Radiator pipe replacement: DIY-able?

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Old 07-06-12, 09:00 AM
J
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Radiator pipe replacement: DIY-able?

If somebody could give me a quick word of advise I'd really appreciate it.

I'm doing a reno which involves taking out a wall. In order to take out this wall, I need to move some pipes for my 100 year old hot water radiator system, which used to be gravity circulated, but now uses a pump. Here's a diagram of the system. https://www.dropbox.com/s/tqi6a201tc...%20diagram.jpg

The pipes being replaced are the ones on the right, going up to the 2nd floor. In order to reroute them, I have to increase the length of these pipes by about 2.5 times. Also I am going from 1.5 inch steel pipes, to 3/4 inch pex, oxygen barrier. In my design of where the new pipes will go, there is never a spot where they will have to go back up, creating a trap. There are about 15 extra twists and turns, but it is always turning down or sideways, never back up.

I'm doing this with a friend, who knows more about it than me. However, he is not a professional. When I went to pick up supplies today, the fellow there created a lot of doubts in my mind, he was very skeptical of me doing this project because neither of us are professionals. He mentioned worries about creating too much resistance in this pipe. He mentioned the fact that my pipes are already laid out in a poor way, referring to the placement of the pump, expansion tank, and the T beam that happens right away in the supply. He mentioned worries about creating traps and air in the system. Is this a DIY job? Or should I hand it over to a professional?
 
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Old 07-06-12, 02:43 PM
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The pipes being replaced are the ones on the right, going up to the 2nd floor. In order to reroute them, I have to increase the length of these pipes by about 2.5 times. Also I am going from 1.5 inch steel pipes, to 3/4 inch pex, oxygen barrier. In my design of where the new pipes will go, there is never a spot where they will have to go back up, creating a trap. There are about 15 extra twists and turns, but it is always turning down or sideways, never back up.
I don't understand what you mean by "back up". The longer length will not be a problem.
 
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Old 07-06-12, 02:48 PM
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Well, what he was referring to was pipes dipping down to get around beams and then going back up, whereas currently the pipes just go straight up through the walls. Does that make sense? He referred to the possibility of traps forming there. Whether that's a legitimate concern or not I don't know, but we can run the pipe without actually having any dips like that anyways.
 
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Old 07-06-12, 06:12 PM
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Then you should run the pipes without any dips. You shouldn't have any problems.
 
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Old 07-07-12, 11:51 PM
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Piping for Modified Gravity HW System

After reading your post & viewing the diagram I too have misgivings about piping a gravity hw system without at least consulting with a Pro (if you can find one) that is familiar with these very old systems.

Could you tell us how the system has performed in recent years since the pump has been introduced---is there a lot of unevenness in the way the rads heat up??
Does the system burn a lot of fuel for the size of the building??

When these gravity system were originally installed 100 yrs ago there were no pumps/circulators-----the HW was distributed to the rads by convection----since HW is lighter & more buoyant than cold it would rise up the oversized supply pipes to the oversized rads, & cascade down the returns back to the boiler as it cooled.

Once a pump is introduced, the HW distribution is completely changed & it is common in such cases to experience rads that have little heat, or none at all----while others get overheated.

If you are just interested in replacing the piping you removed with PEX when replacing the wall, and most or all of the rads have good heat, then the modification you propose may work for you.

Be aware that any Gravity system was by necessity set up with very large piping & large rads---this means such a system has tons of water to heat up on each call for heat, so a major revamp of the distribution piping using small diameter PEX is usually money well spent.

A Pro that you consult might suggest a more extensive modification of the supply/return distribution piping----one possibility might be using a 2-zone system for the 1st & 2nd floors (or 3 zones if the 3rd fl. needs to be separate), and separate the near-boiler supply piping with monoflo venturi valves or zone circulators (hopefully the near boiler pipes are accessible in the cellar/boiler room)------this would greatly improve heat distribution to all the rads and save $$$ on fuel.

This would give you a T-stat for each floor for better comfort and should also help improve fuel savings.
 

Last edited by Dobbs; 07-08-12 at 12:39 AM.
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Old 07-08-12, 10:16 AM
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Hmm, I'm not sure how efficient the system is, apparently it uses about 650 cubic metres a month to heat a 1800 sq ft home. That's averaged through the 12 months, so would be much higher in the actual winter months here in Canada. I did consult with a pro guy over the phone about this, and he approved it quickly, although he wasn't billing me so I'm not sure how much thought he put into it.

In any case, my friend could only work with me yesterday so the work is done already. I'll test it and if it seems to work I guess we'll give it a winter to see how it works.

The rads have heated unevenly in the past but it seems to be corrected with a lot of bleeding. There's currently no air vent so I'm going to put that in properly.
 
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