Cold Radiator

Unknown

Hi Clark-
Sounds to me more like you have a venting problem rather than a "clogged " pipe.

One of the first things you should do is make sure that the radiator has "slope" towards the inlet pipe. Use a bubble level to check this. Pitch or slope is important so that the condensate forming in the radiator drains properly back down the inlet pipe.

Air vents- The air "valves" are actually vents which allow the air in the system to escape but close when steam reaches them so the steam can't escape. If you have air in the system, steam can't get in.

The easiest way to check this is to temporarily install a small (1/8 inch) ball valve on the radiator. (use enough pipe nipples so that you duct any steam away from where it can burn you. Steam burns aren't fun!) You manually open the valve and when steam reaches it, you manually close the valve. If this drastically improves the radiator operation it shows you have a venting problem.

On a one pipe steam system there are 2 types of vent. The first is a "main vent" which allows air to escape from the main steam pipes. This is usually located on the main steam pipe after where the last radiator is connected. Each steam "main" should have its own main vent. These main vents should be large capacity vents like a Gorton #2.

After we have made sure the main vents are large enough and functioning properly, we need to check the individual radiator "valves" vents. These vent the air from the individual radiator to which they are attached so that steam can fill the radiator. These vents come in different orifice sizes (venting speeds)and as a general rule- the farther away from the boiler the radiator is located, the faster (bigger orifice) you need to vent the radiator. What I'm saying here is that you don't necessarily want all your radiator (valves) vents to have the same vent rate. Here are two sites which maybe of help to you:

Gorton vents- http://www.gorton-valves.com/specify.htm

Varivalve- These are vents (valves) with adjustable orifices

http://www.heat-timer.com/literature/VariV056082C.pdf

If you don't have them already, I'd highly recommend you get Dan's books. (See " A Steamy Deal"{ at the bottom of this page) These are easy reading and crammed full of information on the operation and "care and feeding" of residential steam systems. They are a "must" for a home owner with a steam system. Read "We Got Steam Heat" first.

- Rod

Clark

Cold radiator

I have a single pipe gas fired steam system. One radiator in the house (2nd floor)will not heat past the 3rd fin. All other radiators heat nicely. The feed pipe in the room gets hot as well as the union where the radiator and feed pipe are connected. I replaced all air valves with new Hoffmans'. In an effort to see if the radiator was the problem I swapped out a working radiator with the non working one...the result is the same. The working radiator now only gets warm up to the 3rd fin. Could the feed pipe from the basement be clogged? If so how do I unclog the pipe and fix the problem?

Big Ed_4

Check

Remove the radiator vent first , if it heats you need more venting. If you installed the Hoffmann #40 up grade to a adjustable 1A..

If it does not heat make sure mains are insulated. May not have enough steam to heat the uninsulated mains too.

Long out of the way radiator sometimes need a King Vent ..

I seen off set risers plug up but not all that common ..

nicholas bonham-carter

testing for steam pipe obstruction

while you perform this test, listen for "panting" sounds coming from the pipe, indicating a sag in the pipe which could be trapping condensate, through which the steam may have difficulty passing.

also could be that this rad is late, due to poor mainline venting, so that the thermostat is satisfied before this particular rad fills.-nbc

Clark

Thanks for the reply. Last night I took the radiator that was not working properly and moved it to another room. It proceeded to get hot all the way across and heat the room very nicely. I then took a properly functioning radiator and connected it in the problem room and had the same result. No heat in the radiator. I have tried Hoffman 40, Hoffman 1-A with no results.

Clark

I already installed a Hoffman 1-A with no success. I made sure it was pitched properly and even went as far as removed the vent alltogether to see if it would heat properly with no results. The radiator only gets luke warm across the bottom three sections closest to the steam supply connection. The radiator is not at the end of the run. It's somewhere in the middle. I insulated the steam mains when I had a new boiler installed last October.

Clark

I disconnected the radiator at one point and opened the supply valve all the way during a steam cycle. Steam did come out of the feed pipe, but I dont know how much steam and at what rate it should be exiting the pipe at.

Big Ed_4

Check The shut off valve

Open the bonnet of the valve a make sure the flat washer is not dislarged a stuck closed to the valve seat. If clear pour water down into the valve to check for pipe blockage. If the water starts to back up then you have blockage ..

Unknown

Hi Clark- So you're saying that the radiators connected to the main on either side of the lateral going to the problem radiator are working okay? Is there a possibility that the lateral going to the problem radiator also supplies another radiator?

- Rod

Steamhead (in transit)

Clark, where are you located?

Sounds to me like you've done your homework, and may need the assistance of a pro. Try the Find a Professional page of this site, under Resources at the top of the page. If you're in the Baltimore area,contact me.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

nicholas bonham-carter

good point!

i never had that particular problem, but i know it can happen. however if there is a sag in the line trapping water, and preventing steam from getting through as it should, i don't know if it will show up on the "pour water into the valve bonnet" test. wouldn't it just drain down, but still leaving the water in the low spot? if there is debris in the line, you could try the "garden hose flush" by using fittings to adapt the 1/8 in. vent thread to garden hose thread, and flush it out that way. do not open the valve too much as you do this, as the back pressure will be greater than usual in the rad.--nbc