I read that "radiant" (ie. Heat radiates from hot water) systems need to be bled, or purged of air, usually radiators are bled once or twice per season, or as needed.

I've never done mine, but now suspect I have to because of the symptoms explained below, and I want to do it myself.

The bedroom zone has been programmed to kick in at 5:50AM before I get up at 6 and go back down at 7 when I leave for the day.

I've been hearing increasingly more and more sounds from the bedroom rad in morning before I get up and I'm worried something is wrong. It would be the furthest upstairs rad from the downstairs boiler.

In the 3.5 years since being in my 10 year old house with an oil fired boiler, I've heard a few minor tick tick ticks, and more recently a slight hiss- all things I ignored in my layman's way, thinking its fairly normal. Today was the most disturbing sound- that of running water, like a tap was on and it was running down a drain. No signs of leaks.

There is nothing I can see on the finned rads to bleed air. The only "air bleeding-looking thingy" I see is on the top of the regulator just before the 4 "zone controlly-looking boxes". I won't touch it until I find out more about how to do it.
THANKS!

Yes the radiators need bled if you hear water rushing through pipes, but more importantly. What is the water pressure in the boiler, could your pressure reducing valve be bad?

[QUOTE=NorthernHeat] What is the water pressure in the boiler, could your pressure reducing valve be bad?[/QUOTE
Thanks for your response, NorternHeat. If I'm reading the gauge on the boiler correctly, it is H20 feet=80, Psi=15. What does that mean?

15 psi is good that is all I wanted to know. Purge the system of air.

[QUOTE=NorthernHeat Purge the system of air.[/QUOTE]
OK - that's good. Will do- as soon as I find out how.
But I don't see any caps on the baseboard rads. At least the ones I've looked at so far. There is a little black plastic like screw on top of a small brass cast piece with "watts " 150 PSI and some other small letters I can't quite make out. That piece is on top of a large brass piece with the name "Watts Regulator". This is in line with the copper pipe feed to the zones and also sits above a small approx 5 gallon tank.
I backed off that screw until it became loose enough I was afraid it might come right out, so I stooped. A small amount of air came out. I mean a very small- 1 second hiss only.
Is there more I should look for or do?
Thanks very much for your insight.

Can you send some pictures, I think you where adjusting the pressure regulator.
Here is a picture of a purge and balance, note the small screw (butterfly valve) is inline with the pipe, (open position) some of the older purge and balances have a smal knob/lever. Turn it 90 degrees (closed) hook up a garden hose and open the boiler valve knob. Now if the pressure reducing valve is working it will let water into the system as you bleed the air out, when you are done and no more bubbles are coming from the hose close valve, open the butterfly again and be sure water pressure is back to about 12 psi.
Good luck

[QUOTE=NorthernHeat]Can you send some pictures, I think you where adjusting the pressure regulator. Here are 2 different views of what I was describing.
I'm new to this ask me, but if I'm looking at the correct the attachments you sent me, well... I can't see anything quite like that here.

Ok, thanks. The top brass piece is an auto vent, the valve stem cap should never be tightened down, unless it is leaking water. The cast iron piece underneath it is a screen and air scoop to help trap the air bubbles. Inside the auto vent is a float that opens and closes the valve stem valve on the very top. It will slowly work air out of the system if it is working correctly.

Thanks for the parts explanation of my previously sent pictures. I have some questions & I'm sending some close ups to try and get a better understanding. You are very helpful.

Is an auto vent in every system? Or, now that I know I have one, does that mean I don't necessarily have to bleed the system if it is working properly and getting air out automatically?

Since releasing that small gasp of air yesterday with what you seem to be saying is the "valve stem cap", I noticed less noise from the rad. Yesterday I had screwed that back down tight where I found it. This morning, I loosened it back & heard an even smaller gasp of air released from the brass auto vent. Then I took that "valve stem cap" right out completely. All it appears to be is a little black plastic screw. (see pic with fingers holding screw out of to hole) Could you please confirm that is in fact the valve stem cap?

Assuming it is, then, in trying to follow your guidance, I've now backed it off one revolution from the snug position I found it in, in hopes it will make it work correctly in future.

The reason I wonder if that is actually the "valve stem cap" you refer to, is that here is no water stain in that immediate area on top of the auto vent and I wonder why would this screw have been tightened down if no water was leaking out of there? I suppose the previous owner didn't know it had to be loose enough to let small amounts of air out.

However you can see, in almost all my pictures, there once was a water leak from the vicinity of the hole on the side of the auto vent. At first I thought it was an insert screw that could be adjusted with some sort of special tool. Now that I've cleaned it off, it appears to be plastic and very fragile, as the cleaning removed small pieces of it that made it look like some kind of an enhanced special allen socket. Now it looks like an ordinary allan wrench would turn it, if it didn't break and crumble up in the process. I hope I don't have to touch that anymore and leave well enough alone for now. What does that inset screw do?

Also I'm wondering if the system is purging of air automatically now that the screw is backed off, do I ever have to add water to the system. There is a tap on the line leading to the auto vent which I could put a garden hose on. However I turned in the on position momentarily and water came out. If I'm trying to put water IN, in would have to be from a higher pressure source right?