Vaillant Ecotec 438 - s.53 Problem - Fixed?????

5 Sep 2008
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United Kingdom
Hi Everyone

Hope this post helps someone else and cuts short the time taken to resolve this problem. Thanks to all of you that offered your help and suggestions.

Originally I posted a problem topic:

Vented System - Reverse Flow - I think ?

To cut a long story short I introduced multi-zones (2 x CH, 1 X HW) which when a single CH zone was open caused the boiler to shut down after a short while indicating code S.53 - Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)

I called out a Corgi Plumber but although he made suggestions to change pipework and spoke to Vaillant he was honest and said he wasn't sure it would resolve the problem.

I decided to phone Vaillant again today and had a protracted discussion with Vaillant Installation Helpline - it was suggested I change the d.0 'Heating part load' setting to 27kw. This had been factory set at its max - 38kw. I was then told to slowly increase the value ensuring all zones worked independently and am currently at 34kw without any re-occurance of the S.53. on any zone. It would appear that the boiler needs calibrating to operate with the smallest zone whilst still offering a high output to cater for when all zone valves are open. Being set at max 38kw appears just too high when only one valve zone is open.

Fingers crossed.....


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