Buderus 142 issues

lukewarm540

Unit has been fine for last 6 years but recently has been making a groaning sound when going into high heat phase (2 Stage). Quiets down when getting close to temp but then noise returns briefly when boiler stops firing. It seems like gas valve but Buderus thought it was flow issue and asked me to turn circ pump down to low setting- noise still there.
No noise when heating hot water, low heat mode.
Also sounds a little like a tea kettle the few times it's not groaning during heat cycle.
Just had a tech here but he was no help, still got charged a service call...

Mark Eatherton

How many pumps? If two, it sounds as if the space heating circulator is non functional. Also, is there antifreeze in the system?

ME

Ironman

6 years? Has it been cleaned properly and had regular maintenance?

I agree it sounds like a flow issue.

By the way, it's not 2 staged. The burner modulates as the UBA control dictates.

Try the "Find a Contractor" tab above.

lukewarm540

Mark, Yes there is anti freeze in system due to air handler in attic space. Not sure what concentrate or brand.
As for pumps, I assume circ motors? One on loop going back into unit. Upon further inspection, noise does actually change when going through the 3 speeds. Circ for each zone and one for DHW. They seem to be working as you can hear change in water as you change speed. Only circ on unit changes tone of sound.
Ironman, scheduled another tech familiar with unit to run through a thorough cleaning and troubleshooting. Unit is lacking in maintenance so not helping my cause.
Both zones make same noise, not true with DHW.
Tonight unit showing OH, OY codes but still heating.
Fingers crossed
Most of noise happens between 150-170 degrees.
I did have second zone installed in the fall but unit has been quiet until last week, not sure if this aggravated anything.
Thanks for the quick response guys.

Mark Eatherton

You need to have a Chelant (chelates) induced into your system fluid. The antifreeze causes a lag in energy transfer that causes micro bubble steam flash at the fluid to heat exchanger interface.

Sounds like whales in heat?

The DHW pump is a large pump and moves a lot of fluid and creates a lot of pressure, which supress's the production of micro bubbles, hence it is quieter when on.

If you watch the pressure gage, you might see some bouncing if it is severe.

ME

hot_rod

Do you know what type of anti freeze was used originally?

You might need to flush out the old antifreeze, run an aluminum friendly cleaner, then aluminum specific antifreeze.

If the anti freeze has been over heated or put into a dirty system on day one, it is best to start over.

Testing the Ph of the antifreeze is a good indicator of it's condition. if it is in the 7's, coffee colored, and has a sharp pungent odor, time to start over.

You need to really keep an eye on fluid quality in that boiler.

lukewarm540

Yes Mark, pressure bounce on gauge. Worse when in high circle mode. Does sound like whale noise. I will check out chelate intro into system. I just think it's wierd it took this long to be an issue.
Hot rod, I will do a visual on fluid but wasn't rusty colored on last inspection last year.

lukewarm540

System water is relatively clear with slight grey tint, no nasty smell. Will pH test tomorrow.
Running unit at 190 high circle, seems slightly better but will see next few hours.

hot_rod

lukewarm540 said:

Yes Mark, pressure bounce on gauge. Worse when in high circle mode. Does sound like whale noise. I will check out chelate intro into system. I just think it's wierd it took this long to be an issue.

Hot rod, I will do a visual on fluid but wasn't rusty colored on last inspection last year.

This is a GB 142, correct?

Watch your ph if you add chelates, it will drop and aluminum boilers have a very tight 7- 8.5 Ph spec. Then you would need to add a ph buffer.

I'd rather see a conditioner added that is approved by the manufacturer as they have tested and approved several types and brands. Aluminum boilers seem to be the most sensitive of all the types out there.

Here are the Buderus approved treatments and water spec.

Mark Eatherton

Yeah, I forgot about aluminums sensitivity to pH. Need to watch that for sure so you don't dissolve the HXer. Basically, you have accumulated a chemical that has bonded to the heat exchanger surface and is slowing the transfer of heat, causing the steam flash bubbles. Follow manufacturers recommendations as it pertains to chemical cleaners. Sometimes, raising the operating pressure will suppress steam flash.

ME

lukewarm540

Ok, will mention to tech when he does cleaning and service. One thing worth noting is I thought perhaps there might be too high concentrate of antifreeze in system. I purged 2 gal out of system and refilled with fresh water. No more noise at all, it also doesn't sound like a tea kettle anymore. Unit is now sounding like it has last 6 years.
No more whale songs.
Thanks for all your help guys, at least I have some piece of mind now.

Mark Eatherton

Very few people really know how to induce the proper amount of glycol. Premixing is the only correct way to pump it in, and then the system has to be completely empty before it will work right. Most pump 10 gallons in (with their fingers crossed) and top it off with water and hope it works. Too much or too little comes with expensive baggage... Less than 30% doesn't have enough corrosion inhibitors, and the glycol starts eating itself and any metal in contact with the fluid.

If in doubt, blow the charge out using compressed air, documenting how many gallons of fluid came out, then premix with distilled water and pump new fluid back in.

ME

Big Ed_4

Whales in Heat LOL , How does someone from Colorado know that

Mark Eatherton

I watch a lot of Nat Geo XXX