New Backflow Preventer Failed

I had that happen to the check ball on the outlet of a Claeffi PRV, there is a check built in to the valve for markets where a double check isn't required. The scale attached the plastic ball to the brass seat such that it wouldn't flow water. I strongly suspect it is the additives that our treatment pant adds to keep the water from leaching lead and copper from the piping.

if its a residential bolier with only water in it eliminate it. not really necessasary

I'm kind of afraid mine will seize up too since I don't use it anymore! 😅

If you manually keep the MU water shut off to a HW boiler there is no need for a backflow preventer. But you would probably have to take the PRV out to pass inspection.

I think if you direct pipe, hard pipe from a potable source to a boiler you need a BFD, to be code compliant.

The question for an inspector is the level of hazard with boiler water. Plain water, chemicals in the water, what if cleaners or chemicals are added, is PG a hazard? What level? Does EG require a different BFD?

Each has a different BFD requirement.

Some inspectors want RPZ, some accept dual checks with vent, some will allow un-vented dual checks.

Lately some areas require the dual checks have test ports! So we will have 4 different BFDs in the catalog to satisfy all the different interpretations across the US and Canada ASSE 1012, 1013, 1024, and ??

The BFD on the boiler protects the building water system. The BFD on the main line protects everyone else that may be connected to the water supply system.

The only way around a BFD on a boiler fill would be a fill tank, isolated form potable water.

by an 

air gap

 or a reduced pressure principle backflow prevention assembly complying with ASSE 1013, CSA B64.4 or AWWA C511

I'm not a pro, but my inspector, who is a pro, and was sure to tell me about his 30 years as a pro, and yet didn't think a drop header or pressure control water trap assembly was allowable, liked this one OK:

https://www.supplyhouse.com/Watts-0063190-BBFP-1-2-IPS-Backflow-Preventer

Hap Hazzard and I have steam boilers so we are adding water every few weeks probably. I add mine through the skim tapping though so my BFP gets sleepy. I'm planning on skimming soon though, so I'll be able to test it.

@hot_rod was talking about hot water and a pressure reducing valve, not steam. You could put a boiler drain after the backflow preventer to exercise it. The manual bypass should be after the backflow preventer so that should exercise it. Note that I posted the michigan code. Michigan code tends to be on the stricter side of the middle about protecting water for a lot of reasons. I think some state/city codes allow something less than an RPZ backflow preventer with nontoxic chemicals.

the nonpotable is because it isn't low lead. If you read the code carefully it says that low lead components are only required on lines supplying water for cooking or drinking so the feed to the boiler doesn't need to be low lead according to the code.