Valliant ecotec problems

[bobby spray]

Hello, Hope someone can point me in the right direction with problems with my boiler. First the system;
Boiler valiant Ecotec 428
System: open vented ‘S’ plan
Number of radiators: 16 (all doubles) 15mm downstairs, microbore upstairs
Recent History: I did a recent drain down and 2 port valve change on the HW valve. Refilled including sentinel. Desludged the header tank.... not the whole system
Symptoms: all seemed ok for a couple of days. Then I was getting the error s.53 on the boiler panel, which according to the manual is caused by

“Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)”

As the error mentioned water shortage, I checked the header tank and it was full. There was some air I the system and I bled the rads with no change in the error. I then did a bit of reading online and derated my boiler output from the factory setting of 30kw to 21kw. Now I can get the central heating to go on in isolation at the 21kw output. If I increase the output I get another error: s.28 which means:

“Anti cycling mode”


However when I try and get the HW circuit to work I get the original error. I suspect that there may be air in the HW loop near the cylinder but I can see no way of bleeding it off. I was planning of draining down and flushing with system restorer this weekend. Can anyone give me their take on what is happening?

Thanks

BS

 

[lightning]

Do a search on s 53 its quite common.

 

[bobby spray]

yeah, did a search and there seems to be a lot of info out there! i am 'sure' that there is an air lock in the hw loop. any ideas on how i can bleed it? I can see no bleed valve in the system.

 

[Agile]

To help get air out of the system run the heating with one rad at a time on so the whole flow is through each one in turn.

Just running the HW might force any air back to the boiler.

But that may not be the problem!

Have you bled the pump???

Tony

 

[bobby spray]

hi, after some digging about i managed to find the bleed value adjacent to the HW cylinder. Bled it no with difference. I did notice that the pump was pretty hot. I have ordered a replacement. Will let you know how it goes after fitting it.

regards

BS.

 

[Agile]

Did you bleed pump?

Did you check its turning freely?

See FAQ.

Tony

 

[bobby spray]

Hi, yes, bled the pump and it does turn freely. It might not be the pump at all but at least that will be one less variable to check. and worth a punt for £80. The error has slightly changed as well. I now can't get more than 60 seconds heat or hot water through the system before s.53 error appears.

 

[Agile]

You have not mentioned your auto bypass valve or what its set at ???

Tony

 

[bobby spray]

Hi tony, can't see one on my system. It is imperative to have one?

 

[Agile]

Its required by the Good Practice for heating installations, by boiler makers and probably by you if you want it to work properly!

Tony

 

[cozzmic]

Shut isolation valve under boiler????

 

[bobby spray]

Hi tony. it seemed to be working fine before changing the 2 port valve. I thought that the bypass could be left off if there is no TRV valve on the room in which the thermostat is located?

Not looked at the iolation valve... will look tonight

 

[bobby spray]

So it's not the pump! i changed it. The old one had some scale in it but not a lot. I had a heating engineer out yesterday. I wasn't in but he spent about 4 hours sussing out the system then derating the boiler to 10kw and claiming sucess. my house is pretty big (4000sqft) and the house is nowhere warm enough. Getting to the point I'm thinking about replacing the boiler.

 

[lightning]

Have had this before and changed system to a sealed system which cured the problem and put a 15/60 pump on.

 

[The831Bunny]

The correct pump for your system is one with a minimum of 6M head, eg a Grundfos 15-60. This needs to be set at max speed. I wouldn't recommend fitting any of the newer low energy pumps with intelligent speed control.

A S plan requires an auto bypass on the heating flow after the pump, but before the zone valves to provide a route when the valves close and the boiler is in pump over-run.

You are right to think 10Kw is not enough heat, all the heating engineer has done is set the output to match the flow through the boiler thus preventing the boiler from reporting the high differential temperature between flow and return sensors. 16 rads would require more like 20-24Kw in an averagely insulated house.

Your main problem is poor circulation through the boiler caused by a restriction. This can be an incorrectly sized pump, a blocked impeller in the pump, debris in the boiler, air locks in the system, a pump valve broken or partially shut, pipework too small, or any combination of the above.

There's lots on the forum relating to this 'problem', its very rarely an appliance issue though. A expansion tank with sludge in maybe a clue to the water condition in the rest of the system I'm afraid. It may require a chemical flush, but don't expect that to be a 'cure all', it will usually be a combination of causes.