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  1. #11
    Join Date
    Aug 2007

    Default Re: hot water circulation problem


    Yes, thank for the photos; they are very clear.

    That looks like a B&G little red or red fox circulator pump; I couldn't make out the name of the boiler, & we would have to get its total btu/hr output.

    The HTX 30 Flexcon ET's are listed in my catalog as having a capacity of 4.54 gallons each; hopefully, this will be enough capacity for the amount of water in your system.

    The internal bladder prevents complete extension to the full volume of the ET, but the bladder ET's are allowed to be much smaller than your old steel ET because they are under 12 psi pressure.

    I get the impression that in the case of your system there is a LOT of water; when you total up the water in the boiler, the associated piping & the radiators covering 3 floors it could add up to 100 gallons.
    (You might try getting a ballpark figure of this total).

    When this is multiplied by the expansion factor for when the water heats up to ~200 degrees, you're probably just at the capacity of your 2 new expansion tanks if they're charged to the standard 12 psi.

    If this is true, then the ET's won't have quite enough capacity unless you add a few pounds of air in with a bicycle pump.

    I don't see a shutoff valve near the new ET's; the first step would be to shut down the system, drain some water from the boiler, & install a ball valve in the 1/2" copper tubing just above the ET's.

    Once this is done, you can simply shut the ball valve anytime you want without draining the system to adjust the air pressure in the ET's, or remove them for any other reason.

    You should also attach some steel metal strapping right away to the body of the ET's and secure them to the floor joists above; they way they are now, if they should fill with water, they will fall to the floor from the weight of the water.

    It would be necessary to remove the ET's by unscrewing them from their metal nipple.

    You would then need a normal auto tire pressure gauge to press on to the little tire valve to check the psi charge (usually 12 psi).

    The air pressure would be increased to 15 psi on both ET's by using a regular tire air pump and they would be replaced on the system with the steel strapping.

    I've included some sites below that explain the usual causes of too much water pressure in the system & ways to resolve it.

    The Amtrol site has a chart entitled "Sizing the Extrol"

    If you can determine the btu output of your boiler (it may be listed on the housing, or you can check the internet via the model number) you can determine the size ET you should be using.

    The output of your boiler is probably 150,000 btu/hr or 200,000 btu/hr (just guessing).

    If you notice on the chart, this size boiler output requires a slightly larger ET (SX- 30V is listed at 14 gal max. volume) than the combined 2 that you have on there now.

    This may turn out to be the problem, but make further checks on this.

    The psi on the pressure reducing valve is set according to the height of the highest radiator on the 3rd floor, and its distance from the boiler.

    Thus, if the highest radiator in your house is 25' above the boiler, the formula/calculation is:
    25/2.3 = 10.87 + 4' = 15 psi (the cold psi pressure on the boiler dial).
    Last edited by JacktheShack; 11-12-2007 at 01:21 PM.

  2. #12

    Default Re: hot water circulation problem

    you were right about the circulator pump- its a bell and gossett series 100.

    the boiler is a weil-mclain
    uses natural gas
    according to the label on the inside cover:
    "INPUT- 360,000"
    "OUTPUT- 288,000"

    there is a shutoff valve just above the et's. if you look at the close up pic of both tanks, follow the copper tubing up. its about 8 inches up.

    how would i go about figuring out the "ballpark" figure of the water in the system? there are no radiators in the basement. the first floor is a storefront with 2 cast iron radiators. it also has 4 baseboard radiators.2nd floor has 7 cast iron radiators, as does the 3rd floor. they all vary in size.some are quite large. the house itself is fairly large. about 3000 square feet, not including the basement. im thinking it may be over 100 gallons.

    would you suggest moving the et's so they are hanging upside down or straight up? this can be done fairly easily.

    but according to the sizing chart, i should be using the SX-30?

    jack, i just want to thank you for all your help. the tips and information have been a HUGE help in trying to find the culprit here, and hopefully i will have this resolved before winter really gets here.
    Last edited by bicycledr4376; 11-13-2007 at 10:40 AM. Reason: spelling

  3. #13
    Join Date
    Aug 2007

    Default Re: hot water circulation problem

    Thank you for the additional info.

    In a system at 288k btu/hr, all the charts on the Flexcon, Watts, & Amtrol sites are recommending an ET with 14 gal. volume, instead of the 9 combined gal. ET's you have now.

    But you can probably just add a few pounds of air to each of your ET's & they might well work.

    The ET's can be mounted vertically or horizontally; if they are mounted horzontally they MUST be supported by steel strapping attached to the floor joists, so they don't fall if they should fill with water.

    The charts on the Watts & Amtrol sites I listed are based on the standard amount of water a cast iron radiator and boiler system of that size usually contains.

    They don't recommend using the total water volume of the system as a sizing procedure in these cases since it is difficult to determine the amount of water in each of the radiators.

    They also recommend that the ET connection to the system should be made to the SUCTION side of the B&G pump so that the pump is "pumping away" from the ET.

    It's often connected just the opposite in many systems, & this can also cause a rise in system pressure because it lets a little water & unwanted air in via the pressure reducing valve due to a pressure drop at that point (this, however, depends on exactly how the components are connected, and tends to vary from boiler to boiler).

    The B&G site has a section called "Pump it UP" under the "Diapraghm Tanks' heading that is very informative.

    I wonder if you could draw a diagram of your boiler system if you get a chance, take a photo of it then post it; this need include only the boiler and the immediate piping & components attached to it.

    If you could note where the main supply pipe comes out of the boiler (usually at the top) & what is connected to it (water suppy, reducing valve, ET's, air vents, air eliminator, etc); and also include the main return pipe as it goes into the bottom of the boiler, with the B&G pump connected.

    Where & how these components are connected greatly determines system pressure, air in the system, etc.

    The Radnet site has a Watts site citation that is helpful in sizing ET's.

    Watts has free 800 technical help numbers at 1-800-542-1682 and 1-800-476-1682.

    Additional help can be obtained by contacting "The Wall" at and the "boiler help" site at>plumbing--->Boilers.

    The larger ET's like the Watts ETSX-40 are floor models that cost over $100, so try to work with the 2 ET's you have now.
    Last edited by JacktheShack; 11-13-2007 at 11:45 PM.

  4. #14
    Join Date
    Dec 2007
    Chicago, Illinois (western sub.)

    Default Re: hot water circulation problem

    Jack you use the term "water logged" please define this in this context.

  5. #15
    Join Date
    Aug 2007

    Default Re: hot water circulation problem

    Waterlogged refers to the tendency of expansion tanks to completely fill with water in a hydronic system.

    When this happens, the boiler water when subsequently heated has no place to go, and pops the pressure relief valve to dump water on the boiler room floor.

    Waterlogging occurs most frequently in the older, oblong steel expansion tanks that have no pressurized bladder, but can also happen in bladder-type ET's when the bladder fails.

  6. #16

    Default Re: hot water circulation problem

    hey jack, i just want to thank you again for all your help. i know its been a while, but things have gotten really hectic around here, with the holidays coming and having 3 girls. a couple of weeks ago, a friend and i did some tests on my heating system and found out that i had gotten a faulty prv AND innacurate dual gauge! what are the chances of that? lol! turns out the plumbing supplier across the street from my house had gotten a batch of bad prv's from B&G which were set to 20 psi. after we changed it with a new one, thats when we realized the pressure gauge was 5 psi off. with the new equipment in proper working order, we then tested the system again,and realized the et's werent getting hot. we took one off to check to see if the valve was working properly, and it was, but there must have been a blockage that we flushed out because now they are working good. i really want to thank you again for all your help as it was very informative, and i dont think i could have done it with out your help.

  7. #17
    Join Date
    Aug 2007

    Default Re: hot water circulation problem

    Good job!

    Anyone who can hang on a boiler problem as long as you did deserves all the praise in the world.

    I'll say a little prayer that your heating system will be trouble-free for the rest of the heating season.

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