Cold water lower pressure than hot from megaflo

[tominghana]

Hi

I have a megaflo system, but the pressure in the cold tap is quite a lot lower than the hot tap. I understand that the hot from the megaflo derives its pressure from the mains pressure, which also feeds the cold. So the fact that the pressure at the taps is lower on the cold than the hot makes me think that there is an issue with my cold water pressure circuit somewhere after the megaflo.

Is this a fair interpretation?

How would I go about diagnosing the issue?

Thank you!

Tom

 

[chris watkins]

You would be right Tom

Is it all your cold taps including the kitchen?

Problem is that the cold most likely comes from the balanced pressure port on a composite valve which is part of the un-vented hot water system, so you really do need to understand what you are doing, that is why to work on it you have to hold the Part G ticket under the Building Regulations.

 

[tominghana]

Thanks Chris.

Actually it's all of them except the kitchen. Does that make it easier to diagnose?

I don't have a problem with getting someone in to look at it, I'm just wondering how likely it is they will be able to solve it without ripping open all the floorboards which isn't an issue. I don't really want to spend £100 just to find that out...

Thanks
Tom

 

[chris watkins]

It is common that the cold to the kitchen sink is taken off of the rising main before it goes through to the composite valve.

So we know it is not the incoming supply and likely that it is valve assembly or balanced cold water from it but as I say it is time to call someone who has their Part G(3) ticket and please ask to see it, along with whatever confirmation you can get that they are experienced in these systems.

It should not be to difficult for them to sort out what is causing the problem.

 

[Riley]

Thanks Chris.

Actually it's all of them except the kitchen. Does that make it easier to diagnose?

I don't have a problem with getting someone in to look at it, I'm just wondering how likely it is they will be able to solve it without ripping open all the floorboards which isn't an issue. I don't really want to spend £100 just to find that out...

Thanks
Tom

Hi Tom

You've been given good advice by Chris but please don't begrudge paying a trained engineer what he is due for his experience and time to diagnose and resolve your problems. I can guarantee that hundred pounds does not go straight into the guys pocket. Sorry it just rattles my cage a bit when people think we charge money just for the sake of charging money. Hope you get your problem sorted though and happy Christmas

 

[fezster]

One thing worth noting is that Megaflo's have an internal air expansion baffle which has an accumulator effect. It's *very* short lived, but does mean the hot water pressure seems to be significantly higher when you first draw from a hot tap after heating the cylinder.

More likely to be as the guys above said, though.

 

[tominghana]

Thanks Riley. As I said, I'm totally happy to pay someone to look at it, but I came on here to guage the likelihood that it's something that will be able to get solved without major disruption & cost. If, say, it was the kind of thing that could only be solved 25% of the time without that kind of disruption, I probably wouldn't bother getting someone out in the first place (it's only a minor issue we have lived with for years).

From Chris's advice, it sounds like the chances of success are much higher so I will get someone to look at it, fully respecting the time and expertise it takes...

Thank you all !

Tom