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[Cabo]

I was on the jobsite today discussing OWB set ups and a guy with a Central Boiler told me this past fall he had removed the plate exchanger from his set up and the thing has been running better then ever.  I questioned him about tying the 2 systems together since the house boiler is pressurized and he said that the OWB is at about the same elevation as the house boiler thus they balance out.  I continued questioning him and he said that occasionally his 2nd floor baseboards would not circulate if OWB water level wasn't kept topped off.  This whole set up seems very strange to me from what I have read on here.  Maybe I'm not understanding the situation but it seems to be working for him.

[mlappin]

Well....if the closed system is now hooked to a open system, it's no longer closed. Might be working great, might work great for number of years, wonder what's going to happen to the closed boiler though?

Sounds to me like he had a flow problem or should have had a larger HX.

[Sprinter]

Increased indoor boiler corrosion and he will have air problems. If not always, then occasionally. Which he has already learned from topping off the central. If there was a warranty on the indoor boiler, there isn't anymore, so instead of lasting 30-40 years, it could be as bad as just a few more seasons. Hard to judge. Taco and grundfos circulators also require a minimum psi to keep the cartridge from failing according to their manual. It's not much.

[yoderheating]

 With no heat exchange between the two it will work better. But there are changes that have to be done to make it work. I have one customer who wanted it done that way and has had great success for many years.

[slimjim]

I WILL NOT install an open system boiler into a closed system without the use of a plate exchanger for the reasons already mentioned, it WILL lead to more expensive problems down the road.

[LittleJohn]

Also of note, is that once the system is all tied together and "OPEN" you should really begin to run SS or bronze pumps - the whole ozidation of pump valoute comes to mind

**yeah warrenty of gad boiler is shot once system is open

I personally went from open to closed system (OWB seperated by water to water HE) so that I could add Antifreeze to closed side and not spend $$$$ on the good glycol to add some level of freeze protection.  Also so I could install on 2nd floor, with less issues

[Scott7m]

Also of note, is that once the system is all tied together and "OPEN" you should really begin to run SS or bronze pumps - the whole ozidation of pump valoute comes to mind

**yeah warrenty of gad boiler is shot once system is open

I personally went from open to closed system (OWB seperated by water to water HE) so that I could add Antifreeze to closed side and not spend $$$$ on the good glycol to add some level of freeze protection.  Also so I could install on 2nd floor, with less issues

If you open a system up to where it's all one, I don't like that but it you do the water treatment will be in the entire system.   Why would you need to run bronze pumps in treated water then? 

[MattyNH]

I WILL NOT install an open system boiler into a closed system without the use of a plate exchanger for the reasons already mentioned, it WILL lead to more expensive problems down the road.

Agreed!!..I will have to say though CB does says it can be directly hooked up by depressurizing the oil boiler…. I don't dont agree with it at all with a open system

[Sprinter]

Theres no warranty on taco and grundfos circulators when used on open or chemical treated systems unless they are bronze or stainless. I have seen Taco warranty tho when it was a real obvious manufacturer fault regardless.

[idahohay]

Side question: does it make sense to go with a stainless circulator in a stainless OWB?

[LittleJohn]

Side question: does it make sense to go with a stainless circulator in a stainless OWB?

If its an open system (ss and bronze should be your only two thoughts)  - If its closed loop, you will be ok with a cast iron

Oxygen is sneaky it will eat out the hardest to replace Non-ferrous components in your system.

[idahohay]

LittleJohn, thats what I was thinking.  My boiler is a Heatmor and not pressurized. It has a ball on a rod in the top overflow but to me it is open and currently have a ss pump (007) but may need to upgrade and not looking forward to the cost.

[LittleJohn]

Sorry to help in the HIJACK of a thread, but idahohay - could you not just get the replacement cartridge for the pump, instead of replacing the whole pump or pump head.

How about this one - pricing between the cheapest 3-speed SS Grundfos and SS Grundfos Alpha - is typically less than $10; which is still about 3x what you pay for a cast iron pump.

[Sprinter]

Should always use stainless or bronze in any open system. It eliminates any corrosion lock up or failure related possibilities. And it will never add corrosion debris to the system. 007 SSF5 is under $200, a cartridge will also do but only a little cheaper than whole unit.

[idahohay]

Sorry I wasn't clear. I'm adding my in floor primary/secondary loops via fphe and the 007 will be facing more head, especially if I use 30% or more glycol so maybe higher head circulator. Sorry to get off topic.