Megaflow won't switch off - help please?

[DIYqueen2012]

Hi, I have got a megaflow system which was installed 2 1/2 years ago. It has worked fine until now. Three weeks ago, I realised that it kept working through the nights even though it was due to switch off. I tried various things including swiching it off but it would not stop (just to clarify, it did not go into the radiators, it just kept heating the cylinder and pipes around it.) A couple of days later it went back to normal again. However the problem occured again last week, and it does not seem to go back to normal this time around. I have had a plumber out who says that the boiler, system etc seem to be fine so he does not know what the problem is. Please can someone help?

 

[JohnD]

A megaflow is a pressurised cylinder full of water, with some pipes attached to it. It doesn't switch off (or on)

Do you mean your boiler keeps running, and using gas?

where is the heat from the gas going?

- is there a hot water leak?

- is there a radiator leak?

- is water coming out of the pipe behind the boiler?

- is the megaflow getting so hot that it boils>

If you have got a water meter, go and look at it to see how much water s being used when you think all the taps are off.

Look at your gas meter and see how much gas is being used when you think the radiators are cold and no hot taps are running.

 

[doitall]

Sorry JohnD there's a megaflow boiler as well

We need more info from the op or pics.

Probably a stuck MV.

 

[DIYqueen2012]

Thanks JohnD. I have got a boiler downstairs and what I call the megaflow on the first floor next to the bathroom. I regulate the hot water and heating timer from the first floor.

I cannot find any leaks and it is not boiling as such, but the whole tank and pipes around it is hot, and it is keeping the room next to it at about 28 degrees celcius unless we open windows to cool it down. I dont know whether the excess heat goes anywhere else?

Looking at the meter it is difficult to see it moving as such but I assune it will also be a relative little consumption for the water to be hot constantly as long as no taps or rads are on.

 

[DIYqueen2012]

Thanks Doitall. As you can see above the boiler is separate from what I called megaflow. It is a Megaflo unvented water heater connected to a suprima HE potterton boiler and a honeywell timer.

Any ideas? Thanks.

 

[picasso]

you should have a valve that looks something like this next to the megaflo

honeywell 2 port

• picasso
• 18 Oct 2010
• 31

as doitall has already said this valve is probably stuck on, you will need to turn the whole system off or turn down the boiler stat to off if you want to stop the megaflo heating.

 

[Agile]

OP, your cylinder is designed to be heated up and to stay hot until you use the water. Then the boiler reheats it.

The pipework is meant to be lagged!

As far as I can tell your system is working correctly.

That seems to what that plumber said too.

Tony

 

[picasso]

I realised that it kept working through the nights even though it was due to switch off. I tried various things including swiching it off but it would not stop

That does not seem correct to me.

 

[JohnD]

the whole tank and pipes around it is hot,

That's OK, but the question remains, is the boiler firing and using gas all the time?

 

[DIYqueen2012]

Picasso thanks for the advice. Plumbing is completely new for me, so I am not clear on whether trying your recommendation will potential fix the problem ( like a reboot ) or just ensure that the room is not too hot( but then we would be without HW). I will try anyway and let you know what happens...

 

[DIYqueen2012]

@johnD, the boiler seems to be switching on and off around the clock now. So I think it thinks it has to keep the water hot all the time, and the minute the temp drops below a certain point it starts heating again even if no hot water is being used. I also tried to put it in holiday mode but no luck!

 

[JohnD]

Run the hot tap and test it with a thermometer. How hot is it?

Tell us again about how the hot pipes are insulated.

What happens when you set the timer to "off?"?

Can you see your timer http://www.screwfix.com/search.do?fh_search=honeywell+programmer here?

Holiday mode is (probably) for the Room Stat. Have you got one of http://www.screwfix.com/search.do?fh_search=honeywell+thermostat these?

 

[DIYqueen2012]

Picasso, i cannot see a valve like that. Can i safely turn off the boiler and then restart it after a couple of hours to see whether that would help?

JohnD, my timer is the first on the link ST9400C and the thermostat is the fourth item T6360B.

The water temp is around 60 degrees celcious so not close to boiling.

 

[DIYqueen2012]

JohnD, nothing happens when i turn the timer to 'off'. Its light goes off, but it is still on (i can hear the faint noise it makes and it doesnt cool off as it used to). The pipes looks like uninsulated cobber pipes to me.

 

[Agile]

It still sounds like its working correctly.

If you want to reduce hear loss then insulate the cobber pipes!

Tony