I have a megaflow system and by following the service instructions on the side fo the tank, the hot water pressure has been restored to previous levels and is very good. However, the cold water pressure (which noticeably dropped about 6 months ago) is now much less than the hot taps in all but the kitchen sink which is of course fed directly from the mains. I would add that the hot water pressure drops to be seemingly the same as the cold water after running for circa 5+ minutes on full. After turning the hot tap off and waiting a short while (10-15 minutes) the hot water pressure is restored but the cold remains much less. I would guess that the hot is circa 3 bars pressure versus 1 bar for the cold. I was told that all the cold taps in the house are fed from the mains supply and that it was NOT possible that the megaflow system cold do this. It was a visiting British Gas engineer who was servicing my boiler under annual contract. British Gas are also contracted to cover my megaflow unvented system? I can read from research that megaflow system CAN also supply the cold water pressure to taps in the house and want to verify that this is indeed the case. Does anyone know of a reason why my cold water taps aside from the kitchen sink have lost much of their normal pressure and how I can tell if my megaflow system is at fault? Without a header tank could it still be an air gap?
The cold feed will be a balanced cold feed which is the same pressure as the hot,my guess is the inline filter is slightly blocked reducing flow. The reason the hot comes out with more flow is because its under load from your air bubble when that is exhausted the flow is properly equal with the balanced cold.
So, albeit the megaflow could pressurizing the cold water this is extremely unlikely as both hot and cold would be affected. As you mention, there is a block of some sort between the mains supply to the property and the cold delivery to the megaflow and presumably all of my other cold taps are pressurised from a point after the filter. I wondered if it may be the valve that I have read about that prevent excessive mains pressure from affecting the megaflow - is this the same location for the inline filter or will that be separate? Once I know where the inline filter is I can check, but at the moment I'm not sure what it looks like. I guess once known this is a DIY task or does a qualified plumber have to fit such parts as a megaflow is involved? Thxs
Out of curiosity and in the likelihood that BG will claim this is NOT covered by my policy - do any of the images attached highlight the filter than may by now be blocked and need replacing? I guess it's the rather obvious one named 'LIMEMASTER'!!!
I suspect that the LimeMaster is an magnet water 'conditioner' which is 'supposed' to affect the water passing through so that limescale doesn't form on all your thingies as it would normally. So, not a filter...
Could this conditioner element be blocked? - it would be circa 14 years old now. Else I'm not sure that I do have an 'In Line Filter' as these are generally rather apparent things and normally fitted under the kitchen sink where the water comes into the house if I'm not mistaken from my research. Is there anything in the pictures to suggest the cause for low cold water pressure? I've not looked in the loft recently, but the last time I did there was just the small header tank for the central heating system. I can't imagine the in line filter being located in the loft.
Sometimes you have a filter in the inlet to a valve, other times it's a separate piece. The cold supply to the sink comes straight from the mains while I expect the rest of the house comes from the PRV which also feeds the Megaflow. Assuming the PRV to the megaflow is set at about 1 Bar, you draw off some hot water which lets cold water into the cylinder which is heated up. It expands and increases the pressure in the cylinder but not the cold supply as there is a non-return valve to stop this. When you next run off hot water it appears to be at a higher pressure than the cold until the air bubble expands and the pressure drops to whatever the incoming is set at. I'd check the settings on the PRV and also the incoming mains: water boards are reducing pressure all over the place (mine has dropped from about 65-80PSI to 35PSI) so if yours is lower than before it could be the mains pressure is down and with the added resistance through the PRV it's more noticeable.
Does it require a qualified plumber to adjust the PRV on the cold supply to the megaflow and the cold taps that are supplied after the PRV? You've nailed it on the head here, but with my megaflow plumbing installed before the airing cupboad and being 90 degrees out, access to even see things is problematic. I believe that I will need to open another access hole to the right hand side of my airing/tank cupboard from the family bathroom. I don't want to do this if the PRV can be adjusted where it is now (physically at the back right hand side)?
Yes us plumbers have to hold an unvented certificate to work on unvented cylinders which we have to renew every 5yrs.
Gritish Gas engineer kindly agreed to sort my problem as part of my homecare 200 annual cover. It was indeed the cold water combination valve, the old one being blocked with gunk etc.. Water pressure, shower and things back to their best. Thanks for the suggestions and also Megaflow expecrts from Dartford Kent who confirmed by email that it was almost certainly the combination valve. I had priced a replacement on ebay for circa £70, but with British Gas coming up trumps, I'm well pleased to have had it all fixed within my £20+ quid a month cover.
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