Change CH pump or not?

[Silver993tt]

I'll be draining my CH system over the next couple of weeks in order to fit 4-5 new radiators and thermostatic valves etc. My CH pump is at least 18 years old, so I was wondering would this be the appropriate time to get it changed for a new one. It seems to be working ok right now but not sure if I should wait until it packs up. The only problem with that is it will typically stop working when there's a big freeze on.

After changing the 4-5 rads, the system will be about 6 years old except for the pipework & pump.

Any opinions on when others get these changed? Do you wait until they fail or do you go for preventative maintenance?

If I was to change the pump, what should I go for? I have 14 radiators inc towel rails etc.

Edited by Silver993tt on Sunday 15th November 09:39

[Ferg]

I'd fit a new one.
I'd also change the isolating valves and make sure they are proper valves not those stty screwdriver slot ones.
I'd fit Wilo.

[Silver993tt]

Ferg said:

I'd fit a new one.
I'd also change the isolating valves and make sure they are proper valves not those stty screwdriver slot ones.
I'd fit Wilo.

I currently have a Grundfos pump. Why do you suggest Wilo? Are there any particular advantages to Wilo pumps? Regarding isolating valves, I have the large ones that need a spanner. They haven't been turned in at least 16 years so I bet they are jammed and will need replacing anyway.

[Ferg]

If they are like gatevalves then that's quite good, but they do fail when they get old.

I find Wilo more reliable than Grundfos.

[Silver993tt]

Ferg said:

If they are like gatevalves then that's quite good, but they do fail when they get old.

I find Wilo more reliable than Grundfos.

Yes, look like gate valves with the red wheel missing, justthe square lug visible to turn.

Is it worth while getting the 6m head pump or the 5m head pump? Both are available in both makes. I'm in a 2 storey house.

[Ferg]

A 5m head pump should be sufficient.

[Silver993tt]

So, I assume any ofthese would be a good upgrade to my old pump?:

Grundfos Domestic Selectric Bare Pump 15-50:


Grundfos Alpha 2L 15/50 Pump:


Wilo Domestic Bare Pump Gold 50 Bare Pump:


Wilo Smart Pump:

This one looks interesting and only about £25 more than the normal one.

[Deva Link]

I've got a Grundfos Alpha (plumbers merchant "messed up" the price so it was only a tenner more) but on our system every time the boiler (infamous Potterton Suprima) fires it does an electrical test which involves disconnecting the pump momentarily.

So the pump thinks it's starting from scratch each time and starts up at full speed and then backs off gradually. At full speed everything is pretty noisy! In cold weather with the boiler cycling quite frequently this is a real pain so it quickly ended up just set on fixed speed 2.

[Silver993tt]

That's an interesting experience since I also have a Potterton Suprima (with an upgraded PCB!).

[Deva Link]

Silver993tt said:

That's an interesting experience since I also have a Potterton Suprima (with an upgraded PCB!).

I repaired the original a few time but then replaced it a few years ago. It locked out the the other night for the first time in ages so maybe it's on its way out again.

I had thought about adding a relay to stop the pump from shutting down at every test but haven't got round to it.

Another problem with the slower flow in variable speed mode is that the boiler kettled more readily. There may be other reasons why it does that but there's not much water in these little boilers so I feel they need a good decent flow rate.

[Silver993tt]

ok, thanks for the information. My boiler also kettles when only on the hot water circuit (no CH). I've tried turning the boiler heat control right down but it still does it. It might be because my pump is at least 18 years old and even on the fastest setting it's still not enough maybe due to age.