My neighbour needs a quiet pump.

[Brian Gaff]

Why is it that at this time of year, when its hard to get folk to look at central heating my neighbours pump starts soundling alike a very noisy motor bolted to a sounding board. I suspect its somewhere in the room directly next to my listening room, so all I can hear is the rumble driving my mad for the last several hours. Sounds like the bearing is bouncing around. Is there a good way to stop this racket next time? IE mount it in foam or something as this is not the first time in about five years sincce she had this system that this problem has happened. Brian

[polygonum]

Blow their main fuse?

I do agree. Seems worst when the heating is on but little demand for heat - so the pump is pumping more than needed. So it is less of an issue in real cold weather than either side of summer.

[nemo]

After years of service our Grundfos CH pump was clearly on its last legs, making unseemly clattering noises when starting up as well as its normal background rumbling noise, so I decided to get it replaced before it packed up altogether. I chose a replacement Grundfos ALPHA2 L unit that offered high electrical efficiency and dynamic pressure modulation, rather than the cheapest "straight replacement" on offer.

I'm really pleased with the outcome. We no longer have *any* audible feedback as to whether the pump is working: it is practically silent.

It's difficult to identify precisely how much the electrical efficiency aspect has reduced running costs (spec. says 5 to 20 watts versus 50 to

70 watts in my case) but the relief from thirty-odd years of heating pump drone is *very* welcome.

Including fitting, £120 - a real bargain.

So Brian, it may be worth proposing a replacement unit: power saving cost saving for your neighbour and sound reduction for you.

[harryagain]

Most pump noise is due to cavitation. Either directly or indirectly because the cavition has caused uneven wear on the impellor causing the pump to be unbalanced. So it gradually gets noisier.

Cavition is caused by too high a water temperature and too low a pressure in the pump. Sometimes the problem can be cured by increasing the system pressure. Or reducing the pump speed if feasible. Depends on how worn the pump impellor has become. Prevention being the thing.

[Brian Gaff]

Well nobody told the pump this then as last night was the coldest so far this winter. i notice its not doing it this morning so far. Last time it started this sh claimed a gental tap stopped it for a while. Weird. Brian

[Andrew Gabriel]

Could be as simple as something leaning against the pipework which is pushing it against a wall.

There are rubber lined pipe brackets for use near pumps, to reduce the vibration coupling to the wall.

[Richard]

Bit confused here... did you mean genital, or gentle? ;)

[Dave Liquorice]

A pump should last for a lot longer than 5 years. Do they always get it replaced by the same person/company? Is the installer bleeding it after installation? Do they bleed it every year? Is it installed correctly? IIRC the impellor end of the shaft should always be lower than the motor end.

Bleeding it now may well cure the noise.

[Vir Campestris]

The noise reduction may well be welcome, but I doubt the running cost change will be much. You've saved 60W on the pump. Most of the old 60W would have ended up in the water it was pumping, so what you've actually saved is 60W * (difference between gas and electric). Allowing for boiler efficiency of course...

Andy

[nemo]

Agreed. I wouldn't have considered it worth swapping just to get better economy, but the old'un was on its way out anyway. The annual running cost saving is tiny but will actually recoup the price difference within a couple of years or so.