Megaflo losing pressure
Discussion
Ferg said:
Has anyone tested the system without the boiler in the circuit? If the leak is small enough then it can be evaporated and blown out of the flue, or just run away down the condensate drain if it has one.
Boiler doesn't have a condensate drain. And losing too quickly to disappear in evaporation - we'd have a puddle under the boiler..I guess I might throw this in aswell having experienced similar issue in the past.
Being young and moving into my first house, and you know 'handy with the DIY' - decided to bleed the radiators and check the radiator valves...
Anyway quite a few of the valves started to leak, but only enough for the water to escape and evaporate on the hot pipe-work. - It was only closer inspection by leaving tissue paper wrapped around that I noticed the leaks on a couple of valves which I had to replace (on crappy micro-bore).
Being young and moving into my first house, and you know 'handy with the DIY' - decided to bleed the radiators and check the radiator valves...
Anyway quite a few of the valves started to leak, but only enough for the water to escape and evaporate on the hot pipe-work. - It was only closer inspection by leaving tissue paper wrapped around that I noticed the leaks on a couple of valves which I had to replace (on crappy micro-bore).
littlebasher said:
Dunno whether this will be useful, but i'll mention it anyway
We had a problem with our Megaflow years ago when we bought the house. It would continually lose the air gap and used to leak water out the relief valve on the side (visible in the tundish). They changed the relief valve twice and replaced the entire megaflow, neither of which solved the problem.
Eventually a plumber diagnosed the problem. Basically, one of the mixer taps in a bathroom was faulty and was backfeeding the higher pressure cold water into the hot water system. New tap and a load of one way valves (just in case) and the problem was solved.
The megaflo is fed from water mains, that is its job, if anything it has higher pressure than the cold water mains, not lower. It seems you may have a (dodgy) installation with cold water tank in loft, feeding the megaflo, and a mixing tap in the bathroom which is fed cold water mains but hot water from gravity fed water tank.We had a problem with our Megaflow years ago when we bought the house. It would continually lose the air gap and used to leak water out the relief valve on the side (visible in the tundish). They changed the relief valve twice and replaced the entire megaflow, neither of which solved the problem.
Eventually a plumber diagnosed the problem. Basically, one of the mixer taps in a bathroom was faulty and was backfeeding the higher pressure cold water into the hot water system. New tap and a load of one way valves (just in case) and the problem was solved.
The correct solution would be to feed all the mixer taps in the house with cold water from the tank in the loft, leaving only the kitchen tap with no mixer, so cold and hot are completely separate for hygiene and back feed issues.
The best solution would be to remove the water tank in the loft, since you have the megaflo, you do not need low pressure hot water.
rallen said:
The megaflo is fed from water mains, that is its job, if anything it has higher pressure than the cold water mains, not lower. It seems you may have a (dodgy) installation with cold water tank in loft, feeding the megaflo, and a mixing tap in the bathroom which is fed cold water mains but hot water from gravity fed water tank.
The correct solution would be to feed all the mixer taps in the house with cold water from the tank in the loft, leaving only the kitchen tap with no mixer, so cold and hot are completely separate for hygiene and back feed issues.
The best solution would be to remove the water tank in the loft, since you have the megaflo, you do not need low pressure hot water.
No tank in loft, the megaflow is fed straight off the cold supply via a pressure reducing valve.The correct solution would be to feed all the mixer taps in the house with cold water from the tank in the loft, leaving only the kitchen tap with no mixer, so cold and hot are completely separate for hygiene and back feed issues.
The best solution would be to remove the water tank in the loft, since you have the megaflo, you do not need low pressure hot water.
At the time, the cold water pressure was ridiculously high. Ours was one of the first houses built on a new estate, presumably feeding off a big new main in the road. So much so (stupid as it sounds), the pressure destroyed numerous shower heads and a couple of toilet inlet valves.
rallen said:
The megaflo is fed from water mains, that is its job, if anything it has higher pressure than the cold water mains, not lower. It seems you may have a (dodgy) installation with cold water tank in loft, feeding the megaflo, and a mixing tap in the bathroom which is fed cold water mains but hot water from gravity fed water tank.
The correct solution would be to feed all the mixer taps in the house with cold water from the tank in the loft, leaving only the kitchen tap with no mixer, so cold and hot are completely separate for hygiene and back feed issues.
The best solution would be to remove the water tank in the loft, since you have the megaflo, you do not need low pressure hot water.
What!!??The correct solution would be to feed all the mixer taps in the house with cold water from the tank in the loft, leaving only the kitchen tap with no mixer, so cold and hot are completely separate for hygiene and back feed issues.
The best solution would be to remove the water tank in the loft, since you have the megaflo, you do not need low pressure hot water.
littlebasher said:
No tank in loft, the megaflow is fed straight off the cold supply via a pressure reducing valve.
At the time, the cold water pressure was ridiculously high. Ours was one of the first houses built on a new estate, presumably feeding off a big new main in the road. So much so (stupid as it sounds), the pressure destroyed numerous shower heads and a couple of toilet inlet valves.
Ah here we have been suffering from the opposite, very low mains pressure. Have brought the water company person around, he called it "adequate". Rubbish.At the time, the cold water pressure was ridiculously high. Ours was one of the first houses built on a new estate, presumably feeding off a big new main in the road. So much so (stupid as it sounds), the pressure destroyed numerous shower heads and a couple of toilet inlet valves.
Anyway you could simply remove the pressure reducing valve and have same pressure everywhere in all taps around the house. In another country there are no "megaflos" that cost a fortune. You simply have a typical 80 lt cylinder which is built like a thermos, all glass inside, and you feed it straight from the mains with an electrical immersion element to provide the heating. The hot water "expands" into the cold water input. No need for separate "expansion tanks" or the crazy megaflo design which uses a floating polyurethane material which gets mouldy and dirty and you cannot even remove it to clean it. On the hot water outlet you have a pressure release valve which basically lets off steam in case the thermostat goes crazy and overheats, similar to the magaflo's pressure relief valve, only it is a much simpler system.
fulham911club said:
Quick update : the company that installed the system is now saying the issue is the boiler itself and probably the heat exchanger is leaking. Surely if this was the cause I'd have water all over the place from a leaking boiler!
When this happens, well when it happened to me, after the water has heated a bit, it creates steam which sprays onto the gas vents and puts out the fire altogether so you have no CH... Then the pilot restarts the system and all over again. Because the water evaporates as steam you do not see a massive leak, it is taken away in the flue.I have not read the whole thread but it would be that the leak is inside the serpentine in the megaflo. I had mine tested by a plumber once. But unless you have Fernox or something disgusting in your CH system, you might not detect the leak by taste. Another idea is that if you do not have a CH tank in the loft, then the CH system is closed and it could be leaking again as steam from a radiator or somewhere in the loft, you might not find it easily. My CH system has a tank in the loft, so if there was a small leak I probably would not find out easily as it tops up itself.
rallen said:
Ah here we have been suffering from the opposite, very low mains pressure. Have brought the water company person around, he called it "adequate". Rubbish.
Anyway you could simply remove the pressure reducing valve and have same pressure everywhere in all taps around the house. In another country there are no "megaflos" that cost a fortune. You simply have a typical 80 lt cylinder which is built like a thermos, all glass inside, and you feed it straight from the mains with an electrical immersion element to provide the heating. The hot water "expands" into the cold water input. No need for separate "expansion tanks" or the crazy megaflo design which uses a floating polyurethane material which gets mouldy and dirty and you cannot even remove it to clean it. On the hot water outlet you have a pressure release valve which basically lets off steam in case the thermostat goes crazy and overheats, similar to the magaflo's pressure relief valve, only it is a much simpler system.
We used to have glass lined cylinders, but we've moved on now. We use a three-tier safety system which means that there have NEVER been unvented cylinder splits in the UK. Not so in other countries. I don't like the floating baffle, either. Nothing wrong with an expansion vessel though.Anyway you could simply remove the pressure reducing valve and have same pressure everywhere in all taps around the house. In another country there are no "megaflos" that cost a fortune. You simply have a typical 80 lt cylinder which is built like a thermos, all glass inside, and you feed it straight from the mains with an electrical immersion element to provide the heating. The hot water "expands" into the cold water input. No need for separate "expansion tanks" or the crazy megaflo design which uses a floating polyurethane material which gets mouldy and dirty and you cannot even remove it to clean it. On the hot water outlet you have a pressure release valve which basically lets off steam in case the thermostat goes crazy and overheats, similar to the magaflo's pressure relief valve, only it is a much simpler system.
Righto, time for my 2p worth...
As said in numerous previous posts there is nothing wrong with the megaflow cylinder itself. That is as long as your plumber has ruled out the possibility of the coil ( the pipe work inside the tank that heats the surrounding water) hasn't got a pin hole in it. I have had this in the past.
My first check after reading this would be ensuring that the red expansion vessel has the correct amount of air in it. The bladder (ballon) inside these do deflate over time causing similar pressure problems.
Hopefully the pressure relief valve has been checked and confirmed as not passing. Easy check for any plumber/heating engineer.
What make of boiler do you have? Has this been confirmed as water tight?
In my experience lifting floors is the last option and have thankfully has never come to it....
As said in numerous previous posts there is nothing wrong with the megaflow cylinder itself. That is as long as your plumber has ruled out the possibility of the coil ( the pipe work inside the tank that heats the surrounding water) hasn't got a pin hole in it. I have had this in the past.
My first check after reading this would be ensuring that the red expansion vessel has the correct amount of air in it. The bladder (ballon) inside these do deflate over time causing similar pressure problems.
Hopefully the pressure relief valve has been checked and confirmed as not passing. Easy check for any plumber/heating engineer.
What make of boiler do you have? Has this been confirmed as water tight?
In my experience lifting floors is the last option and have thankfully has never come to it....
Don't now of anyone but do you have any areas of discoloured (darker) grout?
Feel for you OP, sounds like a right nightmare!
I seem to remember you mentioning radiators on the ground floor and not underfloor heating, most lightly leak points will be one of the joints in the floor for the radiator upstand, I'm guessing they used plastic to pipe everything up so those should be the only places you SHOULD expect a joint.
Feel for you OP, sounds like a right nightmare!
I seem to remember you mentioning radiators on the ground floor and not underfloor heating, most lightly leak points will be one of the joints in the floor for the radiator upstand, I'm guessing they used plastic to pipe everything up so those should be the only places you SHOULD expect a joint.
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