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My father passed away recently and my sister and I have to look after the house until it can be sold. It is fitted with a Potterton Lynx 2 combi boiler from the early 1990s, that only supplies hot tap water and three upstairs radiators, and I've discovered that it doesn't always fire up when there's a demand, either on timer C/H or opening a hot tap. My brother-in-law has been round with a plumber he trusts, who has diagnosed a faulty pump, and he told him it was obsolete. The pump seems to seize after periods of disuse and cooling, and starts to get hot when power is applied. Tapping the pump with a metal object brings it to life. I've taken the details and it is a Wilo Gold Star, Type F, TF95, apparently one speed (2700rpm). I've found a couple of used examples online, but all three speed, but the highest speed matches the one speed on our boiler. My own thoughts are that 3 speeds are not going to matter. My question is, seeing as new Wilo pumps of a different spec are still available, as well as reading on here a different thread on Lynx 2 pumps where someone recommended "Grundfos every time", how as a layman do I know if a different new pump will suit the old Potterton? I know there's a PCB that fires the pump up on demand, but does the pump need to be matched exactly to the original PCB, or in many ways, is a pump just a pump? Allowing of course for matching up specs like amps, watts and rotational speed (and whatever uF 3.5-400V means. Micro farads?) My dad had the boiler serviced as recently as early October so if the problem existed then, it wasn't attended to. Thanks for any advice anyone can offer.
Mick.
 
Hi
Some pumps were specifically designed to work with a particular boiler. These might have a smaller, or larger pump impeller. So generally, they are not compatible with just any head.

I've had a look and it seems your guy was right. It's probably new boiler time.
 
Okay thanks. It was worth asking anyway. I don't think we will be going to the expense of a new boiler since the house needs to be sold, and needs a complete makeover anyway so will probably be purchased by a developer. The plumber my brother in law used said try to get a secondhand pump, so I think to try to keep the house warm over winter that will be the route to take. We will probably use the same guy to fit it to make sure it's done properly. Thanks for your help.
 
I've bought a secondhand Wilo Gold Star pump and I've come back here just to check something if I may. I've sent an email to the seller but so far he hasn't responded. I'm guessing the pump motor is a brush-less motor, (an induction motor?) but I was a bit surprised that the impeller and shaft has a fair bit of free end float - about 3 or 4mm. The pump is complete with impeller casing so I can only just reach the impeller with a finger tip but it does seem to rotate freely and smoothly - I was just surprised the whole assembly knocked about inside the pump when I took it out of the packaging to examine it. So is that end float normal? The other thing I was wondering is do I have to make a new gasket if I take the two cap head bolts out, that hold the motor in place on the impeller casing? Because the motor needs re-orientating in relation to the impeller casing so that the black electrical box is on the other side to where it is now, in order to fit the pump into the Potterton with the water flow in the right direction. I've got gasket paper and Hylomar Blue if I do need to make a gasket, I just thought I'd ask before I take an allen key to it and learn the hard way! Cheers, Mick.
 
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