Combi's, Flow rates, Standing Pressure

new_home_blues

Hi all

Am new here, and strictly speaking this is not a money-saving question, but from the general tone this forum looks very helpful.

My situation:

3rd floor flat in London
1 Bar standing water pressure
4 litres per minute flow rate from the mains water supply
Very aged tank system boiler.

I recently had British Gas come for a quotation to replace the system with a shiny new high efficiency combination boiler system but, according to their salesman, the flow rate is too low for a combi system.

My neighbours had their system changed to combi though.

My question is whether the 10 – 12 litres per minute that I have been told I need for a combi system is really necessary? I fully understand the fact that 4 l/min is a mere trickle, but I will be more than happy to live with it – provided it won’t make the boiler explode / break etc etc.

Anybody with a similar experience perhaps?

Thanks!

new-home-blues :-)

ps: does 6 grand for boiler / radiator replacement for one bed apartment sound excessive to anyone else?

owned_by_2_Siamese

Hi !
In reverse order - yes 6K sounds way high! BG quoted me for just a replacement boiler 18 months ago £4k- the other two quotes were 2k less (I only needed tanks out combi installing and moving - paid £2k for the lot!)

As regards your pressure - this is the 'combi million dollar question!' We have three bar and a baxi condensing combi (24l flow rate) its good - just like mains pressure hot water. I have though had experience of an older combi with less pressure. NIGHTMARE - not least because at low pressures it wont heat continuously - but cycle on and off as there isn't sufficent flow to disipate the heat. I'd really advise against it at the kind of flow/pressure you have - a shower would be no more than a drip!

However! Check with your local water company as to why the pressure is so low - you may be on a shared main? they will come and look and advise (they may even sort it out!)

Good luck!

Canucklehead

Hi

That's pretty poor pressure. I don't think Thames Water are required to provide more than 1 bar, it helps them get round their dreadful leak rate...lower pressure =less leaks.
That said it could just be bad pipework in your house /flat.

Are you on a shared main with other flats? Perhaps at some time you can have a new dedicated main for your flat.It won't harm the boiler.
I would go for it, but not for 6k !! B.G. that's another thread.!!
Good luck

Corgi Guy.

Snow_Dog

6K way OTT.

As for combis, they are great in the right place, the right place is not low pressure/flow rate.