Boiler popping..

Phil_6

I looked at an old hot water boiler this morning on a no heat call.The customer just returned from Florida for the winter. The circulator was shot, so I replaced it and turned the boiler on.

When the water starts getting hot the boiler starts making these ungodly popping and banging noises. The water temperature seems okay, 160-180, but the thing is freaking out. The needle on the pressure gauge is fluctuating all over the place between 10-25 psi when the burner is firing.

The expansion tank is ok and the water is flowing through the radiators. What's up?? Is this thing shot?

Thanks, Phil

MikeB34

sounds like

Mineral build up on the bottom of the tank. It will form a layer and harded. When the burner fires, the little hot water between the mineral cake and the bottom of the tank boils causing it to bounce and bang.

I would replace and install a water conditioner. Seen it many times in hard water area near me.
Good luck.

Mike

Weezbo

not to dissagree buh....

the expansion tank might not be as O.K.as you first thought. it too dependent upon its location can indeed create the disturbances ,excess air is another biggie.relive the air in the equasion ,turn off the valve to the expansion tank and remove it.turn the boiler off and wire the circulator up and let it run a momment...now what is it that you are observing?

Phil_6

Thanks for the reply...

The boiler operates fine as long as the burner isn't running. once it shuts on high limit the circ keeps running and the noise and fluctuations stop

Weezbo

Mike has a point

sounds like flushing the system will help the most. let it cool down first though by letting the recirculator drive the heat down on the boiler to 70 degrees or so. You are there:) gotta jet. work work work .....

MikeB34

Sorry

I mis read.. I thought you said water heater, not boiler. Although I suppose that sediment could form in a boiler if it sits long enough.

Waylon Lowery

Mike is

right on! We see this all the time. Try flushing out the system. If you don't get much out, you might try using a cleaning agent like TSP or SanaSolv. Once its clean make sure you don't put the same tap water back into it. You'd be better off to bring in some clean water from a good source. Also, you might get a hold of your local chemical treatment guru and have him suggest a treatment that would help keep the minerals and junk in suspension.

hr

What type of boiler

cast or copper tube?

hot rod

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Steamhead

\"The thing is freaking out!\"

Phil, those pressure fluctuations are the result of steam forming in the boiler. I ran into much the same thing on an old Spencer boiler that turned out to have a wildly oversized circulator. Go here-

http://www.heatinghelp.com/newsletter.cfm?Id=119

for more.

Is this an old gravity system? How much radiation is on it? What circ was on there when you arrived? What circ did you use for the replacement? With the answers to these questions, go to-

http://www.heatinghelp.com/newsletter.cfm?Id=125

to find the flow rate you need. Then you can go to your circ's performance chart to see if you're getting the proper flow thru the system.

Also check the firing rate to see that it's not over-firing. The other possibility is lots of dirt in the boiler, which has already been covered.

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Karis hvac

Circulator

Just a quick check---is the circulator flow going the right way? If not it could be hammering against the flow check valve.

Phil_6

more info

The boiler is a 35-40 year old cast iron boiler, a Hydrotherm, I believe, with 2 zone valves on the supply, 2 zones of baseboard and the circ on the return (pointing in the right direction) The old circ was a b&g 100, the new one is a 007. pretty typical set up you might see around anywhere. The boiler is 160,00 btu. The problem probably existed before, as she was in Florida all winter so no one was there to hear it. There's really nothing unusual at all about the whole set up. Just like every one in the neighborhood.
I thought at first the temperature was over shooting the aquastat setting and making steam, but that doesn't seem to be the case. The aquastat and gauge agree with each other. It starts at about 150 degrees or so and stops when the burner shuts off on high limit

Weezbo

hello .

I am sorry ,this morning i was in a rush off to a tribe of minor technicalities:) ...I'd like to say i did a trick response and split. here is the deal,after you shut down a boiler and drain it,usually you have then dumped off all types of stuff within a system not to mention the water that had chance to Prerssurise up in cooler weather ,prior to your first restart. the entrained air is eliminated by purgeing the system and the expansion tank has had a chance to exercise a bit,the fast fill gets a dash of excercise as does the purge valve. ...this is a tad off the subject..a friend of mine found an old boiler excercise switch:))) you turn the switch on you have to walk back to the panel and reset the circuit breaker for that boiler:) now theres one for the uninitiated:))depending on how swooft one is on the up take is dependent upon how much excercise they receive running back and forth to the boiler and electrical baranch circuit feeder:)) Ya gotta Love this worK!:) ok ok ..i digress.... thing is cavitaton of the bell&Gosset probably requires a devise like a spirovent and 35 40 years ago the old Air scoop was more top o the line with a707 maido mist maybe in the equasion. the point i was getting across though air is often THE main cause of what you were observing and the fact that the boiler is a machine and prefers to excercise alot more than say,..... me. when it doesnt it gets persnickety and behaves poorly,expansion tanks that sit for a while "stick"as it were when they are called upon to act...running the recircuit to cool down a boiler after its reached its high limit gives one a chance to "Listen" for some things with out the back ground white noise of a running boiler.for example if you can Hear the 007 then most likely you are hearing air..

Guy_5

noises

I have had several older boilers that would issue similar noises. I was able to quiet them as described above with a boiler cleaner that I picked up at Sid Harveys. I left it in the boiler for the prescribed time, then drained a bunch of debris out of the boiler. I have seen this most often on dry base boilers, where the flat surface above the fire chamber collects deposits.

hr

If

you suspect the boiler is scaled up from hard water minerals, TSP will not help much. You need a cleaner that is acid based to disolve this. Hercules Sizzle is an acid based cleaner I use. Works great on copper tube boilers in hard water applications that have had continous make up water issues

Tsp will handle oil based gunk, or dirty water deposits. won't touch lime or calicum, however.

Sure you can't sell them a new boiler? That's pretty old to be acid or TSPing. You may end up with a leaker after all your efforts

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Phil_6

new boiler

yes, it's about time for one. Not really worth spending more than a couple of hours working on this thing. The changeout would be a breeze, first floor no steps ;-)

She's pretty old and spends the winter in Florida but I'm gonna work on her a little about a new boiler

thanks

Bruce_8

popping

just a thought-have you checked to see if chamber in boiler is broken somewhere? Sometimes flame will impinge on cast where chamber has deteriorated causing a flash to steam and your banging while flame is on. Is there any air in top of boiler? i have had boilers in the past that have had air collect at the crown sheet and rattle like crazy. Good luck!!

Phil_6

popping

I'm going over there Friday to give it a good flushing out and purging and see how I make out. THEN I'll sell her a new boiler.
I'll let you know how it turns out

Phil