petanque
Member
Does anybody have experience with Fluidmaster very low pressure seal for gravity fed cisterns?
What sort of head is needed for them to work properly?
What is the likely fill time for a 6 litre toilet system?
Are there other products that should be considered?
Russell Moore
Member
Gravity fed toilet? aren't they all? hahahaha...
petanque
Member
I suppose you are correct in that it is very challenging to push all sorts of things up hill.
I referring to using low pressure from a rainwater tank to fill the cistern of the toilet.
If I can avoid using pumps it will be cheaper to install and have fewer things to break.
cool at home
Member
We have Rainsaver gutters which feed our toilet cisterns passively. Obviously these are at roof level - on a 2 storey house - with toilets both up and downstairs. As our ceilings are higher than normal so too is the gutter, but not extremely so. Cisterns are slow to fill but no real problem. I doubt the majority of visitors to our home would notice.
Can't really recommend the gutters (they leak in places, which is a pretty big flaw in the system) but can't see any problem with gravity fed from tank. I presume you have a slope, with elevated tank next to but above the house??
Bullwitter
Member
Yes, I have had experience with Fluidmaster so here goes.
I installed a rain water tank a few years ago. The tank was fine but my submerged, stainless steel pump: 1. was very expensive (about $1,000) 2. cost even MORE to install. 3. was more noisy than we expected and 3. increased our energy use and 4. stopped working after a few months. We actually felt relief that it stopped.
I thought, 'there MUST be a better way' and there is. We have been running two toilets successfully for the past 18 months on 100% rain water with NO pumping at all - simple story house. How?
First we replaced the old float valves in each cistern (toilet tank) with TWO new Fluidmaster float valves (one each side of the cistern. See diagram in the ACT Gov. water tank guidelines, page 9 – so, yes, this is legal etc. One float valve is permanently connected to the mains and the other is permanently connected to the rainwater tank (with a stop cock in each case). These valves cost about $20 each from Bunnings – (Fluidmaster 400UK063).
Now for the tricky bit. As you are aware, tank water is seriously LOW PRESSURE. We only had about a meter of ‘head’ – max. That is not enough to operate the rubber flap in the Fluidmaster that we had installed. Then I noticed a small paragraph on the side of the box the Fluidmaster came in which indicated that a low pressure rubber flap was available. So I rushed off to the plumbing shop, bought one for a few bucks and it DIDN'T WORK!! Next I phoned Fluidmaster ‘s Australian help line 1800 808 179 and explained the problem. BINGO, they have a SUPER low pressure rubber flat. It worked perfectly!
So now my two toilets work fine until my rain water tank gets down to about half empty. After that, I could need to turn the mains back on, but I haven't had to yet! Note that with this low pressure set up, the refilling of the cistern is slower than with high pressure refilling and it is totally silent. If I had a party - where people would be queueing up to use the WC, I would temporarily switch back to mains.
Another thing that has helped my rainwater last so long (apart from unusually wet weather) is that I replaced the dual flush mechanisms with much simpler 'lift' knobs. The lift knob only allows water to pass while it is held up. Thus one only holds it up as long as is needed – which, according to Derek Wrigley – reduces water consumption to about 25% of the normal DUAL flush rate. I haven't done any measurement, but I can vouch that it is a big improvement on normal dual flush. Interestingly, an old, single flush cistern can be just as easily (or more easily) converted to a lift knob system. I can't imagine why we still can't buy a lift knob systems in the shops.
Although this works well – with zero energy use and no noise, you will probably not find a plumber who believes it works, so you will have to do it yourself.
Hope that helps.
There is a lot of additional information in the thread below...
If you have any questions after reading the thread, then ask away! There is a bit too much info to transfer. I will be interested to hear your questions. For now, I will answer your opening three questions.
My maximum head is only .9 metres. The water also goes through the pump and a small pressure tank. I generally transfer water once the head reaches .3 metres. As long as there is a head, it works but it gets very slow at .3 metres.
Customers who have heads of 1.5 metres refill a half flush in 5-6 minutes. Mine is usually the 10-15 minute mark, depending on head. I think it would be faster if it was fed more direct. All of my customers feed through the pump and most didn't believe it would work if it went through the pump.
The secret to the Fluidmaster is its compactness which allows two to be fitted. A lot easier to fit and sure beats messing around with fitting various valves and taps to a single line! Regardless of whether you gravity feed or use a pump, using 2 Fluidmasters is the way to go.
I still like having the pump flush the line whenever I use the pump as I don't have filters. My tank water is very clean anyway as I have 4 stage pre tank filtration but I will soon (when I have time) be connecting the tank to the HWS. This will entail filters and a large pressure tank. Once I have the tank, I will leave it turned on. I set up the Fluidmaster system to save pump wear and tear. The average person flushes the toilet 6 times a day. I work from home and drink heaps of coffee, the poor pump was copping a hammering!
If you have a pump, I would strongly recommend that you consider getting a large stand alone pressure tank.
petanque
Member
I specifically wanted to avoid a pump because of reliability and expense issues.
I have a 2-3 Kl tank and thought if I can use this 3-9 months of the year this would save some money and help the environment.
To get the most from the tank it seems that you need to be using water in the wet season.
I was hoping for answers to.
What is the likely fill time for a 6 litre toilet system?
I was hoping for people experiences.
eg mine takes less than 2 minutes when the tank is full and has about 2m of head but by the time the head of water is down to 1m of head the time to fill the cistern goes up to about 5 minutes
Are there other products that should be considered?
Considering the number of houses that would not have mains water in the world I would be flabbergasted if fluidmaster is the only manufacturer. If any of these other parts/methods is commonly available in Australia I have no idea.
petanque
Member
The plumber came and did the job it takes about 4 minutes to fill a 61 toilet cistern with 1.5 m of head.
It seems strange not to hear the water rushing in afterwards.
The plumber gave the impression that the government rebate will completely pay for the job ($380.00).
Does this mean that as I have flushed the toilet once that I am now ahead??
petanque,
Well done.
Is it 4 minutes for 3 or 6 litres? 4 minutes for 6 litres is very fast. I do not know anyone who has plumbed the Fluidmaster with a connection that has not gone through the pump, consequently it is hard to do a flow comparison. How long is the run?
Fitting the Fluidmasters to the cistern DIY is easy and would have saved a few $$$.
Thanks for confirming 4 minutes for a full flush. Impressive!
Re my reference to fitting the Fluidmasters DIY, I meant to convey that by fitting the Fluidmasters to the cistern DIY but have the plumber do the rest would have cut a few dollars off the plumbers bill. Sorry about the ambiguity in my last post.
Hope others follow your example.
petanque
Member
I would guess that the fill time will reduce as the tank empties.
My estimate is that I would save about 700l a week of mains water 2 adults and a child.
the tank potentially holds about 5 weeks of water but even if we only ever half empty the tank at least we are using(/saving) some of the water in the tank
petanque
Member
The run of pipe (20 mm) from the tank to the toilet I would guess is about 5m.
Sorry I missed this answer before.
There is a manual change over with a ball valve for the rainwater and a mini-cock for the mains.
The fill time from the mains is more like 20 seconds.
My wife who while "green" is not prepared to be inconvenienced to be "green" has said the only difference is it is silent after you push the button.
If you listen carefully you can hear the rainwater trickle in but it is quiet compared to the mains.
gav3500
Member
I'm considering gravity toilets for my renovation. Current thoughts 80l wall mounted tank with a double action float switch hooked up to a solenoid for pump filling.
Gravity feed from tank to cistern. I am expecting a short run but I'm thinking 25mm pvc to carry the water, then it's either the fluidmaster valve or one of the commercial float valves.
The philmac horizontal float values claims 23l/min at 10kpa or 1m head in a 25mm inlet.
http://www.philmac.com.au/Product/Product/ProductGroup.aspx?g=43
I've thought about pressure tanks but the big ones are expensive. The industry moved away from pressure tanks to reduce pump cycling during long irrigation runs. I will mostly likely end up with a general purpose pump for toilet and laundry and an irrigation pump designed to run flat out. Alternatively the industry has speed controllers to reduce pump power usage for low flow applications.
petanque
Member
certainly 23l per minute would fill the cistern in less than 30 seconds.
I have mains water to supplement the toilet during dry periods.
so a float valve for both the mains and the tank water is needed.
This ruled out lever style valves.
I was keen not to have a pump for cost and reliability issues.
How it will work when the tank gets down and there is less head of water I don't know yet.
