Standpipe blamed for Tricity Bendix WDR1240 washing machine problem


I have just had a repairman tell me that my self-installed standpipe is too low and causes the washing machine to stick on a fill-cycle. His explanation, which was obviously what he has been taught, is that the water enters the machine, fills the drainpipe at the back, which rises to reach into the standpipe, and as soon as it reaches the top of the drain, it spills over and starts 'siphoning' - which he immediately associated with siphoning petrol ("not that I have ever done that" he pointed out) My problem is - the fault is very interrmittent. On a rinse- cycle it lets water in, and as soon as the level/pressure is great enough, it should stop the intake, and move on to the next cycle. When the fault occurs, the drum does not even start to fill before the water is escaping down the standpipe, and it keeps on like that for hours, or until it is knocked-on. For the water to reach the top of the standpipe to spill-over, there has to be pressure behind it, and if the drum level is low or empty, that pressure can only come from the inlet, and assumes that something is stopping the inflow from getting to the drum, so it carries on to the outlet. He tried to 'fix' the fault by raising the U-bend over the standpipe from the recommended minimum (60cm) to 85cm - near the maximum of 90cm - just under the worksurface, saying that he was confident that would do it. On the first test, it was still spilling over, so he told me that it was probably because it was still too low, and it was all the fault of the 'installation' of the standpipe (ie not his problem). If I replaced the standpipe with a longer one, it would cure it. I tried to get him to explain the difference between raising the drainpipe as he had done, and increasing the height of the standpipe, and he tried to tell me all about siphoning again. Young folk today! He was also careful to get me to sign his paperwork _before_ filling in what he had done (I didn't notice the blanks) so that "standpipe to low" (sic) went in after I had signed! Damn! Also there was a blank box saying "tick this box if you don't want your details passed to third parties" double-damn!
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Having had many a battle with washing machines over the years this is a very common one.
It seems from what you are saying that your 'water full' level sensor is never getting a triggered. This is because the water is not getting high enough.
He is partially right about the outlet pipe being between 75 and 115cm above the floor level. This should be as directly up as possible from the outlet port of the washing machine and then form a neat 10cm 'U' into the waste pipe.
The reason for this requiremnt is that the non return valve will not operate properly unless there is enough reverse flow from the outlet pipe. At 90cm this should be enough. I have seen problems at as high as 65cm and longer pipes that are not a dead straight right angle to the ground.
Anyway this 'return flow' pressure as we can call it helps float and keep in place a large plastic ball. This is contained within the big rubber boot mounted at the lowest point on the outer drum. Best way of finding this is to tip your machine totally upside down. When there is enough water and reverse flow pressure in the boot the ball raises and stays in place against a integral seal.
I would take this boot off (it is a very easy job) and just look inside and see if there is any material knocking around in there. It should be pretty clean. Any forgien objects will get between the plastic ball and seal and make this leak. Hence constant filling!!!
Hope this has helped.
Regards G

too
it
lets
stop
drum
standpipe,
to
pressure
what
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G Cadman said

As soon as my wife has finished swearing at it, I will take a look. Your explanation sounds more plausible than the repairman's. I can't get my head around the concept of an uphill siphon! The standpipe/U-bend is definitely higher than the level in the drum, and I was wondering how it escapes in this way. It sounds as if this part (the plastic ball) is rather crucial. I had better be careful while the machine is still under warranty, especially if it means turning the machine _totally_ upside-down. I think I may just tilt it for a first look.
It means a lot to me to know about these things. Thanks.
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I suppose the only other thing to check is that your waste pipe is not partially blocked. i.e. the the waste water can actually flow away from the washing machine at a decent rate. If the water is backing up say the a head greater than 20cm above floor level then I guess you may have a blockage or restricted flow.
A good test is to use the rinse cycle to test this. Form your usually 90cm peaked u with your waste pipe but drop the end into a standard bucket. Keep the tip of the waste pipe out of the water throughout this test. The washing machine should fill up and empty (into the bucket) as normal within this rinse cycle. If your machine continues to try and fill the washing machine must be faulty, if it operates normally then you have a waste pipe problem. That will also provide you with sufficient ammo to call the repair people in again as it will prove the functionality of your waste pipe.
This test reuires no interferance with the machine so as not invalidating your warrenty.
When I last did this the washing machine only fills the bucket half full with a rinse cycle, which I thought was a small amount of water but is correct.
Regards G.

very
above
outlet
operate
90cm
in
is
and
pretty
my
better
means
a
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As an aside you may wish to buy the haynes manual on Washing machines. (Amazon.com product link shortened)16158682/sr=8-13/r ef=pd_ka_12/202-3225944-4879855
If your have ever used one for a car you will know how useful it is. Amusingly they are also doing one for women!

very
above
outlet
operate
90cm
in
is
and
pretty
my
better
means
a
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G Cadman said

I didn't see the 'women' one, but the washer/drier manual is now on order. When it is out of warranty, I will be ripping that top off with glee. Until then I can't trust myself not to do some permanent damage! Thanks again.
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very
above
operate
in
and
No the engineer will be correct the machine is syphoning. The eco ball in the sump (i dont think this model has one anyway) does not seal the water in, its to prevent the detergent from being wasted down the sump.
Peter
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