Best practices for bleeding away airlock

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Old 11-11-13, 07:43 PM
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Best practices for bleeding away airlock

Had a service man check my boiler after a handyman removed two baseboards from my system as he replaced a floor for me. The handyman seemed to close every valve he could find as part of this project, and the boiler did come on one day before I paid any attention to the settings.

So the service man checked and all components seem to be working, including safety valves. He believes the system is airlocked and warned me that it sometimes takes several hours to fully bleed the system. I decided I could handle that myself. He warned me I'd get frustrated and convinced something was wrong, even as I ran all over the house bleeding off baseboards.

My biggest concern is zero pressure on the cold side when the system is not running. I thought this was probably slowing my process of bleeding the air, but am beginning to wonder if I'm on the right track.

I finally closed all but the shortest zone and am please that for the first time after hours of working on this, I have hot water making it the whole way back to the boiler. I was hoping the pressure would pick up when i did that, but so far it has not.

The thermometer on the hot side spikes very quickly. So except for the first start-up from a cold system, the cold-side psi does not always rise very high even when the system is hot. It does rise on that first start, right up until pressure relief valve goes off underneath the expansion tank.

I continue to get air from the system and have yet to get a steady stream from the small valves on the baseboard. There seems to be one of these valves every place their is a rise in the system (if a pipe goes down into the floor and back on on the other side of a door, for instance, there is a bleeder valve where it comes back up).

When I have a bleeder valve open and I'm getting a bunch of steam, is that a good way to get a bunch of the bad air out at once, or am I creating air by bleeding off steam?
 
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Old 11-11-13, 08:02 PM
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Hi Bruce,

The first thing... SHUT THE BOILER OFF!

If you are getting STEAM out of air bleeders it means that your system is dangerously LOW on water!

You need to take pictures if we are to help you.

If the boiler is HOT, do NOT repeat do NOT ADD COLD WATER IN MASSIVE AMOUNTS!

You need to get the pressure up to where it belongs FIRST.

I can't stay tonight any longer, but get some pictures up and I'll take a look tomorrow.

Look for where the domestic water fills the boiler. AFTER the boiler cools, make sure that those valves on that line are OPEN. There should be a pressure regulator in the line... it is supposed to maintain a MINIMUM pressure to the boiler system. They OFTEN get plugged up and don't feed water.

If that's the case, you need to fix that FIRST! You will either

1. DAMAGE the boiler beyond repair by firing without enough water and then introducing cold water

2. Run back and forth bleeding radiators which will be a total waste of time because you have no water in the system to push the air out.

BEFORE firing a boiler after servicing, the system must be FILLED with water to the correct pressure.

ONLY THEN should the boiler be turned on and bleeding continued.
 
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Old 11-11-13, 08:55 PM
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Thank you, Trooper. That makes sense from the training I barely remember receiving from the plumber that made some improvements to the system for me a few years ago. He has since passed away and I have not been too happy with anyone else's "expertise." But, he installed some valves on either side of the pressure regulator for ease of replacement in the "future" (today?).

Killing the switch to the boiler kills the water pump, but I did notice a wire that I think was safe to disconnect that should keep the boiler from firing up while I see if cold-side pressure comes up. I'm also watching the water meter to see if any water seems to be flowing. It is getting very cold, so even though it's unlikely, I'm concerned if i just turned the thermostat very low it could kick on.

Pictures to follow.
 
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Old 11-11-13, 09:34 PM
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System pictures

Ruud boiler






Cold water supply






Pump and expansion tank - the red valve was closed by the handyman


I know this is bad - didn't understand exactly why until NJTrooper's reply. Thank you!
 
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Old 11-11-13, 09:45 PM
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water pump update

60 minutes later . . . No change in the water meter reading of even a gallon. Pump was too hot to touch. Turned off power to entire system and hooked that wire back onto the burner.

I'm no plumber. Better find one?
 
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Old 11-12-13, 07:54 AM
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Hi Bruce, there are a couple things you can do before calling a plumber...

First, on the red regulator valve there is a large nut on the bottom. Close both the valves on either side of the regulator and carefully remove this nut. There may still be some pressure inside the valve (not much will come out) so hang a bucket under it when you remove. There should be a metal screen up inside that valve which may be plugged up. After you get that screen out, clean it, and before reinstalling it, open the right hand valve to feed water through and flush what you can out of the valve. Reinstall screen and nut.

Next, BEFORE you attempt to repressurize the system, using an ACCURATE tire gauge, remove that blue plastic cap on top of the expansion tank and check the pressure in the tank. If it is below 12 PSI add air with a small compressor or tire pump until you have 12 PSI.

There are step by step instructions in this thread:

http://www.doityourself.com/forum/bo...sion-tank.html

for properly recharging the air in the tank. Follow step by step and make sure that your expansion tank is properly charged.

When that is done, turn the water supply back on and see if flushing/cleaning that valve has helped and you can now get water into the system.

If still no water feeds, yes you will have to replace that red valve. I would highly recommend that you get one that has a 'fast fill' lever on it. Bell&Gossett FB38 would be a good choice. Watts 1156 is OK too... there are others as well. It doesn't appear that the one you have now does have a fast fill lever? Please look over the valve and see if there is one... because if there IS then there is something else to try before doing the following................

If you have no fast fill lever, you can 'back fill' your system using a garden hose from a hose spigot. You will also need an old (or new) washing machine hose in order to change the 'sex' of the garden hose in order to create a 'cross connection' to your domestic water system.

Before starting this, of course make sure that the boiler is COOL!!!! You don't want to crack your boiler!

What you will do is connect the washing machine hose to the garden hose so that you have a hose with two 'female' ends. One will connect to one of your homes hose spigots, the other will connect to any boiler drain on your system.

Connect the hose and open the hose spigot a little bit. Go to the boiler drain that yo have the other hose end connnected to and SLOWLY OPEN the boiler drain.

Water should start to feed into the boiler from the garden hose. Watch your pressure gauge as you do this and run the pressure up to about 25 PSI and close the boiler drain.

Go to your radiator bleed valves and start bleeding air.

Pressure in boiler will go down as you bleed, so keep an eye on it and when it gets to 12 PSI, add more water via the boiler drain to bring the pressure back up to 25 and close the drain again.

Continue to bleed until you get only water out of the bleeders.

At this point, check the pressure on the boiler and adjust to 12 PSI by either letting water our, or feeding water in...

Turn off hose spigot.

Your system should now be full enough of water and at a pressure appropriate for you to fire the boiler. So, give it a try and let us know how you do...

Good Luck!
 
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Old 11-12-13, 08:05 AM
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ADDENDUM:

Please do not leave the garden hose connected to the boiler drain hose connection. You do not want to have a chance of boiler water back-feeding into your domestic supply. This is unlikely to happen, but it IS POSSIBLE. Therefore, take the few seconds to disconnect the hose when not actively using.
 
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Old 11-12-13, 11:54 AM
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air expansion tank pressure

Thank you very much for the info Trooper! Dropping temperatures, wind chills, need to get to work in the office, and a realistic assessment of my skills/abilities led to a phone to the plumber prior to your post this morning. It's a different sense of urgency than the last week I've been working on this. But, it was still a good thing as the plumber is able to accomplish "routine" tasks that I would struggle with and try to do with the wrong tools, etc. He's also not claiming to be a boiler expert (his company subcontracts bigger boiler jobs) and he's willing to listen to the points you raise. I told him my desire for a regulator with a quick fill valve and he's off buying a replacement now after determining we had no flow in the old one. Even if it's the filter, I think I'm going to prefer to quick-fill feature for ease of recharging the system (which is not over my head).

If I can bug you a little more, I wanted to get your impression of the expansion tank. It has served me well for over a decade, but seems to be a higher pressure setting than you or others expect. I'm attaching a pic. It calls for 40 psi instead of 12 or 15. Don't know why and I'm assuming I charge it to its specs, not some other volume? It is currently at 38. The pressure relief has sprung appropriately at several times the last week.



Your thoughts?
 
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Old 11-12-13, 01:08 PM
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It calls for 40 psi instead of 12 or 15. Don't know why and I'm assuming I charge it to its specs, not some other volume?
That's because that is a tank that is intended for potable water systems, and not hydronic heating systems.

With a potable system they would typically be used at the cold inlet of a domestic water heater to control the pressure in the domestic system when water heater runs.

It's been debated before as to whether it's appropriate to use that type of tank on a hydronic system or not, concern being that the tank might not be rated for the high water temps in a heating system, but it was more or less concluded that ... "Yeah, it's OK".

I think they cost quite a bit more than a hydronic expansion tank... so the next time you replace it, get the right one and save a few bucks.

The correct pressure to charge a hydronic tank to is the same pressure as when the boiler is COLD, typically 12 PSI.

Since you have 38 PSI in that tank, for all intents and purposes, you might as well have no tank on the system, and if your relief valve is spewing, that is why.

You need to reduce the pressure to 12 PSI or you will continue to have problems with the relief valve spewing. Follow the step by step instructions in the post I linked previously.
 
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Old 11-12-13, 01:25 PM
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Improvement

Well, at least I have water pressure and the bleeding actually produces more water than air.

Thank you VERY much for the explanation on the expansion tank. I will reduce the pressure before getting back to work on the bleeding.

I need to get back to work but will follow the other instructions carefully for the next steps overnight tonight.
 
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Old 11-12-13, 09:04 PM
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Owe you big time, Trooper. House is already back above 60-deg and I expect to wake to a warm house. Pressure staying steady at the cold side, and I'm amazed how quickly I got the major air out of the system. The system is functional but I will continue to work on getting things quieter by getting even more air out of there.

Do you have any good bleeding tips? Hot or cold? Start at the big spigot at the top of the system in the attic until it's flowing good and then start running to all the bleeders? Do these questions really matter?

I've learned alot from this forum - thank you.
 
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Old 11-13-13, 02:46 PM
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Do you have any good bleeding tips? Hot or cold? Start at the big spigot at the top of the system in the attic until it's flowing good and then start running to all the bleeders? Do these questions really matter?
It always helps to 'jack' the pressure when you are bleeding... run it up to like 25 PSI using the fast fill. That extra bit of pressure helps bleeding.

Basically, do whatever works... shut system down and let it 'rest' for a while so the air might collect under the bleeders... then run the system for a while, let the water get good and hot... push thermostat all the way up so boiler hits high limit and really heats the water to drive the air out...

Then shut it down and let it 'rest' again... and bleed again...

Maybe try again, this time with pump running...

You will probably have to do it all again, maybe a couple times in the next few weeks to get all the air out as it's driven out of the water slowly by heating.
 
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