Not the most exciting topic, granted....
But, our central heating circ pump has been on the way out for some time, and has now all but given up the ghost & needs replacing. It's a Grundfos 15/50 Selectric.
I think our system is an open one, but can't tell you much more than that.
All the literature for the pump recommends that the pump should be plumbed in to pump upwards as this stops air getting trapped in the pump housing & knackering the pump, unless you have an air vent fittted above the pump. I am not sure what a vent looks like, but am pretty sure we don't have one. The pipe above the pump disappears off into the loft, and there's a pipe running parallel this this one (same dia.) with a short branch between the two about a foot above the pump.
I am guessing that the lack of air vent/pump facing downwards is why our system is quite noisy & we often have to bleed the radiators. Does anyone know if this is the case?
Why would our system be plumbed in to pump downwards when the pumps seem to all recommend operating upwards, and why do we appear to have no vent?
Anyone know how easy it is to fit a vent to the system? And how much it's likely to cost?
I spoke to the other half's Dad last night as he's a retired plumber. He reckoned it was fine to just run the pump downwards and from looking on the internet last night there are plenty of others who advocate this, but I don't see how this is a sensible thing to do when the pump manufacturer recommends you don't do it and the symptoms we are experiencing with our system seem to tie up with the fact that our pump is pumping down, not up.
Any help appreciated!


