worcester bosch combi 40kw in 4 bed house?

[jimbob B]

hi all, please can anyone give me a bit of advise...
Moved into new home last year and boiler and cylinder have now quit - very old copper tank and baxi boiler.

We need something in asap and have been quoted £2800 all in for a worcester bosch 40kw combi. we have 4 beds and two showers and the mains pressure is 22l per min. at present there are only myself, wife and small baby so not really a big issue and this combi should be able to cope with 2 showers.

any advice please!

We have thought of pressure tank and system boiler but that would be around £4500 and not sure its worth it just to store extra water...

Thanks

 

[dontknowitall]

I'd ask for more quotes - boiler seems very large in the first quote and second price seems high.

BUT - there's more to new heating systems than just money. Probably most important is can you trust these people in the house without you being around and will they do a good job?

A good plumber will be able to tell you the viable options and the approximate costs.

 

[jimbob B]

thanks dontknowitall!

We originally wanted a storage solution and have 5 other quotes - all around the £4000 mark or more, even British Gas was only £4900 which I thought would be way higher than the others??

Due to the emergency of having no tank or boiler we need to get a fix soon so are limited to who can do it - we have had this chap referred to us by family so trust him...but always good to get another view/opinion, especially as we had dismissed the combi idea ages ago as we did not think it would work in a largish house - however, this boiler coupled with our mains pressure should do the trick, shouldnt it?

Cheers

 

[dontknowitall]

I personally don't like combi boilers and if a customer in a large was insistent I'd go and phone a friend. (Combis in up to 3 bedroom houses are fine as far as I'm concerned.)

Your flow rate is 22 ltr/min which seems fine and presumably your working pressure is around 3 bars? (Make sure at least two taps are open when you/your plumber is trying this one!)

If the "pressure tank" is an unvented hot water cylinder (with system boiler) this would be my prefered option but this is assuming you've a large house - a 40Kw boiler is large. I'm fitting a 25/32Kw (oil) boiler in a 5/6 bed and 2 bath house and this is plenty big enough.

So if your house is 4 bed 2 bathroom with two showers and no bath, water pressure is okay, then a combi should be okay - but a 40Kw??!!

 

[doitmyself]

We have thought of pressure tank and system boiler but that would be around £4500

What size boiler was suggested?

New build 4 bed 2 bath/shower houses near me all have system boilers and unvented cylinders.

 

[Scottley]

I have just sized my boiler for a 5 beds 3 bathroom house (16 rads in all) and a 30CDI still have a bit left so 40cdi is massive

 

[Toddyplumb]

Its a combi , he will be sizing for HW flow hence the size.

 

[Scottley]

Its a combi , he will be sizing for HW flow hence the size.

Oops, that'll teach me not to read it all!

 

[jimbob B]

thanks to all of you - really useful advice and a great forum!

We have decided to take the plunge and go for it for the 40CDI, watch this space....all being well, new system will be in by Monday next week.....

JB

 

[buryboy]

Presume you mean 42 CDi, 40CDi is not listed. Make sure you get good quality Thermostatic radiator valves fitted and roomstat as well if not already fitted, the 42 CDi can output 17.2 litres p/min. The figure of 22 litres p/m is the flow rate. Make sure that cold water main's pressure is checked with a pressure gauge not flow cup. Usually best to test at a busy time of day for water usage. Would agree with toddyplumb about boiler being offered for it's DHW capability. You can get the installer to range rate it down to heat output on the CH side more suitable for your house's heating (kW) need.

 

[tamz]

You can get the installer to range rate it down to heat output on the CH side more suitable for your house's heating (kW) need.

You can't range rate these boilers. They are fully modulating and will adjust themselves.

A storage combi would give good flow rates up to 25 l/m

 

[buryboy]

Responding to Tamz.
Whilst I knew the Greenstar 42 CDi boiler was a fully modulating boiler I erroneously thought it could also be rated down to the houses heating requirement (kW). According to Worcester's tech dept, this is not possible on the Greenstar Combi. The 42 CDi on CH modulates between 9.4 kW and 30 kW.
Whilst on a course at Glow Worm this summer I was told it was possible to rate down their Ultracom combi on the CH side. Their boilers are modulating as well. The trainer told me there is a saving on your gas bill at the end of the day if you can range rate down.

 

[Christophe]

Hi jimbob B ,

REading this thread now and I'm quite interested to know what you think of your system 5 years down the line. Was it a good choice?
I've been recommended a Baxi 40HE condensed combi boiler to replace my current gravity fed system but I keep reading mix reviews about combi boilers for more than 1 shower.
I have an en-suite shower and a family bathroom with bath/shower that is currently only used for guests (but might have kids in near future).
Anyway, if you could let me know your feedback that'd be most appreciated
Thanks

 

[ShaunCorbs]

Hi jimbob B ,

REading this thread now and I'm quite interested to know what you think of your system 5 years down the line. Was it a good choice?
I've been recommended a Baxi 40HE condensed combi boiler to replace my current gravity fed system but I keep reading mix reviews about combi boilers for more than 1 shower.
I have an en-suite shower and a family bathroom with bath/shower that is currently only used for guests (but might have kids in near future).
Anyway, if you could let me know your feedback that'd be most appreciated
Thanks

Really combi boilers are for a single bathroom house as it won't cope with two showers running at the same time, have you looked down the road of an unvented system

 

[Christophe]

I have but been quoted £4.2k for the job which is a bit steep for me considering our gravity system currently works fine but is simply lacking a bit of pressure...

 

[ShaunCorbs]

I have but been quoted £4.2k for the job which is a bit steep for me considering our gravity system currently works fine but is simply lacking a bit of pressure...

Tbh that's about right looking at about 1500-2000 for combi flue etc 500 for pipe and fittings and about 3-6 days work

 

[Gas74]

You ever thought of just putting an electric shower in one of the bathrooms. Means you could still have a combi and if it ever went on the blink you still have somewhere to wash??
Just throwing in an alternative.