Lochinvar whb155n vibrating intermittently on start up

nillort

I just installed a whb155n a couple weeks ago and it is vibrating sometimes on start up. It sounds as if the flap in the Venturi is rumbling/vibrating it is definitely coming from that area of the boiler. I did have to convert it to use propane. Did I miss something?

Alan (California Radiant) Forbes

Did I miss something?

A combustion analysis. Could be too lean of a mix. 

nillort

Here is a video of what it sounds like.

https://photos.app.goo.gl/v4HvPVMLRrFLJpK56

HomerJSmith

A conversion to LP, directions must be followed correctly. The connection of the adapter to the fan is directional, it has an up arrow and the arrow must be installed up and the brass orifice is directional, too, and the orifice number must match the size of the boiler and kit number. The square air reduction plate under the fan to the heat exchanger must be correctly installed with the gaskets provided. Re-read the instructions to make sure the conversion is correct.

nillort

@HomerJSmith thanks for responding to this I double checked the propane conversion and all of the parts were installed correctly.

I wanted to share the out come of this. I had a combustion analysis done and the low end was very rich after doing the propane conversion. It has been adjusted and seems to have fixed the issue. I will update here if it ends up not fixing the issue as it has been very intermittent.

nillort

All the info says to call Lochinvar support to adjust the gas valve. However we found hidden on the very last page of the service manual the combustion levels and how to make the adjustments.

nillort

Unfortunately after adjusting the combustion levels it is still happening . My next thought is maybe the secondary propane regulator. I would love any other ideas anyone has.

nillort

It seems to only happen when its cold outside. During the day I have noticed it does happen as much.

tim smith

Need to have manometer on it, analyzer in flue. Go through low & high fire setup. Verify not too much pressure drop on propane pressure and proper pressure. Sometimes you have to adjust the offset/bias adjustment on low fire. Must follow instructions and be qualified gas mechanic to adjust these boilers. Page 50 of service manual. Also would help to get tech on line, they are pretty good if needed.

Radiant23

What is distance from propane regulator to boiler. I had a couple where the regulator for propane tank was 2’ of pipe length from boiler tap on gas main. Basically 4’ of pipe from main line regulator to boiler hook up. If the volume of gas after the regulator gets removed from the line after the regulator, there is not enough gas filled back in as the boiler is pulling the gas out of the gas line. We added some pipe on the boiler tap, increased the size to ensure enough gas was in the boilers tap to satisfy the gas load for the boiler. 

To be fair, I also have a lochinvar 155 doing the same thing. Was close to same scenario, increased natural gas volume but issue continues. The house has two hot water coils and one loop of cast iron radiators, and had no noise year 1. Year 2 1 hot water coil became second stage heat and radiant was added. The rumble showed up and we still can not find out why. 

PlumbingDumber

On occasion, I come across a Lochinvar with harmonic issues, despite proper combustion and proper gas pressure readings. When this happens, I have had a lot of luck drilling a 1/4” hole into the intake air pipe somewhat (within 2 feet or so) close to the boiler—the intent being to interrupt whistling/harmonic vibrations.  

May be worth a shot if there’s any chance it’s a harmonic problem. 

GGross

Had a similar issue with a different brand boiler, same style venturi with the flapper. Personally I blamed the vent system but contractor didn't want to change it. We noticed when the apprentice accidentally opened the flue test port while the unit was running that it stopped chattering. Tech support told us to drill a hole in the intake pipe inside the unit as @PlumbingDumber stated. I didn't particularly like that solution but it did fix the problem for them

nillort

Hey all thanks for the tips. Im going to adjust the secondary propane regulator first and see if that fixes anything. Then I will try "the hole method".

Radiant23

Thanks from me as well. Have never tried the hole method either but will try as well. 

nillort

I just drilled the hole. Now we wait.

nillort

@Radiant23 let me know how it goes curious if it fixes your issues.