Fitting an American water hammer arrestor to UK washing machine.

[jackthom]

Screwfix do a good Honeywell Pressure Reducing Valve (15mm or 22mm available) which can help tame the whole cold water system.

http://www.screwfix.com/p/honeywell-pressure-reducing-valve-with-gauge-15mm/69396

 

[eternaloptimist1]

Screwfix do a good Honeywell Pressure Reducing Valve (15mm or 22mm available) which can help tame the whole cold water system.

http://www.screwfix.com/p/honeywell-pressure-reducing-valve-with-gauge-15mm/69396

Thanks.

 

[ree]

OP,

yes, your arrestor will make a sound connection - use 2 x wraps of tape, and compound on the tape.

There's a piston in the tube and the piston can be renewed in some Souix Chief's. (unlike the membrane in a Thermal Expansion Tank).

 

[St0rmer66]

I have a 2 litre expansion vessel on my cold main, never get even a hint of hammer even with 6 bar standing pressure.

 

[eternaloptimist1]

OP,

yes, your arrestor will make a sound connection - use 2 x wraps of tape, and compound on the tape.

There's a piston in the tube and the piston can be renewed in some Souix Chief's. (unlike the membrane in a Thermal Expansion Tank).

Thank you. Just need to ask you what you mean by tape and compound on tape. I have PTFE tape. Will that do? and what compound? I have BOSSWHITE.

 

[eternaloptimist1]

I have a 2 litre expansion vessel on my cold main, never get even a hint of hammer even with 6 bar standing pressure.

Thanks. This something I will also consider if all else fails.

 

[Madrab]

Or install the PRV before the washing machine to 'reduce the pressure' as Jack mentioned.

 

[eternaloptimist1]

Or install the PRV before the washing machine to 'reduce the pressure' as Jack mentioned.

Thanks. I have actually done so. I will post a picture. The PRV is followed by the mini restor. The trouble is, when pressure is reduced sufficiently so as not to cause the water hammer, the damned washer says there is no water and instructs me to turn it on! This is one of the stupid things modern machine designers do! The design of the machine is such that it waits for a specific time after requesting water intake and if the water level check fails, it concludes that water is turned off and aborts the whole program. Audible water hammer is increasingly being reported and a good design should recognise its existence and should give the customer the option to prolong the water intake phase. In my case all I need to do is to reduce the flow and avoid this problem.

 

[Madrab]

Yeah, they do re-design their intake valves, so the solenoids don't shut so sharply but like everything they never seem to get it right. The other issue is that the rubber washers in the valve get old over time and become less flexible and can then close more severely. That's why sometimes even a new solenoid valve can fix it.

I'm surprised that reducing the pressure does that with the washing machine would have thought that would have been a result of reducing the flow but the PRV shouldn't have done that, what do you have to set the PRV too before it removes the hammer?

 

[eternaloptimist1]

Yeah, they do re-design their intake valves, so the solenoids don't shut so sharply but like everything they never seem to get it right. The other issue is that the rubber washers in the valve get old over time and become less flexible and can then close more severely. That's why sometimes even a new solenoid valve can fix it.

I'm surprised that reducing the pressure does that with the washing machine would have thought that would have been a result of reducing the flow but the PRV shouldn't have done that, what do you have to set the PRV too before it removes the hammer?

Thanks. Sorry for the delay but had to terminate conversation last night as was getting close to din din.
1. Heres a picture of my installation.

2. I dont know the pressure setting as I have not attached the gauge. Believe it could be down to 1 bar.
3.Just thought that perhaps I should move the PRV upstream past the point where the banging occurs.

 

[SteveP86]

I got water hammer as a result of the stop cock not being fully open. I thought that would cause a more violent hammer being open more but you live and learn I suppose

 

[Madrab]

Where specifically does the water hammer occur, where in relation to the PRV/Arrestor and washing machine?

 

[eternaloptimist1]

Where specifically does the water hammer occur, where in relation to the PRV/Arrestor and washing machine?

Thanks. The water hammer occurs upstream of the PRV. I fitted the PRV just before the arrestor as it was the easiest place but in retrospect, I need to fit it further upstream so that pressure is reduced in the plumbing system, not just to the washing machine. In theory, since I had no problem with my old low pressure system, reducing the pressure in the system ought to cure the problem.

 

[eternaloptimist1]

I got water hammer as a result of the stop cock not being fully open. I thought that would cause a more violent hammer being open more but you live and learn I suppose

Is it the main stop cock you are referring to?