Hot Water System Air Problem & Questions

MikeC_3

I have a 4 zone gas hot water system in my building with baseboard heaters that is 4 years old.  Each floor is a zone with a thermostat for each.  There is only one circulator pump for all zones. 



This year when I fired up the boiler the top floor would not receive any heat.  I was able to bleed out the air in the zone and get it to work thanks to the information posted on this board.  The radiators do not have any bleeder valves on them on the 3rd & 4th floors (they do on the 1st & 2nd because there are cast iron radiators by the entrances).   I had to drain it from the spigot in the basement.



Now my questions:



Should the 3rd & 4th floors have bleeder valves or are they OK as is?

Is it ideal to have a circulator pump for each zone?

Should the bell valve below be open when filling the boiler or just in the normal position?

Any way to lessen the chance of the air issue from reoccurring?



Also, the valve like things (name?) below the spigots began to leak for some reason.  I was able to stop it by tightening the nut.  I was told that I should really have a temperature gauge on each zone in order to adjust these things - but since I don't I should leave the parallel to the pipes.  Any information on the correct function of these "devices" would be greatly appreciated.



Thanks in advance!

Steamhead

Take a pic of the boiler

and the piping, expansion tank, circulator and zone valves so we can see how they are installed. If the circulator is on the return line, it's making the air problem worse. "Pumping Away" is the cure. 

Gordan

Those are balancing valves

Their function is to balance flow through the branches, compensating for different circuit lengths (and therefore pressure drops.) Those who told you that you need a temperature gauge are probably thinking that you should measure the branch return temperatures and make sure that they're all the same. That's not a bad approach, given that radiation is usually designed for a given design day temperature drop. You can just use a contact thermometer; heck, even one of those cheap digital meat thermometers will be better than just setting everything wide open!



Once circuits have been balanced, they shouldn't need to be messed with.

MikeC_3

Pics Requested

As requested.  Rust is from last year's issue!  TY

icesailor

Bleeding Air:

For me personally, the only reason I put air vents on baseboard heaters is to shut people up who think you need them. You need to have sufficient system pressure to hold the water up to the heater. I figure 10' per floor. Look on the pressure gauge on the boiler. The one that shows you the temperature and the pressure. On the pressure scale, notice that there is another scale that says either altitude or feet. You need a minimum of 40' of head to have water in the top floor baseboards. Which is just a pipe with fins on it. To be technical, 1# of pressure on a gauge  will support a column of water, 2.31' high. You need to "purge" the zone of air to get the air out. But if the water pressure isn't high enough or other factors come into play, you will have air problems. I have put in a lot of systems. I do them so I can fill and purge from one point. I NEVER go upstairs to vent air. I only go to make sure that the heat is flowing.

Steamhead is right about the circulators on the return. But that's where I always put them because I feel that other problems occur when they are on the supply. But that is my opinion and I don't debate it. I've never had a problem in any system I have done. But I've seen more than one of many systems with over sized pumps on the supply. But that's my debate.

It is very common to use one circulator and multiple zone valves on a system. It is a lot cheaper to install and works as well or better than a gang of pumps running. But that is my opinion again. I don't debate it.

If that fill valve you have is the one shown, it does not have a by-pass lever. You need to adjust the system pressure and the expansion pressure tank to keep water above the top radiator when the system is cold.

It sounds like you have a common system. Purge the air like it was designed to have done and you are good to go.

MikeC_3

Balancing

OK great - do you balance them one at a time or with all heat going to all zones?

MikeC_3

Pressure

Thank you.  I will check the gauge and report back.



I posted more pictures that might clarify things a bit.



I will look on other posts on how to adjust the expansion tank pressure - I know I read it someplace.



Yes that is the bell valve I have  -- what does the lever on the top do exactly?

JStar

RE

The pump is on the supply, but it's before the expansion tank, which makes it the same as if it were on the return. The circulator should be after the tank. And as touched on before, the static fill pressure needs to be a minimum of 24 PSI. I would go to 30 PSI to be safe. The relief valve has to be rated for the extra pressure, and the expansion tank air pressure needs to be increased to the same as the water pressure.

icesailor

Second look:

On second look, the lever on top of the fill valve is the fast fill feature. If you lift it up, it will bypass the setting of the pressure reducing valve (PRV). Look and see what the pressure on the boiler gauge is. I roughly figure 10' per floor. Three floors is 30'. A foot for the baseboard on the fourth floor and 7' for the cellar if the boiler is in a cellar. So 40' is a good "head" number. 18# on the gauge will give you enough pressure to get up to the 4th floor. ( 18# X 2.31' + 39+') so set it for a minimum or 20#. It is probably already set there. Whomever installed the system, know what they were doing. That is a #60 Extrol tank. I've seen a lot of scorched air installers use #15's.

The way I purge is to have a 5 gallon plastic bucket and a washing machine hose. Or a very short hose with a female end. You only want to purge the third and fourth floors with the baseboard heaters. Close the by-pass/stop valves below the drain on the return. Open the zone valve of the zone you want to purge. If you don't open the zone valve, you can't purge it. Put the short hose on the drain and put the other end of the hose in the bucket. Raise the by-pass lever on the fill valve. You should hear water running into the system. The pressure should start going up in the system. When it gets to over 25#, open the drain valve and drain the water into a bucket. Put the end of the hose in the bottom so if bubbles come, you will see them in the water. Watch the pressure gauge. Be ready to close the bypass lever if the pressure gets to 30#. The smart guys usually connect the cold water feed to the system above the boiler so they only add cold water to the system. I, on the other hand, was taught by old dead guys that boilers should be fed on the bottom. If your boiler is fed on the bottom, the water being purged, will become hot. When it comes through hot, you should be purged. If the feed is the top, the water will be cold. Do the other floor. Repeat the process. It should be working.

I would let the system settle down and see what the pressure in the system is when it is cold. I think it is all OK. It just needed to be purged.

It looks to me to be a quality install. But if the pressure isn't at least 20# when it hasn't been running for a while, you will need to raise it. If you need to raise the pressure and can't figure it out, ask here. Someone will help you. Don't do it if you don't need to.

As long as there is enough pressure, even if it is 1# on the third floor, it is enough. It is when it goes negative that you start getting air problems when oxygen separates from the water. And if the system isn't excessively hot, you won't get boiling on the supply when the zone calls.

Good Luck.

icesailor

System Pressures:

I would definitely NOT set the system pressure at 30# because that is usually the rated boiler pressure and the Boiler Pressure relief Valve setting.

That looks like a Taco 007 circulator. It can not develop enough head pressure to overcome the system pressure. The system pressure and the pump head pressure have nothing to do with each other. If that was a Taco 010 pumping 40+ GPM, maybe, but that is the wrong pump for this application and the guy who installed this system, knew what he was doing. It just needs to be purged.



As far as venting on the second, third and fourth floor, I only install "Jet Tees" with the caps on them. I grease them when I install them and never touch them again. If anyone thinks that at my advanced age, I would willingly walk up four floors a few times to vent baseboards, they have been smoking something. Not this old fart. I vent and purge the entire system while standing in front of the boiler and I have never had to go back to vent something.

MikeC_3

Thanks!

Wow!  Thank you all so much for the information - I am going to take the weekedn to digest it all and report back.



One question - although not ideal is it OK where the tank is placed?

Mark Eatherton

PONPC defined....

Read the attached from John Siegenthaler and it will hopefully clear up any questions.



Although (obviously) it CAN work when installed wrong, it works MUCH better when installed correctly. And your continual air problems will disappear....



ME

JStar

RE

He'd have to check the nameplate, but I believe the boiler is rated up to 50PSI with a maximum allowable working pressure of 30. So maybe 25 is the maximum setting to allow the expansion up to 30.

icesailor

50# boiler, 30# Pres. Relief Valve:

The boiler may be rated for 50# but if it has a 30# Pressure Relief Valve, it will be leaking at 30#. You only need enough system pressure to get the water to the top floor radiation level. Any pressure/expansion created by the heaating of the water will just be absorbed by the expansion system. Even if the high limit had the supply temperature leaving the boiler at 215 degrees, you can be sure that it will be lucky to be 200 degrees by the time it gets to the top floor.

In my experience, as long as there is sufficient pressure maintained in the system, it will work trouble free for years. Or until something lowers the system pressure.