Drain down taking too long. (1 Viewer)

[JockandRita]

Flair 8000i 2006

Although I was warned of the slow drain down by the previous owner, draining down a full water tank after sterilising the system, took an hour and twenty minutes, (yes I actually timed it ). The hot and cold water lines took no time at all, in comparison. I had the taps open on the cold side, and I even opened the tank cap, to relieve any possibility of a vacuum forming. No joy.

I have blown back using lung pressure, then tried compressed air. I have back flushed with mains tap pressure, hoping to maybe dislodge a blockage of some kind. So far, no joy with increasing the pitiful flow.
The pipework is 15mm speedfit, so a kink in the line is highly unlikely.

Has anyone experienced the same problem, and if so, what was your solution please?

Thanks in advance,

Jock.

 

[68c]

15mm is very thin for a drain pipe, most are at least 25mm if not wider. Is there an access hatch to the tank, perhaps under the van, you may be able to clean out through there. If you can gain access to the inside of the tank fit larger bore pipework, may give you the opportunity to fit the tap in a good position. A straight through tap is best with a large diameter hose clipped on to reach any drain point. CAK Tanks have good supply of these fittings.

 

[JockandRita]

15mm is very thin for a drain pipe, most are at least 25mm if not wider. Is there an access hatch to the tank, perhaps under the van, you may be able to clean out through there. If you can gain access to the inside of the tank fit larger bore pipework, may give you the opportunity to fit the tap in a good position. A straight through tap is best with a large diameter hose clipped on to reach any drain point. CAK Tanks have good supply of these fittings.

Thanks for your reply.

The pipework is factory fitted, and the other two 15mm drain lines flow much better. If the outlet on the base of the Hymer tank was 25mm, which only took about 10 x minutes to drain from full, then I would expect the Flair to drain in double that time.
There is no access to the tank that I can see, apart from the inspection hatch to the tank cap, in the vanity area floor. The tank drain comes from the base of the tank, through a bulkhead, and into the wet locker, where it's all J G Speedfit drain taps and 90 degree joints.

Edited.................If I got half the flow from the drain tap, that I am getting at the sink taps, I'd be happy. Even without pump pressure, you'd think that pressure head within the tank would accelerate drainage.

Cheers,

Jock.

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[Gerby]

Thanks for your reply.

The pipework is factory fitted, and the other two 15mm drain lines flow much better. If the outlet on the base of the Hymer tank was 25mm, which only took about 10 x minutes to drain from full, then I would expect the Flair to drain in double that time.
There is no access to the tank that I can see, apart from the inspection hatch to the tank cap, in the vanity area floor. The tank drain comes from the base of the tank, through a bulkhead, and into the wet locker, where it's all J G Speedfit drain taps and 90 degree joints.

Edited.................If I got half the flow from the drain tap, that I am getting at the sink taps, I'd be happy. Even without pump pressure, you'd think that pressure head within the tank would accelerate drainage.

Cheers,

Jock.

Don't forget that if you double the diameter of a pipe you will quadruple the flow and if you half it you will reduce it to a quarter.

Therefore you would need 4 x 15mm pipes to equal 1 x 30mm pipe assuming length and pressure remain constant

 

[pappajohn]

Can you cut the pipe at the closest accessible place to the tank.
Then use something like a net curtain wire to see if there is a blockage. Maybe a small piece of rag attached to the end.
If the wire is turned as you push it will go around 90° bends eventually.
If that ends clear try the other way towards the tap.
You'll be able to buy a straight coupler to join it together again.

 

[Lenny HB]

15mm is very thin for a drain pipe, most are at least 25mm if not wider.

He is talking about freshwater system, the waste on a Flair will be either 40 mm or larger.

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[JockandRita]

Can you cut the pipe at the closest accessible place to the tank.
Then use something like a net curtain wire to see if there is a blockage. Maybe a small piece of rag attached to the end.
If the wire is turned as you push it will go around 90° bends eventually.
If that ends clear try the other way towards the tap.
You'll be able to buy a straight coupler to join it together again.

There is no access to the tank that I can see, apart from the inspection hatch to the tank cap, in the vanity area floor. The tank drain comes from the base of the tank, through a bulkhead, and into the wet locker, where it's all J G Speedfit drain taps and 90 degree joints.

See photo below please John. I did try a flexible cable, but it wouldn't go past the first 90 degree joint.

Don't forget that if you double the diameter of a pipe you will quadruple the flow and if you half it you will reduce it to a quarter.

Therefore you would need 4 x 15mm pipes to equal 1 x 30mm pipe assuming length and pressure remain constant

Whilst I do appreciate what you are saying, although hydraulics wasn't my best subject..............................

The hot and cold water lines took no time at all, in comparison. I had the taps open on the cold side,

All the drains are 15mm speedfit, and the other two flow fine.

Cheers,

Jock.

 

[jongood]

He is talking about freshwater system, the waste on a Flair will be either 40 mm or larger.

Ours are 40mm, Are you sure you ve got the right pipes Jock? Ours says Abwasser. that looks more like the drain to get the last dregs out of the pipes for winter storage without heating.
Jon

 

[Steve and Denise]

These fittings are easy to remove and put a piece of hose on to pin point your flow problems ie before the bends or after

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[Off da Grid]

If I’m doing a drain down I run the tank to near empty on site then let the pump do the work to empty the system with the hot water drain down plug upon then undo the tank drain and go have my lunch or tea

 

[Gerby]

No Worries dude (unfortunately I was the sad one on the watch that actually understood hydraulics) are any of the speed fit connectors of the non return variety as they have been known to stick closed and would also prevent you being able to blow back up the line to see if there are any blockages

 

[The Wino]

I would drain the tank and take the tap off the fittings should separate if you push in the collar on the fitting. I would replace the tap as long as they still make the same size and fitting and poke something up the pipe into the tank to make sure it's clear.

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[funflair]

Ours are 40mm, Are you sure you ve got the right pipes Jock? Ours says Abwasser. that looks more like the drain to get the last dregs out of the pipes for winter storage without heating.
Jon

That’s the one he is draining Jon, fresh tank.

 

[JockandRita]

Ours are 40mm, Are you sure you ve got the right pipes Jock? Ours says Abwasser. that looks more like the drain to get the last dregs out of the pipes for winter storage without heating.
Jon

Jon, it is the fresh water drain taps I am asking about. The one on the right is the water tank drain, which has a pi$$ poor flow. there are no other drain taps for the fresh system.

These fittings are easy to remove and put a piece of hose on to pin point your flow problems ie before the bends or after

Yes Steve, I have some experience with Speedfit, but taking that bulkhead off to get behind it, is a major faff.

No Worries dude (unfortunately I was the sad one on the watch that actually understood hydraulics) are any of the speed fit connectors of the non return variety as they have been known to stick closed and would also prevent you being able to blow back up the line to see if there are any blockages

Ha ha, L x W x D x 1000lts, (rectangular tank) and H x Dia x 800 (cylindrical tank) was about my limit on hydraulics.
Re speedfit connectors of the non return variety, I doubt it as I could blow back no problem, and could feel the pressure causing air to rise through the water in the tank.

Cheers,

Jock.

 

[Lenny HB]

Just done some measuring.
Internal dia of 15mm Speed fit is 11.5mm if the inserts have been used at the connections they reduce it to 9.2mm.
Your Hymer would have a 10 mm internal dia connectors in the system have an internal dia of 8mm.

So in theory the Hymer should drain slower.

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[JockandRita]

If I’m doing a drain down I run the tank to near empty on site then let the pump do the work to empty the system with the hot water drain down plug upon then undo the tank drain and go have my lunch or tea

Thanks.
Yes, that's what I have been doing for the past 30 x plus years, but I am referring to drain down from full after sterilising the system in this particular model, not near empty after a weekend away. Please see my original post, and the photo posted almost an hour ago.

So in theory the Hymer should drain slower.

Thanks Lenny, however, the theory will have to go out the window on this occasion, (with respect) as I bought a 7/8th inch (22.225 mm) replacement drain plug for the Hymer tank, some months before selling it, and from my 15 x years of ownership, I can categorically confirm that from full, it drained down in around 10 x minutes.

Cheers,

Jock.

 

[Gromett]

JockandRita That is pretty normal.

I made a self build with a 155L tank, at the bottom of the tank it had an outlet with a single elbow pointing downward and out through the floor. The total length was around 12 inches from the tank outlet to the exit point. Took forever to drain. That was also 12mm ID john guest speedfit pipe.
It was actually quicker to run the pump and drain via the gray water outlet.

The only solution if you want it to be quicker is to fit a bigger outlet pipe.

 

[Off da Grid]

I did this from full as well after adding puriclean on site to enable 1/2 hour slosh about while driving home.
just opened all the taps and let the pump do it’s thing till she gurgles like a baby once home.
Left the grey tank for a day or two before emptying.

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[JockandRita]

Thank you everybody for taking the time to reply.

Much appreciated,

Jock.

 

[Robert Clark]

Flair 8000i 2006

The hot and cold water lines took no time at all, in comparison.

Based on that observation Jock I’d suggest draining down fully, then remove and swap round the drain off valves.
This will show is the valve itself is faulty and allow you to take a look up / down the pipes with the tap removed

 

[jongood]

Ours are 40mm, Are you sure you ve got the right pipes Jock? Ours says Abwasser. that looks more like the drain to get the last dregs out of the pipes for winter storage without heating.
Jon

Sorry Jock I had misunderstood what you wanted to do. The later model Arto's have a 40mm drain on both tanks which is much better. But I'm pretty sure our previous gen arto had a plug on a chain inside the fresh tank yours might have the same. Geoff nicholsong might know?

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[JockandRita]

Based on that observation Jock I’d suggest draining down fully, then remove and swap round the drain off valves.
This will show is the valve itself is faulty and allow you to take a look up / down the pipes with the tap removed

Thanks Robert. I might do that on Sunday, when I have drained down to come home.

What I forgot to add above, was that yesterday I noticed a better flow when I closed the other two drain taps, ie, less aeration and a slightly smoother flow.

Sorry Jock I had misunderstood what you wanted to do. The later model Arto's have a 40mm drain on both tanks which is much better. But I'm pretty sure our previous gen arto had a plug on a chain inside the fresh tank yours might have the same. Geoff nicholsong might know?

No sweats Jon. Re the chain and plug, that was the method of draining in our old Hymer. A pain in the ar$e to get to, but a good flow once pulled.
Definitely no plug and chain on the Flair though.

Cheers,

Jock.



Cheers,

Jock.

 

[CazPaul]

I just move this lever and what's left in the fresh tank gushes out when draining down, hope you can sort it as there must be a slight blockage somewhere Jock.

 

[Reallyretired]

The drain from my fresh tank is useless. I just drain it through the grey tank by turning on the taps till the pump gurgles.

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[JockandRita]

The drain from my fresh tank is useless.

I'm glad I'm not on my own.

Cheers,

Jock.

 

[Ridgeway]

Not sure if it's possible but if you extend the length of the drop from water height to pipe exit then this will increase the flow rate. Simplest way to do this is by extending the drain pipe at the outlet with the same ID pipe, the longer the better.