Vacuum Breaker Flush - Household Use

[baumgrenze]

This is a point of clarification. Is the reason that vacuum breaker flush devices (the kind used in public restrooms) are not used in household bathrooms is that they must be fed via at least a 1" water line and household are normally plumbed with 1/2" copper? Can I safely conclude that the latter size pipe will not deliver enough water for a good flush?

Thanks,

baumgrenze

[Gary Swart]

You've got it. There is really no point in going with a large line and high pressure with new low flow toilets. You are only using 1.6 or even just 1.28 gallons of water per flush, so high volume and high pressure are absolutely not needed and in fact would probably be damaging to a normal home toilet.

[jadnashua]

Most of the newer, good flushing toilets designed for homes use a 3" diameter flush valve. That allows a quick dump of sufficient amount of water from the tank to provide a good flush if the whole thing is designed and built well. Same idea with the commercial flushometer valves - you need a lot of water in a short time to make it flush, and you can't get it without a large pipe.

[baumgrenze]

I have a bathroom where space considerations suggest that it would be more practical to do away with the flush tank on the toilet altogether.

Does a vacuum breaker flush valve deliver enough water at once to cause a standard toilet (or a low flow toilet) to flush if it is supplied via a 1/2" water line. My observations in public restrooms suggest that the feed line needs to be bigger.

[Terry]

Does a vacuum breaker flush valve deliver enough water at once to cause a standard toilet (or a low flow toilet) to flush if it is supplied via a 1/2" water line. My observations in public restrooms suggest that the feed line needs to be bigger.

A commercial flushometer valve plumbed with a 1" supply line is very different than a tank slowly filled with a 1/2" supply line.

The 1" supply flushes in 3 to 7 seconds
The 1/2" supply may take 120 seconds to refill.

Imagine being in the shower when somebody flushes the toilet.
All of the cold would be gone, all you would have left is scalding hot water.

If you want to go with the commercial flushometer,
1) Change your water meter to a larger size and upgrade your water service to 1.5"
Then Run 1-1/2" to your bathroom set, and stub out with 1" using a 1-1/2" x 1" tee.

It should only run you a few thousand dollars.
Skimp on that, and be like all the homeowners before you that wish they hadn't tried.

[Alan Muller]

If you really want to use a flushometer, I you could put a well (bladder) tank somewhere and run a 1" line to the flush valve. That would give you a complex, noisy and expensive version of a Flushmate toilet, but you could set a top-entry pressure bowl close to the wall.

European toilets quite often have the tank ("cistern") hidden in a wall or cabinet.

If you used a 10" tank on a normal bowl, and framed up a recess for it in a "2 x 4" stud wall, you'd gain 6" of space, more or less.

[hj]

Your basic premise is incorrect. With a Sloan valve type toilet, the incoming water is doing the flushing so it has to be large enough to supply the "momentary" inflow of water to do it. A tank type toilet's flush is COMPLETELY dependent on the water in the tank, so it makes no difference what size pipe supplies it. Too small of a pipe, and it just takes longer to refill before the next flush will be adequate. Too large of a pipe and it has no benefit because the fill valve will still take the same to as the proper sized pipe to refill the tank. THEREFORE, both toilets will flush adequately, and as designed, if they have the proper sized pipes for their designs.

[baumgrenze]

Thanks to all for participating.

I've gathered the following:

1) It takes a big supply line to provide enough water to allow a 'Sloan' or vacuum breaker flush valve to flush a toilet.

2) By implication I gather that the toilet itself must be matched to a vacuum breaker flush valve.

Thanks for the other suggestions.

baumgrenze

[hj]

First, it is NOT a vacuum breaker flush valve. It is a flush valve with a vacuum breaker, and ALL toilet fill valve also have a "vacuum breaker" function if they are an approved design. Flush valve toilets do NOT have any provision for attaching a tank, and tank type toilets have NO WAY to connect to a flush valve, so yes, the toilet matches the flushing METHOD>