please help- System is overpressuring

[ewdudley]

thanks for the advice guys... ill give some of these things a try.

Do:

Old news, but you only need the pressure relief at the unit that can create the dangerous pressure (the boiler). I would plug the storage one.

The storage pressure relief serves no purpose.


Do not:

I would remove some pressure from the expansion tank when the water tanks are up to their high limit temperature. I would get the pressure in the expansion tank down to 15 psi in the expansion tank.

This is flat wrong.

 

[in hot water]

The pressure in the expansion tank needs to be set before you fill and pressurize the system. If your final fill pressure will be 12 psi, enough for a multi story home, then adjust the air charge in the tank to 12 psi. you really don't want to let air out without knowing the pre-charge pressure or you limit the expansion capacity.

It sounds like thermal expansion not pump head. Try turning all the pumps off, I'll bet the pressure stays the same at 180F or so.

www.amtrol.com has a free tank sizer. Knowing the entire system capacity is key.

hr

 

[eriesigtau]

I drained off about 5 gallon of water and now the pressure is about 25lbs at full temp with circs on. I guess I just need to do this drain thing every now and then.

 

[maple1]

That might create another issue - if water is drained off every once in a while, that means fresh water is also periodically entering. Fresh water = fresh oxygen = more chance for internal corrosion.

 

[eriesigtau]

Going back to the flow problem I have. I got to thinking and I was wondering what you guys think of this. If I removed the bottom return pipe at the manfold and made a connection from the bottom of the tank to return going to the boiler, would that correct my flow problem? What I'm thinking here is that would force all return water from the manafold to flow through one return pipe until it gets back to the storage. If the boiler isnt hot and storaage is on, the return water has to go to the tank because the danfoss valve will be shut off at the boiler. The only question is if the boiler is hot and danfoss is open, will the return water go to the tank back through the dip tube to the boiler or would it go staight to the boiler? Pic is on page 1. I mentioned my problem of cyphoning throughout this post.

 

[in hot water]

water is lazy, it will take the path of least resistance. When you pipe pumps in series/ PS it becomes very hard to predict when, where and how much of the flow will go to where you want it too. You have created a hybrid primary secondary series piping layout of sorts. Trial and error changes may get you to where you want to be, as it is right now it will be a system with a mind of it's own.

hr

 

[rkusek]

thanks for the advice guys... ill give some of these things a try.

Do:

Old news, but you only need the pressure relief at the unit that can create the dangerous pressure (the boiler). I would plug the storage one.

The storage pressure relief serves no purpose.


Do not:

I would remove some pressure from the expansion tank when the water tanks are up to their high limit temperature. I would get the pressure in the expansion tank down to 15 psi in the expansion tank.

Most of us if not all would have isolation valves between storage and the boiler or storage and the primary loop. Wouldn't it be wise to have one at the storage too or is there no danger? I'm just looking at all possibilities. I guess it's not like I'm going to heat up my shed to 180* with the tanks isololated so I kind of see your point.

This is flat wrong.

 

[eriesigtau]

Well guys, I rerouted that return line from the manafold to the tank today like I mentioned in one of my last posts and its working very well. The boiler is running hard and gassing. The tank is charging fastly. I started the boiler at 530pm and the tank went from 110 to 150 (815pm). I'm going to watch the pressure for the next couple hours but right now its holding at about 21psi.
Its about 40 deg out right now. I guess the only worry I have for the future is that with cooler temps, more zones will be running and the storage may never get a chanced to charge. Its too bad I don't know of a way to give the house just enough heat to satisfy its needs and dump the rest to storage so that the boiler is always running. As of now, the house is calling or the tank is calling but they cant at the same time.