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Hydronic heat quiz

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Eric Johnson, Feb 12, 2006.

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  1. Eric Johnson

    Eric Johnson Mod Emeritus

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    This may be slightly off-topic but since this heating system is currently running on wood, I think it is appropriate to the topics at hand.

    This is kind of a contest. The winner gets.....nothing.....but the satisfaction of being right, and at least as smart as me, which probably ain't saying much.

    I've wanted to replace the ugly and basically non-functioning hot water baseboards in our kitchen with a cast iron radiator for some time. Now when you don't need a cast iron radiator, they seem to be all over the place. But it seems when you need a specific size and shape, lots 'o luck finding one.

    I finally found one in Albany, NY, thanks to a classified ad on the internet. Drove over there, paid the guy $40 and hauled the thing home. It was a steam radiator, but my understanding was always that steam rads and hot water rads are interchangable, as long as you can get a bleeder into the top of a radiator rigged up for steam. But when I got to looking at this one, I realized that it has no air flow across the top (aka a "pipe" made with push nipples holding the cast sections together). No airflow means no way to bleed the columns of air, since air rises and they're not connected.

    Thinking maybe I could get my money back, I called a place locally that gets $100 each for used radiators, and even more for the short ones like this one. The guy offered me $10. I'm not inclined to eat $30 if I don't have to.

    Turns out this is a really old steam radiator, manufactured before 1880. As such, it's a steam only radiator.

    But I got it working on my hot water system. There's no air in the columns and the water seems to circulate just fine.

    How do you think I managed that?

    Here's a couple of pics show the rad in place but not installed, and a top view, showing the absense of a top air passage.

    Attached Files:

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  2. elkimmeg

    elkimmeg Guest

    You win if you were smart enough to bleed the entire system once you installed it leaving no air in it.

    Can't tell you the number of those radiators I have deposited into dumpsters. Such a shame nobody wanted them and no place to store them But I did have the low profile ones once
  3. wingnut

    wingnut New Member

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    Is it possible to drill and tap a hole on the top of one end and install a bleeder?? At the same time you may never get enough water to flow through it for good heat transfer seeing how it was made for steam??


    Good Luck!
  4. babalu87

    babalu87 New Member

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    PFFFFFFFFFFFFFFFFT
    What kind of post is this
    Boonies of NY and NO SNOW while we're getting POUNDED ;)
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    Wish I had those dumpsters, elk. You should go on Ebay and see what they get for cast iron radiators in England. Like upwards of $500. The scrap value these days is $80 a ton.

    Of course I bled the entire system when I started it back up. That's not the answer to how I vented this particular radiator. I assure you there's no air in it now.

    Wingnut: bleeding one of the cells wouldn't work because the others would still be full of air. No way for the air to get back down to the bottom of the radiator and out the vent. I thought of that first.

    Think out of the box, people.
  6. Jay Shank

    Jay Shank New Member

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    is that a shut off valve there? and is there on on the other side (don't see one in the)?
  7. Eric Johnson

    Eric Johnson Mod Emeritus

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    It's not hooked up in that pic. That's just piping to help me move it around. But I do have shut-offs on the installation.
  8. webbie

    webbie Seasoned Moderator Staff Member

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    Is that a trick question? Did it just happen to work or did you make it work?

    My first guess would be that there are some feed and return passageways inside the radiator - or at least inside the oversized feed tub at the bottom....just guessing.
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    No trick, Craig. I just figured out a way to do it (while taking a shower, no less). And no, there's no internal piping or tubing other than what you see. The only modifications I made to the radiator itself were to put a plug in the steam vent and reducer bushings into the inlet and outlet taps to get them down to 3/4 inches. No vents on the radiator now. But there's no air in it, either--guarantee you that.
  10. Jay Shank

    Jay Shank New Member

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    Upside down. air rises only hole are the bottom. so flip it over there at the top.
  11. annette

    annette Member

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    This would take a lot of muscle, but you could flip it upside down and fill it. Almost all air could be removed if you hooked up a pressurized hose to one side, and tilted up the opposite side. Is household water pressure enough to do that? Otherwise just stop up that end, tilt the radiator, and pour water into it.

    I guess if you had installed valves on both ends, you could then close off the second end, flip the radiator again, and hook it up.

    But I think doing it that way you'll get air buildup eventually, so maybe you just rigged up some legs and got some pipe elbows in order to install it upside-down?
  12. annette

    annette Member

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    I knew someone was going to post the same thing while I was typing! But... but... I gave more detail!

    darn.
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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    Bingo hawkeye. You win!

    I knew you were on to me with the isolation valve question.

    You win too, Annette, except I have to deduct points for your idea about installing it upside down. Not in living space! I don't think that would work anyway.

    All I did was turn the rad over, filled it up past the isolation valves (which at the time were the high point), closed the valves, turned the rad over and connected it to the system, then filled and vented the system up to the valves (the ones with bleeders built in), then opened the valves.

    The long-term flaw with this arrangement, as Annette suggests, is that as air migrates into the tops of the columns over time, there will be no way to vent it out except disconnecting it and repeating the filling process. I did pipe galvanized unions in behind the valves in case that becomes necessary. However, none of the other 9 radiators on my first floor ever spit anything but water when I vent them at the beginning of the heating system, so I'm guessing that shouldn't be a huge problem. (The upstairs rads are a different story). Other heating system work doesn't automatically mean turning the thing over and filling it again, however. All you really need to do is isolate the rad before draining any part of the system. After everything is vented back up, open the valves like nothing happened.

    In any event, this was more a fun exercise than anything else. Most of the work went into getting it piped up. When I find a compatible hot water radiator, I'll swap it in and find another home for this one. But I'll get another season out of it, at least. And it does a lot better job of heating the kitchen than those old baseboards.
  14. annette

    annette Member

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    I wasn't sure what causes air to accumulate in radiators/water systems, I just know it happens. Shutting those valves before doing any work on the system seems like it should do the trick.

    I wasn't suggesting that you prop the radiator upside down on milk crates with bungee cords holding it to the wall or anything--I figure you probably have a welder, plasma cutter and a nice stock of steel? Or maybe some antique iron scrollwork to stick-weld into a nice base for the radiator?

    My dad replaced our radiators with baseboard water heat in the 70s, and it was a huge improvement. It's interesting that you and another on this site find it ineffective and prefer the radiators.
  15. zogboy

    zogboy New Member

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    Eric are you using a monoflow system? Why won’t the radiator work as it is? It seems the water should flow.
  16. djamwolfe

    djamwolfe Member

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    I had one of these in an old rental house, and they ended up putting a bleed screw at the top of every colum. Ill tell you though, that thing put out a ton of heat.
  17. Eric Johnson

    Eric Johnson Mod Emeritus

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    zogboy,

    I don't know what a monoflow system is. The problem is not getting flow through the radiator, it's that there's no way to vent the air out as you fill it. If you've got water coming in from both sides on the bottom, the air gets compressed up into the columns and prevents the water from flowing around over the top. The only flow you would get, in other words, is across the bottom and the heat would only extend up as far as the water level, which would be somewhere below the top of the radiator. There are only two radiators on this zone, so I piped them in series instead of the more conventional way of branching each rad off a main line.

    annette,

    Baseboard heat works fine if the water in your system is really hot. In my case, I'm generating hot water with a wood-fired boiler (big old house, too), and by the time it gets through the heat exchanger and into the radiators, it's down around 140. That's fine if you have lots of water and cast iron to hold the heat, but it won't have much effect with baseboards (a lot less water flowing through the system). With lower temp water, it's all about surface area.

    djamwolfe,

    Yes, it kicks out some heat. I'd take a stab at drilling and tapping one or two vents, but with 15 or more, you know something is bound to go wrong. Plus, anything made out of cast iron this old is not going to be consistent, section to section.
  18. djamwolfe

    djamwolfe Member

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    I just know as annette seid, air did build up in the fins - so much so I had to bleed it every month. Never did figure out where the air came from.
  19. zogboy

    zogboy New Member

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    It comes from the water ,
    As the water heats it releases gases.
    Over time this becomes less and less.
    Your system should have a built in bleeder vent near the expasion tank.

    Hope that helped
  20. zogboy

    zogboy New Member

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    Eric; monoflow is a 1-pipe loop with venturi tees leading to and from each radiator or fin tube section.
    I was thinking the cast iron would conduct and hold heat efficiently enough to work for you without being filled to the top with water. I would think you are running at 170 –190 degrees. You may need to install a flow control valve to slow the flow on the radiator to allow time for proper heat transfer.
    You could also place a thermostatic control on the radiator to control the temp of the zone that radiator.
  21. Eric Johnson

    Eric Johnson Mod Emeritus

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    Like a monoflow "T"?

    If I had more radiators on that particular zone I would have to branch them off a loop like you suggest. As it is, with just two, there's enough hot water getting through to the second, bigger rad, to where it works. But with 140-degree water, I need all the surface area I can get.

    I posted this question on several plumbing/heating boards to get some professional reaction before doing the work. As you might expect, some people said it might work and others said it def. wouldn't. Nobody seemed to think it would be dangerous (besides moving the radiator around), so I decided to give it a shot. I'm not surprised that it works; no reason why it shouldn't.

    Thanks for the reminder on the air scoop. My wood-fired side has one, but there isn't one on the gas boiler side (which this rad is hooked up to). I should put one in. As I recall, it should be on the supply line as close to the expansion tank and circulator as possible. Since my circ pumps are all plumbed into the returns, which side do you think I should put the scoop on?
  22. joshuaviktor

    joshuaviktor New Member

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    Zogboy, got a question, sorta related. I have an ancient house, with hot water radiators, currently oil fired (just give me a few years and I'll fix that). I believe I have a monoflow system, as it is one pipe, with venturi tees off it. However, 2 radiators have 1 venturi tee, and 1 regular t, and the t's are only 6 or so inches apart on the line. Wouldn't this create stagnant water in the radiator?

    My though is that I need to cut out/plug the non-venturi t, and move the line farther away(if it's supply, move it closer to the pointing out from boiler pump, and if its return, move it closer to the into boiler pump) Do I just need to replace the regular tees with venturi tees? Or do I need to move the piping as well? It just seems strange to see the Tees literally six inches apart.

    Thanks,

    Joshua
  23. zogboy

    zogboy New Member

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    Eric , Yes monoflow tees placed in the one pipe loop.
    I placed the air scoop/expansion tank fitting 24" past the flow control valve on the outlet side of my boiler.
    I set up 3 zones

    zone1 is the monoflow that serves the main house with 80' of fin tube and one 8' burderus radiator

    zone2 servers the mother in law apartment I built in 1990 3 iron radiators from burderus
    http://www.buderus.net/Default.aspx?tabid=36&cid=14&ctitle=multi-purpose they work off a thermostat that has a max setting of 85 degrees for Mom

    zone3 supplies heat for my domestic hot water tank that can be ran 7-24 and never go cold.

    Now I need to add a wood / coal boiler to my house this summer. any ideas?
  24. Eric Johnson

    Eric Johnson Mod Emeritus

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    Marathon Furnace in Richford, NY (south or Cortland) makes a nice wood/coal/oil boiler in several sizes. I bought one new about 12 years ago and recently helped a friend install another new one. Old tech, I suspect, but it does get some secondary burn & has an ingenious grate design. Draft control is with a bimetal device, so no blower or need for electricity. I know where there's a leaky one that you could pick up cheap, assuming you know a very good welder.

    I've got a Royall, circa 1980. There's a pic on here somewhere. They still make them the same out in Wisconsin. I'm in Clinton; let me know if you want to swing by to take a look sometime. The Royall can burn coal, too. It even has a place for electric coils. If push came to shove, you could probably poke an oil jet through the ash drawer door and heat some water that way. (You just heard my sales pitch for when I sell this house).

    Ebay is always a good place to shop for used stuff like that. I've seen a number of used Tarms for sale, mostly over in New England. If money were no object (maybe it's not with you, LOL), then I'd take a serious look at the Tarm gassifier.
  25. zogboy

    zogboy New Member

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    Josh I up-fitted my system when I bought the house. They originally had one monoflow tee per set of radiators.
    Upon checking I found that what is recommended but I needed to place more radiators in my system and some of those were close to the existing monoflow tees.
    For my own peace of mind I replaced every tee in the system as I did find a few that were put in backwards.
    While doing this I put monoflow tees on the inlet and outlet side of the radiators and fin-tubes.
    As for the tee placement I try to keep them as far apart as possible. The closet tees I have are 18" apart (inlet outlet) and 24" between sections.
    My system works wonderfully and it is oil, a burdarus Laguna model 115,000 btu’s from 1993.
    I want to add a coal / wood boiler to supply my heat next year.
    Hydronic is really nice when it works properly. Every inch of my home is comfortable. No Hot spots and no cold spots,
    If it just didn't cost over $600 to fill the tank. Last year I spent $2000 that was at $1.39 a gallon prepay
    This year I am using a coal stove 1&1/2 tons so far at $300 and 200 gallons of oil at $2.39 a gallon
    I am about $300 to the good with the coal...so far
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