Added new radiator to existing system

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Old 12-21-07, 08:51 AM
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Added new radiator to existing system

Hi,

I added a Myson Select panel radiator to my existing hot water system. I have 8 100 year old cast iron radiators with a brand new Slant/Fin Victory boiler.

The problem is that the new panel radiator won't heat up! The radiator is the closest to the boiler, but seems to be running into some resistance. The pipes are hot about half way to the radiator, then gradually cool off. I've seen suggestions for balancing the system, but I don't see a way to do that with my old cast iron radiators. They don't have any flow adjustment valves, other than the on/off valve for water going INTO the radiator.

Also, there doesn't seem to be a problem with the TRV going into the new radiator. The pin moves up and down freely. And it's not a bleeding problem, the radiator is filled with water, it just doesn't circulate.

Any suggestions?
 

Last edited by Raymodj; 12-21-07 at 08:53 AM. Reason: added more info
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Old 12-21-07, 09:14 AM
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How do you have it connected into the existing system?
 
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Old 12-21-07, 12:14 PM
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connection

The kitchen was remuddled in the 60s or 70s and they removed the old radiator and capped the pipes. (and put in an electric baseboard, but that's another story).

So I just used cast iron pipes and hooked up to the old connections, which are Tee's coming off the main pipes. Had to reduce from 1" to 1/2" to fit to radiator valves.

And I forgot to mention in my original post that this is a 2 pipe direct return system.

Thanks.
 
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Old 12-21-07, 03:23 PM
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How close is the rad to the main/return tees ?

When you said "cast iron" you meant 'black' ?

Were you able to tell if the old pipes were 'clear' when you did the install ?

It sounds like air to me, how do you know the rad is full ? were you able to bleed all the air out until you got water ?

If the valves on all the other rads work, you could try shutting them off and forcing more flow through the new rad and see what happens. If there's air stuck there, it might move with more flow.
 
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Old 12-22-07, 01:18 AM
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Galvanized

Sorry, I meant galvanized iron pipes. The silver ones, not black.

The Tees are about 5 feet from the rad.

I've bled the rad a LOT. I also shut off all the 2nd floor rads, and at one point I even shut off half the system from the basement, leaving my rad as first in line, but it still didn't clear. Not sure if I should increase PSI temporarily to force air out?

The old pipes were "clear" (because they still carry water to rad further down the line), so maybe there's air trapped in the return pipe tee elbow joint? I'll try draining the whole system again and see what happens.
 
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Old 12-22-07, 08:07 AM
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Hmmmm.... galvanized ain't the right stuff... shoulda used the black.

Drain it again ? won't that put the air back in ?
 
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Old 12-22-07, 10:39 AM
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galvanized vs black

I thought that galvanized pipe is used for water systems, and black pipe for gas? Anyway, doesn't really make a difference because when things warm up I'm replacing all the pipes with copper and rerouting. They're in the way, always bumping my noggin on 'em. But I'd love to have this rad working until then.

Ok, I tried a few things with no luck. First, drained and refilled. Nothing. As you said, just added more air. Next, bled the radiator and got all the air out, still nothing. Incoming pipe to rad got hot, but cooled off. Then I shut off the TRV and bled again to pull water back thru return pipes. return pipes were hot all the way to radiator, no air came out. The pipe is hot about half way to rad, but won't go any further.

I'm ready to give up. I've bled all the air out so I don't see how it can be an air block. Not sure what else it is other than a balancing issue, and I'm not sure what to do about that since i don't have balancing valves on any of my other rads...
 

Last edited by Raymodj; 12-22-07 at 12:24 PM. Reason: added what i've done
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Old 12-22-07, 03:52 PM
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System Info.

I didn't see where the new rad is in the house, nor how much pressure is on the system.
 
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Old 12-22-07, 04:34 PM
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The new rad is in the kitchen, which is directly above the boiler room in the basement. So there's a few feet of main pipe from the boiler, then the tee branches off and goes another 4 feet or so, then up a foot or two to the kitchen rad. The return pipe has to travel a little farther (and around a corner) to get back to the return tee.

The boiler pressure is 12 psi.
 
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Old 12-22-07, 04:41 PM
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Piping/Pressure

If there is any horizontal section in the piping, I'd bet there is the source of your trouble. You can try kicking up the pressure to 20-25# to see if you can force the air out. Sometimes it works, sometimes not.
 
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