Cold Radiators hot water system

digger

Are the radiators fed from overhead? If so, "jump starting" may work. Cool the Entire system. restart while making sure that the affected zone is circulating. As the cool system warms, the radiators should warm with it. Make sure throttling valves on radiators are not closed (I am sure you have already done this)

Mikey_2

Cold Radiators hot water system

I have a house with three heating zones. In one of the zones, three of my radiators are cold. Only one of the three cold radiators has a bleed valve. I have vented the bleed valve, no air came out just cold water. The remaining 5 radiators are working ok. I tried venting all eight radiators in sequence, got no air, only water, hot water from the good radiators, and cold from the one bad raditator that has a bleed valve. Any suggestions?

Timco

Are the cold rads on a seperate zone? Do you have seperate pumps or zone valves? May be a circ problem. Did this just happen?

T

Mikey_2

all three cold rads are on same zone. there are a total of eight rads on this one zone, three are cold. this just happened. circulation is good, return is hot. just cant figure it out.

Timco

Is it a 2-pipe system, or loop...where the pipes go from one rad to the next? Sounds like some rads are air-bound, and you may need to purge them out. Are the valves fully open?

T

Mikey_2

I think its a one pipe system. I agree that they are probably air bound, but
only one rad has a bleeder valve. When I vent it, I only get cold water no
air, and the other two rads dont seem to have bleeder valves.

Adam_12

When your bleeding the air and water comes out are you replacing the water that is being removed?.Is the zone valve working ? .If it is not some can be overriden by moving the armature to the open position.For the air binding ideally you would like a vent on each rad ,do your rads have vent tappings?.
If so you could go to your local hardware store and buy 1/8 coin vents.Shut your wateroff to your rads ,install the vents,turn the water back on ,add a little make up water and bleed the air out.
If you donot have air vents and your 3 rads are connected in series you may need to do forced purge by having a boiler drain installed after the supply valve to the first rad and a boiler drain installed before the return valve on the 3rd rad.After the drains are installed hook a garden hose up the 3rd rad BD and one to the 1st BD .One of the hoses is to fill the other is to drain,turn on the water and drain .
When the water coming out of the hose stabilizes{it is not jumping around,air will make the hose dance}shut off the fill and close the drain.Open your supply and return lines and hopefully this fixes your problem.Feel free to contact one of the PROs on this board,they have the skills and knowledge to assist you.

Mikey_2

When your bleeding the air and water comes out are you replacing the water that is being removed?. No, I open the bleeder valve, cold water comes out, no air, and I shut the valve.
Is the zone valve working ? Yes, there are 8 rads on the zone 3 are cold, 5 are hot . Only one of the three has a bleeder valve.
If it is not some can be overriden by moving the armature to the open position... Whats is an armature?
For the air binding ideally you would like a vent on each rad ,do your rads have vent tappings?. Dont know, on one of the rads whith no bleeder valve, there is the water supply valve on one side, and on the other side there is the outgoing pipe which is sweated onto the rad coming out of the top. But I see that on the outgoing side, under the rad there is a water valve (like a hose valve) and a spot where a hose can be screwed on.

Thanks for your input!!

Adam_12

Perhaps they purged the air out adding water on the return side and the vent is probably the last rad in the series.Beware the drain may open but may not effectively close,no problem just get a hose cap at your local hardware store.It will screw on the BD no problem.Some zone valves have a manual over ride switch .It is an arm that sticks out the side of the valve body ,there should be writing normally open normally closed.Just pull it backwards {ensure thermostat is off}and hook it up on the grove in the slot.