Unvented Megaflow - Water not maintaining heat once boiler is off

[Elvbee]

• I have an unvented Megaflow system which is just over 2 years old and I have noticed recently that the water does not stay hot for a long time after the boiler (3 year old) has gone off. For example in the evenings it' on between 7:00pm and 9:00pm and without much water being used it's cold by midnight. Anybody know why this is happening?
  
  When I use the GAS to heats up as usual. In the mornings it's on between 5:45 to 9:00. Everybody (3 people) get their shower by 08:15. If the 4th person try to get a shower at 11:30 the waster is cold. Normally the waster would stay hot the whole day.
  Using the IMMERSION heater it will take approximately 2hrs to heat tank, Yesterday the IMMERSION heater was on between 10am to 4pm and some time after 8pm someone was trying to take a shower and the water was cold and i mean cold. There are no leaks from Turk (or whatever it is called)
  
  I have replenishment of the tank etc.
  
  
  
  ​

 

[kimbo]

Has it got a secondary return fitted to it. This could be stripping the hest out of it.

 

[Elvbee]

I don't know. It used to work perfectly ok until recently.

 

[diamondgas]

Either a leak on the hot water circuit or as said above you may have a secondary circulation on the hot water circuit that's draining the heat.. ?

 

[Gray0689]

I'd put money your expansion vessel is bust or needs recharging
Passing on temp/pressure relief valve when water hot due to increase in pressure

 

[Elvbee]

I'd put money your expansion vessel is bust or needs recharging
Passing on temp/pressure relief valve when water hot due to increase in pressure

I have done the recharged and it's still happening.
I don't understand the rest, maybe it's because I don't fully understand how the megaflow works.

if say one of the hot water pipe (to the radiator or otherwise) has a leak, would this drain out the hot water from the tank over a period of 1 to 2 hours?

 

[Dotty]

Give up while you're ahead and get a plumber with a G3 ticket in to look at it.

 

[Gray0689]

I have done the recharged and it's still happening.
I don't understand the rest, maybe it's because I don't fully understand how the megaflow works.

if say one of the hot water pipe (to the radiator or otherwise) has a leak, would this drain out the hot water from the tank over a period of 1 to 2 hours?

Time to get someone in as said ^
Ps I forgot megaflow have internal bubble

 

[Elvbee]

I have one coming tomorrow morning, hopefully he can find what the issue could be.

 

[Gray0689]

I have one coming tomorrow morning, hopefully he can find what the issue could be.

My money is on tpr valve

 

[Elvbee]

My money is on tpr valve

Plummer turned up today and can't anything wrong with Megaflo, so the only conclusion is that there must be a leak in the hot water circuit downstairs, now where do I start? :mad2:

Any ideas?

Anybody want a job to find the leak and run new pipe etc?

 

[Megaflo-Experts]

Can you isolate the Megaflo, whenever you don't need the hot water? Do this between showers and see if it works as before.

However, be aware that at this time of year, the incoming mains to refill the Megaflo is colder, and therefore the hot water temperature willmdrop quicker as it is being used. Hope that makes sense

 

[Elvbee]

Problem solved - The hot water copper pipe from the megaflo which was under the house had 2 pin hole leak and this was draining out the hot water. Had to rip up my new flooring but such is life! :74:

 

[Ray Stafford]

Thanks for coming back to let us know how it ended.

 

[Gray0689]

Plummer turned up today and can't anything wrong with Megaflo, so the only conclusion is that there must be a leak in the hot water circuit downstairs, now where do I start? :mad2:

Any ideas?

Anybody want a job to find the leak and run new pipe etc?

Lol can't win them all

 

[bobsy852]

Hi,

I live in a rented property which has a megaflow DD170 electric immersion heater installed (been in since Nov'05 according to the sticker on it). This last week I have a similar problem to the OP, the cylinder heats up over night with very hot water in the morning. Yet by the time I come home from work it's gone luke warm/cold.
I can then put the hour boost on and that will give me hot water again but obviously not a full tanks worth.

Before I call my landlord I thought I'd try learn of these systems and try find the fault. There's no water coming from the over flow of the cylinder.
And I checked the water meter this morning before work when the tank was hot, and i didn't use any water while I was at work, so I presume there is no leak in the system?


Can anyone help as to what could be wrong with it?


Thanks

 

[bigman]

There isn't much you can do these systems without the correct qualification working on these without qualification is illegal, contact your landlord it's what you pay rent for

 

[Ermintrude]

My thoughts too. If you want to Learn about them go on a g3 course not a forum full of crackpots!

 

[bigman]

Be fair Ermi it's only 95% full of crackpots!

 

[Ermintrude]

5% spammers? Seems a bit high to me.