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Where did the air and noise go?

DanInNapervilleDanInNaperville Posts: 23Member
edited December 2017 in THE MAIN WALL
We moved to a new house last winter that has hot water heating (so much more comfortable than forced air - a very pleasant surprise!). Here's the background: Mid 1980's vintage Burnham boiler 266k input 190k output with 5 zones, 2 fin tube and 3 pex, and a single taco 007. I had a chance to meet the previous owner (nice guy who had built the house) and he talked about the "comforting" sound of the boiler banging on a cold night. Apparently it had done that for a long time.

Not long after we moved in, a zone valve started leaking and the rate increased rapidly starting on a Friday night. The zone it was on had had a tap added to it (for staple up pex under the master bath floor when it was given a minor remodel, probably to help sell the house). The tap was added between the zone valve and the 1.25" manifold tube, meaning that it was sweated in about an inch from the valve. I think that's why that one valve failed. It took 30 minutes of patient chiseling to get the valve seat out, but I was able to replace the valve head with one from the local hardware store before the house got too cold. It left me thinking that the initial installation was good, but that later changes maybe weren't as well thought out.

In the spring, I pulled about 3/4 of a gallon out of each zone and a gallon or so from the boiler drain. The water had some grit and rust in it, but wasn't too bad. It also had ethylene glycol anti-freeze (I'm pretty sure - there was an ethylene glycol tester left behind next to the boiler). I added two quarts of Hercules boiler and heating system cleaner to try to suspend any scale (I'd hoped that would quiet down the boiler but it had no effect).

This fall, the first time I tried the heat, it didn't come on. the circulator (taco 007) had stopped working. I had to drain abut 6 more gallons before I could replace the pump, but that got the heat back. I closed the purge and drain valves then let make up water re-fill the system. My hope was that all the air would be taken out by the air vents on a separator and one mounted on the boiler by the relief valve. I replaced the air vent but it showed no evidence of air being released (no sound of air coming out, no drips or stains from any moisture leaking past the separator). I can imagine that the oxygen in the air would be bound by the rust and grit, but the ~80% of the air that was nitrogen shouldn't have had anywhere to go but the vent. There are no gurgles, all zones heat well. There's no sign of air in the system.

- where could the air have gone?

This fall, I drained another 6 gallons and added 5 gallons of cryo-tek 100, plus sludgehammer corrosion inhibitor, plus another quart of "leave in" cleaner. The boiler never banged again. Both the cryo-tek and corrosion inhibitor mention having silicon to lubricate heating system parts. Did that help with the banging?

- was the banging from movement between boiler sections and the silicon lubricated it? I've been doing a lot of reading and haven't found any mention of boiler sections making noise when they expand and contract, but can't think of anything else that might have been causing it. It used to sound like a muffled shotgun was going off inside the boiler and the attached pipes would shake. The noise wasn't from pipes or fin-tube units (still plenty of that). it used to come from the boiler.

Is this typical? (some chemicals causing that change)

Comments

  • STEVEusaPASTEVEusaPA Posts: 2,546Member
    Why all the chemicals and the glycol?
    Do you need the glycol? Because you don't mention checking it, or adding back to it. If not, I would've drained the entire system, flushed and re-filled.
    I'm sure you're aware you can't dump the glycol down the drain.
    steve
  • EBEBRATT-EdEBEBRATT-Ed Posts: 4,946Member
    @STEVEusaPA always has good advise (except we differ on oil piping LOL)

    I would dump all the chemicals, clean and flush and use polypropolyne glycol (if you need glycol)

    And no you can't dump ethylene glycol down the drain. Then see what happens
  • DanInNapervilleDanInNaperville Posts: 23Member
    edited December 2017
    The existing anti-freeze is why I couldn't do a full drain and flush. I spent a fair amount of time trying to figure it out. Small quantities of either glycol are often permitted in municipal wastewater systems (much to my surprise) but I'm on well and septic and this would be a lot more than small quantities anyway.
    Propylene glycol isn't an issue and can be processed by a septic system but Ethylene glycol is nasty stuff and can only be processed by a septic system in very small concentrations (a little can be digested by the bacteria in septic tanks, given time, but too much at once and it kills the bacteria). Polyethlyene glycol, not that it matters much, is a popular laxative and consumed by millions - gotta keep track of which glycol you're using!
    Over time, I plan to replace what might be ethylene glycol with propylene glycol. Hopefully it's just a coincidence that an ethylene glycol tester was left on a shelf next to the boiler, but I'm not going to take any chances.
    I added the cleaner because our water is very hard and scale is often listed as a cause of boiler noise (kettling) even though this didn't really sound like that. Phosphonate (boiler cleaner, i think) dissolves mineral scale and keeps it suspended in the boiler water where it can't hurt anything. I think that's main ingredient in the boiler cleaner I added.
    The rust inhibitor was because the water I drained was rusty. Keeping antifreeze protection in place was because the garage is heated, but the thermostat is only set to 55 degrees (it's not all that well insulated and I can't afford to keep the garage at 70 degrees). If the boiler or any of its parts fail, the pipes in the garage floor would probably freeze pretty quickly. Some winters it gets to 10 or 20 below, here.
    Any ideas on why corrosion inhibitor stopped the noise from the boiler or what happened to the air?
  • hot_rodhot_rod Posts: 10,981Member
    With all you have added it must be a very weak solution of glycol at this point. Do you have a tester to show the freeze protection level? An inexpensive automotive floating ball type would give you an indication.

    Noises are hard to troubleshoot via the WWW. Most often the noise is percolation, sounds like a tea kettle when they get a lime scale layer in them. Pop, bang, rumble different sounds are all percolation caused by the scale build up inside the boiler.

    The cleaners you added will dissolve and lock up those scaling minerals, clean the inside of the boiler and the noise goes away.

    It is a very common fix for banging copper tube boilers also. Some cleaners stay in and suspend the minerals, others need to be flushed out, the strong acid based cleaners for example..

    I'd run a cleaner and dump all the fluid. Then replace it with demineralized water, add glycol only if you absolutely need it, most homes don't unless there is outside piping or pipes in exterior walls.

    I suspect you have hard water and that is where the problem starts. Glycols also breakdown after time especially in dirty systems, it needs to go. The ph is another indicator of bad fluid.

    EG can be recycled at most any auto parts supply, repair shops etc. Diluted enough and it can go down the drain. A tester is the only sure way to know exactly what % solution you actually have.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Maybe if you are constipated............NBC
  • DanInNapervilleDanInNaperville Posts: 23Member
    edited December 2017
    hot rod said:


    ....I suspect you have hard water and that is where the problem starts. Glycols also breakdown after time especially in dirty systems, it needs to go. The ph is another indicator of bad fluid.

    EG can be recycled at most any auto parts supply, repair shops etc. Diluted enough and it can go down the drain. A tester is the only sure way to know exactly what % solution you actually have.

    Thanks! I live in an area where 99% of the homes are forced air heat and the ones with boilers usually have a small area with pex. I figure most local HVAC guys work on 1,000 forced air systems and one hot water heat system each season (so they aren't really fans of hot water heat).
    This house has some pex in/under slab, some baseboard, one small area with stapled up pex, and a single kicker in a kitchen baseboard. It's almost a test lab for HW heating and it's been really interesting trying to figure it all out.
    I think things were done differently in the 80's compared to today. The basement is heated with pex under the slab, but installed as one loop spaced something like 10 feet apart (can't quite justify buying a Flir, so this was determined using the "walk around in your socks system").
    I figured that I took about 15 gallons out and replaced it with 5 gallons of propylene glycol and 10 gallons of make-up water which the label says should provide burst protection to -20 (as long as what was in there was already as good or better - given the smell and "slipperyness" of the boiler water I took out, it was probably pretty close. I've read that a refractometer is the only way to get an accurate reading with propylene glycol (which is why I figured that seeing a float style anti-freeze tester meant that ethylene glycol had been used). The refractometers aren't cheap. Will an automotive style tester work for propylene, too? (I should start tracking down specific gravity, etc. but asking is so easy!). If glycol breaks down in dirty systems, I'll figure out a way to test.
    The whole system is running perfectly now and I feel a lot better about the anti-corrosion chems being in there to keep it that way. But I wondered why that seems to have made such a dramatic difference in the boiler noises and there really ought to be about a cubic foot of air in there causing problems - but there isn't (or doesn't seem to be). Laws of physics and all made me wonder what's going on with the air.

    The air scoop is on the pressure side of the pump - probably why the automatic vent isn't venting anything. The old automatic vent on the boiler had shown signs of something having come out of it in the past (stains). I replaced both and neither seems to have vented anything.
    The graphics in one of the "coffee with Caleffi" series were just great for visualizing why "pumping away" is so important - they're all excellent. Thanks for those!

  • hot_rodhot_rod Posts: 10,981Member
    The air scoop is on the pressure side of the pump - probably why the automatic vent isn't venting anything. The old automatic vent on the boiler had shown signs of something having come out of it in the past (stains). I replaced both and neither seems to have vented anything.
    The graphics in one of the "coffee with Caleffi" series were just great for visualizing why "pumping away" is so important - they're all excellent. Thanks for those!

    It's more about the expansion tank connection in relationship to the pump. The air sep can be downstream of the pump, but try to always pump away from the tank connection.

    Yes automotive antifreeze testers will test both PG and EG. Car manufacturers have been switching to the less toxic PG for antifreeze.

    Sounds like you have a witches brew of fluid, might want to test it before it causes harm. If automotive EG was used it can and will sludge component due to the silicates the use as an ingredient. Use only hydronic fluids, including inhibited glycols blended wit DI water.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • DanInNapervilleDanInNaperville Posts: 23Member
    edited December 2017
    hot rod said:

    The air sep can be downstream of the pump, but try to always pump away from the tank connection.
    ....Yes automotive antifreeze testers will test both PG and EG. Car manufacturers have been switching to the less toxic PG for antifreeze.

    It would be great if what was in there was just propylene - then I really could do a full flush and refill. I just have to figure out how to do it without wrecking the house...

    Unfortunately it has an old taco air scoop that was installed with the expansion tank under the separator (downstream of the circulator). When I update the system, I plan to replace the current air scoop with a Discal Dirtmag - that's a nice looking piece of equipment and would take out the grit as well as air. That would be when I could move the air tank.
    I tested the water for pH before I did any of the other things (except fixing the leaking zone valve) and it was OK at low 8's. Same for the make-up water, so it should stay that way.

  • hot_rodhot_rod Posts: 10,981Member
    EG really isn't that wicked of a fluid, it was and maybe still is sprayed as de-icing and anti icing fluid at airports, although PG and some non glycols are also being used more so.

    The problem is mixing multiple fluids with various different inhibitors. And hard water is bad for any hydronic conditioners or glycols, it breaks down or uses up the inhibitors right away.

    EG like DowTherm™ is still common in hydronics where it cannot be exposed to potable water like DHW HX or indirect tanks. It is usually less $$ and a better transfer fluid than PG.

    Was a time when the glycols at some airports would go into bio ponds, one exposed to O2 for a period of time they were flushed into the sewers.

    PG in the food grade form is used as a scent and flavor enhancer in many products, baked goods, toothpaste and such.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • LeonardLeonard Posts: 626Member
    edited February 2018
    For testing a car coolant of mixed types I once just put a 1/4 inch of it in cup and put it in freezer. My freezer will go down to ~ minus 20 deg if run it ~ 15 hours straight.

    I had a thermocouple wire for quick temp test of the liquid
  • DanInNapervilleDanInNaperville Posts: 23Member
    Leonard said:

    For testing a car coolant of mixed types I once just put a 1/4 inch of it in cup and put it in freezer. My freezer will go down to ~ minus 20 deg if run it ~ 15 hours straight.

    I had a thermocouple wire for quick temp test of the liquid

    Great idea! If the hygrometer and thermometer were accurate enough, you could even calculate the the glycol type(s).
    Just have to remind the wife not to pour the "leftover" gravy over the roast beef sandwiches....

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