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Thread: Please help me to understand why here is no heat to radiators

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    DIY Junior Member epoxybreath's Avatar
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    Default Please help me to understand why here is no heat to radiators

    I am a handyman not a plumber so I'm looking for some help to guide my customer in the right direction. I have a client that is getting ready to sell his house and asked me to put some electric baseboard into a room of the house that has " never been warm." The room has 2 radiators, each on a separate loop with runs of 15 feet from the primary loop. These runs are tapped into the primary as shown in the pictures. When the system is running the pipes that run to these radiators do not heat up at all so I suppose very little circulation to the radiators. Is there a solution to making these radiators function. Radiators are bled. Should there be good flow or is this a design flaw? Thanks for any insight Name:  Heat2.jpg
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    Retired Defense Industry Engineer jadnashua's Avatar
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    Is that a steam system? IF there's only one pipe to each, it must be. It could be that there's a lot of rust in those radiators, and a good disassembly and cleaning might resolve the problem...or, the valve is packed up with crud. Wait for someone with more experience with those to maybe provide a better answer...good luck.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the trades Dana's Avatar
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    If the system is configured as a loop off the side of a main loop it needs something to force flow into the branch. If it doesn't have a mono-flow tee or a branch pump direct water from the main loop to the radiator it'll pretty much just sit there, since there's very little pressure difference between the tapping points on the fat-pipe main loop to induce water to flow through the branch loop.


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    DIY Junior Member epoxybreath's Avatar
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    These loops are set up like this.Thanks for the response. I thought it might be something like that with the water having no reason to branch off, path of least resistance etc. Name:  Loop.jpg
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    My client is moving, so wants the room to be warm for showing the house etc. Will it be a major task for a plumber to do the work? What I am really asking is I can install electric baseboard for $600-$700 But if a plumber can do the work & make the system right it seems to me to be a better way to go unless it will be too expensive. Thanks again.

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    In the trades Dana's Avatar
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    The plumbing aspect of fixing it is probably pretty minor, but it may take a bit of designer time to fully analyze the solutions that would make it work without interfering with the operation of the other radiators and getting decent room-to-room temperature balance. The system topology looks as if it was a 2-pipe steam system (see the picture below) converted to pumped hot water, which is successfully done every day by competent hydronic designers.



    Looking at your simple sketch diagram, installing a valve (or even a narrower section of pipe with a ball-valve for throttling it) at the U between the supply and return sections of the the main loop puts an impedance to flow on the main loop to impose a pressure difference to induce flow through the radiators. If each radiator has a valve (as in your photograph) the flow balance from radiator to radiator can (and must) be tweaked. A really fancy/nice system would use adustable thermostatic valves for each radiator which would be easier for balancing the system, with less interaction between radiators during adjustments.

    On the existing system as-is I expect you'll find all of the gate valves (like the one in your photo) for all of the radiators in the fully open position, which is lowering the pressure difference to something really tiny at the two that have no flow. Closing down the valves on the other radiators slightly may raise the flow through the cool radiators sufficiently to work at least a little bit, but it can take a lot of tweaking to get the room-to-room temperature balance perfect. Barring thermostatic valves, ball valves would be far superior to gate valves for tweaking flows. Gate valves will become eroded to where they can't fully close when used for flow adjustment, and it's possible that the system was once tweaked into reasonable balance 40 years ago, but that the flows have changed over time as the gates eroded away. (Just a WAG.)

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    In the Trades Tom Sawyer's Avatar
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    Quote Originally Posted by epoxybreath View Post
    I am a handyman not a plumber so I'm looking for some help to guide my customer in the right direction. I have a client that is getting ready to sell his house and asked me to put some electric baseboard into a room of the house that has " never been warm." The room has 2 radiators, each on a separate loop with runs of 15 feet from the primary loop. These runs are tapped into the primary as shown in the pictures. When the system is running the pipes that run to these radiators do not heat up at all so I suppose very little circulation to the radiators. Is there a solution to making these radiators function. Radiators are bled. Should there be good flow or is this a design flaw? Thanks for any insight Name:  Heat2.jpg
Views: 67
Size:  48.9 KB
    Most likely,
    gate valves stem broken off gate in the closed position.
    You think there's no air but there is
    Venturi plugged with crap
    Insufficient circulator flow through the main loop
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    In the trades Dana's Avatar
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    Replacing the nylon rope pipe-hanger with something steel won't help the radiator, but might make the place easier to sell.

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    DIY Junior Member epoxybreath's Avatar
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    Thanks to all of you for your input. It has given me the information to reasonably inform my customer. I will replace the nylon with metal strap and encourage the homeowner to have a good plumber take a look at the system. The neighborhoods where I work are full of boiler systems which I find fascinating but I learned a long time ago that they are largely outside my skill package. It is fantastic to have a resource like this and help educate me. Stay Warm.

    Bruce

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