I have a two story saltbox home being heated with an oil hot water furnace and radiators for heat. The home has two zones, one for down and one for up. I can't seem to maintain a comfortable temperature on both zones. Upstairs is always cooler than downstairs. Both thermostats are set to 69 degrees. Any suggestions.

Also there seems to be heat getting to only the 1st two radiators of the upstairs zone. I suspect an air lock preventing full circulation. These radiators are the new style without anyway to bleed air out of the system. I know there is a way to flush the zone, can anyone explain it well enough for me to give it a hook.

Sounds like airlock. If there is no air bleed on the loop, (look around, there may be ONE somewhere) you have to flush it out with a fast volume of water.

Is the circulator on the supply side or the return side of the loop? Does this system have isolating valve(s) above and/or below the circulator or somewhere on the loop near the furnace? Does it have a valve on the loop that looks like you could hook a hose to it? This should be close to a loop isolating valve. Where are the backflow preventers? Does the pressure reducing valve have a "fast fill" feature on it? I need a bit more info before I can give you step by step instructions.

Probably a couple of pictures would be in order. If you don't understand what I am asking, or are unsure of yourself, maybe you should call a professional. If you are lucky, you could watch (stay out of the way!) and learn for the next time.

There should be air release valves on the system and these air vents are usually located at the high point of the system. Unvented systems are rare but they can usually be pressure vented buy the installer or by a person who is knowledgeable of the system design. Without seeing your complete system I would be hard pressed to be able to advise you in how to bleed it. Sorry.

hvac1000: I see a lot of bleederless systems around here, especially on tract houses. Jobs are usually done by the lowest bidder. :D Makes me mad though. I don't like the idea of introducing a whole loopful of new oxygenated water into the system every so often just to purge some air. Which of course can cause the problem to reoccur. Air scoops only catch the air coming out of the furnace and you can't circulate that loop air back through the scoop. Sometimes I wonder why scoops are put into the system.

Bleeders systems are junk in my opinion and a major headache. You ave correct in the fact that it is a no win situation when all the new water you put in the system eventually has to give up its oxygen content when it is heated and the whole problem starts over again.

On a second thought it could be possible his system is under pressured or lacking altitude. That was not brought up in my post but that sure plays you know what with the second floor heat.

Wow, you are right. That didn't occur to me either. I have seen that so seldom. Almost always they are over pressure.

johntodd: Check the pressure gauge on your furnace. Usually they are a dual gauge, one half temp and the other half pressure or altitude. If you have a 2 story house with baseboard heat and furnace in the basement, the altitude should read about 20 ft or 11 psi. A couple more psi will not hurt things, but less than 10 could be the cause of these symptoms.

I had a furnace man purge the air out of this zone a couple of years ago, but was at work and did not see how he did it. Seems to be a re-occurring issue and would like to be able to do it myself. I know he did hook up a hose and force water through the zone. I do have valves in place to isolate the zone, just need to know how to hook up the hose and what to do to flush the zone. This picture will give you an idea. There is only one pressure gauge and the furnace runs at about 15 psi.Attachment 27538

15 psi is plenty. I don't have time right now to explain how to flush that zone, but I think I can tell you from the picture. Maybe someone else will do it first.

Here are my belated instructions for flushing out an airlocked heat zone. Sorry about the time delay, but you can't schedule emergencies.

1) Turn all tstats down so they are not calling for heat. This will close the zone valves. The zone valves may take a minute or so the shut down. The circulator will stop when they are all shut down. Hopefully one of the zones that are working OK is hot.
2) Shut the furnace electric off. You do not want it to fire or run the circulator or electrically operate zone valves while you are doing this. Note the system pressure (altitude) on the gauge.
3) Close the two valves on the left hand side for the zones that you do NOT want to purge.
4) Hook a drain hose to the purge drain valve at the back on the left below these shutoff valves. Leave the valve closed for now.
5) Manually open the zone valve (over behind the expansion tank on the right) on the zone you WANT to purge. You might see the word OPEN or MANUAL and an arrow pointing in the direction you want to rotate the disk under the control head to open the valve manually. It should be about 1/4 of a full rotation. It will stop at the end of it's rotation, you shouldn't have to force things.
6) Close the gate valve (blue handle) below the circulator.
7a) If the pressure regulator (PRV) has a fast fill capability you can use that and skip step 7b.
7b) otherwise you will have to connect a fill hose from a hydrant or wash tub somewhere to the boiler drain valve (BDV, below the gate valve) for your line pressure water and CLOSE THE RED BALL VALVE BETWEEN IT AND THE PRV. NOTE: Bleed this feed hose, you don't want to push that much EXTRA air into the system.
8) Open the purge drain valve (mentioned in step 4) and then activate the fast fill on the PRV (to allow full pressure and flow). If you had to use the 7b method, open the BDV. You did bleed and pressurize that supply hose didn't you? :)
9) When the air stops bubbling out of the drain hose and the water gets hot your zone is purged. 10) Disable the quick fill or shut the BDV. As quickly as possible shut off the purge drain valve to keep from getting any air back into the system.
11) If necessary, use the boiler drain valve to slowly reduce the system pressure to what it was before you started.
12) Now open the blue circulator isolation valve, the red handled zone isolation valves, and the PRV isolation valve if you closed it in 7b. Ignore that zone valve, it will take care of itself. Check for any leaks at the valves you connected hoses to.
13) When you are satisfied that your system is back to normal, as in valves and pressure, set the tstat on that warm zone mentioned in step 1 to call for heat and then turn the electric back on.
14) After the furnace comes up to temperature, reset all tstats to normal, which should call that newly flushed zone, and feel the heat where there was none before. :)

Hopefully I got it all down neatly and completely. It is easier for me to do that job than to describe it. Especially from a picture. There are things I check while I am doing a job like this. I can't even think of them all while at my computer. If you had a good furnace repairman do this job he would be checking for other problems which you will not notice. This obviously would be value added for his time, but I can appreciate you wanting to DIY. Good luck. And as a final note, you just got 1.5 hours of my time on all this for FREE. Go figure what that was worth. And to all you other pros on the list, if I missed something please correct it. I got to hit the hay.

Looks like a great job EPMILLER. I am glad you had the time to think it out and post all those goodies.

Thanks EPMiller for the information. I asked a plumber this question today and he explained it pretty much the same way, only now I won't have to worry about my memory because you took the time to write it down so well. I will let you know ow I get along.