boilers.  Like others have said, it might be some kind of deposit on the heat exchanger (HX).  But I've always thought it was not enough water flowing through the boiler.  The HX on the Laars is made out of copper and has excellent thermal conductivity...........when there is enough water flow to pick up all the heat.  If only one or two small zones are calling for heat, the HX can't pass off the heat as quickly as it is picking it up from the hot gases and it starts to complain.............in this case, it sings.



My solution would be to repipe the near-boiler piping to primary-secondary.  That way, the primary pump will satisfy the flow demand of the HX.

Joannie

Noise

Most of the time, when a copper boiler manufacture hears words like "howling" "singing" "whining", the noise is a result of too little water flow through the heat exchanger, or an older unit that had marginal water flow through its life which has now stressed the heat exchanger enough that the heat transfer is affected.  Steam can be created right at the inside surface of the heat exchanger and can cause a whining sound.  Extreme cases of very low flow or no flow results in steam inside, as well, but it's enough steam in those cases that it'll bang and knock.



If it's a new unit, I would suspect low water flow.....check the temp rise across the heat exchanger.  The temp rise will tell you what you have for water flow and if it's adequate.  The temp rise vs. water flow charts are in the manual.



If it's an older unit and this just started, there may be some blockage that is now hindering the flow, or the copper in the heat exchanger may be stressed enough that it can't move the heat as well anymore.



Aside from that, the comments on the flex-type gas line and the glycol are very good ones, as well.



Hope this helps.



Joannie

Plumdog_2

Plumdog

It could be burner harmonics. I've seen this often with stainless burner tubes, and not just on Mini-Therm boilers; it can occur on the cast iron ones as well. Most gas work I do is at higher altitudes (6000-10,000 feet) and the phenomenon is cured by de-rating the input by decreasing the orifice size and then fine tuning pressure and primary air shutters (if equipped). Try closing the gas cock part way when the sound is really going good. This howling can occur on a brand new boiler with proper piping and pumping (even over-pumped). More often with propane than with natural gas, also. 

Alan (California Radiant) Forbes

Just today

I serviced a Lochinvar RBN09; looks, smells and feels just like a Laars Mini-Therm.  The owners were complaining about harmonics and knocking.  Luckily, the installer had piped a by-pass with a gate vale and when I started to open it, the sound went away.  Too bad it's not a ball valve



My take is that these boilers with copper heat exchangers will tolerate low flow until they get older and then they start complaining.  It's like the human body;  when we're young, we can withstand all sorts of extreme conditions, but when we get older we start to complain.  And we have by-pass options as well.