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k sharma
hot water radiator heat

I have 12 radiators throughout the house, all supplied by one furnase. Two radiators (baseboard type) remains cold. Both are supplied by the same hot water line (which is warm to toch in the basement) and drain back to the radiator through a shared pipe. I am guessing that there is a blockage in the return pipe. How can I unblock this pipe? Does this sound like a trapped air pocket? Any tips will be big help

Re: hot water radiator heat

Most likely, it is an air pocket, as you mentionned.
-an air pocket will definitely block hot water from moving
through a radiator (and thus prevent heating)
At the beginning of each heating season it is important
to remove air pockets by purging the air from each radiator
There should be a needle valve at the bottom of each radiator end
Once you have started the boiler, wait for 1 hour, then locate
the needle valves, turn the needle screw left to open the valve,
keeping a bucket handy because once the air is purged, hot water will come pouring out!

Re: hot water radiator heat

K. Sharma:

The above posts are accurate & should be followed.

You have a BOILER, by the way, & not a furnace.

The site below will take you to the title page of the articles on different HW piping arrangements.

You should read this so you can understand how only one or two rads are cold while the others heat up.

Scroll down to the bottom of the page and click onto "Loop hot water heating".

You will notice in the diagram that the hot water HAS TO FLOW from one rad to the other, so there is no chance of one rad not heating up.

Try to follow the piping from the boiler; the boiler heat up the water & the circulator pumps it out the large MAIN SUPPLY pipe (usually at the top of the boiler); the hot water goes thru all the radiators, according to how the rads are piped, & the then cooled water is returned to the boiler to heat up again via the MAIN RETURN pipe (usually to the bottom of the boiler) & the process is repeated.

In the article "Diverter-tee hot water heating" you can see by the way the rads are piped, if air or anything else partially clogs one of the supply or return pipes of the rad (risers), the rad can go cold.

There is also a diagram of a "two-pipe" system, in which a rad can also be stopped by air, etc.

In every case, the pumped hot water, as it is flowing thru the piping WILL FOLLOW THE LEAST PATH OF RESISTANCE.

Read the whole article; then go down in the cellar & determine which piping arrangement you have.

Do you have diverter tees on your piping???

Diverter tees usually have a large arrow stamped on their housing; or the words "supply" or "return".

Do you have a loop system???

Do you have a two-pipe system???

If the suggestions made by the other posters don't do the trick, post back & additional procedures can be explained.


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