Prob with Vaillant Boiler

[Ynots]

Hi, I'm hoping someone can help me here.
I have a Vaillant eco TEC plus boiler, 2 mornings a go my hot water seemed to be running out and its getting worse.
I checked the boiler on the first morning and there was a flashing radiator symbol. I turned the central heating dial down as I'm not currently using it. I checked back later that day and it had stopped flashing. Tested the water and seemed to be getting hot. The next morning i noticed again that the water wasn't that hot at all. I looked at the boiler and gave it an extra hour heating.
This morning yet again the water is only warm.

Ive looked at the boiler again and it seems the temperature won't go above 20 degree. I turn the dial and the temp indicator shoots right up but then goes straight back to 20.

Is there any common reason for this?
Im happy to have a look myself but not sure where to start.

Any help will be greatly appreciated.

 

[picasso]

Is your ecotec a combi boiler or do you have a hot water cylinder?

 

[Ynots]

It's not a combi, I have a megaflo tank.

 

[scoobydo123]

What model is it

 

[Ynots]

I'm not too sure on model?
I'm at work at the moment, just grabbed the manuals this morning as I was leaving.
The boiler manual says ecoTEC plus 415, 418, 428, 438.
The water tank manual says megaflo HE system fit per-plumbed unvented water heater.

 

[scoobydo123]

If you turned the dial down for change then you are reducing flow temp for primary water flow both ch and he. The dial for hw has no effect unless advanced control and vaillant cylinder are installed I believe. Where in Essex are you. Does the boiler sound normal during heat up. Has anyone adjusted state on megaflo

 

[Ynots]

Both dials were left turned up this morning.
The water tank hasn't been touched. When I increased the heating time by an hour yesterday morning it sounded like the boiler fired up ok.
I'm in hornchurch.

 

[scoobydo123]

I'm not that far from you. Get the model number from the flap on the front of the boiler. Could be diverter valve or circulator issue. Try it on CH see if same happens

 

[dreadnoughtheating]

Sounds more like a 'megaflo' issue than boiler end. Air pocket needs recharging?, filter in cartridge blocked? - perhaps I would suggest a repair/service visit for both the Gas Appliance and the Megaflo required, bearing in mind that a service DOES NOT INCLUDE repairs to ongoing problems. (in my book).

Should the OP care to take a look at the CIPHE 'find a plumber' website (based in Hornchurch as it happens) or the GasSafe register site, the OP can check the relevant credentials required especially the G3 Unvented Cylinder accreditation.

As said already the Radiator knob on the Gas Boiler controls the output temperature from the boiler, both to the radiators and to the Megaflo, I would suggest a temp (as shown on the boiler boiler display) of minimum 65 degrees - this will be high enough to kill an bacteria lurking within the megaflo.

DH

 

[scoobydo123]

Boiler flow of 70 and megaflo stat at around 60 is normal not sure about air gap causing fault symptoms noted

 

[holty]

Boiler flow of 70 and megaflo stat at around 60 is normal not sure about air gap causing fault symptoms noted

i think dreadnoughtheating was referring to when the water gets heated up. the T&P relief valve will open up thus causing cold water to replenish the tank. beacause the water has nowhere to expand. very common on megaflows for the bubble to need replenishing. could be numerous different faults. e.g circulation, 2 port etc.

 

[scoobydo123]

OP assume you haven't got discharge into tundish hopefully you have one near the megaflo

 

[scoobydo123]

Any updates on this?

 

[Agile]

I'm not that far from you. Get the model number from the flap on the front of the boiler. Could be diverter valve or circulator issue. Try it on CH see if same happens

An update could be that as its a 400 series it does not have a diverter valve?

 

[scoobydo123]

Yes my error meant zone valve wrong words were typed. Ps my circulator still not turned up for my thread