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[Ross]

I have an indoor wood fired boiler (New Yorker) with an expansion tank, 35 psi pressure relief valve and an automatic water regulator set at 12 - 15 psi.  The system is a closed hot water system with finned baseboard rads/ 

My problem is that the water pressure is running at 32-35 psi constantly, causing the pressure relief valve to blow off, but no water is being added to the boiler since the pressure is so high.  I have been told this is caused by air in the system somewhere.  I don't know of any way to get rid of the air except by draining the entire system and refilling system.  Due to the cold weather, this is not really an option presently.

If anyone can offer any suggestions \ advice it would be greatly appreciated, thanks.

Ross Kennedy
Nova Scotia , Canada

[rhugg]

As I remember my old oil boiler had an expansion tank but it had one or two Taco air vents that would capture and eliminate air.  Has your system been running for a long period with no problem prior to this?  Why would it be getting air in a closed system now?

Is it possible the relief valve or pressure regulator are acting up?

[MattyNH]

As a closed loop OWB user here.. Open the relief valve and let water out it will bring down the pressure..

[RSI]

Does the pressure go up and down with the temperature? If so the problem is the expansion tank. If it is a bladder type then the bladder probably broke and if it is just a tank with air space it probably filled up all the way.

If this is the problem, the reason the pressure got so high is because when the boiler was not running the water shrunk and the pressure went below the fill valve pressure. Then when you fired it up the water expanded and had no where to go.

[BoilerHouse]

I don't think it should be running st such a high pressure.  The designers must have intended it to run below 10 psi.  Is there a control device which has failed?  Not trying to be alarmist but low water and over pressure is potentially an explosive combination.  If it were me i would allow it to cool to the point where the pressure is 0, make sure the water level is at normal, and than try to figure out why it is over firing.  Is there an aqastat that is supposed to turn on and off a combustion blower fan? 

[RSI]

I don't think it should be running st such a high pressure.  The designers must have intended it to run below 10 psi.  Is there a control device which has failed?  Not trying to be alarmist but low water and over pressure is potentially an explosive combination.  If it were me i would allow it to cool to the point where the pressure is 0, make sure the water level is at normal, and than try to figure out why it is over firing.  Is there an aqastat that is supposed to turn on and off a combustion blower fan?

If it has a properly sized and functioning expansion tank the pressure will not go down when it is cold. (unless it has been boiling and has steam in the system)

[Scott7m]

Does the pressure go up and down with the temperature? If so the problem is the expansion tank. If it is a bladder type then the bladder probably broke and if it is just a tank with air space it probably filled up all the way.

If this is the problem, the reason the pressure got so high is because when the boiler was not running the water shrunk and the pressure went below the fill valve pressure. Then when you fired it up the water expanded and had no where to go.

[MattyNH]

I don't think it should be running st such a high pressure.  The designers must have intended it to run below 10 psi.  Is there a control device which has failed?  Not trying to be alarmist but low water and over pressure is potentially an explosive combination.  If it were me i would allow it to cool to the point where the pressure is 0, make sure the water level is at normal, and than try to figure out why it is over firing.  Is there an aqastat that is supposed to turn on and off a combustion blower fan?

If it has a properly sized and functioning expansion tank the pressure will not go down when it is cold. (unless it has been boiling and has steam in the system)

Like I said open the relief valve..Let some water out.. It will bring the pressure down..I own a closed looped OWB..No different than my oil boiler that is a close loop boiler.. 35 psi isn't gonna blow the furnace apart...I had to change a relief valve before I fired it up for the season..I added too much water..Pressure was up..Opened the relief valve..Pressure normal 10-15 psi..

[BoilerHouse]

Good point - Regardless, the control device(s) should be double checked.  Something is not quite right.

[Ross]

thanks to everyone for all the helpful advice. 

1) Relief valve and pressure regulator have both been changed 2 days ago
2) Expansion tank has no bladder, just the tank, no air vents on the tank, tank has been drained
3) Pressure does not go up and down with temp, seems to stay at 32- 35 psi regardless of temp (as long as temp is above 120 degrees
4) Will try opening relief valve and taking some water out of the system (since I may have too much water in the system, as one poster indicated had happened with his system)
5) All control valves, etc were serviced by technician about a month ago and I was told everything was fine.  This was before I fired it up for the season.

Again, thank you all for your help, if opening relief valve does not work to correct problem then I will have a tech come in and diagnose the problem

[beeman]

i also have a gas fired boiler cant recall what the presser would run but am trying to think of a way to hook my wood boiler to it  ie sidearm or tap into it and the hole thing would be little to no presser if i find the owners manule see what the presser is to run

[RSI]

If you let some out and the pressure comes back I would shut off the supply to the auto fill valve and see if that fixes it. It might not be completely shutting off.

Do you heat domestic hot water with it also? If you do, what type heat exchanger do you have?

[beeman]

i think your right  RSI your house water from the main is about that 30 to 35 mine just hase a ball valve so if i kned water you have to turn it on  but the ato fill could be stuck open