pressure issue with a newly installed boiler

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Guy in DC

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Could someone please advise how the boiler/ system pressure can be fixed?

Last Spring, a company installed a new Burham X-205 boiler with all other elements (zone valves, autofill feed valve, expansion tank). Three zones’ house: two for the aluminum baseboards and one for the large cast iron radiators (most 100 YO).
  • The boiler was fed with cold water up to 12 psi as recommended by the installation guide
  • The autofill feed valve was closed so no additional water is added to the system
Just after installation, a pressure relief valve started to open when the pressure reached 30 psi with temperature reaching 170F. The installer has come a few times to check everything (autofill feed valve, boiler settings) and replacing (PRV, and adding a larger expansion tank – extrol #15 to #30 NOTE: installation with pre-charge settings) and the problem still persists: when the cast iron zone heats up, and reaches 170F, the pressure reaches 28-30 psi and the water starts to drop from the PRV.

The last visit, the installer heated the system and when it reached 30 psi, drained around 1 gallon of water from the boiler so the pressure dropped to 20 or so psi. However, when the boiler doesn’t run (room temperature), there is no pressure, and, in all radiators, there is some air. I checked the pressure in the expansion tank, and it reads 12.5 psi.

When, it heats up, the pressure reaches 25 psi, and everything works fine. All radiators works and no air when I bleed.

My concern is that I don’t know what pressure, and its variation, I have in the system.

I read most of the related posts on this forum. In the past, Dana was very helpful to me with a similar problem on the old boiler https://terrylove.com/forums/index....r-system-plumber-in-washington-dc-area.85119/ , so I have some understanding: maybe the expansion tank is too small or maybe it wasn’t charged to a proper setting? If someone assisted with my measurement and questions, it would be very much appreciated.

In my house, the upper most radiator is 20 feet above the boiler, should the expansion tank be charged to 20ft x 0.433 = 8.66 psi and add around 5 psi so targeted around 14 psi? If so, it is almost what I have now. Would 2 psi make such a big difference?

I also consider changing to a bigger expansion tank: from #30 to #60. However, I am confused about the maximum acceptance volume: https://www.amtrol.com/wp-content/uploads/2022/05/MC4400_04_22_Submittal_Data_Book-37.pdf

It is said that an EX-30 tank volume is 4.4G with max acceptance factor .57 so 2.5G; and an EX-60 is 6.7G with .4 so 2.7G, respectively. Does it mean that the EX-30 can accept the same volume as the EX-60? If so, why to install bigger if the smaller is almost the same?

Thank you all.
 

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John Gayewski

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Could someone please advise how the boiler/ system pressure can be fixed?

Last Spring, a company installed a new Burham X-205 boiler with all other elements (zone valves, autofill feed valve, expansion tank). Three zones’ house: two for the aluminum baseboards and one for the large cast iron radiators (most 100 YO).
  • The boiler was fed with cold water up to 12 psi as recommended by the installation guide
  • The autofill feed valve was closed so no additional water is added to the system
Just after installation, a pressure relief valve started to open when the pressure reached 30 psi with temperature reaching 170F. The installer has come a few times to check everything (autofill feed valve, boiler settings) and replacing (PRV, and adding a larger expansion tank – extrol #15 to #30 NOTE: installation with pre-charge settings) and the problem still persists: when the cast iron zone heats up, and reaches 170F, the pressure reaches 28-30 psi and the water starts to drop from the PRV.

The last visit, the installer heated the system and when it reached 30 psi, drained around 1 gallon of water from the boiler so the pressure dropped to 20 or so psi. However, when the boiler doesn’t run (room temperature), there is no pressure, and, in all radiators, there is some air. I checked the pressure in the expansion tank, and it reads 12.5 psi.

When, it heats up, the pressure reaches 25 psi, and everything works fine. All radiators works and no air when I bleed.

My concern is that I don’t know what pressure, and its variation, I have in the system.

I read most of the related posts on this forum. In the past, Dana was very helpful to me with a similar problem on the old boiler https://terrylove.com/forums/index....r-system-plumber-in-washington-dc-area.85119/ , so I have some understanding: maybe the expansion tank is too small or maybe it wasn’t charged to a proper setting? If someone assisted with my measurement and questions, it would be very much appreciated.

In my house, the upper most radiator is 20 feet above the boiler, should the expansion tank be charged to 20ft x 0.433 = 8.66 psi and add around 5 psi so targeted around 14 psi? If so, it is almost what I have now. Would 2 psi make such a big difference?

I also consider changing to a bigger expansion tank: from #30 to #60. However, I am confused about the maximum acceptance volume: https://www.amtrol.com/wp-content/uploads/2022/05/MC4400_04_22_Submittal_Data_Book-37.pdf

It is said that an EX-30 tank volume is 4.4G with max acceptance factor .57 so 2.5G; and an EX-60 is 6.7G with .4 so 2.7G, respectively. Does it mean that the EX-30 can accept the same volume as the EX-60? If so, why to install bigger if the smaller is almost the same?

Thank you all.
Can you take a picture of how evergreen is set up? With as many components in the picture as possible. No close ups just a picture standing far away with everything in it.
 

Guy in DC

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Not sure, but your logic seems quite sound.

Page 3 puts the acceptance in gallons rather than as a factor, and it agrees with your math.
https://www.amtrol.com/wp-content/uploads/2021/05/MC2680-6_21-EXTROL-Brochure.pdf
The EX-90 would give you lots of margin.

I wonder why the acceptance factor is that way.
Has a good selection.
Thank you. I wonder the same and what the difference is between these two tanks. I thought about the EX-90 but its dimeter is 15 inch so it might be a little bit too tight to install - see pictures below.
 

Guy in DC

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Can you take a picture of how evergreen is set up? With as many components in the picture as possible. No close ups just a picture standing far away with everything in it.
Thank you, John. Attached are the pix - if you need more, please let me know.

Note that the zone valves for the baseboards are in the supply pipes (the highest point of the installation set up); for the cast iron is in return pipe.

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Reach4

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How about adding another tank elsewhere in the system?
 

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I am not a pro, and I may be mistaken. But I think anywhere for a supplemental thermal expansion tank would be OK. See what the others think.
 

John Gayewski

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Can you reiterate what the problem is? As I read it your system is working fine after the volume of water was changed.

Your system will be different sizes at different times based on what zone valves are opened. So the expansion tank should be sized based on the whole system at its biggest. If they pumped too much water in it by mistake and then came back and fixed it I think your fine. Is it just that you want to know your current pressure? It'll be different everywhere in your system as it runs and changes size. If you could force all of your zone valves open and attach a gauge at a spot near in the main loop piping near the boiler you could get a reading at cold state and then run the boiler and check it at high temp state, but I'm not really sure what your trying to achieve.
 

Guy in DC

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Can you reiterate what the problem is? As I read it your system is working fine after the volume of water was changed.

Your system will be different sizes at different times based on what zone valves are opened. So the expansion tank should be sized based on the whole system at its biggest. If they pumped too much water in it by mistake and then came back and fixed it I think your fine. Is it just that you want to know your current pressure? It'll be different everywhere in your system as it runs and changes size. If you could force all of your zone valves open and attach a gauge at a spot near in the main loop piping near the boiler you could get a reading at cold state and then run the boiler and check it at high temp state, but I'm not really sure what your trying to achieve.
It sounds like it is fixed but I doubt.

Imagine, I need to drain the system, fill with water up to 12 psi as recommended by the Burham (and the autofill feed valve will stop at this pressure). Then, when the boiler heats up and reaches 170F or so, the pressure goes up to 30 psi. I could do what the technician did (when the boiler is hot, drain some water to 20 psi), but is it how it should work?

I would like to achieve:
  • Establish a relatively consistent pressure range of operation, for example from around 12 – to targeted (should it be 20 psi or 25 psi?) and then to return to 12 psi.
  • How to determine a safe pressure value when the boiler is hot (at the max temperature of 180F)? Is the 25 psi fine or is it too high or lower?
Thank you, John!
 

Fitter30

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Boiler piped wrong. The ex tank, make up water and air scoop is on the supply side of the taco 007 pump needs to be moved to the suction side of pump.
 

Guy in DC

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Thanks. Does it mean that on the supply pipe: the pump first and then the expansion tank? Could the expansion tank be on the return?
 

Fitter30

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Lets double check the ex tank pressure. Need a 0 to 50 lb tire gauge and a tire pump. With water temp 100° or less with boiler and app pumps off measure tank pressure at the bottom of ex tank under the plastic cap. Pressure should be set at boiler pressure 10 - 12 lbs single story. Get water out of test port ex tank is bad.
 

John Gayewski

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Lets double check the ex tank pressure. Need a 0 to 50 lb tire gauge and a tire pump. With water temp 100° or less with boiler and app pumps off measure tank pressure at the bottom of ex tank under the plastic cap. Pressure should be set at boiler pressure 10 - 12 lbs single story. Get water out of test port ex tank is bad.
You can't tell by the pictures which way that pump is pumping. But if you follow the post according to the poster it's pumping toward the upper zone valves which is away from the expansion tank.
 

Guy in DC

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If I fill the cold boiler to 12psi, the pressure reaches 30 psi with temperature near 170F and water start to drop from the relief valve. The last time, the installer reduced the hot boiler pressure from 30 to 20 psi so it won't reach 30 psi anymore, but when it cools down, the pressure is 0.

I am attaching the pix: the exp tank is on the supply line, then the pump, then the pipe divides to three zones.
 

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John Gayewski

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If I fill the cold boiler to 12psi, the pressure reaches 30 psi with temperature near 170F and water start to drop from the relief valve. The last time, the installer reduced the hot boiler pressure from 30 to 20 psi so it won't reach 30 psi anymore, but when it cools down, the pressure is 0.

I am attaching the pix: the exp tank is on the supply line, then the pump, then the pipe divides to three zones.
We need to see the back of the pump to make sure which way its pumping.
 

Guy in DC

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Please see attached. I marked water flow direction. Thank you all for your help!
 

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John Gayewski

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Please see attached. I marked water flow direction. Thank you all for your help!
The pump is not causing the over pressure. If you want to monitor pressure the point where the full valve, sep., and ex. Tank is where I'd go.
 
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