Megaflo dripping discharge pipe

[Chris Radford]

We have unvented megaflo hotwater tank and a Potterton Suprima boiler with a red expansion kettle

Our Megaflo has a dripping discharge pipe we have endless qualified plumbers around who have replace the cold water combination valve twice and recharged it and tried various things

But every time it continues to drip cold water out of the tundish and down the outlet pipe.

Anybody any ideas. other symptons are erratic pressure in the system so sometimes showers are strong and sometimes feeble. Pressure is always strong after a recharge and then it weakens

 

[corgiman]

I think your expansion bubble in the megaflow has failed

There should be instructions on the side on how to re do it but if not


Isolate cylinder
turn on the lowest hot water tap untill water runs out
turn water to cylinder back on
wait untill water is flowing from tap
shut off tap

and bob should be your mothers brother

 

[Chris Radford]

Thank you for the quick reply

I have tried what you suggest and when I do it seems alright for a short while (a few hours) and then it stgarts .

After we have done this we get some erratic flow from the upstairs cold water taps but that settles down once the water has run through the pipes.

Does any of this point to anything else?

Thanks for the ideas

 

[oilman]

This is a repeat of corgiman's instructions:

Isolate cylinder

turn on the lowest hot water tap untill water runs out

But here add:

hold open the trmperature and pressure release valve (on the side of the cylinder) until the gurgling stops in about 15 to 20 minutes. Then close the valve.

turn water to cylinder back on

wait untill water is flowing from tap

shut off tap


When it drips after this exercise, it may be the seat on the temp & press valve , but that should happen all the time. How "qualified" were these plumbers? were they G3 certified? It needs investigating by someone with some diagnostic ability, changing bits is not the way.

 

[corgiman]

I bow to oilman

 

[Chris Radford]

We have done all this
the plumbers are qualified and have the necessary training from Megaflow but we are all still struggling to solve this
We are trying to work out when the dripping starts after a reset ie is it when the shower goes on or the taps or what?

Any more hypotheses?

Thanks again for the tips

Chris

 

[htgeng]

How old is the installation?

 

[Chris Radford]

How old is the installation?

4 years about

 

[htgeng]

Any chance of a few pics of the installation showing the pipework in proximity to the cylinder? We might spot something that has been missed before.

variable pressure hot water suggests your cold water main is inadequate but thats another issue.

 

[Chris Radford]

I will try and take some pictures and upload them

Thanks

Chris

 

[oilman]

There are two places water can overflow from, one is the trpperature relief valve on the side of the tank, the other ids the expansion relief valve usually mounted on the pressure regulator.

You need to find which one is leaking. You shouldn't do it, so you will need to get it done by someone. Ring Megaflo.

 

[ChrisR]

Pipes from the two valves combine before they get to the tundish (almost always) so you won't know which one the water's coming from. I suggest you simply undo the connections to the pipes at the valves and have a butchers.

I do wonder if you're getting the air gap recharging properly. I always stick a pressure gauge on an unvented cylinder - marvellous for seeing what the heck's going on!

 

[Chris Radford]

The leak is definitley the pressure relief valve on the cold water feed not the hot one attached to the tank. we have tested this and worked this out

I dont know if the recharge is right but your idea is a good one

The cold water feed is after a pressure relief valve but before the dual valve fitted as per the megaflow advice

 

[htgeng]

The cold water feed is after a pressure relief valve but before the dual valve fitted as per the megaflow advice

A picture would speak a 1000 words when trying to understand what you describe.

have you already replaced this prv? Sometimes they get debris under the seal and have to be replaced, although you say the combination valve has already been replaced.

 

[ChrisR]

The cold water feed is after a pressure relief valve but before the dual valve fitted as per the megaflow advice

eh

To check that you're recharged properly - turn off the cold water inlet at the combo valve. Then open a hot tap. It should run for bloomin ages, like several minutes at a good pressure. If it don't, you ain't.