Vaillant ecotecplus 624 - heating not working

[steve72]

Hello everyone, I'm wondering if someone can help. Sorry that it's such a long post but I'm giving you a rundown of what has happened so far and what solutions I've tried.
I've got a vaillant ecotecplus 624 boiler used in conjunction with a drayton rf1 wireless thermostat.
I have hot water at present but the heating is not working.
There are no fault codes (F) displayed on the boiler's display. When I turn the heating on, the boiler fires up and steam comes out of the flue outside, the display shows S. 4 (burner ignited). However, the radiators do not heat up and after 2 or 3 minutes the boiler display goes to S. 7 (pump overrun) and steam ceases to come out of the flue.
This is the 4th time this has happened in 2 months. The first time it happened in November, I called in a plumber and he said that the zone valve was broken. This was replaced with a new one (Honeywell 22mm 2 port zone valve) and the heating was restored.
Then in early December I again had no heating. I replaced the batteries in the digistat RF1 transmitter and everything was fine again.
Then on Tuesday evening my heating packed in again. Because it was following the same pattern as previously (when the batteries had failed) I rechecked the batteries and even replaced them with new ones. I then fully re-commisioned the wireless system and the RF1 appeared to be showing no faults. However, I still had no central heating. On Wednesday I lowered the SET temperature on the RF1 to below the room temperature and turned the system off. I then adjusted the temperature upwards and turned the system on and my heating returned.
My heating was working fine throughout Thursday and Friday, but this morning the heating failed to come on (yet I do have hot water).
Is my problem a faulty RF1 transmitter, or is it a fault with the pump of my central heating system or is it another problem?
Thanks for reading and any advice offered.
Steve

 

[Tipper]

It could be the motorised zone valve playing up....again.

Try moving the manual lever on the valve across and latch it in the open position.

If that works then the valve is failing.

If you leave it in that position the heating will be on 24/7.

 

[steve72]

Thanks Tipper you were spot on. I moved the latch across and now the heating is working.
Presumably then I will need to get the part replaced a 2nd time?
Is there a deeper fault that has led to the same part failing in such a short period of time, or is it just bad luck that the replacement part installed was substandard?
Thanks once again
Steve

 

[kevindgas]

most likely the system water is filthy and crud is jamming the ball in the valve. ask your plumber/rgi to check the water when he does the valve.

 

[steve72]

thanks Kevin

 

[Tipper]

Don't pay for a whole new valve as just replacing the motorhead is cheaper and DIY if you want to do it.

(Involves some wiring though which you mustn't mix up!)

 

[kevindgas]

Don't pay for a whole new valve as just replacing the motorhead is cheaper and DIY if you want to do it.

(Involves some wiring though which you mustn't mix up!)

under normal conditions then yes, but in this case the OP has said it is the second time recently they have had this happen, this indicates an underlying problem which they need to address or they will be putting a 3rd one in within 6 months. better to check it properly on this occassion.

 

[Tipper]

But you could spend a lot of money paying a plumber to drain down, remove the valve, fit a new one, etc, etc, and generally justifying his high costs!

A new motorhead can be had for about £40 plus only 15 minutes or so to fit.

Must be cheaper than doing all the rest?

 

[kevindgas]

to drain down change the valve and refill should take no more than 2 hours hardly a big bill!

 

[Tipper]

How much then? £200?

 

[mickyg]

It could still be the wirless stat or reciever causing the problem. The valve might not be getting any power. Easy to jump to conclusions.

 

[gassafeengineer]

motorhead £40 how about synchron motor £7.50 and no chance of getting the wiring wrong. sounds easier and cheaper to me

 

[Tipper]

Cheap as chips......but usually fails to cure the problem in my experience.

Far better to change the motorhead complete with the comfort of knowing the gears and contacts are also new.

 

[gassafeengineer]

hell you are unlucky works every time for me never failed unless gears slip then yes new head

 

[Agile]

Replacing the motor only works if its just the motor failed !

Other faults, gears, switches will need a new head.

If the existing motor is working then something else is at fault. Other parts of the head or the shaft is seized or the internals are failed ( although thats usually typified by not turning off ).

Tony