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Relief valve discharge resolution (temporary?)

D107
D107 Member Posts: 1,777
edited November 2014 in THE MAIN WALL
The boiler and indirect relief valve releases from last week's thread seem to have been resolved for now. The tech came and measured the expansion tanks pressure for both and found 0 pressure. So they were replaced with Flex 2 tanks. It does concern me though what kind of water/air leaks in the system might deflate those tanks? They weren't checked in over seven years so I guess their failure may be somewhat normal(?) ––but at nearly the same time? What should I be looking for? This monoflo system, even before the new boiler was put in '06 has had air buildup for many years. I usually bleed a few of the convectors a few times a season.

Comments

  • billtwocase
    billtwocase Member Posts: 2,385
    No need to say what brand they were.
    Steam_Starter
  • D107
    D107 Member Posts: 1,777
    I disagree; I purposely mentioned the brand not to promote it but since I'd never heard of that company I hoped to elicit opinions on the quality of the product. I should have been more direct with that aspect of the post.
  • Zman
    Zman Member Posts: 6,993
    I agree with 7 years being "somewhat normal". I am puzzled as to why anyone would object to naming brands. It is done on here all the time. I don't know that brand, the design looks similar to others.
    Back to your original problem.Air separators and tees have a tendency to also work as sediment traps. Any debris that is floating around your system will be likely to find it's final resting place there. This debris then settles on top of the tank bladder. With the bladder constantly expanding and contracting, this debris can shorten it's life expectancy. Even though your installation is very common and is depicted in many installation manuals, I (and several manufactures) believe your tank will last longer if it is offset from it's present position with a flush-able sediment leg located directly below the air eliminator.
    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • D107
    D107 Member Posts: 1,777
    Thanks Carl, your post does seem to hit on a common problem, at least for boilers if not for the indirects. I wish I had verified that the techs had checked that the feed valve was keeping pressure up properly, otherwise exp tanks were replaced prematurely. (Low pressure could explain the need to bleed rads.) Don't know if boilers have their own prv but if so that should have been checked. House water has no prv; I measured pressure at 60.
  • billtwocase
    billtwocase Member Posts: 2,385
    edited November 2014
    You misunderstood David. I am quite sure I, and others know what was on there previously for a tank. That is what the comment was about, not that you are being stifled on here. I have been having issues with them for years.
  • SWEI
    SWEI Member Posts: 7,356
    OK, I had to go back and search for the other thread. What is the taboo against mentioning a well-known product that has been giving you problems?
  • D107
    D107 Member Posts: 1,777
    Ok, billtwocase, so you said 'no need to name the product' meaning 'we all know that product.' Ok, it was rhetorical, you weren't saying I mentioned the replaced product. I'm sure the photos made it clear. Ok that's what led to confusion. Anyway, As a layman, I'm not in a position to complain about a product that apparently worked well for 8 years. And the jury is still out on the old tanks, as others have pointed out air separators and tees could be depositing debris into the tank; and if the system pressure was not being maintained correctly, etc that could be the cause of the problem, maybe not the tanks. (As far as I know the Wall policy is that product defects can be discussed as long as its done respectfully with an eye towards helping pros, consumers and the manufacturers themselves work around issues or help correct the problem. Seems like a vital way for pros to exchange experience and ideas.)
  • Zman
    Zman Member Posts: 6,993
    A slow leak will introduce O2 to your closed boiler loop causing tank corrosion.You leaking relief valves were also doing this.
    The tank on the domestic side should be designed for potable water. Both tanks should have been pressurized (or double checked at install) for the pressure of your system. You should have a gauge on the boiler that allows you to monitor pressure.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • billtwocase
    billtwocase Member Posts: 2,385
    Flex is a good tank. I was referring to what was on there, and not what is. I have tanks out there from the 60's and 70's still doing their job. Mentioning certain brands are very acceptable here, and constructive criticism is always welcome. As much as I have an issue with a manufacture, I don't agree with bashing. It is never helpful to others, and that is what this place is all about. Even with a mere 32 years in the business, I come here to learn as well. Thank you Dan and others
    D107
  • D107
    D107 Member Posts: 1,777
    The upshot is that last week both expansion tanks were replaced and set to 12 and 75psi respectively. Both anode and sensor resistance was measured and checked out OK. Pressure was measured manually and a new Tridicator gauge installed--old one was stuck--pressure goes from about 16-20 during a heat cycle then back to 16. (which I'm told is normal, though I just got a call telling me it now reads 12.) No more relief valve releases. Feeder seems to be working ok. Still can't say we know the cause of the original problem. I'm told that pressure spikes from dish or clothes washers can cause this. Only thing that wasn't checked was the B&G EASB-JR air separator--debris can be checked by unscrewing the top piece off but we decided not to go that extra step. There are no really clear instructions for doing this, except to 'be careful for some small plastic pieces.' Thanks for your responses. Great site for learning. I never knew pressure fluctuates a bit as water is heated--I had thought expansion tank would absorb that.
  • icesailor
    icesailor Member Posts: 7,265
    What size Extrol/bladder type tank did you install and/or what was in place before?

    If it is now going from 16# to 20# and back, and it is now at 12#, I might personally, feel that the tank is too small and needs to be bigger. If it is going to 12#, the fill valve could add water during a cold cycle. Then, when it heats up, there isn't enough expansion room so the relief valve leaks.
  • D107
    D107 Member Posts: 1,777
    Note that this is not a cold start boiler, it's constant circ running off a Buderus room sensor. originally for boiler there was an Extrol 30 set to 13, now a Flex 2 30 set to 12; for indirect originally was an Amtrol Therm-X span T-12 set to 75lb, now a Flex 2 PH12 also set to 75lb. Since install there has been no leakage. It's a two zone system 2000 sq ft house, I'd guess no more than 15 gallons of water volume all together. And it all worked with no problem for 8 years with original expansion tanks as described.
  • icesailor
    icesailor Member Posts: 7,265
    Sounds like a "Flex 2 30 is the same as a #30 Extrol. You understand that the Flex 2 12 has no effect on the heating system.

    If the relief valve isn't blowing off anymore, that the tank was bad. Was it full of water and heavy when you took it down? Drop a full one on your foot and you will take the Lords name in vain.
    jonny88
  • D107
    D107 Member Posts: 1,777
    Yes it was very heavy--techs were careful. Always tricky that moment when taking it off and it suddenly comes loose. They were ready though. Both measured 0# pressure. Yes the Flex 2 PH12 is just for the indirect. Thanks.
  • icesailor
    icesailor Member Posts: 7,265
    I always worked alone. When faced with a bad tank, there was usually no way to know if it was full if water, I would do all in my power to get a 5 gallon bucket under the tank and tie the bucket to the piping. Unscrew it (easy) and when it came, it fell in to the bucket.

    Never something I looked forward to.
  • billtwocase
    billtwocase Member Posts: 2,385
    I will drill a hole in the bottom, and lighten it up that way
  • j a_2
    j a_2 Member Posts: 1,796
    I see very few tanks gone bad…providing they were installed in the correct position…Leave the feed valve off, it can only add to existing problems...
  • SWEI
    SWEI Member Posts: 7,356
    We replaced two last week. Both c. 2001 vintage, both Watts. Neither was subjected to excessive makeup water, but also zero service since installation. Both PRV's replaced (dripping) as well.
  • D107
    D107 Member Posts: 1,777
    To j a: How is the feed valve turned off? We have a TACO water pressure control feed valve Model #329-3 and as far as the tech showed me it's either on manual --which constantly adds water--or auto, which only adds water when it perceives pressure low. or perhaps you mean keep a shutoff valve leading to the feeder off? And if you did that then you'd just check the tridicator gauge occasionally to ensure system water/pressure level hasn't diminished below 12?
  • icesailor
    icesailor Member Posts: 7,265

    I will drill a hole in the bottom, and lighten it up that way

    I've done that.

    Time is money. You need more than one hole to break the vacuum.

    My ADD gets out of control while waiting. Takes away from Billable Time. The bucket under the tank works best. It has a handle on it for carrying out of the basement and I don't get water on myself or the floor.

  • Hate to be the one to say this, but anytime I've had to change an expansion tank that is less than 15 years old, it was to small for the system and was expanding more than 15% of it's wet side capacity each heating cycle causing premature failure at the diaphragm to tank connection. Yes they work when they are undersized usually, but you are guaranteed a premature failure almost linear with how much it is below the 15% expansion per cycle rule.
    Colorado Heating Man
  • D107
    D107 Member Posts: 1,777
    @Pattersonheating: Well for this small system (maybe 15 gal volume, 2 zones etc.) 30lb exp tank would seem large enough. However since pressure seems to run between 15-20#, should I have techs adjust pressure downward on the pressure/feed valve?