Lochinvar WHN Noise

Ironman

I just installed a WHN085 on LP gas. We've done several of these and really love this boiler.



The only problem we've had is the occasional high pitched hum at low modulation. This is usually corrected by opening the throttle to make the fuel/air mixture a little richer.



This one didn't respond much to that and it's at the high end of the c02 parameters.



We've seen this on other brands as well and it's usually cured by having at least 10' of piping between the boiler and the LP regulator and/or adjusting the throttle. This one has 13' of 1/2" black iron and 5 turns. Inlet pressure is 11". Flue is 3" PVC, 10' with three 90*ells and the flat termination kit that comes with the boiler. Removing the intake pipe makes no difference.



We cured a couple of Buderus' that had this problem because the regulator was too close to the boiler by adding an over-sized drip leg that was 1 1/2" x 2 ft. That will be my next step here if no one has a simpler solution.



Lochinvar has taken done their VIP blog where this came up before and I can't find any other tech info on this issue. Anybody had this issue and gotten it resolved?



Please assume that the obvious things have been done correctly before replying.



Your help is appreciated.

ced48

My WH55 Running On

propane, whines at some firing levels as it modulates down. Guess I should be trying to get rid of the whine-Maybe I'll try running a little richer- Carbon Dioxide is at 10.5 now-

Mark Eatherton

Try Paul Rohrs yet?

If Paul doesn't have the answer, he knows who does.



The only time I've had a harmonic issue was on NG, with CSST, and the secondary regulator was right at the boiler. We cured it by throwing a large loop of CSST between the regs, and it quieted right down.



I've also had situations whereby O had to drill a relief hole (1/4") into the PVC elbow that connects to the intake horn on the blower/gas valve assembly. I've had to do that on the larger units and not the smaller units, so not sure it would work on yours, but I've had to do it to three different manufacturers boilers using the Giononni platform with the Honeywell negreg gas valves. That was more a problem of fog horning then resonance.



Good luck and let us know the final determination.



ME

Ironman

Got it fixed

We ended up backing out the throttle screw another three turns, for a total of six turns. Kinda strange: it put the C02 at 11.0, O2 @4.8 and C0 @ 2 - 4 ppm on low fire; C02 @ 10.7, O2 @ 4.9, and C0 @ 72ppm on high fire. I would have expected the C02 to have been higher on high fire than low fire.



The odd thing about this one was that noise would only happen at start up. The boiler would ignite fine at 57% and then ramp down to 20% for two minutes. When it got to 25% or below, the harmonics would start. As soon as it ramped up to above 25%, it would stop. After that, it could ramp back down to 20% as it approached target temp and it would do fine - no noise at any speed. I disabled the ramping as it was not necessary with this system, but it was the throttle adjustment that cured the problem.



We had to switch analyzers as the O2 sensor went out on mine today. Of course, they give no warning and since the life expectancy is shelf life, it does no good to have a spare one.



Thanks for the help.