Tight hot water taps water dripping at overflow

[noidea121]

Megaflo -Tight hot water taps water dripping at overflow

Got a Valliant boiler (ecotec 630) connected to a megaflo installed about 2 years old.

Every time I turn the hot water on at the programmer, after about 20 mins the hot water tap in the kitchen and both hot water taps in the bathroom become quite tight. On opening there is gush and then the pressure is fine. Once one tap (doesn’t matter which) has been opened for a few seconds then the other taps are no longer tight. However if the hot water light (on the programmer) is still on then once again after about 20 minutes the taps become tight. Once the water light is off (we have it on for about 90mins) then there is no problem. This has been happening since it was put in.

I have also noticed that as the taps become tight water is coming out of the overflow. I am 99% it isn’t directly out of the megaflo tank. I have replenished the airgap in the megaflo but like I say I don’t believe it is from the tank directly and only happens when the hot water is turned on.

On the picture (A) I don’t believe it is coming out of the blue/grey coloured part (think it’s called temperature pressure relief valve) on the tank but rather from the pipe coming horizontally across the tank with insulation on it and joining the pipe that does come out of pressure relief valve. I can see/touch the water dripping inside the black plastic just below where the two pipes meet (picture B) and then the water flows through the pipe and out of the property and into my garden. I have also noted that once I do open any of the taps then the water stops dripping at the overflow on the tank.

Does anybody have any ideas as to the reason.

Could it have something to do with other valve in the picture (close up picture C) to which the horizontal pipe is connected? When I once turned the valve in picture c i got the same gush that i get at the taps and then it didn't drip for another 20 mins

Not a plumber so please keep the technical stuff as simple as you can, thanks. Just concerned about any safety issues.​

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[SimonG]

Where is thr pressure relief valve on the incoming mains cold water. Normally reduces cold pressure to between 1.5 and 3 bar. Does sound as though the air bubble is faulty as your problem only seems to occur on water heating i.e. expansion. Also the pipework from the plastic tundish is incorrect. There should be a minimum of 300mm before the first bend in the pipe.

 

[noidea121]

Also the pipework from the plastic tundish is incorrect. There should be a minimum of 300mm before the first bend in the pipe.

Is this dangerous?

 

[SimonG]

Is this dangerous?

No, but it's an indication that whoever installed it either doesn't know what they are doing (because details of discharge pipework is given in mi's) or isn't g3 qualified, or maybe both. This then raises issues about other aspects of the installation. To me anyway.

 

[noidea121]

No, but it's an indication that whoever installed it either doesn't know what they are doing (because details of discharge pipework is given in mi's) or isn't g3 qualified, or maybe both. This then raises issues about other aspects of the installation. To me anyway.

thanks again you mention "G3" what is G3? If i get an annual inspection done by British gas would they be qualified and would it be checked under annual service?

 

[SimonG]

It's the building reguations. Part of the G3 building regulations is specifically for unvented hot water systems. If bg do an annual service on the unvented cylinder then the engineer that performs this service must have is unvented qualification (G3). But does your bg policy cover the unvented cylinder, if it does I would be asking them why they haven't picked up the discharge pipework issue.

 

[SimonJohns]

I will get caned for this. But on the front of the megaflow is a sticker and it has instructions on what to do if water comes from the t and p valve

 

[SimonG]

Is that the instructions for re gassing the bubble. Don't do megaflo's as there are better units at a more reasonable price.

 

[SimonJohns]

Is that the instructions for re gassing the bubble. Don't do megaflo's as there are better units at a more reasonable price.

Yes. All megaflows have them. And I could tell it was an internal bubble from how low the t and p was

 

[Mike Jackson]

Resetting the air gap in a megaflow is something that Heatrae Sadia advise that a consumer can do but looking at the plumbing in the pictures I'd suggest that a G3 registered engineer takes a look at the installation to ensure that it is safe. It should be serviced anually anyway.

 

[noidea121]

I will get caned for this. But on the front of the megaflow is a sticker and it has instructions on what to do if water comes from the t and p valve

Have followed this no joy.

 

[noidea121]

Resetting the air gap in a megaflow is something that Heatrae Sadia advise that a consumer can do but looking at the plumbing in the pictures I'd suggest that a G3 registered engineer takes a look at the installation to ensure that it is safe. It should be serviced anually anyway.

Do you notice something unsafe from the photos?

 

[SimonJohns]

Do you have any thermostatic valves in your house

For eg shower?

 

[noidea121]

Do you have any thermostatic valves in your house

For eg shower?

No not on the shower just on the radiators. Shower is basic as they come.

 

[Mike Jackson]

Do you notice something unsafe from the photos?

Isolating valve between the pressure relief valve and cylinder and not enough drop before bend on pipe D2 after tundish.

 

[tamz]

The internal air bubble needs reformed. If you have tried it you are not doing it right.
They are a pain and need constant doing and one reason i stopped fitting megaflows.

 

[noidea121]

Have added several extra pics to the original post.

The temperature on the boiler(heating dial)) is about 60C, I have been told that the dial for water on the boiler does nothing, and that temperature is controlled by the heating dial.

The temperature on the Megaflo has been set in the grey box on the Megaflo tank itself, the thermostat is between the number 2 and 3 goes up to 5.

My installer thinks the problems may be caused by the valve shown in picture "8extra" closeup shown in pic "C" see below, does anybody have a view on this, i do belive the water is coming from here and making it's way to the tundish. If it is from here would it be airgap related.

Also rang Heatrae sadia they said that to recharge the airgap I should drain the tank from the bottom of the tank, because the lowest hot water tap in the house is on the same level as the tank itself (i.e ground floor of the house)and therefore following the procedure stated on the tank would not work. Couldn't help with the tight taps though.
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[SimonJohns]

this def sounds like an air bubble problem

recharge that first and then start spending money on valves etc

 

[noidea121]

this def sounds like an air bubble problem

recharge that first and then start spending money on valves etc

I really hope so, thanks for the reply, feeling stressed, just watched a video of exploding megaflo on youtube!!

 

[SimonJohns]

I really hope so, thanks for the reply, feeling stressed, just watched a video of exploding megaflo on youtube!!

lmao the tpv and prv are plugged on that thou