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Buderus SST250-65 Possible Leak ?

zooba72
zooba72 Member Posts: 25
Hello Everyone,

I have a Buderus SST250-65 Indirect fired water heater and I just noticed that the concrete slab that sits upon is a little wet. I cannot find any fitting that is leaking and wondering how to start the troubleshooting process . It's about 11 years old - not sure if I should be thinking about replacing or repairing ? Any thoughts or suggestions would be appreciated. Thank you

Comments

  • zooba72
    zooba72 Member Posts: 25
    edited May 2023
    Adding a picture of the bottom of the tank. The black plastic ring does have a little water around the top which makes me believe it's leaking from the bottom. Thanks
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    edited May 2023
    Relief valve?

    Other than that, you need to isolate the tank from all other water pressure sources to see if the leak stops. 11 years is not very long for that tank. There may be warranty on that tank. You may need to pay a professional to verify the leak in order to claim the warranty benefits.

    There are 5 openings that can leak if the fitting or valve is not properly sealed and tightened at the time of the original installation. There are 2 boiler connections (Supply and Return), the hot water outlet, the cold water inlet and the temperature and pressure relief valve opening. If you can be certain that all 5 locations are leak free, then you may have a defective tank. Since that tank is covered in insulation, it is usually not possible to do a visual inspection of the tank to find the leak since the insulation will cover the leak location and the visible water may exit in a completely different location. I believe the aquastat well is welded in place but that may also be a leak location to check out
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • zooba72
    zooba72 Member Posts: 25
    Yes, thanks, there is a warranty that is prorated after 11 year - I believe like 65%. The relief valve is on the side and there is no indication of any water coming from it
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    If you close the cold water inlet valve, then make sure to open a hot water tap to relieve the pressure overnight, then dry up all the water around the tank. Tomorrow you can look at the tank to see if the leak is gone or less. Then turn on the cold water and observe if the leak grows again. This will indicate the leak is from the tank location. Then you can start to remove insulation to pinpoint the leak location.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • zooba72
    zooba72 Member Posts: 25
    Thank you - I appreciate the response. When you say "open a hot water tap" - should I keep that open - let it run all night ?
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    It could be a leak at a pipe connection. And I would be shocked if it were a tank failed ..
    I have enough experience to know , that I dont know it all
  • zooba72
    zooba72 Member Posts: 25
    I've looked at all the fittings, relief valve, drain pipe and everything is completely dry - the only water is coming from the bottom of the tank. I've been reading another thread on this board that others have experienced tank failures with the Indirect Buderus Water Heaters - hoping it's not that
  • Big Ed_4
    Big Ed_4 Member Posts: 2,761
    The bottom of the Buderus is a single plastic pan , If the water is coming from the tank you will see water at the lip . Not sure what sensor well was used , The stainless model sometimes leak ..
    I have enough experience to know , that I dont know it all
  • zooba72
    zooba72 Member Posts: 25
    I see water at the lip of the black plastic ring (or pan) that surrounds the bottom of the tank. I'm not sure whether it's visbible in the picture I provided. Based upon your response it sounds like I'll need to replace this.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    zooba72 said:

    Thank you - I appreciate the response. When you say "open a hot water tap" - should I keep that open - let it run all night ?

    Yes, leave the tap open... it will not run all night... that is because the cold water that feeds the tank will be closed. You do understand that if the cold water pressure that feeds the tank is closed, when you open any hot water tap to release the pressure, the flow will stop after the pressure is released. So to be perfectly clear.
    Step 1. Close cold water feed.
    Step 2. Open a hot water tap to release the pressure on the suspected leaking tank,
    Step 3. Mop up any water from the area around the suspected leaking tank,
    Step 4. Wait 24 hours with the cold water tap closed and the hot water tap open.
    Step 5. Inspect the area around the suspected leaking tank for signs or water on the floor.
    Step 6. Compare the amount and size of the water leak to the size of the water leak from from a time previous to the test.

    If the leak is the same as it was before the test and after the test then the leak is not from the tank. it is from a place that still has water pressure. If the leak is less or non existent, then the tank may be the source of the leak. close the hot water tap and open the cld water feed, remove insulation from tank to locate the leak.

    If this sounds like I am over explaining the procedure, I am. I just was not this clear when I proposed the test. I want to avoid being misunderstood again. I hope this helps.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    zooba72
  • hot_rod
    hot_rod Member Posts: 22,018
    Then the first step is to remove enough insulation around all the connections and look for a thread leak. Before condemning the tank.
    The threads on nipples can some times corrode away and cause a leak path, dissimilar metals for example.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zooba72
  • zooba72
    zooba72 Member Posts: 25
    I appreciate the explanation - the additional detail is very helpful for me. Thank you
  • zooba72
    zooba72 Member Posts: 25
    Quick update, I did as instructed above, closed the cold water valve that feeds the tank and opened a hot water tap. Everything was as dry as I could get it prior to doing this - I kept it that way for maybe 18 hours and the volume of water leaking from the tank was very similar. I closed the hot tap and restored the cold water to the tank.

    Would anyone be able to explain how I get inside this unit ? Do I need to remove the Boiler water in/out fittings? etc. ? Sorry for the stupid question. Thanks again for the help
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    edited May 2023
    Is it possible that you have ground water coming up from the ground near the tank location? Can you post a picture of the tank?

    Second option is that the boiler still had pressure and the leak source is the boiler water pressure. To test that
    Step one, close the feed valve to the boiler
    Step two, open a boiler drain valve to get the pressure in the boiler to drop to zero on the gauge.
    Step three, close the boiler drain.
    Step four, turn off the power to the burner ( you don't want the run the burner for this test)
    Step five, Dry up the area around the water tank
    Step six, Check for a change in the size of the leak tomorrow.

    This is the same idea, but with the other water pressure source. The boiler pressure.

    There is a slight chance that you may get air in the radiators during this test, so be prepared to vent or purge the air from the boiler system radiator to each room.

    If there are valves on the boiler supply and boiler return between the tank and the boiler, then you can close them to isolate the tank from the boiler system after you do steps one thru six. Once the tank is isolated (both valves closed off) then you can restore the boiler system to operational mode. If you do not have isolation valves, then the boiler must be off the full time of the test.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • zooba72
    zooba72 Member Posts: 25
    Hi - Yes, the water heater can be isolated, I have valves on both sides - but I have no issue turning off the boiler for the test. The water is definitely coming from the water heater, I can see the water build up around of the black plastic pan on the bottom, and I believe it slowly spills onto the floor. I do not have a pressure gauge on the water heater (at least I don't think I do), but there is a sensor that feeds a logimatic temperature info, but I do not believe it tracks tank pressure? I'll need to check that. The logimatic has been operating on manual mode for a while now.

    The property is probably 60' above sea level and are cesspools are extremely deep - no way water could be coming up from the floor. Some additioal info, this is a split monoflow system and I have convectors throughout the home to deliver heat.

    Attaching a few pictures of the boiler room. Lighting is not great, but hopefully you can see the layout. Thank you again for detailing the procedure, I'll probably do this over the next day or so.




  • hot_rod
    hot_rod Member Posts: 22,018
    If it is not leaking around the nipples or welds at the nipple connections, it has a tank leak.

    If the coil inside had a leak, generally the water pressure in the tank would cause the boiler relief to trip. Assuming the relief is not stuck :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zooba72
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    edited May 2023

    I wonder if this is the domestic water connection? If this is the cold water opening and the nipple and reducing coupling are not brass, You could have a steel nipple that has rusted away at the tank connection and the leak is traveling inside the insulation to the bottom.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    zooba72
  • zooba72
    zooba72 Member Posts: 25
    The cold water-In connection appears to be galvanized, it's magnetic. The threaded nipple is non-magnetic, but I cannot determine whether it's stainless - it doesn't look like brass, but that could be my lack of experience. It's connected to copper. I attached close-up pictures

    The boiler water-out connection is rusting - and the black pipe that it's connected to is also rusting. Could this be the issue ? Would it make sense that this rusted in the other direction, into the tank ?









  • zooba72
    zooba72 Member Posts: 25
    This is another shot of the cold-water In -


  • fenkel
    fenkel Member Posts: 162
    edited May 2023
    what type of water do you have ? is it hard or softned water? have you tested the water quality of your water? do you use the same water to supply the boiler ? I'd get a copy of the manual for the water heater and check the requirements for PH and chloride (PPM).
    to test the tank the best way, would be to mty the tank. fill with compressed air. a simple 60 pound guage from a big box store would work.. pump it up and see if it drops. Watch the pressure in boiler as well...
    what type of aquastat controller are you using?
    id then check the income water/ drain pipe at bottom of tank.. Take off that black ring and inspect the area around the incoming water.. id then take that pipe out and inspect it, I dont think its welded in place.. put new tape and sealant on it replace it and retest with pressure....Id do the same for the relief valve and where aquastat mounts. the top of tank for DHW is welded in place.. I think the boiler supply lines are welded in place as well.
    another area id check is the incoming supply line from boiler, looks like there is a coupler there, Id make sure that this is tight! this could be leaking and causing the rust to the pipes below it and maybe might be your leak as well.
  • zooba72
    zooba72 Member Posts: 25
    We do not use a water softener and have never seen any signs of hard water. The water authority regularly publishes water quality reports - no idea wheter they can be trusted. I've tested our tap water (which is what feeds the water heater) with a pool test kit and PH is in the normal range, chlorine is detectable but not very high. I have the manual and PH and Chlroide are within the acceptable range - the chrloride number is based upon the water company test. Aquastat is handled via Buderus Logamatic.

    Would anyone happen to know whether it's possible to remove any part of the jacket without disconnecting all of the inputs/outputs ? How are those black rings removed, do I simply pry it off ? Thanks for the replies
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    Removing the black escutcheons and the insulation will pretty much destroy the look of the water heater. If you locate the leak and find that it is not the tank but some repairable fitting, you will need to use duct tape, glue and other sealers to put the tank back to something close to the original insulated condition. There is just no way to remove the coverings and return them to the original factory finish.

    Chances are... if the tank is really leaking, then you will be replacing it anyway. If the leak is at a repairable fitting, Then you will be living with a tank with some cosmetic damage but at least it won't be leaking.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    zooba72
  • hot_rod
    hot_rod Member Posts: 22,018
    You can split those black rings with a razor knife. Trace around them first and then cutaway the foam around the nipple into the tank. The black ring can be reused if you find the leak is repairable at a connection

    On some tanks those stainless nipples are welded to the tank, some are threaded.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zooba72
  • zooba72
    zooba72 Member Posts: 25
    sorry to resurrect this thread, another question if someone has the time. I'm still dealing with this situation as I've been working with Bosche warranty and it's been dragging on. If I need to leave the house for a few days, can I simply turn off the feed to the indirect, and turn off the boiler ? Is there any problem with doing this ? I suppose I would drain the indirect too. Thank you
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,713
    If you don't want any leak to cause any problem, then a shut off valve is always the way to go. That said, you do not want to operate a burner in a boiler that has all the water leaked out and end up with a "dry fire failure" situation, so I would also turn off the power to the burner.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    zooba72
  • zooba72
    zooba72 Member Posts: 25
    Thanks Ed - It certainly makes sense, but I have read that turning off the boiler for extended periods of time can cause other issues.