Megaflow question

[nysk2008]

Hi all, its Friday :17:

Well just been out to have a look at a faulty Megaflow and just want a few thoughts and opinions if poss (sorry if people have asked about this before)

Water is being discharged via the tundish at a v.slow rate probs about 1 drip every 5 seconds. The water being discharged is not mega hot but nor is it cold. I recharged the system and checked the T&P relief was correctly seated. It seems to have lost a bit of pressure and when I pushed the valve on the expansion nothing came out - no air or water (maybe i didn't push it in enough)

With this I am thinking faulty expansion vessel but just want a bit of confirmation. Cheers all

 

[SimonJohns]

Is te cold supply in the house fed from the balanced draw off point. And are there any thermostatic mixer valves in house. Showers or tmv's benith sinks or baths


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[diamondgas]

Have you got a tyre pressure gauge? You need to turn water off and open a tap to remove system pressure first then check the white/blue expansion vessel. If it's dead you'll need to recharge it. Do this with a tap open yeh?

 

[nysk2008]

Hi Simon,

Yes the cold is balanced and to the best of my knowledge there are no TMV's.

Hi Diamondgas,

Dont have a tyre gauge but have already turned water off, drained via hot tap at lowest point and recharged, still dripping

Cheers peps

 

[diamondgas]

Do you know what pressure ther system's at mysk2008? sounds like it's getting up to the 6bar mark. Unusual if there's a pressure reducing valve fitted that'll not happen like!

 

[SimonJohns]

I would hazard a guess that poss the valve isnt reseating properly


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[nysk2008]

Hi Diamond gas,

According to the gauge it was at 1.4 bar ish so pretty low, the Pressure Ruducing valve is standard at 3bar so well within that.

Hi Simon,

That was my initial thought.

Maybe i'll replace both the T&PRV and Expansion Vessel this way I have covered all angles, customer will be happy with this, bit more work I guess but while its drained may be an idea?

 

[diamondgas]

Sorry my friend I wasn't talking heating system pressure I was on about domestic system, I should have made myself a bit clearer lol ... Depending on what model megaflo I believe they're set around 6-8 bar but your pressure reducing valve will be set around 3 Bar yeh? End of the day it'll be either a dodgy TPRV or the domestic hot water system pressure is geting too high somehow! Expansion vessel usually, but there are other causes.

 

[pobsdad]

The exp. vessel needs pumping to 3 bar.

 

[ecowarm]

Sounds to me like the air gap in the megaflow needs restoring, the instructions to do it are on the side.

Follow this video Replenishing the air-gap on a megaflo cylinder from heateam

 

[diamondgas]

Good call ecowarm, I immediately assumed that the megaflo relied on an external exp vessel when one was mentioned.