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Stop rainwater pipes freezing

(15 posts) (6 voices)

Started 9 years ago by LaSource
Latest reply from Diver

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LaSource
Member

I have recently installed a 23,000 l, tank and thought I was smart running a pipe into the ground across the garden and up into the tank. In Spring a cold snap broke the tank exit tap so this made me realise my piping may freeze and break pipes in winter and it has permanent water in it. Should I change it to an Arial (no water held) configuration?

Basically the horizontal length (Buried max 15cm deep) is about 4 meters long however the two verticals are just under 3 meters high and contain water for most of that. I am using 90mm pipes.

We get a few below zero nights a year and a few below -7.

Any experience ideas would be appreciated.

Posted Monday 9 Jan 2012 @ 11:06:44 am from IP #
Russell Moore
Member

I seriously doubt that the buried pipes would freeze, and the above ground pipes being open ended may not be a problem. Others with more experience with very cold conditions may be able to give you some more accurate information.

Posted Monday 9 Jan 2012 @ 12:12:27 pm from IP #
Diver
Member

LaSource said:
In Spring a cold snap broke the tank exit tap

Basically the horizontal length (Buried max 15cm deep) is about 4 meters long however the two verticals are just under 3 meters high and contain water for most of that. I am using 90mm pipes.

Was the outlet valve a ball valve or spindle? Ball valves are generally preferred but they are known to crack in cold areas.
If the 90mm pipes you are using are UPVC downpipes, they are not pressure rated and should not be buried as the thin walls are only 2mm thick. If they crack at ground level for whatever reason, you will lose all of your water.

Temperatures below freezing could freeze the surface water in the pipe's two upper sections as it is the surface area of the exposed water that is the critical factor but so is time. There are many variables in play including convection currents and the freezing rate of the larger mass would be difficult to estimate. It is difficult to imagine a freezing of the total mass in the pipe unless sub zero temperatures were sustained.

Wet systems are not good at the best of times and they should be regularly drained to prevent stagnation. Doing this before cold snaps would be a good idea but eliminating the wet system completely would be an even better idea.

The "Arial" pipework you referred to is known as a dry system. Both dry and wet systems have faults.

Posted Monday 9 Jan 2012 @ 12:51:15 pm from IP #
gazmo88
Member

If your layout requires charged pipes then this looks like it might be a good idea as it drains them automagically:

http://rainharvesting.com.au/products/pre-filtration/first-flush-water-diverter/in-ground-diverters

Have not tried it myself but it _looks_ like a good idea.

Posted Monday 9 Jan 2012 @ 10:07:54 pm from IP #
Diver
Member

Underground divert system need a suitable slope as they need to be dug in and the one linked would need a trench 500mm deep. This also makes access for cleaning impossible.

The one linked is also designed to be fitted with 90mm UPVC downpipe. This pipe is not designed or regulated for use as shown. As such, the linked unit is not compliant with plumbing regulations.

A more suitable DIY unit using 100mm DWV pipe is easy to make.

Posted Tuesday 10 Jan 2012 @ 12:34:24 am from IP #
Ueee
Member

I've made one before just by putting a T at the lowest point of the pipe and running another pipe somewhere (slightly downhill) where you can terminate it with a screw on cap (exposed) that you have drilled a small hole in. This way the system will always drain and the first lot of water in diverted. You can also unscrew the cap every now and then to clean the system out(like in heavy rain). Of course you need a bit of slope and somewhere for the water to go for this to work.

Posted Tuesday 10 Jan 2012 @ 5:03:41 am from IP #
gazmo88
Member

"A more suitable DIY unit using 100mm DWV pipe is easy to make."

The same people have various patterns for different purposes they look easy enough to fabricate:

http://rainharvesting.com.au/products/pre-filtration/first-flush-water-diverter

I don't really understand why the units have a ball seal. I would have thought that something such as Ueee's suggestion would work just as well and be simpler (possibly at the cost of a little more water loss).

Incidentally the spec sheet for the underground unit says it has a dual 90 / 100 mm fitting but I don't know if this means it would take the 100mm DWV Diver mentions.

Of course, anything unmaintainable will break and sooner than you would have liked.

Posted Tuesday 10 Jan 2012 @ 5:22:54 am from IP #
Diver
Member

gazmo88 said:
I don't really understand why the units have a ball seal. I would have thought that something such as Ueee's suggestion would work just as well and be simpler (possibly at the cost of a little more water loss).

Incidentally the spec sheet for the underground unit says it has a dual 90 / 100 mm fitting but I don't know if this means it would take the 100mm DWV Diver mentions.

If the flow runs horizontal and the diverter forms a Tee, a 'stopper' is needed to prevent a venturi effect recirculating the flush. An advantage of Ueee's DIY unit is that it will continue to capture debris long after the 'flush' container fills. It is accumulated debris in wet systems that cause problems.

The only thing I would do differently would be to step reduce the main chamber outlet to 25mm and fit some 25mm poly pipe and a 25mm inline tap. This way, the more flexible poly pipe can be directed to a drain off area and the tap opened to flush. The head will provide a high velocity flush out that will also self clean the drain pipe.

The spec sheet states 90mm or 100mm inlet but a 90mm outlet only.

Posted Tuesday 10 Jan 2012 @ 9:46:47 am from IP #
gazmo88
Member

" If the flow runs horizontal and the diverter forms a Tee, a 'stopper' is needed to prevent a venturi effect recirculating the flush. An advantage of Ueee's DIY unit is that it will continue to capture debris long after the 'flush' container fills. "

Thanks for that.

"The spec sheet states 90mm or 100mm inlet but a 90mm outlet only."

Where do they find em ??

Posted Tuesday 10 Jan 2012 @ 10:50:45 am from IP #
Diver
Member

gazmo88 said:

Where do they find em ??

What are you looking for? Pipe, spec sheet, diverter, inlet, outlet? You can easily make a diverter, just make sure the parts and pipe all match, there are a lot of different PVC pipes & fittings. The 100mm DWV pipe and fittings are all found in the big green shed.

Posted Tuesday 10 Jan 2012 @ 11:47:54 am from IP #
gazmo88
Member

"What are you looking for?"

Sorry sarcasm.

Tr: What idiot designs a part that is designed to be buried that does not accept pipe suitable for burial ?

Posted Tuesday 10 Jan 2012 @ 9:26:04 pm from IP #
Diver
Member

gazmo88 said:
Tr: What idiot designs a part that is designed to be buried that does not accept pipe suitable for burial ?

Any attempted answer to your question exposes a lot of the problems within this industry.

The manufacturer of the underground diverter you linked is Rainharvesting. They are an innovative and leading Australian rainwater harvesting company who now have a presence overseas, particularly in the U.S.

The design of the underground diverter should never have included the use of a thin walled and non pressure rated 90mm PVC pipe for the flush chamber's drain. People do get confused with the different types of PVC pipe and their respective sizes but 'professionals' should know better.

It is also interesting when you look at the top LH chart on the linked page that gives the 300mm flush chamber's capacity per metre. Given that the internal diameter of 300mm DWV pipe is actually 294mm, the internal volume is actually 68 lpm.

The chart's notes also give the volume of 100mm DWV pipe as 8 lpm and yet further down the page on the bottom chart it is shown as 8.8 lpm. The internal diameter of 100mm DWV is 102mm, making its volume 8.2 lpm.

http://rainharvesting.com.au/products/pre-filtration/first-flush-water-diverter/in-ground-diverters

The problem is that mistakes are copied by other industry 'experts' and is why various manufacturers of first flush kits will claim that the lpm in a 90mm PVC pipe can be anywhere from 6.5 to 8 lpm. As the actual diameter is 86 mm, the lpm is a much lesser 5.8 lpm. Correct information is of importance to persons when setting up their rainwater harvesting systems.

It is a sad industry indictment when the people who design products that use pipes and fittings don't even know pipe types, volumes and applicable regulations.

There are a staggering number of non compliant products on sale in the majors as a casual walk through the big green shed will reveal. An even worse thing is that plumbers fit these products and issue compliance certificates which Joe Public also pays for. As an example, I know of a grey water unit (that attracts a $500 govt rebate) that is designed with an under sized (non compliant) outlet pipe. It can also be found at the big green shed.

A lot of the 'experts' have now gravitated to the solar industry.

Posted Wednesday 11 Jan 2012 @ 1:36:37 am from IP #
pulpo
Member

I doubt also that 90mm pvc pipe would freeze solid anywhere in Australia.

Especially if some is buried.

As pointed out previously 90mm pipe should not be used in a wet system particularly if buried, 100mm is the go.

I did my wet rain water with the 90mm, as sold by the plumber store who knew exactly my setup.

I have no issues with a wet system by far the most common around my area full of hobby farmers, yes you need to have a drainage point, I have an in ground first flush diverter with ball; it must be manually drain as the small hole method always blocks.

As for the bottom tank outlet which is usually around 40mm often supplied with gate valve.

This also is unlikely to freeze if left on (open) same with ball valve.

However if you turn the valve off or close it then they will crack from freezing.

You need to get a ball valve antifreeze, or often covering the tap/valve will do the trick.

My experience is in the Goulburn region.

Good luck

Pulpo

Posted Thursday 12 Jan 2012 @ 10:15:48 pm from IP #
pulpo
Member

pulpo said:
I doubt also that 90mm pvc pipe would freeze solid anywhere in Australia.

Especially if some is buried.

As pointed out previously 90mm pipe should not be used in a wet system particularly if buried, 100mm is the go.

I did my wet rain water system with the 90mm, as sold by the plumber store who knew exactly my setup.

I have no issues with a wet system by far the most common around my area full of hobby farmers, yes you need to have a drainage point, I have an in ground first flush diverter with ball; it must be manually drain as the small hole method always blocks.

As for the bottom tank outlet which is usually around 40mm often supplied with gate valve.

This also is unlikely to freeze if left on (open) same with ball valve.

However if you turn the valve off or close it then they will crack from freezing.

You need to get a ball valve antifreeze, or often covering the tap/valve will do the trick.

My experience is in the Goulburn region.

Good luck

Pulpo

Posted Thursday 12 Jan 2012 @ 10:27:23 pm from IP #
Diver
Member

pulpo said: As for the bottom tank outlet which is usually around 40mm often supplied with gate valve.

This also is unlikely to freeze if left on (open) same with ball valve.

However if you turn the valve off or close it then they will crack from freezing.

You are correct and I should have elaborated this point.

Posted Friday 13 Jan 2012 @ 12:19:47 am from IP #

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