What is the object (air valve?) mounted above hot water tank

dougrainer wrote:

gutfelt wrote:

Hondavalk wrote:
Ya who needs the silly pesty codes. What ever could they be good for. :B :E :B

agree theres a ton of em out there that serve no purpose except in some ah engineers weird mind
actually never thought about what doug thinks its for but could very well be

No, they are there for a purpose. Just because YOU do not know enough to understand the purpose does not mean they have no purpose. READ my response after yours. BTW, did not understand your post about a Diplomat. I never stated that they are not at the Lavy sink. I stated that AFTERMARKET installs will not have that type check valve. Doug

so what did u say besides what u said ?

so there will be NO check valve under the Lavy sink. Doug

I never ever said there was no purpose I just said its not a mandatory thing to have in other words we can live with or without one when mine went bad and friends I simply eliminate the useless POS back flow check valve assembly

As their NAME implies they are an 'ANTI-SIPHON' 'Vacuum Breaker' 'BACKFLOW PREVENTER'

Anti-siphon so Contaminated black waste liquid does not flow out the flush connection
Vacuum breaker because they allow atmospheric air into flush system and stops any negative pressure which could allow siphoning from waste tank
Backflow preventer because internal Disc closes and physically stops any back flow

They can fail.......disc hangs up and doesn't seal off opening to atmospheric air thereby allowing flush water supply to spray inside the RV (typically under bathroom sink, in closets and some are even behind the shower wall......none are ideal spot due to water leaking)

LOTS of things would have to fail in order for black tank waste liquids to backflow.
Supply water source would have to quit
Black tank liquid level would have to be extremely high....high enough to be above top of piping for flush system ie: backed up into vent line high....in order for waste liquid to backflow.
That means waste tank line to toilet would have to be pressurized/toilet bowl seal holding/not overflowing in order for waste liquids to back up high enough in vent line to force liquids thru the flush spray nozzle into flush lines up to connections where anti-siphon valve was and then out side of RV into water supply system.

Possible...........sure
Probable ...........Not very likely

Besides a simple hose end vacuum breaker would be all that is necessary should anyone CHOOSE to eliminate the piece of junk anti-siphon vacuum breaker backflow preventer valve inside their RV so that WHEN it leaks it doesn't cause damage inside their RV

Hose bibb vacuum breaker





Anti-siphon vacuum breaker backflow preventer valve (RV Flush System)






SO YES.they can be removed -----hard piped if OWNERS choose to do so.
Then just attach a hose bibb vacuum breaker to flush connection and SAME prevent is in place WITHOUT leaks inside the RV





NOW if OP would just reply whether or not this is the valve he is asking about??????

gutfelt wrote:

Hondavalk wrote:
Ya who needs the silly pesty codes. What ever could they be good for. :B :E :B

agree theres a ton of em out there that serve no purpose except in some ah engineers weird mind
actually never thought about what doug thinks its for but could very well be

No, they are there for a purpose. Just because YOU do not know enough to understand the purpose does not mean they have no purpose. READ my response after yours. BTW, did not understand your post about a Diplomat. I never stated that they are not at the Lavy sink. I stated that AFTERMARKET installs will not have that type check valve. Doug

Hondavalk wrote:
Ya who needs the silly pesty codes. What ever could they be good for. :B :E :B

agree theres a ton of em out there that serve no purpose except in some ah engineers weird mind
actually never thought about what doug thinks its for but could very well be

Ya who needs the silly pesty codes. What ever could they be good for. :B :E :B

dougrainer wrote:
OK, NONE of the answers to WHY it is needed are wrong.
1. There is NO way the black tank can backfeed to the fresh system as long as all connections are to factory install and use while camping. There is NO cross connection to the fresh system at all.
2. The REASON the check valve is installed and the REASON it is HIGHER than the Black tank is to keep Black tank odors from migrating back out the Inlet in your water bay. Most OEM installs the inlet does NOT have a check valve like the check valve on the City Water inlet. That is designed so when the black tank flush has completed, when you remove the pressure hose, you will see about a pint of water flow back out. That is fresh water in the line up to that check valve. Then the check valve keeps the odors inside the tank.
3. Aftermarket Black flushes have the check valve either at the tank inlet or the connection has the check valve like on a City Water connection, so there will be NO check valve under the Lavy sink. Doug

2012 Monaco dimplomat had the valve under the lavy sink I know because it leaked and I bypassed it for my friend

gutfelt wrote:

dougrainer wrote:

gutfelt wrote:
as I was also and now u see why u need a 90 degree 1/2X1/2 connecter to bypass this unneeded valve

Why is it unneeded??? Doug

ok I think u know what a I mean your not dumb so I ask why is it really required? I know exactly what its for and for the most part I thinks it code to have one but I don't believe its at all necessary
in a MH

You obviously do NOT know:B Doug

Executive wrote:
I was always taught not to bypass anything that I wasn't absolutely, positively sure nothing bad would happen if I bypassed it. I'm also sure the cost of the valve, assuming it's the BTFV, will cost no more than the fitting necessary to bypass it...Dennis

to each their own I doubt a 75 cent fitting is the same price
I bypass because their a pain every time they stick or break
Iam 100% absolutely positive nothing bad will happen;; some plumbing code guy came up with a possibility about a possible situation in the same % category your DNA exactly matches your neighbours

OK, NONE of the answers to WHY it is needed are wrong.
1. There is NO way the black tank can backfeed to the fresh system as long as all connections are to factory install and use while camping. There is NO cross connection to the fresh system at all.
2. The REASON the check valve is installed and the REASON it is HIGHER than the Black tank is to keep Black tank odors from migrating back out the Inlet in your water bay. Most OEM installs the inlet does NOT have a check valve like the check valve on the City Water inlet. That is designed so when the black tank flush has completed, when you remove the pressure hose, you will see about a pint of water flow back out. That is fresh water in the line up to that check valve. Then the check valve keeps the odors inside the tank.
3. Aftermarket Black flushes have the check valve either at the tank inlet or the connection has the check valve like on a City Water connection, so there will be NO check valve under the Lavy sink. Doug

wildmanbaker wrote:

gutfelt wrote:

dougrainer wrote:

gutfelt wrote:
as I was also and now u see why u need a 90 degree 1/2X1/2 connecter to bypass this unneeded valve

Why is it unneeded??? Doug

ok I think u know what a I mean your not dumb so I ask why is it really required? I know exactly what its for and for the most part I thinks it code to have one but I don't believe its at all necessary
in a MH

Really? You a have been around long enough to know that if something can go wrong, it will. The last thing you want is to have the spray nozzle hang open after flushing the empty tank, and not knowing it, and finding out as your black tank fills. Remember the movie "RV"?

absolutely not even close as to what the valve does better go back to RV school