Megaflop Cylinder not calling for hot water

[Mwild]

Hi everyone,

I’ve browsed quite a bit over the last few days but haven’t been able to solve my problem.

I have a megaflo unvented hot water cylinder. The hot flow into the cylinder from the boiler has a 2-way zone valve (Honeywell) inline.

I woke one morning and was greeted with a cold shower. My first port of call was check the stat was requesting hot water. Sure enough I keep it on constant therefore it was requesting hot water. I then checked to see if the valve was opening. The valve was not open. I tried to put it in manual and it worked therefore the valve wasn’t stuck.

I then thought the motor which opens the valve may have gone (as they do), so I called in an electrician. He tested the motor with a multimeter and said it was working fine. *scratches head*

I did some more reading and found that it may be a depleted air gap. Sure enough when I manually opened the valve to allow the tank to heat, water drips from the tun dish. Whilst megaflo have a guide on how to replenish the air gap, I live in a bungalow therefore I have no taps below the tank.

Am I correct in thinking the tank is not heating up because of the depleted air gap? If this isn’t the reason, what could it be?

Also, is it dangerous to be manually opening the valve for a few hours of an evening to get a full tank of hot water?

(Just to note, the central heating is underfloor, therefore controlled with its own 2-way valve and individual stats in each room)

thanks!

 

[Razor900]

Thats not the stat you're talking about its the time clock.

The sparky should have checked to see where the voltage stopped between the timeclock and the brown wire of the valve.

Get a proper G3 qualified plumber in. They should find the problem within 15 minutes but its definitely not the air gap I'm afraid...

Btw as long as the bath tap is below the level of the tprv on the cylinder you can recharge the air bubble

 

[ianmcd]

Also, is it dangerous to be manually opening the valve for a few hours of an evening to get a full tank of hot water?

Possibly as the valve may be closed because it is also a safety device and that may be why it is closed