New boiler installation help needed?????

[knowledgeseeker]

Right I'll start from the beginning'

I bought a house two years ago and underwent the task or a referb, the house is semi detached in London with 5 bedroom and 3 bathroom sounds big but not loft conversion and a (downstairs bedroom).

Main bathroom: 1 main shower (currently pumped) and a bathtub
Downstairs bathroom: electric shower, toilet and basin
ensuite in loft: currently installing but will have shower, toilet and sink.

We have my disable nan who lives downstairs so downstairs bathroom is hers with a kitchen ( granny flat)

We have our kitchen So technically two sinks ( to run at same time)

Currently have a gravity fed vented system and the water pressure was poor. Had old 15mm pipe from outside stopcock and recently (two days ago change to 32mm from stopcock)

Right so know you know what we currently got....

We want to change our boiler and upgrade as boiler is on its way out and get the best availed option for us.


What we want is to have a powerful shower in the main bathroom and ensuite and to have hot water without the current 1hour wait.

Current mains is at 12ls and 2.4 bar

Unvented has been suggested but the plumbers can't confirm the shower pressure will be adequate for a power shower and said that option would be a breaker tank then pump.

Other suggestion is to keep vented but upgrade cylinder and boiler and cold storage tank.

Or one other option was to have an accumulator

Last option was to have a unvented cyvlinder split the hot water feed out from the tank one to kitchen taps and basins. The other feed to pump then to shower.

Last not least was to have an unvented cylinder to all sinks, then a feed to unvented cyclinder to a vented cyclinder which will then be pumped to the showers.

As you can see I am in need of some help because if all the plumbers can't make their mind up on what's best, How can I.

Your help as always would be appreciated...

 

[Dan Robinson]

My first inclination would be an accumulator in the loft and change cylinder to unvented.

Maybe relocate cylinder to the loft as well.

 

[knowledgeseeker]

Thanks for the reply, would the accumulator gives more pressure to the showers?

 

[Dan Robinson]

I forgot to say move the cylinder and change it to an unvented.

The accumulator will give you mains pressure at improved flow rates for the duration of its charge.

The capacity needs to be sized accordingly.

People usually confuse the need for more pressure with the need for more flow.

You can put break tanks and pumps in and get guaranteed performance, but they can be noisy.

 

[picasso]

If you have upgraded the mains to 32mm why are you only getting 12 lpm (I take it 12 ls is per minute ?)I would double check that your stopcock is fully open and ask your neighbours what there pressure/flow is like.

 

[knowledgeseeker]

Sorry that was 23 the reading on a plumbers device

 

[dcawkwell]

Glow worm ultrapower a combi and unvented cylinder all in one.
With 23 litres a minute you are fine.
Job done gas boiler and unvented cylinder all in the one nice box.
Never run out of hot water as it falls back to combi mode.
Backup immersion should the boiler fail for hot water.

 

[Dan Robinson]

How id I know you were going to say that?

 

[knowledgeseeker]

Hmmmm I had a look but the problem surely will still be that the showers will not powerful engough. Unless I am missing something and you can install a shower pump with this????

 

[Dan Robinson]

You are not missing anything. You need to address the flow questions before worrying about how to generate hot water.

 

[knowledgeseeker]

23 litres a minute is the flow

 

[Dan Robinson]

Then flow regulated showers of an unvented cylinder.

 

[knowledgeseeker]

??? Can you explain Dan. Thanks

 

[Agile]

23 litres a minute is the flow

Yet again I have to point out that's an open pipe flow rate.

You need a dynamic flow of 20 litres per minute @ 1 bar pressure as a MINIMUM to run just ONE good shower and a little ( 6 li/min ) fro a kitchen sink at the same time.

IF you want a proper ability to use more than one outlet at the same time then I would advise a break tank with pump like the Grunfos Home Booster system at about £1100 to supply OR alternatively a proper new connection to the street at perhaps £500-£1000 if you are already in 32mm from there.

I consider that any plumber who does not understand the need for a dynamic flow rate measurement will not be fully in command of the situation. I would guess hardly 35% even know what it is!

Tony