Hi I would like to drain the water out of my radiators so I can change the 2 zone valve on my heating system. It is allowing water to bypass so needs replacing but i dont want to flood the house. Please could you advise how I go about this? Thanks in advance Shaun

There could be a few possible causes for the rear heater not blowing hot air in your 2003 Chevrolet ASTRO van. Here are a few things you could check:

1. Make sure that the rear heater control valve is fully open. This valve is located near the heater core and controls the flow of coolant to the rear heater.
2. Check the coolant level in the radiator. If the coolant level is low, the heater may not be able to produce hot air.
3. Check for any leaks in the coolant system. If the system is leaking, it may not have enough coolant to produce hot air.
4. Check the thermostat. If the thermostat is stuck closed, it may not be allowing enough coolant to flow through the system to produce hot air.

If these steps do not help, it is possible that there is a problem with the heater core itself, or with other components of the heating system. It may be necessary to have a mechanic diagnose and repair the issue.

At the boiler should be a purge setup. This consists of a valve to shut the zone off, and downstream of that valve is a drain ****. Attach a hose to the drain ****, and with the boiler running, close the valve and open the drain ****. (Turn the heat up on one zone at a time if you have multiple zones.) You should be able to notice when the air comes out of the hose by hearing it and the hose twitches and jumps when large amounts of air come out. After the air stops coming out, open the valve , close the drain, flip the bypass closed, and let the water circulate, then reapeat procedure. Do this until you hear or see no more air. You can run a long hose outside or you can use a bucket and a short hose. Using the bucket allows you to actually see the bubbles of air, but you will be dumping many buckets before you are done. Most boiler feed valves have a fast fill lever that bypasses the slow 12 psi that the boiler is normally fed at. Using this will speed up the purge considerably, but don't forget to flip the lever back down between, and after purging or the boiler relief valve will blow off and make a mess. Good luck!

Heater needs Heater Core, Heater control valve, air diverter inside the car and hot water in the heater core. If you just change the thermostat you must have had a reason. If the car was running hot it could be a radiator clog. If the core is clogged no heat. If the heater core was drained when you changed the Tstat there may be air in it - if so no heat. If the control valve (on the heater hose) does not shift- no heat. If the diverter door in under the dash does not direct the fan air through the heater core- no heat.

The answer to your question depends on the design of your heating system. There are two common piping arrangements. The first is called a Venturi system. In this type of system you have a main loop that runs around the house with "scoop" tee's that force the water through each radiator/baseboard in the loop. With this type of system you must bleed each radiator individually. At the end of each radiator you should find a bleeder that will require either a flat head screwdriver or a square "key" (available at the big box hardware stores) to open the valve and bleed. This can be a somewhat time consuming process as to do it correctly you must go around the entire loop (preferably in the order of flow) 3 or 4 times to ensure you have moved all the air out of the system.

The next type of arrangement is know as a standard loop. This is where the water flows from one baseboard to the next, in a loop. (ie the baseboards are connected to each other, not just pulled off a common loop). In this type of a system you should find a "stop and purge" set up at the boiler. There should be a valve on the return close to the boiler, and just above that a boiler drain. (faucet type fixture). If you close this valve, connect a hose to the boiler drain and let the water flow into a bucket, you will be bleeding the hot water loop. If you have more than one zone, you will want to close all the valves at the return, and bleed each zone out indiviadually. After all zones have been bled, you can then re-open the valves.

As a note, you should see a water feeder located on the piping going into the boiler. (This device is connected to the cold water line that feeds all your household fixtures. ie sink, tub, etc) If you move the lever to the fast fill position it will allow water to flow into the boiler at a much faster rate, thus helping you push the air out easier. This is only really possible with the Standard Loop layout, because you need to monitor the boiler pressure anytime it is "fast filling". If you are "fast filling" you MUST ensure to release the lever prior to closing the boiler drains or you run the risk of causing the pressure relief valve to open, which can and will cause personal injury and property damage.

Hope this helps

heater control valve not allowing radiator water to flow through the heater core where the heater blower motor blows the heat that radiates off the heater core into the vehicle cheap fix or you can bypass yourself by replacing valve with piece of 3/4 copper pipe and 2 hose clamps

Hi.
No the water does not have to run through all of them....if you have what is known as a mono-flo system.
With this type of system there are tees that divert some of the water to the radiator and some of the water bypasses and goes on to the nest radiator and so on....

If you look on the radiators that are not getting warm or any of the rads for that matter you will see a silver bleeder valve. Some of these take a "key" to open and some just have a screw driver slot.
If you open the beleeder you will probably get air out of the radiator. Leave the bleeder open till the valve spurts water out, then close it.
Continue this until all the rads are full of water.
If no air or water comes then your "fill Valve" on the boiler may be faulty and not allowing water into your system. You may need to replace that and then bleed the rads.....
Bottom line.... air does no heating, the rads must be full of water to make heat. Air in the rads also air locks that loop in a mono flo system...thus no heat...
Sometimes even after bleeding it can take sometime for the water to start flowing through a rad again... be patient...

I hope that this will help you to solve your problem!

Thanks for using Fixya!!

Heatman101

when i flush my radiator.i would first drain out all my old antifreeze.fill radiator up with water then put a bottle radiator flush. pour in radiator.then i will crank car up turn on heater wide open allowing radiator flush flush out radiaator and heater core when done i will drain out water. put in more water flush out all radiator flush out engine and radiator.then put back in antifreeze.you dont want to run water hose to heater core it will rupture it water pressure too high.

I Suspect that you have AIR in your COOLING SYSTEM Fallow Procedures BELOW to Insure there is NO AIR IN COOLING SYSTEM


Draining and Filling Cooling System

Draining Procedure

Important: Do NOT add any engine coolant supplement sealant pellets to the cooling system. Drain and refill the engine cooling system every 5 years or 240,000 km, (150,000 mi) , whichever occurs first.

1. Park the vehicle on a level surface.
2. Remove and clean the coolant recovery reservoir.

Caution: Refer to Radiator Cap Removal Caution in Service Precautions.

1. Remove the radiator cap when the engine is cool:

3.1. Slowly rotate the cap counterclockwise to the detention tab. Do not press down while rotating pressure cap. 3.2. Wait until any residual pressure, indicated by a hissing sound, is relieved. 3.3. After all hissing stops, press down on the radiator cap and rotate the cap counterclockwise in order to remove the cap.
Important: Recover and store used coolant in a used coolant holding tank and submit the used coolant for recycling on a regular basis. Do NOT pour used coolant down the drain. Ethylene glycol antifreeze is very toxic. Disposing of ethylene glycol into the sewer system or ground water is both illegal and ecologically unsound.

1. Place a drain pan under the radiator drain valve in order to collect all of the used coolant.
2. Open the radiator drain valve located at the bottom of the radiator tank. If only partial cooling system draining is required, drain enough coolant to perform the procedure.
3. Open the air bleed valve on the thermostat housing 2 full turns
   1. Open the air bleed valve above coolant pump 2 full turns.
   2. Place a drain pan under the engine block drains in order to collect the used coolant.Important: Allow the coolant to drain completely.
      
      
      1. Remove both of the engine block drains.
      • The front left engine block drain is located between the starter motor and the engine oil filter.
      • The rear right engine block drain is located near the crankshaft position sensor.
      Filling Procedure
      Reinstall the engine block drains
      
   3. Close the radiator drain valve,
      1. Install the coolant recovery reservoir. Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL coolant. If Coolant other than DEX-COOL or HAVOLINE DEX-COOL is added to the system the engine coolant will require change sooner; at 50,000 km (30,000 mi) or 24 months.
      2. Slowly add a 50/50 mixture of GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL and clean, drinkable water to the radiator until the coolant level is at the base of the radiator fill neck.
      3. Wait for 2 minutes and reinspect the level of the coolant in the radiator. If necessary, add coolant to the radiator until the coolant level is at the base of the radiator fill neck.
      4. Install the radiator cap.Ensure that the radiator cap arrow points toward the radiator overflow tubeImportant: The air bleed valves are brass. Do NOT over-tighten the air bleed valves.
         
         
         1. Close the air bleed valve above the coolant pump.
            1. Close the air bleed valve on the thermostat housing.
            2. Fill the coolant reservoir with a 50/50 mixture of GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL and clean, drinkable water. Caution: Refer to Radiator Cap Removal Caution in Service Precautions. Important: If the coolant temperature indicator turns ON, turn the engine OFF immediately and allow the engine to cool. Do NOT remove the radiator cap.
            3. Start the engine and allow the engine cooling fan to cycle on and off 3 times. If the low coolant indicator does not turn OFF and the coolant level is above the Full Cold mark on the coolant recovery reservoir, refer to Engine Coolant Temperature Gage Inaccurate or Inoperative.
            4. Turn off the ignition.
            5. Allow the engine to cool.
            6. Ensure that the engine coolant concentration is sufficient.

I will work on the sys.further as I try to locate and replace the bad zone valve--------------------------thank you-----------Lacy Smith

Since you have three on/off timing modes could there be an overlap in the times?
The wires in the unit might be crossed. (don't always assume the contractor who wired maintained the correct colors , I have a friend who blew out a heating pipe because when a replacement motor valve was installed it was never wired right and the plumber assumed the colors were correct so no overtemp shutoff created steam in PVC pipes, OPPS)
There fore maybe one is still coming on. Do you have more than one heating zone? IF so see below

I guess the main question is why manually turn it off? why not use the program.

I will assume your heat is know as forced hot water heating. My house is multizoned however when the zone calling for heat turns off (zone valve closes) I installed a bypass valve in the lowest zone in the house, and reduced the circulator low shut off temp to 130 F which means even though the heat isn't on my circulator will continue to run dumping this excess heat in the lowest part of house to rise through house. (the spring loaded water valve allows the heated water to flow into this zone )We do have two thermistats. And even though the lowest one is not calling for heat the radiators are hot when the excess is dumped into this zone. So investigate and see if your system might be similar. (multizone).

Investigate your wiring, reprogram, replace any battery backup.