Boiler fault

It's just the way it goes. When the fan went on mine (Ideal Logic) I got a 'pull' off ebay - quarter of the price. Still going fine (touch wood).

Just to add, have removed the fan assembly. The fan itself is marked ebmpapst, so I'd guess not made by Viessman. Remember Papst being the maker of pro capstan motors on 1/4" tape machines, etc.

The data connector has three wires. Marked on the wiring diagram PWM, HALL and GND. So presumably Pulse Width Modulation to control the speed and a Hall sensor to confirm it. Just looking through the vent slots, the fan contains electronics.

Viessmann also got back to me this morning - after I'd asked for a fixed price repair via their website. About £400 - but doesn't cover the heat exchanger or PCB.

Bit more than that for a Viessmann 200w system boiler.

To be fair, it's more than just the fan. It includes the casting which links the gas valve to the burner. It does look lie the fan alone could be replaced - indeed you can get exchange units on Ebay for about £70. But they want the old one back before sending out the replacement.

They are a big supplier of electronically commutated motors/fans, and they're not cheap so the price you've paid sounds reasonable given an inevitable Viessmann markup. There should be a part number on it that you could look up directly on their website if you wanted further information.

On Ebay, I found refurbished fan assemblies at £67.90 (exchange) which I assume have a new fan fitted. But they wanted the old back before sending out the new, and I don't want to wait that long.

If the new assembly from Viessmann sorts things, I'll look into buying just the fan, fit it to the old casting, and perhaps flog on Ebay, if worth the bother. The fan does have an ebmpapst barcode etc on it.

I'm sure they would send the new one at a premium and then refund on receipt of your old. Can you ask them?

Fan arrived about 17.30 yesterday. Boiler working as normal again by about

It says in the description they won't.

Just had another look on Ebay. More than one seller offering re-cons, and one does indeed allow what you suggest.

And I trust you left with a warm feeling that had nothing to do with the heat from the boiler.

And stopped working yesterday. After being used for heating for a couple of days.

Water all over the floor. Looks like the return from the heat exchanger is the problem.

My manuals show both the in and outs being copper. But on my version, hoses like you'd find to a car radiator. I'd guess to reduce NVA.

One failed some years ago, and was an easy change. This one goes to the back of the boiler lump, so a total strip down to replace.

With hindsight, it would have made sense to change them both when the first failed.

I've never worked out quite why my own system only seems to develop faults at the beginning of Autumn - despite the boiler running all year round.

Mine is a system boiler so used all year round for hot water. It even operates the 3 way valve a few times before first firing up - to stop that sticking.

Valve faults I can live with - it's easy open doors to let heat get to another room and then to swap a head, before fixing the old head as a spare. What I can't understand is why our previous boiler ran all year with no problems, but 3 times it got to autumn and the fan bearings seized!

And it proved a nightmare. Heat exchanger (mounted on three studs in the backplate) came off easy enough. Massive split in the hose.

Got new hoses and flue seals.

The correct way would be to remove the flue, fit the heat exchanger, and replace the flue. Except my flue goes out through the wall as close to the boiler top as possible - to give the biggest airing cupboard above. And has mortar all round it. And not ground floor.

The heat exchanger is a cylinder on its side. Flue connection offset to one side. So the rubber seal an odd vaguely oval shape.

The HE is obviously quite heavy. And you can't do a straight lift up onto the flue - as it has to clear the studs, so at an angle. I couldn't manage holding it long with outstretched arms, so got a much younger pal to help.

Ended up jacking the flue with a scissor jack to get the right angle. And a second jack to raise the HS a tiny bit at a time. And eventually - took an entire afternoon - got it all in place without damaging the all important seal. Looked round the back with a dental mirror to make sure it was good.

Then discovered the flue gas sensor would no longer push in and stay. Likely just the gasket - but didn't have a spare. So had to order a complete new one which will arrive later today.

Seems a nonsense to be to fit hoses that can't be easily changed.