Gravity fed combi boiler?

[tgreen1]

Hi,

I live in a top floor flat in a converted Edwardian house and have a problem with my shower pressure running off a combi boiler.

Mostly (daytime and evenings) the shower pressure is ok, not great, but in the mornings it often dribbles with lack of pressure for upwards of 15minutes. I think this maybe to do with people in the other flats below taking showers at the same time thus decreasing mains pressure.

Currently my boiler runs directly from mains, and I've had two plumbers round to investigate the problem/come up with a solution (at £100 call out each) and both have very different solutions:
1- New conventional boiler + pressurized hot water cylinder (£4.5k)
2- Pump between my boiler and shower (£500)

The first is too expensive and seems to be overkill for a 2-bed flat with 4No. radiators total. The second I've read is illegal/dangerous??

I think all I need is a cold water gravity tank with a pump creating a new feed to my current boiler (admittedly its a pretty basic 'Main 24kW' but it seems ok).

Can anyone advise the best solution? I really don't want to pay ANOTHER plumber for questionable advice!

Many thanks.

 

[Eeejit]

top of the evening
a new boiler and unvented? cylinder wouldnt sort your morning
pressure problems.with 24kw and only 4 rads your best option
would be an indirect hot water cylinder fed from cistern,possibly pumped,
from the loft above you.

 

[Doctor Drivel]

**** abuse removed by moderator ******

Fit an accumulator. No pump needed. If it can go in the loft above then great. 200 litres is what you need. A double check valve on the cold water mains and just a 22mm pipe from anywhere on the mains pipe to the accumulator. Sorted!!! Could DIY it.

This will work out cheaper than a tank and pump and does hot and cold with equal pressure.
http://www.rwc.co.uk/Product.aspx?page=CAT6
Look at No. 3

Also DPS use them too.
http://www.heatweb.com

 

[Agile]

A 200 li accumulator woulf give you about SIX minutes of good showering at 10 li/min. Still not acceptable for most.

The best solution is a pumped storage system if you have space for a big cistern in the loft. 200 li will give you 20 minutes of showering!

Its not that easy though! The flow rate will be insufficient to activate most shower pumps and you may have to use a negative head pump which has a button you press to start it!

Tony

 

[scaby]

dr drivel why dont you read the replies properly before ranting

 

[simond]

240 litre accumulator is likely to give 13 mins showering at 10 litres per min, but this depends on a few other variables such as the standing pressure of your water main.

RWC and DPS can't sell them for this application though. But the Coldstream product will deliver a solution, at a price.

 

[tgreen1]

Thanks for all of your replies! I'm pretty new to all this technical talk, but it seems that an accumulator, upwards of 200l, is the way to go.

There are three of us using the shower each morning so the sound of 13 minutes of shower time seems worryingly low, unless it is constantly re-filling from the mains? Do accumlators provide hot water direct to the shower, or do they provide cold water to the combi boiler? Please excuse my ignorance, as I say i'm pretty new to all this.

What kind of price, all in - including labour should i expect for this work? I realise that it will be subject to lengths of pipes and location of accumulator, but my loft is directly overhead and my boiler is in the room next door...

Many thanks again for your help guys.

TG

 

[Doctor Drivel]

***** more abuse removed *******

A 200 litres accumulator will hold 100 litres, that is 100 litres which is 10 minutes and that is if the water mains is cut off. An accumulator stores cold mains water. Realistically the cold mains will be assisting and more than 10 minutes in the shower. They generally recover very quickly too.

 

[Doctor Drivel]

240 litre accumulator is likely to give 13 mins showering at 10 litres per min, but this depends on a few other variables such as the standing pressure of your water main.

RWC and DPS can't sell them for this application though. But the Coldstream product will deliver a solution, at a price.

They can sell them. You say I want that one and they send it.

 

[Doctor Drivel]

Thanks for all of your replies! I'm pretty new to all this technical talk, but it seems that an accumulator, upwards of 200l, is the way to go.

There are three of us using the shower each morning so the sound of 13 minutes of shower time seems worryingly low,

The accumulator is generally recovering as you draw off. As one person gets out of the shower it will be recovering for the next. What is does is store cold water at the mains pressure. and locks it in. Draw off and the water comes out at mains pressure but with "flow". You will not runs out of water, it will just reduce in flow/pressure.

unless it is constantly re-filling from the mains?

That it does.

Do accumlators provide hot water direct to the shower, or do they provide cold water to the combi boiler? Please excuse my ignorance, as I say i'm pretty new to all this.

It provides cold water at flow and pressure all around. You could have do only the combi and cold to the showers(s) and have the rest directly off the mains before the double check valve. Then the high flow/pressure from the accumulator is not used up by draw-off that don't need high pressure/flow.

What kind of price, all in - including labour should i expect for this work? I realise that it will be subject to lengths of pipes and location of accumulator, but my loft is directly overhead and my boiler is in the room next door...

Many thanks again for your help guys.

TG

An accumulator is cheap to a cold tank and noisy pump that will do all the flat. It is silent and trouble free. A great idea that few use as few know or understand them. They are simplicity in themselves.

See the http://www.heatweb.com site They explain an accumulator and swill sell one too.

 

[Nixt]

Can't be Drivel rapped by Mods as he's always said personal abuse is given by those who've lost the argument.

 

[w.a.l.o.Baloney]

would that moderator chappie please stop using "abuse"

 

[Doctor Drivel]

Can't be Drivel rapped by Mods as he's always said personal abuse is given by those who've lost the argument.

Exactly!

The mod said..."Drivel, please lay off abusing other members." Who?

 

[Bamber gaspipe]

quote="tgreen1";p="835059"]Hi,



I think all I need is a cold water gravity tank with a pump creating a new feed to my current boiler (admittedly its a pretty basic 'Main 24kW' but it seems ok).

Correct. But that would only supply cold water to your thermostatic shower. you need an independent hot water source.

Accumulators are ridiculous in a domestic environment, no need.

 

[pipe strangler]

Drivel, please lay off abusing other members.

Abuse will lead to your account being suspended

so get on with it then