Drying Cycle Moves Pipework for the Whole House

[Sylvia]

Hello All,

We have a Hotpoint Aquarius WDF740 washer/dryer.

Last month we had central heating installed. Before that, we had the main water tank in the loft (which was used for cold water for the shower and supplied water to the immersion heater tank), as well as an immersion heater tank for hot water. Now there are no tanks as we have the combi boiler. 

Since then something very annoying is happening. Everything is fine during the wash cycle. But during the drying cycle every 30 seconds or so there is a bang/click in the pipework around the whole house, with visible movement if you look at the pipes  (I opened the shower we have installed inside the wall so that I can see pipes with my own eyes). Every 30 seconds, it seems, the machine draws water from the main for literally 1 second. After speaking to hotpoint support they confirmed that this is indeed the case. But the byproduct of that action is that the pipework around the house is moving. I can only assume that it creates some violent vacuum within the pipework system. But I have no idea why this happens now, and did not happen before, and how to remedy it.

Any advice will be greatly appreciated!

Thank you,

Sylvia

[Whitegoodshelp (Andy)]

Hello Sylvia. This problem is almost certainly caused by a loose pipe in the plumbing and / or changed water pressure. The fact that this problem only started after plumbing work confirms that. The first thing to try is turning the water pressure down preferably on the tap that supplies the washing machine. If you have high water pressure at the sink tap you could try turning the mains water pressure down at the stop cock.

Basically there is a pipe somewhere that isn't securely fixed at some point. When a tap is turned off (when the water pressure is high) it sets off a wave that travels through the pipework causing a knocking sound. If you can't stop it by the methods I suggest you should get the plumber back and explain that this fault started immediately after the plumbing work was done.

 

[Sylvia]

Hi Andy,

Thank you so much for your reply! 

I have tried to reduce the water pressure to the washing machine and indeed it made a difference - the level of banging was reduced considerably. The only problem is that it still happens, and I cannot reduce the pressure any further because then no water will go to the washing machine. I am also worried how such low pressure may affect the actual machine.

The pipework where the banging happens is inaccessible. It goes from the ground floor to the loft in the corner of the kitchen, embedded into the wall behind all of the kitchen units. 

It seems that what has happened is that previously the cold water pipe (which now vibrates during the drying cycle) would go up to the loft and into a large water tank. Therefore, there was more weight attached to one end of that pipe (tank is huge), reducing the vibration to almost zero. Now, the pipe goes to the loft, and then down to the combi boiler and the shower. So there is less weight to prevent the vibrations. 

Everything else is fine - it is just that drying cycle on the Hotpoint machine. I am wondering, do some washer/dryer units work differently? i.e. Without drawing water during the drying cycle? Because I think it will be far easier for us to change the machine then to break walls/kitchen units to access pipes.

Thank you!

[Whitegoodshelp (Andy)]

Hello Sylvia. Thanks for the update. I would try to secure the pipework much more in the loft where it is accessible. If you think about it the pipework that is inaccessible and is currently banging has not changed. As you say the reason it didn't bang before was that it was connected to the heavy water tank. So being secured up in the loft should stop it banging. You may just need to secure the pipes in a different way. I would get the washing machine on the dry cycle and have someone up in the loft. When the pipes start knocking get them to hold the pipe firmly in various places to see if they can stop it. If they can, that's the place it needs securing properly to joists. It's not guaranteed to work but well worth a try.

Other than that yes, many other washer dryers don't operate like that. Many of them just have the cold water supply constantly running (at a trickle) not the condenser chamber. That type would cause far less if no banging at all. I couldn't give you a list of ones that do though. At a guess I 'd expect most washer dryers to not constantly turn the condenser valve on and off so frequently but you'd have to try and get an answer from the manufacturer before buying.