Boiling Hot Water Boiler

Joe West

I have a Weil Mclain 368 hot water boiler with a glycol/water fluid mixture. The system starts to boil shortly after the burner starts sometimes as low as 140 deg F and escalates to where the boiler and piping begins to vibrate. The tridicator gauge starts jumping all around the relief valve starts spitting. When the burner stops the boiling subsides. This boiling happens while running for hot water and heat as well. I have purged the system of any air and the boiler psi is at
20-25.
Any suggestions on how to stop the boiling would be appreciated.

Thanks.......Joe

Firedragon_4

What's the

pH value of the solution. Are you sure it's glycol and water or acid?

That stuff goes to acid after a while. The timeframe is dependent on the system components and the water's abse pH.

Joe West

PH

This glycol mixture is fresh. It test neutral with the PH test strips.

JeffD

Hmmmm,

Are you sure the temp gauge is right? Could the aquastat be bad? Has this thing been leaking, maybe the sound you hear is from lime and sediment creating localized hot spots. If the fill water is really hard I'm willing to bet that this is the problem.

Firedragon_4

I agree with Jeff

and you may have to isolate the boiler or save the fluid and boil out the boiler.

Joe West

Jeff,
There is no makeup water entering the system. As for a defective gauge, why does it quiet down as soon as the burner is turned off? Fire it up again and it returns immediatley.


Joe

lchmb

How about

Is the coil plugging around the fins? Aquastat not sensing temperature fast enough...just a thought..

Joe West

What is the process for boiling out the boiler? Does it work? And what will this accomplish?

Joe

kevin coppinger_4

test strips ....

are not a good measuring device...a refractometer is the only reliable way to test glycol...kpc

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Joe West

There has been a new coil just installed in the last six months, and I did pull it to check it again because the customer had complained of a loss of hot water.

Joe

Drew_2

Boiling Glycol

Joe, Propylene glycol solutions boil at a higher temp than plain water. Also, if your reading a 7.0 pH with the test strip, something else is wrong. A properly inhibited PG should read 8.5/9.5 pH in a mixture of 32% to 35% PG.

Guy_5

boiling

Since it is a 68 series, the boiler is more than a few years old. What type of radiation is on the system- old iron? Could there be a sediment buildup above the chamber causing percolation? An easy check could be to drain a couple of gallons out of the system from the lowest point and see what might be in it. If there is something above the chamber it will most certainly be in the wet base.

Timco

my boiler did the exact same thing due to a severly under-sized run...causing severe flow restriction. the fluid could not get through the boiler fast enough, and boiled.

t

Weezbo

Joe.....

forget everything you thought you knew...turn off the boiler...let every thing cool off to like 100 degrees...open the pressure relife valve...and bleed off a couple gallons of water....that should drop the pressure right off the boiler.........now if you have a spirovent then open the fast fill and re pressure the boiler to 8 psi...if you dont have a spiro vent then open the maid o mist or air eliminator on the boiler or taco air bleeder or whatever you have for the air relife....open the zone valves for any zone on the same floor level as the boiler...this should bring the pressure back up in the boiler a bit...open the purge valve again and let off some more pressure so it reads like 8 psi...open up the fast fill again till it reads 12 psi...turn the boiler back on....tell me what the tmp and pressure reads if and or when the boiling starts again...i am sorta handy at this stuff *~/:)

sootmonkey

hey

Ah, Hey guys... I think Weezbo my be on to some thing....I think I know where he is headed......Oh my!!!! Did I just say "I know where weezbo is headed".....I FOUND THE RIGHT BREW ...

Weezbo

Dude *~/:) ...You see so clearly yet , you forgot to go out to

the truck and get your crystal ball....otherwise who will belive you ) see what i say isnt as transparent as a bag of chips it comes from far too many hours working in the cold and way too many 2 a.m. calls ....Now that kinda coffee is justa bout right

Steamhead

A couple more possibilities

First check the burner's firing rate. The nozzle size is only one factor here- you must also check the pump pressure. I've seen pressure regulators in pumps stick closed, sending about 300 PSI to the nozzle when it only needs 100 (or whatever the manufacturer specifies). Obviously this would result in a flame way too big for that little boiler.

If the firing rate is OK, check the circulator size. A too-small circ won't move the fluid fast enough, and one way too big will move it so fast that it won't have time to pick up heat in the boiler. Either scenario can cause boiling, and the radiators won't heat well either.

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Weezbo

I Too , will chirp up for the oil burner as a possibility.

and an EXTREMELY DANGEROUS condition at that. when isolating the possibilities one needs a plan that is functional, something that like a tool, is for the most part ,..applied when needed...there is nothing wrong with opening the eyes of ambitious homeowners and helping them to realize that there is quite often a few possibilities that would elude even well trained and experienced workmen...meaning,i am not at this momment feeling comfortable teaching someone over the internet how to check for overfire nor would i suggest anything other than what i have so far in order to diagnose the problem.owing to the frustration in helping someone when they only hear what they want to hear or are conditioned to hear, makes me far more cautious than many...in other words, first.. isolate some of the unknowns and have a plan on where to go next.overfire is quite often direct intervention with a wrench , meaning it didnt get that condition by sheer luck. heres where "and be ye wise as serpents" comes into play...*~/:) at the momment i am isolating for three variables,had the guy done as asked and then supplied the "Eyes on" information .... this brings up another "topic" of consideration... The idea that it could be over firing few people would consider i would consider the means to identify that is alone fairly exceptional diagnostic skills from the information given...isolating that specifically as the cause requires a few more steps for me the weezbo :)to go into the place with a new fuel pump and the correct nozzel from my home from the info given would be damm near clairvoyiant.and would indeed make me belive i was extremely favored by god to do so.

Plumdog_2

Boiler Boiling

You need to check the pump, it sounds like no circulation. Also you need to check the high limit setting and function.