3rd Floor Radiators Not Getting Hot

tbacon · December 2020

My 3rd floor radiators are not getting hot. I tried bleeding them and air would come out for about 10 seconds then stop, I tried heat on and off. Kept bleeding regularly for a week but no improvement. I then had a heater person out. They said given the age of the system it was not worth alot of investment and said I should have it replaced. I then did some Internet research. The PSI was about 10 cold and still 10 hot. So I decided to add water. I used the auto water feed valve and added water till PSI got to like 20 and then bled the radiators on 3rd floor, repeated until I got water at the 3rd floor and a cold pressure of 15. I was then getting heat on the 3rd floor which seemed great! However, the release valve keeps letting water out on a irregular basis (I have a cup under it about 16 ounces that fills up once or twice a day for the last say 4 days), the pressure was going to 25 to 30 when if was actively coming out, I was assuming it would slowly let it out enough water to the right balance but I assume I am also draining the water out of the radiators again. So back to the internet. My current guess is the expansion tank must be full (when I filled the system with water there is now no where for the water to go when pressure increases cause of heating), so my plan was to drain it. It is one of the old steel ones in the ceiling. Any thoughts appreciated. I will also update this after I drain it to let you all know how it goes (it maybe tricking because I dry walled the tank in and might not have a air release.

Jamie Hall · December 2020

The steel tank in the ceiling is -- technically -- an expansion tank, but it's usually referred to as a compression tank. Which is more or less irrelevant.

It should be about half full of water and half full of air when the system is up to pressure. This isn't all that hard to accomplish -- close the valve between it and the rest of the system, and then there are two possibilities. There may be a special fitting on the bottom called an Airtrol, which when opened allows the water level to drop to the correct level. There may not be. If there isn't, just a drain valve, not to worry -- just drain the tank empty and open the valve connecting the tank to the system. Add enough water to bring the pressure up to where it belongs cold (20 psi or so for a three story house).

The tank shouldn't waterlog. However, if the piping has been significantly rearranged, it may -- simply because the tank should connect to the system at a high point near the boiler, and the pipe between the system and the tank should be a straight shot vertical. Also, there should be a fitting at that connection which separates any air in the system and directs it to the tank -- and there should not be any other air removal gadget on the system (that sometimes gets added, too, by mistake).

EdTheHeaterMan · December 2020

based on the story you told, You need to add air to the expansion (compression) tank. When there was air in the radiators, that air was being used as the compression air. Now that you removed the air. you need your tank to have more air in it.

I will look for a comment I made earlier to give you an easy way to get air in the tank. BRB

EdTheHeaterMan · December 2020

Here is an easy way to "Drain the expansion tank"
https://forum.heatinghelp.com/discussion/comment/1620527#Comment_1620527

JUGHNE · December 2020

And now you know who NOT to call in the future for service or even replacement.
3 floors with only 10 PSI is an obvious.

tbacon · December 2020

Appreciate all the information, definitely helps me understand the whole thing better and how to drain the tanks, EdTheHeaterMan! I will report back on the draining of the expansion tank.

tbacon · January 2021

As suggested I drained the compression tank (going to give all the details in hopes of providing back something to the forum), I closed valve to isolate the tank, connected a hose and opened the tank drain. Nothing came out because I needed to let air in, it turns out someone had put one of those taps (like for an ice machine) to allow you to let air in to empty the tank. I opened that and out the water came. It was a big tank probably 20 to 30 gallons roughly given all the buckets I filled (hose was a bit short of drain). I then shut the air value and tank valve off and opened the isolation valve. My pressure dropped to zero (It was holding 10 when isolated). The automatic water valve started to let water in and after a few minutes the pressure went back up to 10. Then I manually added more water to get the pressure to 15, using the bypass on the automatic water valve. We then turned the furnace back on and so far, so good, been about 24 hours and has run alot. The low pressure is about 16 and the high I have seen is about 20. So no more pressure release valve opening and the 3rd floor radiators have water and are hot.

The only thing is seems I should probably do is adjust my automatic water valve to maintain a pressure of 15 instead of what is seems to be set to, about 10. I am thinking to do that I would shut off the system let it cool, then release some water to drop the pressure below 15, then turn the adjustment screw on the valve until it turns on, and keep adjusting screw until it gets the pressure to 15 and is off. Any thoughts on this appreciated.

Again thanks for all the help, I will monitor the thing closely for a few days and hopefully have nothing further to report!

Jamie Hall · January 2021

"The only thing is seems I should probably do is adjust my automatic water valve to maintain a pressure of 15 instead of what is seems to be set to, about 10. I am thinking to do that I would shut off the system let it cool, then release some water to drop the pressure below 15, then turn the adjustment screw on the valve until it turns on, and keep adjusting screw until it gets the pressure to 15 and is off. Any thoughts on this appreciated."

That should work -- and you definitely need to do it to get the water up there.

SteamingatMohawk · January 2021

@Jamie Hall What's the possibility his tank has a bladder in it? I have an unused Xtrol tank sitting around in my basement and it has a Schrader valve stem sticking out of the side. My recollection from my days of owning baseboard hot water is that the expansion tanks had bladders so the pressure cushion (air) didn't get absorbed by the water over a long time.

Jamie Hall · January 2021

Almost anything's possible! But my impression was that it was a rather long cylinder, smaller in diameter, hung from the ceiling. Unless it actually had a Schrader valve on it on one side, and a label, I'd be doubtful fo a bladder...

tbacon · January 2021

My compression tank is long and cylindrical and hung from the ceiling.

3rd Floor Radiators Not Getting Hot

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