HELP potterton lynx2

[wagggy]

i have a potterton lynx2 fitted about 14 yrs ago,, everything works ok but has started getting very noisy when ch working,, noise seems to comes from pump, very loud mettalic banging,, but when hot water is used the pump is quiet,, my sons run shower for at least 20mins and boiler is quiet but as soon as the ch comes on theres a loud mettalic banging noise which you can hear from every radiator in the house,, if it is the pump why is it quiet when it pumps the hot water round the boiler,,,

would appreciate any ideas

 

[chrishutt]

Sounds like boiler overheating due to obstruction of CH circulation. Most likely to be sludge in a system of that age. Check out flushing options - there's some stuff in FAQ topic if you want to DIY.

 

[wagggy]

would that cause a mettalic knocking, sounds like a lump of metal in pump banging about,, what i cant understand is that its silent when running hot water,,,, 2 years ago the boiler was moved and flushed out and it has a descaler in the water system

 

[chrishutt]

like a lump of metal in pump banging about

That could be air. You need to check the feed and expansion tank. Is it reasonably full and does it take in more water if you drain some off lower in the system? Also does air collect in any of the rads?

 

[cross thread]

might be wrong but i think lynx 2 is a cross flow heat exchanger ,pump may only work in c/heating try replacing it cheapest option

 

[andsam]

I have had the ball in the diverter valve swelling, restricting the flow. Some chemicals can cause this.

 

[wagggy]

this is a combi so no tanks,,, the pump does run when the hot water is used as i listened to it ,, but it only makes a rattling sound when it switches to heating,, if i then turn on a hot tap is goes quiet,, i use a large wooden handled screwdriver to listen to where the sound comes from and it seems to be the pump at the impellor end,,, this boiler uses a divertor valve, doesnt that divert the water from CH to DHW when required,, im not a boiler expert , so might be wrong

thanx for your help

 

[chrishutt]

Lynx 2 does have cross flow heat exchanger but also has diverter valve so pump continues to run for CH or HW.

 

[Soggy_weetabix]

the potty lynx 2 is a real rouge. As an engineer, the puma's were bad enough until they were compared to something even worse.

It did seem impossible that potterton could really get any worse than the puma but they tried and tried. Once they did, they called it a lynx2.

Shame because the Lynx original aint a bad boiler and one I love to work on.

David

 

[corgiman]

I thought the puma came after the lynx 2??

I always found the lynx 2 brilliant, manly breakdowns were down to a blocked low pressure switch

maybe i was lucky

 

[Soggy_weetabix]

I maybe wrong CORGIMAN!

The lynx 2's alyaws seem shinier and so looked newer! Pumas are shiiite but easily repairable.

Guess Ive just taken dislike to the diverters on the lynx2

Mind you thay dont have that dreaded BACK NUT!

Anyway, that discussion been done before.

David