Expansion tank pressure

[Bangon61]

Have almost finished my infloor heating using a hot water heater and grundfos pump. My expansion tank is pre charged to 40 psi. Should I lower the pressure on it?

 

[Mr onetwo]

If you are asking this question I question wether the system is installed correctly.Domestic water pressure starts at 40 psi generally...well tank should be 2 psi below setpoint. An extrol for heat comes from factory 12 psi

 

[mlyonsdc]

Have almost finished my infloor heating using a hot water heater and grundfos pump. My expansion tank is pre charged to 40 psi. Should I lower the pressure on it?

Did you fill the system yet? My system is set to work on 18psi MAX on output to the boiler. When pressurizing the system I have just a few psi 12 max in expansion tank and will let some out to get the charge pressure adjusted to 18psi.

 

[Mr onetwo]

don't touch the pressure in the heating system expansion tank...12 psi is fine

 

[Mr onetwo]

proper piping-system pressure between 12 and 20 psi

 

[fitter30]

If adjusting pressure and more pressure is needed use a bicycle pump not a compressor. There's very little air volume using a compressor could blow the bladder.
Low pressure tire gauge.

 

[chinboys]

It would depend.
If your hot water heater tank is rated for your well or street pressure or more BUT your heating system is designed for lower pressure, you may be overstressing your "heat emitters".

I use a DHW and heat emitter boiler with DHW priority (I set this default).
I have in-floor PEX pipes as well as steel baseboard radiators.
I have a double problem to lower the heated and treated water being fed into my radiators (lower pressure and higher heat (temp) and my PEX system requires lowered temps and can handle more pressure than my radiators.

I have a dedicated water temp mixer to manage the PEX side's output temperature of 110 degrees F. The PEX side's pressure is regulated by the pumping system as well as what I set my expansion tank's pressure at.

Yes, I am aware of my steel baseboard radiators being designed to handle larger pressure but I rely on the set pressure of my expansion tank to maintain pressure as well as absorb over pressure from the boil when DHW or heat is demanded.

The focus is now on my boiler and its pressure relief valve which is set for 30 PSI and ? temperature.

In conclusion, I have a water makeup feeder system that I set for 15 PSI and set my pressure on the expansion tank at 12 pounds.
I also have an expansion tank set for 65 pounds on the external DHW tank as my street water pressure is at 80PSI but I also have a who house pressure reducer that lowers the pressure to 65PSI.

 

[Bangon61]

It's a closed loop system. There is no incoming water. The only pressure would be from the tank and the pump. It precharged to 40 psi. I'm going to lower it to around 18 psi I think.

 

[Bangon61]

If you are asking this question I question wether the system is installed correctly.Domestic water pressure starts at 40 psi generally...well tank should be 2 psi below setpoint. An extrol for heat comes from factory 12 psi

It's closed loop. The tank is on the hot side of the water heater(which is a 40 gallon hot water tank). The pump is right after the xpansion tank .

 

[Mr onetwo]

You need to post up photos.If the expansion tank is pre- charged at 40 psi then you have the wrong tank.

 

[svtride]

My closed loop (sealed system) shop HHS is heated with 50 gallon water heater. My expansion tank maintains / varys between 10-20 psi. When system is off and cold (summer time), expansion tank maintains at 2-6 psi.