What valves to use for hot water cast iron radiators?

[Eclecticmn]

I have a hot water cast iron radiator system. It has separate supply and return pipes. My kitchen had slant fins that never got warm. I do not want to rehash that issue. The kitchen had not seen heat since at least before 1998 I recently learned.

In a desperation to troubleshoot I cut the 3/4 copper back near the 2 1/2 in mains and looked for blockage. None. So now I am going to re-pipe with O2 barrier PEX and install two under window used cast iron radiators in series. I think they have one pipe up and one down. In my house the valves are on the lower opening where there is one up and one down. Many are both down. I do not think it much matters where the supply goes as that seems mixed in the house.

I read that steam valves allow the radiator to be removed with the system on. If so, then I need one at each end as the supply AND return are under pressure, correct? I replaced all the valves 10 years ago and all I recall is buying "radiator" valves from the local best supply place.

 

[Fitter30]

I'm confused first writing about hot water then steam valves. Was this system steam at one time? Lines don't normally get clogged up unless there has been a leak that introduces alot of water. Then sludge ends up in boiler right before oxygen corrosion eats the boiler. Main problem not heating correctly? Needs pics of boiler, pumps and piping. A drawing how radiators are piped would be nice.

 

[Sponsor]

 

[Sylvan]

YIKES confusing YES

"I read that steam valves allow the radiator to be removed with the system on. If so, then I need one at each end as the supply AND return are under pressure, correct? I replaced all the valves 10 years ago and all I recall is buying "radiator" valves from the local best supply place."

A "Steam" valve used on a steam radiator is either fully open or fully closed NOT used for throttling, that have air vents for this purpose

A valve used on hot water heating ideally has a small hole in a tube that will allow a tiny bit of circulation to help prevent freeze ups even when the valve is in the closed position there is some circulation (hopefully).

Now with the thermostatically controlled valves they are positive shut off and this can cause a problem

Also it is a terrible idea to Mix copper, and steel and plastics on the same heating system as the coefficient of expansion per degree is a lot different of each material and can cause erratic heating at best and premature failure of piping

Also the materials (gasket) on a steam valve is not meant to be in water constantly as it would be prone to failure

 

[Eclecticmn]

I'm confused first writing about hot water then steam valves. Was this system steam at one time? Lines don't normally get clogged up unless there has been a leak that introduces alot of water. Then sludge ends up in boiler right before oxygen corrosion eats the boiler. Main problem not heating correctly? Needs pics of boiler, pumps and piping. A drawing how radiators are piped would be nice.

I'm confused first writing about hot water then steam valves. Was this system steam at one time? Lines don't normally get clogged up unless there has been a leak that introduces alot of water. Then sludge ends up in boiler right before oxygen corrosion eats the boiler. Main problem not heating correctly? Needs pics of boiler, pumps and piping. A drawing how radiators are piped would be nice.

Thanks for the reply. I tried to troubleshoot this system for a long time and gave up. I previously posted piping diagrams and photos elsewhere.
The only radiator not working was the slant fin pair in the kitchen. They are the highest point in that loop and I put elbow bleeder valves which were higher than the copper at each end. No air pock.
The house was first built in 1915. Maybe the it was steam long ago then converted. The hot water boiler is 10 years ago. Burnham. When I moved in I replaced the valves as they were stuck open or shut for the most part.

I will need to replace one valve and learned of steam vs hot water valves. I have one loop in the basement missing the radiator where the valves shut all the way off so they must be steam valves. When I opened one it shot out hot water.

 

[Eclecticmn]

YIKES confusing YES

"I read that steam valves allow the radiator to be removed with the system on. If so, then I need one at each end as the supply AND return are under pressure, correct? I replaced all the valves 10 years ago and all I recall is buying "radiator" valves from the local best supply place."

A "Steam" valve used on a steam radiator is either fully open or fully closed NOT used for throttling, that have air vents for this purpose

A valve used on hot water heating ideally has a small hole in a tube that will allow a tiny bit of circulation to help prevent freeze ups even when the valve is in the closed position there is some circulation (hopefully).

Now with the thermostatically controlled valves they are positive shut off and this can cause a problem

Also it is a terrible idea to Mix copper, and steel and plastics on the same heating system as the coefficient of expansion per degree is a lot different of each material and can cause erratic heating at best and premature failure of piping

Also the materials (gasket) on a steam valve is not meant to be in water constantly as it would be prone to failure

So, I cannot use a steam valve to throttle. I did not know that. When I bought "radiator" valves from the best old plumbing supply store long ago I hope they were hot water valves. Can I tell from looking which valves are which? Steam vs hot water? I learned the hard way that a one inch valve is still one inch but the height got shorter so the steel nipple coming out of the floor had to come up some or be replaced.

Also
I just came upon this which says steam valves CAN be used with hot water. Hmmm.
https://terrylove.com/forums/index.php?threads/steam-radiator-valve-for-hot-water-heat.30840/

 

[Sylvan]

You CAN use a steam valve to throttle ON HOT WATER heating not Steam