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Thread: Weil McLain boiler problems.

  1. #1

    Unhappy Weil McLain boiler problems.

    Hi all,

    I am seeking an answer on a issue I am having with my boiler furnace. The heating unit is about 12 years old and has worked fine until I had a Plumbing and Heating service tech work on it a few years back. It has a cast iron tank, and is natural gas fired.

    About 2 to 3 years ago I had a service tech just do a check up on the boiler, well he told me that the system needed drained and fresh water put back in, so me not being to bright about what would happen told him to go ahead and do it. At about mid winter out furnace started to sound like a coffe maker, we have all low profile baseboard heat and 1 inch copper lines. Then we started to get air in the system soon after the the noise started on the boiler. We road it out for the remainder of the heating season and made plans to have the service tech take a look in the spring. His advice was to flush the system again and bleed the air out or put a new boiler in, which he suggested would cure it, he said our boiler is old. So I did the water change again on his instructions. Well the next winter brought more noise from the boiler and air in the lines, bled off air out of the baseboards and boiler, it seemed like all winter that year, the noise was just terrible.

    I ended up contacting another service tech about the problem and he took a look at the boiler and explained that it was limed up do to to much fresh water being added. He inspected for leaks and did notice the high preasure releif valve was dripping which could have lead to the lime build up in the tank. He gave me instructions on how to delime the boiler, but was not real clear on some of the instruction. He said use muratic acid 50/50 mix, close the input and out put of the feed lines and drain boiler and fill with mixture of acid. I did do this and what a stinky mess it made. I did rinse the boiler tank several times and then drained the whole system again and refilled with 50/50 of water and automotive grade antifreeze, which I just found out is a " big no no'' for the weil McLain boilers from the manufacture. We got through most of the winter with no noise problems or air in the system, but it started up again at the end of the heating season. I called both tech, and they are eager to just install a new boiler. I would rather delime the unit again, and we are having a water softener installed this week, so we have soft water in the boiler, our water is very nasty anyway, I know this will help the boiler from liming up again. And from what I have learned, the 2 service tech pretty much did everything they could to help it lime up. Below are a list of question I really need answered and help with, going to try this myself again.

    1. Should I use muratic acid to clean it, and what ratio should I use?

    2. How long should I let the acid sit in the boiler before I dump it?

    3. How many times should I rinse the boiler after delime work is done?

    4. Should I run just straight water in the system or put in a additive?

    5. Will the soft water prevent the lime build up?

    The sytem is a sealed closed loop system which when operating right gets no air unless you have a leak in a line I have inspected for leakes several times this year and found none. But if tank is limed up, the deposits will produce bubbles when boiler gets up to temp, just like a pan on the stove boiling, hot spots in other words. My boiler temp is set on 170 degree's.

    From other things I have learned that antifreeze in the system mixed with water will walk when it is heated so to speak and cause's foaming at the pump, which in turn will lead to air bubbles later. The auto bleeder is working fine on the boiler. It spips water every now and then with air bubbles in it. I really need some advice from someone.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Once you get the air out of the system, unless there are leaks, you should never have to add any again. The system pressure must be within the specified range for the boiler. If it peaks too much, then you need to add water, the expansion tank is probably shot. The amount of minerals in what is probably less than 30-gallons or so of water should not require deliming, or if it does, not very often. You just can't disolve that much. Now, if it is constantly refilling because there are leaks, then yes, it could be a significant problem.

    A new boiler is likely to be more efficient, so you'd have to do a cost analysis to see how long the payback period would be. There are often rebates from the utility company and possibly the feds if you buy one that qualifies, so take that into consideration.

    Unless the system has loops that go outside, typically you don't need antifreeze in it (unless you turn the heat off for extended times in the winter). Adding antifreeze decreases the efficiency of heat transfer, so your boiler needs to be bigger or run longer to transfer the same amount of heat to your house.

    I'll defer to the pros for your other questions....
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Master Plumber nhmaster's Avatar
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    In 36 years I have never de-limed a cast iron boiler. Shut the water feed off. Drain the pressure off, not the whole system. Replace the air vent that should be on top of the air scoop. Turn the wter back on. Run the system for a bit. Next look at the high limit when the boiler is at max operating temperature. If the temp gauge is above 200, turn the limit down to 180 or 190. If the boiler is running hot it will make steam and the resultant air problem.

    Soluting # 3 Find a service tech that isn't a moron.

  4. #4

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    Thanks for the response guys, I'm just up in arms over this whole deal. First off, our water here where I live is really nasty. About every 2 weeks I have to clean the shower head do to lime build up. I never really had any problems with this system until the first service tech told me to dump the water out of the system. We did not have a water softener at the time when we refilled.

    As far as leaks go I did check several times to see if something was leaking, even pumped up the expansion tank to about 18 pounds with the whole system filled, and let it set a month this summer. It never lost more than a pound or 2 of preasure. I am costantly bleeding it though at least 2 time a week since heating season started. After softener is installed this week, I will completely drain the system and rinse it really good to get all the anti freeze out. I will hold off on doing the acid clean for now though.

    As far as buying a new furnace, I want to hold off on that. This unit is only 15 years old, and was expensive. From info I have gathered this year, if the boiler is limed up this would cause hot spots, which inturn produce gas which is steam. This inturn produces air if I am not mistaken. and since there is antifreeze in the system right now, this would or could be walked which cause foam, and air bubbles.

    The system is a closed loop system, with a tank fill of about maybe 2 to 3 gallons. Cold preasure is about 10 pounds, hot preasure at peak temp "180" is at 22 pounds. Expansion tank preasure is set at 12 pounds cold fill.

    I did a test tonite and turned the boiler temp to almost 200, noise was even worse, and more air seemed to be in different rooms now.

    If I should delime the tank, what would be the ratio needed, and how long should it sit before being dumped and rinsed.

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    Regardless of your water quality, it should never need to be delimed. You should not need to add any water. Since you do regularly, there is a leak. With the antifreeze and the pressure, it should probably boil at 240 or higher (the pressure raises the boiling point), depending on the actual pressure and antifreeze percentage. IF the circulator isn't working well, the water can stay too long in the boiler and it could get too hot. If the pressure is proper and the water is being circulated, even with some hot spots, it should not make those noises. If there is a valve that isn't fully opened, it could restrict the flow and allow it to boil.

    You need to find the leak. You have one or you wouldn't need to add water.

    You aren't sitting on top of a mountain are you? That lowers the boiling point and could be part of the problem. The water pressure should compensate, though.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6

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    Jim,

    I thank you for your replys they are helpful to a point, but you keep saying there is a leak. There was a few years back when the high preasure releif valve was dripping. This valve is like ones one a water heater when you buy one. This valve did not start leanking and was not noticed leaking do to the way it was put into the drain in the floor. The way I caught it was by a service tech when he undid the pipe to the valve. It was about one drip of water every 3 minutes. Which could mean a couple of gallons every 2 days or so, that was the only leak I had, and it was taken care of about 2 years ago, and I check this quite often. As I stated earlier I never had any problems with the boiler until we dumped the system and added fresh water. The first winter was ok until noise started late into heating season, and discovered releif valve leak was part of the problem that winter of 2005. The next fall in 2006 I delimed the boiler with the acid, nasty job to do by the way! I ran the waste water and acid threw a old bath towel into a bucket, and it looked like sand was in it, at least a cup or so of it. After I got done rinsing, I flushed out the lines had a tech come and fill system with 50/50 anti freeze, and it was ok for most of the winter, then the noises came back. It sounds like an old water heater thats 40 years old clicking and bumping, but the gurgling is terrible. And the surging at the boiler wich sounds like air trying to pass through the pump, I'm told this is foaming going on.

    I did get intouch with the original installer this evening on the phone, he's retired but told me that it should have been filled with soft water like it was in the beginning. He did say that the releif valve leaking was a bad thing because it kept adding water which will create lime aka hot spots when fired up. He told me that I never did get it delimed very good and said that the 50/50 should not be in there, that it can foam in hot spots and walk through the pump fins. then turns into bubbles.

    The boiler is the same as is was last year, same noises and sounds. Ive only done an acid clean once and am ready for another, and as I said our water is terrible here in this little town I live in, not fit to drink.

    If I had a leak in it, why would it hold pressure for a month with the water feed shut off? The 2 service tech's, keep saying I need a new furnace, and will not give me advice on deliming it. I know its limed up just by the way its acting and the techs agree, but don't want to help me out with the use or best way to delime it. As I said our new softner will be installed this week, so soft water with "no" antifreeze is going to be used in replinshing, just clean soft water.

    I should have never dumped the water in the sytem, and this would have never happened, but whats done is done. I just found out today also a home owner down the street has the same problem I have, but his furnace is really old though. Our water lines here in this little town are 90 years plus old, so all the junk and stuff ends up in our sinks and tubs, looks like pond water some days.

    Whats the best way to delime the boiler and keep this from happening again??????????????????????

  7. #7
    Master Plumber nhmaster's Avatar
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    Turn the limit down to 180 to start with. The expansion tank should have about 15lbs of air in it if it's a diaphram tank. Pressure should not vary more than a couple pounds between hot and cold. If it does the expansion tank is bad. Forget de-liming it's a waste of time.

  8. #8
    Retired Defense Industry Engineer jadnashua's Avatar
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    Do you have an autofill valve on the boiler? If you do, you could have a leak and you don't know it.

    Leaks can be in and or out. A circulator with worn bearings can inject air. The packing on a shutoff valve if worn can leak air, but not necessarily water. If the expansion tank is shot, it can allow the system to generate a vacuum when cooling off and suck in air.

    In a boiler, whenever the burner is on, the pump is supposed to be on, moving the water across the heat exchanger. This should never allow it to get hot enough to flash boil the liquid unless you are running the upper limit too high or the pressure is too low. A water heater is a different animal...the water often isn't flowing over the heat exchanger so direct comparisons aren't valid.

    If you have a primary/secondary circuit for the water from the boiler, it could still heat, but one of the pumps could be shot. If you have multiple pumps to control zones, one of them could be failing. If there is air in the system, you could end up with an air lock, and the water isn't really circulating. If you turn a zone off by shutting valves, you might need a bypass valve.

    So, if you are getting boiling (unless the upper limit is way high or you don't have the proper pressure), look for bad flow which could be a pump, valve, or air trapped creating an air lock. Also, look at any valves in the system that could be partially closed that might restrict flow. Think of it like this, if you don't move your hand across a candle fast enough, you'll get burned, but do it with some speed, and you may not notice it getting warm at all. The pump's job is to continually move the water (your hand) across the heat (the candle) while it is on.
    Last edited by jadnashua; 11-12-2008 at 07:56 PM.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  9. #9
    Moderator & Master Plumber hj's Avatar
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    The above replies are too voluminous to read in their entirity, so this might have been covered previously. The most common source of air in a closed heating system is a bad pump seal which sucks in air while it is operating, but does not leak water when it is shut off. Air in the system is not a reason for changing the boiler, unless the contractor needs a new truck and is looking for the down payment. Muriatic acid in the boiler is fine for a copper tube boiler, but could be detrimental to a cast iron or steel tube boiler. Besides the volume that would have been necessary, along with the hazards while using and draining it, would have made it a hazardous operation.

  10. #10

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    Hi,
    Thanks for the reply it was the answer I was looking for somewhat. You are so very right about the acid being so dangerous, I have done the delime once, and it is not any fun.

    My tank is a cast iron unit on the boiler, a 3 section design that is held together with long bolts that pass threw the sections, each section has a gasket face surface. The tank is then bolted together using the long bolts, which make it into one peice. I have copper lines on all the plumbing part of it, but there is black pipe used on the pump section. I put a new pump on last year because the old one died in the middle of the nite leaking all over the place, but the boiler had the same issue as it does this year with the crackling and surging noises at the boiler, this does not start until about 150 degrees and then the noise starts, by the time it get to 180 it is making all kinds of surging and gurgling noises then. several rooms have water moving noises in the baseboards then.

    I checked the presure at the expansion tank and it is about 13 pounds, the gauge reads 22 at 180 degree's when up to full temp. Today I talked to the neighbor down the street who has the same issue that I have, but his boiler is older than mine. I just remembered that our town board drained the tower a year ago to do work on it, after it was refilled him and I both dumped our system water and refilled we think, that we got a bunch of lime, and junk build up in it, he had the same service tech I had, and the tech is eager to sell him a new boiler also, so maybe the tech needs some extra cash for bills as you said. In other words I should have never dumped the system.

    Today I talked to a new tech and he said that soft water is critical in my area for the boiler refill. He did say that acid clean out is a last resort before having to purchase a new unit, he gave me no real direction for the deliming.

    He did give me another test to run before I have to do the delime, and thats pump up the psi to 20 pounds on the expansion tank, and shut off the water feed, and shut down the furnace all together. then let it sit for a day or 2 and monitor the preassure. I told him I did do that and it passed. He never did mention about the pump like what you said it could be doing with sucking some air in.

    There is a manual bleeder on the return side of the pump, just above the pump, everytime I open this manual bleeder its full of foam and bubbles at high temp. Thats on the in side of the pump. On the pipe coming out of the top of the tank to the plumbing theres another bleeder that has nothing in it but strait water and no foam or bubbles.

    Last nite I ran the furnace all nite with the feed water shut off, and still no change, and psi never went down at all when I checked it in the morning, same noises all nite though, nothing changed.

    I know the automotive grade antifreeze needs to be out of there am I right?

    If and when I do the acid rinse, whats the best ratio to mix it, and how long should I let it sit?

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    If you were to take a large pot, fill it with water, then boil it. Do that a few times until you have boiled away what you think is the volume of the heating system's fill, what would be left on the bottom of the pot would be the maximum amount of minerals in the water...it won't be much. Not enough to worry about.

    Where is the pump in relation to the expansion tank? It should be on the inlet side. What model pump are you using? What size pipes do you have? If you have a pump that is trying to pump too much water for your system, it will cavitate which is essentially water boiling because of the low pressure spots caused by the pump trying to run faster than the pipes can accomodate the flow - the water boils at the lower pressure. that's the reason you want the expansion tank to feed into the pump on the low or inlet side. Air accumulates at the high point, so if you don't get air out the bleed valve that is higher, and do on the lower side doesn't compute.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #12
    Master Plumber nhmaster's Avatar
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    The circulator should be after the expansion tank and fill valve, pumping away from the boiler. It's probably on the return side pumping tward the boiler.

  13. #13

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    Jim,
    Im using 1 inch copper pipe on most of the unit, we have I think 3\4 inch on the the heating bases, this is copper with the fins on it. My expansion tank sits close to the floor right next to the boiler. This is a diaphram type expantion tank. The pump I have is a TACO brand, this sits above the expansion tank via plumbing, the water inlet valve or feed is in between the pump and expansion tank, and this is where a drain is also located to drain the system.

    The unit is a CGM-4 series 9

  14. #14

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    Ok,

    I had the old retired plumbing tech come down this morning and check my boiler out. He stood their and had allot of thinking going on, and tried some different test. He suggested replacing the explantion tank first, so I went out and purchased one from the local dealer. We chraged the tank, 12 to 15 psi, took the old one off then. I pumped 25 pounds into the old tank out in the shop then, and let it sit on the bench for an hour, checked it later then and it had no psi at all. So we pumped it up to 30 psi and listened threw the other end and could hear a slight hissing noise coming from it. The tech said it might have a pin hole in it.

    After the new tank was installed we bled everything after refilling the boiler tank, fired it up, and it came to 180 with no noise. psi on the boiler does not change as much now, it is running 20 pounds at cold and 26 pounds hot.

    Soft water was put in after flushing system and all points are go now. So its pretty much a learning lesson that I got, always get a second opinion.

    Thanks guys for the help and trouble shooting you all did for me.

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