Trying to understand Megaflo system

[endaxi]

Hi all,

Forgive my second attempt at explaining a problem but my first thread died an early death. I'll try to be more concise this time.

I have a 15 year old Megaflo CL210 fed from a gas boiler and after a partial drainage of the tank to fit a new kitchen tap now have hot water backflowing from the tank out to the cold water bathroom taps for about 30 seconds before they run cold again.

The cold water mains enters the airing cupboard and into an old type Heatrae Sadia 95 605 869 combination valve. When it leaves the valve it enters a T Piece where one side goes straight to the Megaflo inlet and the other to the cold water bathroom taps, I believe.

Should there be another PRV/NRV between the Megaflo inlet and the T piece to stop this backflow to the cold taps? I never had a problem before the cylinder drainage but a NRV between the tank inlet and the cold taps would stop the backflow, right?

Educating myself on the internet and found that the Megaflow should be serviced annually by G3 qualified engineer. Always get boiler serviced but never had the Megaflow serviced. I should get that done soonest.

Finally, I believe the Megaflo has an airgap inside. My system also has an expansion tank so I'm a bit confused with that.

Would it help to recharge the air gap? Nothing flowing through the tundish.

Grateful for any advice.

Thanks.

 

[HERTS P&D]

I thought you had booked someone to come and sort this out for you or are you trying to DIY it?

Andy

 

[endaxi]

I thought you had booked someone to come and sort this out for you or are you trying to DIY it?

Andy

Hi Andy,

It seems I've got the bit between my teeth now. Got someone coming from BG on Monday but now I know this is a specialist area (G3) I'm trying to understand things so I can gauge whether I'm getting good advice. I don't want to have to believe one person who may not be properly qualified to deal with the problem. I know through reading on this and other forums that there's a multitude of opinions on any one subject and contributors often disagree. I've learned that I can re-charge the air gap myself if that's needed.

I'm really interested to know how things work. Every day's a school day.

 

[MeldrewsMate]

Hi all,

Forgive my second attempt at explaining a problem but my first thread died an early death. I'll try to be more concise this time.

I have a 15 year old Megaflo CL210 fed from a gas boiler and after a partial drainage of the tank to fit a new kitchen tap now have hot water backflowing from the tank out to the cold water bathroom taps for about 30 seconds before they run cold again.

The cold water mains enters the airing cupboard and into an old type Heatrae Sadia 95 605 869 combination valve. When it leaves the valve it enters a T Piece where one side goes straight to the Megaflo inlet and the other to the cold water bathroom taps, I believe.

Should there be another PRV/NRV between the Megaflo inlet and the T piece to stop this backflow to the cold taps? I never had a problem before the cylinder drainage but a NRV between the tank inlet and the cold taps would stop the backflow, right?

Educating myself on the internet and found that the Megaflow should be serviced annually by G3 qualified engineer. Always get boiler serviced but never had the Megaflow serviced. I should get that done soonest.

Finally, I believe the Megaflo has an airgap inside. My system also has an expansion tank so I'm a bit confused with that.

Would it help to recharge the air gap? Nothing flowing through the tundish.

Grateful for any advice.

Thanks.

 

[endaxi]

Sorry, I seem to have confused things by running two similar threads. Really appreciate the help so far on both threads but any further comments on the issue are best put on the original thread,''Warm Water From Cold Taps''.

Sorry again for confusing things.