MegaFlo - Heatrae Sadia Not heating up fully

[im516791]

Hi, I have a large Megaflo that has decided not to heat up fully. My heating/water system has 4 paths (Underfloor heating ground floor / radiators upstairs / towel rails / hot water)

The feed to the hot water is at boiler temperature and I can feel this at the feed pipe at the bottom of the cistern.

I have reset the air gap in the tank itself (and have done this successfully previously on 2 occasions over the last 6-7 years)
There was an old style (black plastic) air release valve on the hot water feed to the cistern which stuck when I tested the plunge so I replaced this yesterday with a new brass one.

I have the water pressure set at 2 bar without any load.

The water heats well if I use the immersion heater.

Could there be air trapped in the cylinder itself ? How would I test this ? Could I drain the flow and return pipes and easily repressure them ?

Any help would be appreciated...Thank you

Ian

 

[Howsie]

Welcome to the forum.

When was it last serviced?

 

[lame plumber]

more likely a motorised valve isnt opening or closing fully somewhere

 

[im516791]

more likely a motorised valve isnt opening or closing fully somewhere

Just sussed this myself but thank you - you are right, the motorised valve for the water is not opening. Next Questions , sorry I'm an ex TV / ATM (cash machine engineer so go logical, my dad was a plumber but unfortunately no longer with us.

I have reset the power and still no change..The valve is Honeywell..Do they often go faulty ? or does the megaflo thermostat control this once the water is at temp. ? Could this be faulty...How do I test from here ?

 

[lame plumber]

opens till megaflo stat is satisfied and then it closes. lever at end will fully open it and then check to see free movement, if ok then motor may be burned out and you need to test for funtion with a meter, best to use a plumber if your not sure and he must be registered to work on unvented cylinders, hell have a nice card to prove it.

 

[Howsie]

Welcome to the forum.

When was it last serviced?

Oh as soon as that...

 

[lame plumber]

Oh as soon as that...

morning Howsie, Ive got a crock leg why arent you working?

 

[Howsie]

Morning, I'm watching the lad plumb up a thermal store. So I'm sitting on my arse on the iPhone drinking coffee.

 

[im516791]

Thanks Chaps...Ive called a 'proper' plumber...I hate being defeated.....Appreciate the quick responses !

 

[SafeGasInstall]

, sorry I'm an ex TV / ATM ?

y are you sorry ?