Pressure too high when tank gets up to temp.

[VtRv]

I've had my Tarm Solo Plus 30 with 500 gallons of pressurised storage up and running for a few days now. The boiler seems to be heating fine although I'm only reaching flue temperature of around 400 degrees. My problem is that when my tank temperature starts reaching 165 on top 145 on bottom my pressure is in the area of 23 PSI. As it climbs toward 170 on top my pressure relief valve on the back of the tarm starts leaking out a small stream of water at 24 PSI. Last night I managed to get the tank up to 170 on top at which point I shut off the fan with only a little wood and coals left in the firebox. I have to push in on the pressure relief valve to stop it from leaking and seal. I have a Extrol SX90V which is a 44 gallon pressure tank. When I got up this morning and checked the max. temperatures on the tank it had gotten to 173 on top and 172 on the bottom.

I feel like I can't leave the fire to heat my tank and go to bed for fear of excessive pressure. Any ideas on how I can reduce the pressure?

 

[2.beans]

do have any controls that isolate the storage tank when it hits your max temp?if so is it isolating the expansion tank from the storage tank? 44 gallons should be more than enough for 500 gallons.

 

[VtRv]

do have any controls that isolate the storage tank when it hits your max temp?if so is it isolating the expansion tank from the storage tank? 44 gallons should be more than enough for 500 gallons.

No, the only control I have is for the low limit of the tank which tells my gas boiler to take over.

 

[slowzuki]

I'm curious if the expansion tank bladder is torn or if it wasn't precharged right?

 

[VtRv]

I'm curious if the expansion tank bladder is torn or if it wasn't precharged right?

The tank is supposed to be precharged at 12 PSI. I don't have a gauge that goes that low to check it. I did check the bladder by letting a little bit of air out of the valve stem and there was no water.

 

[Medman]

I think I would check that expansion tank to be sure. My tank was supposed to be precharged to 12 PSI but was only at 5. I use a digital tire pressure gauge that reads down to 2 PSI for sport balls, etc. If the pressure in the tank is low you will be reducing the effective expansion room for the hot water. Start with the simple things first.

 

[BrownianHeatingTech]

Put a gauge on the tank. There are no guarantees on the pre-charge.

Joe

 

[VtRv]

Right now with no fire in the boiler since the early morning hours when I shut it down the boiler, the water temp is 170 and shows 15 psi in gauge. The storage tank temp is at 140 top and 137 bottom. I checked the pressure tank with a tire gauge and it show 23 psi.

 

[jebatty]

The specs I read on the Extrol SX90V are 44 gal tank and 34 gal max acceptance volume. After verifying charge pressure and testing again after time for it to show if any leak, just be sure that your total system volume does not exceed the 34 gal max acceptance volume. 34 gal acceptance should allow up to about 850 gal system volume (4% expansion), or to play it real safe 680 gal (5% expansion).

 

[VtRv]

34 gal acceptance should allow up to about 850 gal system volume (4% expansion), or to play it real safe 680 gal (5% expansion).

I'm sure that I'm below the 850 gal volume but may be getting close to the 680 gallon mark.

Let me show my ignorance by asking if I can release some of the pressure in the pressure tank to help lower the pressure on the system when hot? Ideally I'd like to be able to bump my tank temp up into the 180's or so.

 

[Kipstr]

Do you have all the air out of you storage tank? A big pocket of air in the tank can give your high psi. What is your cold psi. ? My system psi. 115 deg. to a high 185 deg. is 12-14 psi and a high about 22 psi.

 

[VtRv]

I do have an air purge on the storage tank and I'm pretty sure all the air is out.

 

[BrownianHeatingTech]

Let me show my ignorance by asking if I can release some of the pressure in the pressure tank to help lower the pressure on the system when hot? Ideally I'd like to be able to bump my tank temp up into the 180's or so.

Yes. Just be sure to use a gauge while doing it, so you don't release too much.

Joe