Only one home radiator is getting hot but no water or air when bleeding?

loubif

I hope I can get some advise on how to proceed. I have a natural gas boiler/furnace with radiation heat and up until 3 days ago when the arctic below zero air moved in the system was keeping my home up to temp but has since been dropping and not maintaining temp in my home, I normally keep my thermostat at 65 but temp has dropped to 53 in the last 4 days or so. Here are the symptoms.
1. The heater cycles off and on without being able to maintain thermostat temp.
2. Only one of my radiators is getting hot and its the one closest to the boiler/furnace.
3. When I went to bleed the radiators I'm not getting any water or air coming out of any of them, even on the radiator that is getting hot (top and bottom of radiator is getting hot).
Is there a process of elimination to determine what may be the cause of the constant cycling and no air or water from bleeding the radiators? Suggestions?

Jamie Hall

I'm going to bet that something froze...

Gordy

What’s the system pressure at the boiler gauge?

loubif

The on off cycling has been going on since fall (temps above freezing) and that is when I tried bleeding the radiators and didn't get any air or water, thermostat was set at 65 as this was the temp the system could maintain, when I set it at 70 it seemed as though the boiler/furnace kept cycling and not getting up to that temp.

Gordy

What’s the pressure gauge reading??

Alan (California Radiant) Forbes

Gordy said:

What’s the system pressure at the boiler gauge?

loubif

I'm currently at work but I will have to take a look when I get home. Is there a parameter for pressure I should be looking for?

Gordy

If the system pressure is not high enough to raise the water up to the highest emitter then you won’t get any air, or water when bleeding.

12-15 psi for a two story home.
Apparently this has been an issue in warmer weather.

If it is low, or zero trying adding water to bring pressure up to range. Proceed with caution. If pressure keeps dropping there might be a leak some where especially after this cold snap. The possibility of a pipe freezing, and splitting.

If you couldn’t get air, or water out of the emitter closest to the boiler, but it’s heating. I bet your system pressure is to low.

Gordy

Why it has dropped if it has is another matter. Either you bled emitters, and didn’t replenish the water level, or you have a slow leak somewhere.

loubif

Thank you sooooo much for the comments, I feel like an idiot as I have in years past bled the radiators getting air then water but not once have I replenished the water, I some how thought it would do it automatically, I will have to check on the pressure as well as the overflow tank to see if there is any water in there. My house is old and the water pressure over the last 4 to 5 years has dropped substantially, could the issue be that the system isn't getting sufficient water and if so can I just add some to the overflow tank?

Gordy

There should be an automatic water feeder. However if the main water valve to it is off it won’t keep the proper water level. Or if the pressure reducing valve is fouled it won’t let water into the system.

When you get home post some pics of your boiler, and it’s piping including the feeder valve.
And the boiler gauge reading.

stlvortac

Could the circulator pump be INOP?

JUGHNE

Pump could be not working, but system should always have that 12-15 PSI which would bleed air or water out anytime.

Gordy

Could be the pump. Need to get pressure up first. Pump won’t circulate up to highest point if pressure is zero.

This would also explain cycling. Water is not moving. I still go back to system pressure when nothing comes out at closest emitter to boiler.

Most likely auto feeder screen is limed up.

loubif

I will report back after checking on what everyone has suggested, again, thank you all!!!!!

EBEBRATT-Ed

We are assuming this is water. Could be steam

Gordy

Well, I assumed baseboard emitters, and bleeding of such as to be water based.

Could be steam with baseboard steam emitters.....

unclejohn

Check the pump

loubif

Took some pics, pressure seems to be at 20psi for 3 story. Cant tell if the circ pump is running.

Gordy

So you are saying the system pressure is 20psi, and you are not getting water, or air when bleeding anything?

Gordy

When the boiler kicks on the pump should be running. Feel the pipes to see if water is moving they should get warm/hot going out from the boiler.

DZoro

Does the pressure gauge move when the pump cycles or when you throttle a valve?

D

JUGHNE

Gauge could be stuck, if you tap on the side of it with a tool the needle should giggle.
If you open the boiler drain for a couple of seconds the pressure needle should drop. (It is a good idea to have a brass hose cap available as it may not shut off completely and drip).

Do you ever move the closed ball valve that is on the short horizontal pipe between outlet and inlet of boiler?

loubif

So, the short cycling seems to have stopped after closing the bypass valve that was partially open allowing the outing supply from the boiler to go to the supply lines as well as the return lines (pic 20190202_152351.jpg), as soon as that was closed (pic of the valve in the closed position stopping any flow back into the return side) the short cycling seemed to stop as well as maintaining the temp set on thermostat. Immediately before doing this the boiler was short cycling and 5 min. later after closing off the valve it stopped short cycling??? Also, the expansion tank at first didn't release any water, just air but again, after closing this valve I did start to get some water to come out of the expansion tank? The pressure never changed but the temp did fluctuate dropping as low as about 80 and when cycling as high as 170, we did take the motor off of the housing and the impeller did spin freely. What do you guys think?

loubif

JUGHNE said:

Gauge could be stuck, if you tap on the side of it with a tool the needle should giggle.
If you open the boiler drain for a couple of seconds the pressure needle should drop. (It is a good idea to have a brass hose cap available as it may not shut off completely and drip).

Do you ever move the closed ball valve that is on the short horizontal pipe between outlet and inlet of boiler?

Thats the one that was partially open and we closed it so all boiler supply went directly and only to the supply.

loubif

DZoro said:

Does the pressure gauge move when the pump cycles or when you throttle a valve?

D

Only the temp was fluctuating but not the pressure, may be stuck???

loubif

Gordy said:

When the boiler kicks on the pump should be running. Feel the pipes to see if water is moving they should get warm/hot going out from the boiler.

When the boiler would cycle on the supply gets hotter but can't seem to tell if the pump is running, my brother is going to put a meter on it to be sure.

loubif

Gordy said:

So you are saying the system pressure is 20psi, and you are not getting water, or air when bleeding anything?

I am now getting air out of the radiator/s but no water yet? Gonna get a meter on the pump to see if its working correctly. Maybe thats the reason for the lack of water when bleeding the radiator on the first floor.

DZoro

You have to get all the air out of the system, before the pump can do its job. Keep the pressure up around 20psi while bleeding the air out.
D

JUGHNE

An amp clamp meter might show current draw even if the pump is stalled....and the pump will get hot.