depressurizing a pressure system?

[skidsteer]

I'm in the process of putting in a new boiler system. going from a pressurized gasser with storage to a big osb non pressurized
I'm thinking of de-pressurizing my indoor back-up oil boiler and not using a heat exchanger just to get away from the extra pumps&piping; involved with adding the exchanger.

 

[sdrobertson]

If it was mine I would add the exchanger and leave the house pressurized. The reason is that I wouldn't want to have my home system become a open system and introduce O2 to the full system as then you have that issue to deal with over the life of the new boiler. Also you have to worry about where the highest part of the system is because if the boiler is below the house, then when its a open system the water will want to find its level point and that will be above the boiler vent. It can be done but my opinion is that it would be worth it in the long run.

 

[WoodNotOil]

I'm in the process of putting in a new boiler system. going from a pressurized gasser with storage to a big osb non pressurized
I'm thinking of de-pressurizing my indoor back-up oil boiler and not using a heat exchanger just to get away from the extra pumps&piping; involved with adding the exchanger.

What is a "big osb non pressurized"? What is your current boiler and storage setup and why are you switching?

I too would suggest leaving your current system pressurized and using a heat exchanger. Will cause less headaches down the road for the overall system...

 

[tom in maine]

I run an unpressurized system. There is, however, no ferrous material in the loops--no cast iron pumps, boiler or fittings.
Everything is copper, plastic and stainless.
That being said, you can treat the tank water with a corrosion inhibitor, but I am not sure that is worth the risk of corroding an expensive boiler if the treatment is not right.

My boiler is all non-ferrous materials, so it is not an issue.
We pump tank water through the mostly radiant heating loops with no treatments. There is only a dhw hx.

It is simple, inexpensive and works well. I can pull the system down to 104F and still get modest dhw and space heat.

Of course, my house is R-65+.

Things are simple and inexpensive when the heat load is low.