Combi HW Pipes and Corgis

[glynn]

Hi

I've just ordered a new combi boiler- nat gas Worcester Bosch CDi40, reasons for choosing this boler were firstly because I believe this model is reliable and due to power will give me loads of hot water, and secondly because I got it cheap through a company scheme (I work for Siemens who have a tie up with Bosch). We recently moved in to a late 50's 3 bed detached house, which we plan to extend later to 4 beds, and there are 5 in our family. The new boiler will be certainly more than adequate from a heating point of view, but I wanted the extra power for the hot water capability which I envisage will become a big need once my 3 daughters get to be teens (hope to be able to run 2 showers simultaneously).

The existing system is ancient gas fire/back boiler with gravity fed HW, I want to rip this all out and use the cylinder cupboard to make bigger bathroom. I will however retain the existing copper pipe runs to rads where possible (have you seen the bloody price of copper now!)

I'm basically a competent DIYer, my dad was a plumber and taught me quite a bit, and I've installed an oil boiler before but am aware of the new regs for gas installations. Nevertheless money is tight therefore I intend to replace rads, fit TRVs and flush the system, hang and flue the boiler , connect up water myself, leaving only the gas connection to Mr Corgi, am I allowed to do this? If so any idea what is a reasonable cost for Corgi in West Midlands (I estimate less than 1/2 day's work to connect the gas + whatever else is needed to commission boiler)

Also I read in the Worcester boiler literature on the web that it is OK to run hot water pipes to individual taps in 10mm pipe, but instinct tells me to steer clear of it, I guess there would be savings in terms of less wasted dead heat in the pipes, and also less time for hot water to arrive at tap, but Im worried about flow rates. Anyone have any real world experience if 10mm really works OK for HW, especially for baths and showers?

Sorry for lots of questions!

Glynn

 

[solo]

Zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

 

[chrishutt]

..... Anyone have any real world experience if 10mm really works OK for HW, especially for baths and showers?

I've used short (<2 metres) 10mm connections for wash basins without any problems and I'd consider longer ones, subject to available pressure and HW flow rate from combi.

Your 40CDi gives 16 litres/minute, which is a lot more than you'd normally want at a basin tap (maybe 8 l/m) and more than most showers would require, but you may want all that flow for bath filling. I'd stick with 15mm for the bath at least, and probably for the shower.

 

[Paul Barker]

I would change the hot water cylinder for a new bs1566 one, install a new full set of controls either Y plan or S plan. Use your combi to provide hot water to the showers (but only because you foolishly already bought it before seeking council) and the gravity hot water system with imersion heater failsafe to supply baths basins and kitchen applainces. You can always take a bath when the combi is on one of it's frequent shut downs and you wait two weeks during the busy time to get someone to it.

Don't be so rediculous, a house that size you can manage without robbing the airing cupbaord.

Fluing for condensing boilers is a big issue, get your expected corgi in on the ground floor and do as much as he is comfortable with you doing. Definately don't run any gas pipe. If boiler isn't sat on top of gas meter the gas pipework is going to cost you. Your fault for buying a 40kw gas guzler.

Worcester are not bullet proof, I'm OK about them but if you expect many years with no service engineer at your door, you're a "dreamer, nothing but a dreamer".

I love the optimism of diy folk on here. as someone who is regularly got out of bed by stressed phone calls I am probnably a pessimist over these things.

You have to decide whether I am the fool or you, and plump for a back up plan if you think I know what I'm on about, or go for the bigger bathroom if it's me that's the fool.

 

[doitall]

Thats very good Paul and Oh so very true

and all before 08:00 on a Sunday.

 

[Softus]

...leaving only the gas connection to Mr Corgi, am I allowed to do this?

I believe that if it's your house, and you're competent, then you don't have to use an RGI, but you would be well advised to do so.

If so any idea what is a reasonable cost for Corgi in West Midlands (I estimate less than 1/2 day's work to connect the gas + whatever else is needed to commission boiler)

It would be better to get the RGI to estimate the time required, and the cost of that time.

 

[DP]

Plainly a case of a 'self proclaimed competent' DIYer jumping in feet first.

While there are RGIs out there who do not know their a**e from their elbow, there are plenty DIYer who think they know it all. Have come across DIY work that knocks spots off registered gas installer's efforts, but these are few and far in between.

A semibullet proof boiler would be one that is not a combi boiler, definately one that is not a combi streamer, almost certainly not one that is aluminium combi streamer. You want relaibility (and be in pocket) then your bogstandard Potty kingfisher fits the bill. Not much to go wrong. When it does, it does not cost a fortune to repair.

 

[Agile]

The official line is that a CORGI must as a minimum fit the hanging bracket, assemble and fit the flue, connect the gas and commission the boiler.

ONLY if he has done those things can he fill in the Benchmark Certificate and notify CORGI of the installation.

If you are competent you can do the lot but you will not be complying with Building Regulations ( unless you get the BCO to inspect it afterwards ) and you will not have the certificate and you may have some difficulties with the warranty.

Best to talk to the CORGI before you even choose the location as that may be totally unsuitable.

We would charge £180 in London if the new gas supply length is shortish.

Tony