Gravity fed vs mains pressure systems

[cbasson]

Hello,

I am contemplating changing the gravity fed system in my house for a main pressure closed system. Mainly to make more room in the loft.

Someone has mentioned that I will need to changed the water cylinder for a bigger version if I switch over, also that one reaosn for switching over is that more components are made for mains pressure systems now.

I can see how the first would make sense, using more water with a higher flow rate...are they both correct?

Thanks

 

[dcawkwell]

Mains pressure tank provided you have a good cold mains flow into
the house of 20-25 litres a minute.

 

[warmadmax]

Not just a "bigger version" but a stainless un-vented one,

your current one is a vented cylinder, in that if it starts to boil over, the excess hot water (hot water expands in volume) it escapes back up to the tank in the loft which then should start pouring out the overflow on the header tank.

un-vented can't use this method as you have to keep the water under pressure, instead it uses a pressure relief valve that opens when a pressure threshold is reached.

verify the flow rate as mentioned by dcawkwell
But you'll need someone qualified in un-vented DHW to install it even if your main is suitable.

 

[cbasson]

ah, ok thanks

How about the: You get more components for main pressure systems now? I think the likes of taps/mixers, etc

 

[cbasson]

ah, ok thanks

How about the: You get more components for main pressure systems now? (Im assuming the likes of taps/mixers, etc)

Anyone enlighten me on this part??

Cheers

 

[phatboy]

Your current taps & showers may well be OK, ours were.

You may just need to change washers, or maybe some fittings will need replacing.

Also in an older house, some of the pipework may start to leak under the pressure. Hopefully a plumber would pressure test for leaks before starting the job!

 

[Terry lambert]

Some Showers are made for gravity and not designed for mains pressure, you would need to check with the manufacture.

An engineer is unlikely to pressure test your system but would give you a disclaimer that existing pipe work may leak.

It's rare but does happen, normally toilet valves need the orifices changing, unless it's a poorly installed system your heating carcass should be fine

The engineer installing should be able to give you an opinion of the condition of your system

 

[KFZ]

I think you have realised the pro's and cons.

When we went to mains pressure hot it blew the system to bits. House is 1968 and previously owned by someone in the trade (never buy a house off a professional, not one job been done properly). Including under the bath, under the fitted wardrobes. We had 7 leaks in the course of the first year. Touch wood I just need to re-pannel the downstairs loo (ruined) and touch wood we are in the clear. Not much of the old system left now.

ITs had been worth it mind, We lost the giant tank in the loft, the small heating tank and the hot tank (now combi), probably added eqivelent of a small room to the house.

If you pipe work is old or you have any doubts on it, I'd be very careful.

Kev

 

[Terry lambert]

Old pipework well installed would not be a problem, I look for things like compression fittings everywhere under the floor for example and other poor install practices

If the pipework looks professionally done, chances are it will be fine

 

[cbasson]

Hmmm. House is old (1900).

Showers work fairly well no real grumbles. Just considering changing to main pressure to free up the room in the loft. Though its not essential - from the perspective of space - to do so.

Sounds to me that if components are still readliy available for gravity fed systems, i shouldnt be in any great hurry to change the system..

 

[cbasson]

Mains pressure tank provided you have a good cold mains flow into
the house of 20-25 litres a minute.

So the strangely helpful people at Affinity let me know that the water pressure they are supplying is 4bar.

I was concerned about the flow rate/diameter of mains pipe I have but having carried out a basic flow test into the sink in the utility room (where the cylinder is/will be), the result appears to be approx 26litres in 1 min.

So it would seem that i have the basics to switch over to an unvented system? Or have I missed something?

(Should I put this post in a new thread? )

Thanks