banging hot cold water vaillant

[jcorbin]

found this answer from goole search

//www.diynot.com/forums/viewtopic.php?t=129697

I have a banging from diverter valve and hot cold water Banging happens when hot water called for with heating on. the water temperature set at 12 oclock the display showing 69 and from tap 38 and 45 c. I put my hand under tap its too hot then cold then warm.The engineer called to fix it checked diverter valve and heat exchanger behind it and said they all do that !!!!!!
Do the ntcs need changing and electonics or gas valve or heat exchanger getting very confused by deferrent 'engineers' .how much are gas valve ntcs and heat exchangers ?

sorry for longand rambling post .

 

[gas4you]

Do we assume you also have a turbomax?

It still sounds as though you have a flow problem, the most usual cause of banging and water temp fluctuation. Did the engineer actually replace the DHW palte to plate HE, or just try to clean it?

 

[jcorbin]

Do we assume you also have a turbomax?

It still sounds as though you have a flow problem, the most usual cause of banging and water temp fluctuation. Did the engineer actually replace the DHW palte to plate HE, or just try to clean it?

Sorry Dave turbomax plus engineer looked in "big sardine can" heat exchanger and diverter valve then fitted both back. Dave where is flow problem in?

 

[gas4you]

If he just looked at the plate to plate HE (large sardine can) and the DV then he has done s*d all to fix your problem

The problem usually lies with the system side of this HE blocking up, partially or fully. This then restricts the flow of water through it from the main HE when just on for HW, therefore causing very poor circulation and consequent banging. The other effect of this is the other fault you describe, water going hot, cold, hot etc.

This is caused by the boiler overheating, cooling and working again, then overheating etc etc.

I would suggest replacing the plate to plate HE and cleansing (flushing) your heating system, otherwise your problem could soon come back.

 

[jcorbin]

If he just looked at the plate to plate HE (large sardine can) and the DV then he has done s*d all to fix your problem



The problem usually lies with the system side of this HE blocking up, partially or fully.



I would suggest replacing the plate to plate HE and cleansing (flushing) your heating system, otherwise your problem could soon come back.

Dave will x200 clean or x800 dont wont to block everything with dirt how long will it take ?Googled for replacing HE is this cheap copy http://www.ezypart.co.uk/parts/part_id__2179 about £90 do spirovents work http://www.bes.co.uk/products/110.asp part number 18497 £114
x200 2004 vintage donated free will it work or bin it ?
Will print this page off for next engineer/plumber who hasnt got a clue thanks dave

 

[jcorbin]

Dave will x200 clean or x800 dont wont to block everything with dirt how long will it take ?Googled for replacing HE is this cheap copy http://www.ezypart.co.uk/parts/part_id__2179 about £90 do spirovents work http://www.bes.co.uk/products/110.asp part number 18497 £114
x200 2004 vintage donated free will it work or bin it ?
Will print this page off for next engineer/plumber who hasnt got a clue thanks dave

Not a good plan ?