Greenwood Question - help!

I am new to the world of wood burning (I received a lot of advice/assistance on a previous thread to get the stove up and running). I had been running smoothly since Wednesday. Tonight, at 1:00 AM, my wife and I were awakened by tremendous knocking in our pipes. I called a good friend immediately who confirmed that the sound was air in the system. As soon as I turned off the water flow to the furnace (which is in an outside shed), the knocking stopped. When I went outdoors, the air release valve was really blowing steam and the temp on top of the stove was maxed out - 250 degrees. For now, the only thing we did was unplug the stove for the rest of the night. The pressure release valve is not popped, but it is able to be. The temp had started to drop by the time I came back inside.

Can someone help me diagnose the problem? This is a Greenwood 100 in an outdoor shed, set up as a closed system.

Your help is greatly appreciated.

ISeeDeadBTUs said:

Is there a circulator pump on the back of your GW? If there is, you need to get that circulator going without opening the damper until the GW cools down.

After that, you will need some more advice from the guys here that are running their units in a closed system.

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I can't get the water circulating without that tremendous knocking sound (which sounds like my pipes are going to explode). I just checked the furnace, and five hours later not much has changed. I know it needs to dump that heat, but I don't know how it can do that and avoid the knocking.

2.beans said:

did you loose power last night by chance? if the temp gauge was at 250 the t/p valve must have blown off which would introduce air to the system. if you already had air it the system the circulator may have become air bound causing the water to stop circulating. you should have left the water on to cool the boiler down. thats the intent of the fill valve. id bleed the air out and start over today. make sure you have all the air out before starting a fire.

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Didn't lose power. The boiler is still hot...should I just let it circulate despite the intense knocking?

2.beans said:

can you try bleeding the air out now, once it cools down the knocking will stop. if you have to open up the pressure valve on the boiler then turn the water on and let run out on the ground untill the boiler cools down, thats if you can open it safely. it probably will be steam and that will burn you real bad so were gloves or something. remember if you did get air in the system the whole house will have air in it

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Released the valve and turned on the water. Got LOTS of steam out the release pipe (no water). I'm sure the temp will creep back up, so should I continue to open the valve? Do I need to let the system on, with the knocking, so the air works out of the system?

2.beans said:

id leave the valve open untill water came out, then you need bleed of the air off manually or it will just do the same thing again. i dont believe the system will take that much air out itself. once you get the boiler cooled down the knocking will stop. you do need to figure out what made it do this before you start burning again, may just be air but you really should check things over.

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After leaving the valve open, it does eventually turn to water. You mentioned manually bleeding off the air. Can you tell me how to do this (remember, I'm a newbie!)

Perhaps this will help someone diagnose the problem. I have the thermostat turned up, but the radiators are not getting hot. There's also making a soft noise (almost sounds like a car trying to turn over, but on a much quieter scale).

I can feel hot water coming in from the stove to my oil furnace, but it doesn't seem like it is being circulated through the house.

2.beans said:

you got air

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Here are the pics of the inside pipes

2.beans said:

you got air

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PICS

Hi everyone. You will be happy to know that I did NOT blow up. Unfortunately, the air that got into the pipes has caused quite a disturbance and we've spent the last three days working with the previous owner (the builder) to replace valves, bleed pipes, etc. etc. As of now, things seem to be running smoothly. The wood stove is back in operation, and the temp has been running at a normal level. Many thanks for all of your input, especially to 2.beans. It was greatly appreciated.

I don't think we really came to a firm conclusion. This is what I know:

1. The blow-off valve on the back of the Greenwood had to be replaced. Whether this was part of the initial problem, or a result of the problem, I don't know.
2. My GW had been running hot the first 4 days of operation (usually 225+), and now seems to be running more normal.
3. The pressure on my oil stove inside may not have been set at the right temp (it was worked on by a technician about a month ago before we started wood). I can't be sure of this because, truthfully, I never paid any attention to this.

So, one theory I have is that the stove was running hot and the blow-off valve was not releasing steam, which resulted in the pipes air locking. Another theory is that there was pressure problem inside which didn't push the water out to the woodstove, causing air.

As I've said before, I'm new to all of this, so these are just some thoughts. They may be totally off course. Whatever the case, things seem to be running more even-keel at this point, which tells me something was off-kilter before.

For those of you wondering about the back-flow preventer, I did ask about this. I do have one, although I'm not sure where.

2.beans said:

how did you make out

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Once again, thanks for all of your help. I really appreciate the amount of time you took on Sunday to walk me through things. After the previous owner came over, I understood the "home side" of my system a whole lot better. I still plan to have a plumber take a look at things at some point to see what he would recommend that we do for upgrades.