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What is this (from very top of gravity heat system)? [SOLVED!]

papakpmartinpapakpmartin Posts: 16Member
edited October 2017 in THE MAIN WALL
Is this a condenser? More to the point, can it be replaced (see the rust that's developed on the bottom)?



  • SteamheadSteamhead Posts: 12,039Member
    That looks like an old expansion tank. The second pipe might be to allow warm water to circulate thru the tank to keep it from freezing, or it might be a "tell-tale" piped to the basement so you could see water coming down and know the tank was full.
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  • JUGHNEJUGHNE Posts: 4,359Member
    Sometimes the overflow pipe is hard piped into the house drain line with a trap. They would fill by looking at the pressure/feet or elevation/temperature gauge.
  • papakpmartinpapakpmartin Posts: 16Member
    Indeed there is an "Altitude Gauge" downstairs.

  • papakpmartinpapakpmartin Posts: 16Member
    Which probably came from here... lol!
  • JUGHNEJUGHNE Posts: 4,359Member
    Yes, that the word I was trying to remember.
    The fixed red line indicator would have perhaps been set on original install for the homeowner to know when the tank is full.
    Is this the original boiler?
    That is a sweet gauge BTY.
  • papakpmartinpapakpmartin Posts: 16Member
    Yep... original, converted from coal to gas. It's a beast.

    So does anyone know if that condenser/expansion tank can be replaced or reconstructed? Is it just a (formerly) watertight box with a feed pipe and a drain pipe up higher?
  • papakpmartinpapakpmartin Posts: 16Member
    And yep... looks like this is the drain side down in the basement... drains into the laundry sink.

  • IronmanIronman Posts: 4,217Member
    It's an expansion tank (not a condenser).

    Is the system still gravity flow or is it pumped? Is there an expansion tank near the boiler?

    Please post some pics of the boiler and its near piping so we can better see what's there and answer your question.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 3,935Member
    Yes, the old tank can be disconnected and a new bladder type expansion tank can be installed
  • JUGHNEJUGHNE Posts: 4,359Member
    If that is truly your connected expansion tank, you could have an exact made from steel by a welding shop. The top of this should be open so any air that finds its way up there can escape.
    So you would typically top this off until water came into your laundry tub. This would be completely full then, once the water heated up some more water would come down the drain line....due to the expansion of heated water.
    Your manual cold water fill valve should feed into the lower return part of the piping.
    As I look at your drain line coming down thru the floor, (probably buried inside walls), we can see water stains on the floor boards.
    There doesn't seem to be any obvious leaks on piping in your first 2 pictures. My guess is that somewhere inside your walls you have a leak on that drain pipe. (Unless there is some other obvious leaking). True it took a 100 years to stain the flooring, but these leaks/drips do not heal themselves.

    So you could replace the exp tank as is or: add a fairly large bladder type expansion tank in the basement, you would need some form of air removal as you would no longer have an "open" system which allowed some of the air to escape. Also probably need a fill valve to keep the system at 12-15 PSI or so, (you could maybe avoid this if you had an accurate gauge and would add water as needed but then you would not have the cushion/storage capacity of the old water tank and you most likely do not have a low water cut off).
    Also a new pressure relief valve set to 30 PSI as you lose the open expansion feature of the open tank.

    You got your money's worth after about 100 years of usage.

  • papakpmartinpapakpmartin Posts: 16Member
    Thanks for the responses, all. I'll get a couple more pictures taken and posted.
  • papakpmartinpapakpmartin Posts: 16Member
    Just a few more photos... share the misery! :)

    @JUGHNE I think the evidence of leak you saw in the basement was from water traveling down that pipe from this apparently long-time leak. The hardwood floor in the closet where the tank is/was shows plenty of evidence of this.

    Now to find, fashion, or commission a replacement...
  • leonzleonz Posts: 214Member
    I would have a new tank built or an equivalent volume tank and rather than have a two pipe entrance into the tank I would simply have one tapping with a short nipple then a pair of unions then a short nipple connected to a Tee coming from the base of the tank connected to two elbows that permit the heat to rise quickly and then travel back down to the boiler sump in the two existing pipes plus the overflow drain pipe back to the sink.

    There is no reason you cannot have an external drain pipe connected to the exterior of the tank draining to your cellar-normally the open to air expansion tanks have the overflow passing through the roof and an elbow with a screen connected to the pipe above the roof line to allow the water to escape if the water gets too hot.

    Replacing it with a bladder tank with a diaphram will require a lot of work and a very large diaphragm tank to have the equivalent volume and an automatic fill valve and a low water cut off installed in the boiler if it does not have one already.

    What you have is a very simple cost effective way to heat a home or building up to three stories tall simply using gravity and I would not change anything other than having a new tank made and perhaps using a soft copper piping from the high water height connected to the exterior of the tank.

    I would change the triple gauge and purchase a new square Marshalltown triple gauge from a Marsh Instruments reseller as they offer a good warranty and test each gauge before its sold.

    Keep what you have and have a new tank made with an external drain tapping to connect to the existing drain pipe to simplify your life rather than dealing with a diaphragm tank and more plumbing.

  • leonzleonz Posts: 214Member
    I could not edit my posting and I wanted to add this:

    I forgot to add-a faster install would be to purchase a larger round steel expansion tank of equivalent volume from a B+G plumbing supply distributor and mount it vertically and just build a shelf to sit it on and connect the piping to it using the upper side tapping for the drain line to the basement.
    You will be back to heating in a much shorter time with much less work and extra time invested except for a carpenter to make the shelf for the tank and new fittings as the plumber will be there for half a day at most anyway.

    If you do all your own work all the better of course.
  • papakpmartinpapakpmartin Posts: 16Member
    Something like this? tank

    I'm calculating that my old tank was barely over 5 gallons.
  • papakpmartinpapakpmartin Posts: 16Member
    Wait... nevermind... i thought it was 5 gallons... its five *years*. :)
  • papakpmartinpapakpmartin Posts: 16Member
    Maybe like this?

    I'm not sure where to find a "B+G plumbing supply distributor"... Googling it doesn't give me anything super helpful...
  • Danny ScullyDanny Scully Posts: 931Member
    That is for domestic water, you probably need a #60.
  • leonzleonz Posts: 214Member
    edited October 2017
    A 30 gallon steel expansion tank is more than enough replace you current tank. Can you tell me which state you are in? I can give you the name of a nearby Bell +Gosset Distributor and a technical sales rep for your area.

    There is plenty of useful information for the layperson at the Bell & Gossett web site.

    You can simply replace the old tank with a new vertical steel expansion tank and reconnect your plumbing after you have a shelf built sturdy enough to support a 30 gallon vertical tank as it will be carrying 25 gallons of water in it at a maximum load plus the actual weight of the tank.

    The water in your heating system or the "tank" does not move, the heat in the water rises and then it cools down and falls back to your boilers sump.

    With your system you do not need to bleed any more air once the radiators are filled with water and you have water coming down through the drain line to the laundry tube.
    You do not a bladder tank rated for your heating needs just the right size steel expansion tank to maintain your system.

    If your system still has water in it all you need to do install the new tank and open the fill valve and wait for the water to come down the drain line and your system is filled to the proper volume indicating the altitude on the upper floors.

  • papakpmartinpapakpmartin Posts: 16Member
    This was about a 9 gallon box that I removed (8” deep x 12” wide x 22” high translating to about 1.22 cu ft). Why would I need such a large replacement? Because it's "different technology" (charged with diaphragm vs the mostly open box)?
  • leonzleonz Posts: 214Member
    edited October 2017
    Please order a copy of Classic Hydronics and a copy of Pumping Away from Dans bookstore, in both of these very well written books about heating and plumbing Dan goes into great detail about gravity heating and other types of heating and he makes it easy for the layperson and plumber to understand how gravity hot water heating works and how efficient it is as all too often plain steel expansion tanks are ripped out when they do not need to be ripped out.

    If you have an exact duplicate made of the tank you can keep it as it is but a taller round steel expansion tank can be mounted vertically and also be connected to you current drain.
    When that tank was made it was solder welded together and by the pictures you have provided to us it probably has an air space for insulation between the exterior and interior of the tank.

    Your house probably does not have an attic as that is where these vertical expansion tanks were originally placed sitting on planks resting on the rafter trusses with the vent pipe coming off the top of the tank and through the roof to allow the excess water/pressure to be discharged safely on the roof away from the living space of the home/apartments. The book Classic Hydronics written by Dan Holohan is another book you should have as it describes hydronic heating from the very beginning when a french chicken farmer first used hot water carried by pails to heat his hatchery to today.

    I have both Pumping Away and Classic Hydronics and What Hydronics Taught Dan Holohan and they have been a godsend to me as far as heating my home is concerned.

    A larger/taller steel open to atmosphere expansion tank gives you more water to act as a cushion and will provide you with more water in the system. I have a 15 gallon tank hanging horizontally in my laundry room ceiling and it has 10 gallons of water in it with a 5 gallon air cushion using an B+G airtrol valve to remove air bubbles because I have baseboard heating.

    A vertical open to air steel expansion tank does not require an air water separator as the water level and THE system pressure is correctly maintained using the altitude gauge(triple gauge) on your boiler by just opening the fill valve until the water comes down the drain line into your laundry sink to be drained away.

    What you have in your home is what is commonly referred to as a "Standing Water Column" by well drillers being the water volume in a water well" EXCEPT its above the ground in the stand pipe used to create the gravity hot water system to feed the radiation in your home.

    All you will need is to install the new open to air expansion tank, reconnect the drain line to the new tank, bleed the radiators if needed and then make sure the new tank is filled with water to the point where the excess water is vented to the basement laundry sink.

    SO if you are sure you have a 9 gallon tank there you can purchase a 20 gallon steel expansion tank and mount it vertically on a shelf and attach the drain line to the upper side tapping and then fill it.

    With your open to air system it is simple and basic and just lets the hot water rise through the system to the radiation and sink back to your boiler sump from the radiators when its cooler to be heated again.
  • leonzleonz Posts: 214Member
    edited October 2017
    What probably happened was they did not want to run a vent line through the roof and the plumber put this soldered tank in the highest place inside the building and then ran the drain line to the basement.

    A larger tank gives you more of a water cushion and still allows the gravity hot water heating system to work well without creating a mess of plumbing with a diaphragm tank and an air scoop as you lose the simplicity of the open system with its vertical pipe stack to the upper floors and you have to add a relief valve in the steam chest of the boiler IF it has a tapping available in the steam chest.

    I would talk to a plumber that does steam work and size the proper open to air(atmospheric) steel expansion tank for your needs as all you may need is a 15 gallon tank(model 15) like I have or the next larger size 24 gallon tank(model 24). Then you just mount it vertically using the 2 side tapping's for the entrance pipe and the drain pipe coming off the upper side tapping. In this way you avoid all the extra plumbing you do not need by replacing the damaged tank with a new open to air tank that drains to the basement it eliminates the work and need to create a pressurized system if a bladder tank is installed instead.

    I am not trying to spend your money, you can keep your heating system simple and basic by replacing the old tank with a new one just like it was designed to do.

    The Bell and Gossett 15 and 24 gallon steel expansion tanks have one inch tapping's.
    My 15 gallon tank was ordered from the folks at Tribro supply in Vestal, NY and paid for before shipping it and I received it from the Bell and Gossett warehouse in Buffalo, New York a week later. It would not take long for a new tank to arrive at your home from one of their regional warehouses.

    You would need two 3/4" pipe plugs to seal the gauge tappings and whatever fittings you would require to transition to the lower one inch tapping and the one inch pipe tapping used for the drain tapping on the side of the tank.

    EDITED for clarity on 10/9/17
    Judging by the first photo image you could build a shelf next to the risers for the new tank and then connect the upper tapping to the drain line and the lower tapping for the hot water line entering the tank using 2 more one inch unions and nipples of black steel pipe making an upside down U at the bottom tapping with two elbows connected with a short nipple to the one inch tee that is connected to the botttom tapping with a third one inch union from the Tee and nipple entering the bottom tapping.

    I would use the unions and plug them and then just fill the pre-assembled piping and tank to check for leaks before installing it.

    The cooler water will travel back down to the boiler sump from the tank base using the existing unions on the two riser pipes that are already there and the top one inch tapping can be used for connection to the boiler drain pipe connection.

    By creating the upside down U in the bottom tapping it also keeps the water in the steel expansion tank warmer to reduce any chance of freezing as the heat in the water is always moving by simple gravity.
  • papakpmartinpapakpmartin Posts: 16Member
    Today's update: I found someone who could remake the tank, so that seems like great news. Price is higher than I expected so I'm talking to a couple of other shops tomorrow just to verify.

    @leonz, thanks for the good info and the book recommendation.
  • leonzleonz Posts: 214Member
    I am glad I could help you. You have a great heating system there and I would hate to see you lose it as it has worked so well for so long. It will continue to work well for you as long as you maintain the water PH and drain the sediment form the boiler as needed.
  • papakpmartinpapakpmartin Posts: 16Member
    First quote to build a replacement tank was $550. I looked a little more and found a local sheet metal fabricator who will have it done for me tomorrow at half the price. :)

  • leonzleonz Posts: 214Member
    edited October 2017
    Be sure to have them fill it with water and leave it for at least 48 hours before you pay for it. No amount of spot welding will seal it but gas welding with the white flux rod will as long as they are careful gas welding it if they are not using 1/8" steel sheeting for the tank walls and base.

    I hope that they will weld in the the new nipples for you and leak test it for 48 hours.

    I want you to succeed not fail my friend.
  • papakpmartinpapakpmartin Posts: 16Member
    I appear to have succeeded! :)

    There were some gotchas (of course). They'd mixed up the tall and short pipes a bit; they were in the right places, but on the bottom they'd reversed the lengths. Then I learned that unions back when the rusted box was installed are slightly different than unions today (read: leaked).

    In the end, I got it installed (much more solidly attached to the wall than before), filled it *and* had to reinstall a radiator into the bathroom I'm remodeling and bleed that.

    Filled it all up and bled all the radiators, cranked it on, and boom... all good. Being able to fill until I saw the drain line starting to flow was very nice.

    I don't think it's ever worked this well... seems more even upstairs. (I could be projecting, though.) :)

    Just in time for the chilly weather.

    I really appreciate all the feedback here... it was really helpful... THANKS! :)
  • papakpmartinpapakpmartin Posts: 16Member
    Bonus content: The bathroom radiator had been removed because the entire room had to be gutted... all the way down to the joists. All new flooring and tiling installed, I moved it back and and, yep, 3/4" too high relative to the pipes. Of course, the pipes being ancient, I couldn't modify that without pain.

    So, I shortened the radiator.

    Of course, I was terrified. I wasn't sure it was safe, and Googling around provides contradictory answers. But it seemed to me that the radiators were just the same part attached over and over, and the legs seemed "added on" to the standard part, so I went for it. It took about 20 minutes with a reciprocating saw and a couple of new metal blades. Then it fit right in. Seems to be all good. :)

    Fun extra: Cleaned up the mess with a magnet inside a ziploc bag...

  • leonzleonz Posts: 214Member
    I am so glad that the replacement tank is working for you you will be very happy with the heat you will be getting from the system with no issues.

    Did you purchase a new actual triple gauge to replace the old one or did you keep the original one that was on the boiler?
  • papakpmartinpapakpmartin Posts: 16Member
    I kept the old for now... seems to do what I need and I'm hesitant to touch anything else. :)
  • JUGHNEJUGHNE Posts: 4,359Member
    Good story on cutting off the legs to correct the height issue.
    I have always wondered about that as there are many times with valve replacement that todays valves are shorter than original.
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