Can Valve on damaged/leaking cast iron radiator just be closed without radiator being removed?

radowner

Hello, I'm trying to learn more about how my radiator system works. My boiler recently stopped working right before a cold snap and one of my small radiators in an enclosed hallway near a drafty door must have frozen because it's damaged. I've been told the radiator needs to be removed and it needs to be capped off. I'm wondering why the valve can not just be closed on leaking and damaged radiators to stop the water from flowing through. I found this online: "With a simple central heating system, each radiator has a basic screw valve at the bottom. If you turn the screw down, you switch the radiator off: the valve closes and hot water flows straight through the bottom pipe, bypassing the upper part of the radiator altogether. Turn the screw up and you turn the radiator on, allowing water to flow right around it. In this case, the radiator is on." If this is how the system works, why can't I just shut off the valve?
Thanks. I appreciate any answers.

nicholas bonham-carter

If there is a valve on each end of the radiator, which will actually close, you can try it, but turning a screw sounds like some sort of flow retarder, rather than a real vave. Remember there is pressure on the system, acting on both ends of the radiator.
You may want to close down your auto-fill, and monitor your pressure, for a few weeks.
I would be interested to know where this advice came from on the Internet.--NBC

Eric_32

What he said.

You need a valve on both ends of the radiator to isolate it from the system.

It only takes one valve to stop flow thru the radiator, that's why there is only one.

If it is cracked and leaking, it will have to be isolated, either by adding shut offs on both lines or remove the radiator and cap both pipes to it.

radowner

nicholas bonham-carter said:

If there is a valve on each end of the radiator, which will actually close, you can try it, but turning a screw sounds like some sort of flow retarder, rather than a real vave. Remember there is pressure on the system, acting on both ends of the radiator.
You may want to close down your auto-fill, and monitor your pressure, for a few weeks.
I would be interested to know where this advice came from on the Internet.--NBC

Hi, Thanks for your response. I'm trying to understand how the system works and found the information on one of those sites explaining how things work. If the hot water flows from the boiler to a pipe system that flows from one radiator to the next, how will the water continue to move to the next radiator if I remove and cap off one of the radiators? How does the hot water continue to flow to the other radiators? Is there a pipe below the radiator that will continue to pass water to the other radiators if the damaged radiator is removed and both ends are capped off? I have a valve that looks something like the attached on the bottom right of the radiator. I always thought if this valve was turned, it would shut off the water flow to the radiator, that's why I thought if the radiator was damaged and not usable, I could possibly shut off the valve and this would stop the water from flowing to the radiator. I just thought this would be easier in case I find another problem on 1 of my larger radiators that would be harder to remove to cap off. It will be relatively easy to remove the current one that's damaged because it's only 36” H x 20” W x 5” D, but I have one radiator that's 10' wide. Do you think I should I keep the damaged radiator and try to find someone to fix it or just have the contractor haul it away? Is it possible to replace a cast iron radiator that's needs to be removed due to damage with a new lighter weight model or does a cast iron radiator need to be replaced with a cast iron radiator? Thanks for your help.

radowner

Eric said:

What he said.

You need a valve on both ends of the radiator to isolate it from the system.

It only takes one valve to stop flow thru the radiator, that's why there is only one.

If it is cracked and leaking, it will have to be isolated, either by adding shut offs on both lines or remove the radiator and cap both pipes to it.

Hi, Please see my response to NBC. I'm wondering how the water will continue to flow to the rest of the radiators if one of the radiators is removed from the system and capped off. Also, wondering if the damaged radiator can be repaired ( a chunk of the radiator came off the upper left) or if it should be scrapped. Thanks

R2.0

radowner said:

Hi, Please see my response to NBC. I'm wondering how the water will continue to flow to the rest of the radiators if one of the radiators is removed from the system and capped off. Also, wondering if the damaged radiator can be repaired ( a chunk of the radiator came off the upper left) or if it should be scrapped. Thanks

Hie tee to the System Help section of this site, which has MUCH better information than almost any other place on the internet for older hydronic systems. Block out a few hours - at least. Here are some links to articles to start you off.
Radiators
Boilers
Loop Hot Water Systems
Diverter Tee Hot Water Systems
Gravity Hot Water Systems


Not trying to put you off, but there have been so many different system designs and configurations over the years that your questions tend to have multiple answers. Give some of these a look, and you will get a much better idea of the questions to ask.

R2.0

radowner said:

I have a valve that looks something like the attached on the bottom right of the radiator. I always thought if this valve was turned, it would shut off the water flow to the radiator, that's why I thought if the radiator was damaged and not usable, I could possibly shut off the valve and this would stop the water from flowing to the radiator.

As an illustration of my comments above about different systems, my house has radiators with valves that look almost exactly like that as well - but they are not shut off valves. The handle only turns 180 degrees - it's a balancing valve, and water always flows through the valve.

ww

you have a cracked radiator..you never know if the water gets really hot..it rises and could hit crack and leak and flood...the hot water valves have a small hole in them..look at one at plumbing supply house...don't look at a steam valve they try to sell you..they are different..the hole is for some flow to go thru so it won't freeze.

i don't know how skilled you are but i'd just drain the system some so i could take the radiator out of the loop until you get another one...check the edr of the radiator you have and try to match it up with a similar one..you can check if the one you have in there is correct by doing some room size calculations too.

if you've concerned about flow just use a two bypass nipples..a union in between with two 90 degree elbows on the supply and return line. i did that before when i had problems and it worked..and also capped it off...you can even use a radiator you have for now that's good..just pipe it in.