What boiler / heating system - loft conversion

3 Mar 2007
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United Kingdom
Hi all, thamks in advance for any advice given. Currently have a 4 bed semi and hot water / Ch is delivered via a somewhat unreliable old Netaheat.

I am however pricing up a loft conversion and a downstairs extension as an alternative to moving. Loft conversion will require the romoval of cold water feed tank and ch expansion tank from the loft, also need to remove hot water cylinder from airing cupboard as new stairs will go there. This leads me to think that a combi boiler may be the best option? Will need to feed 13 rads and hot water to kitchen, bathroom and to en suite Shower in loft. Heard lots of horror stories about combis and their inability to feed more than one tap at a decent rate. Happy to run both showers as electric from cold water if necessary but would like the combi to at least heat up the rads effectively and to provide a decent flow of hot water.

What are my options, any advice from anyone that has done similar. dont want to go to cost of unvented system if i can help it.

All advice welcomed. Cheers
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Most combis will handle all your heating requirements. Combis should be sized up for your hot water usage. I always warn customers to expect only one tap to work efficiently at once. One shower on electric would cure this problem. Personally I would fit a 28/31 Kw or above combi
If you can, try and limit your hot pipe runs from combi. It can take ages for hot water to get through all the pipework to feed the basin in the loft, if the combi is located down stairs in the kitchen.

By the time you have turned on the hot tap to wash your face, 20 gallons have gone down the plug hole before it's got hot :rolleyes: or you get fed up waiting and wash in luke warm water. :(

I appreciate most combi's come with a pre heat button, but that would annoy me after a time as when you are out all day it will keep on working, wasting money.

It's a compromise, but with combi's, you do get quite good pressure for the shower, without the need of a noisy pump.

I would also get the bigger btu combi, so it doesn't have to work so hard.

Good luck with the new build.
tryitandsee said:
I appreciate most combi's come with a pre heat button, but that would annoy me after a time as when you are out all day it will keep on working, wasting money.

The Vaillant Ecotec Plus range can be fitted with the vaillant plug in 2 channel timer. Timeswitch 140 or VRT360. The 2nd channel allows you to set the times of day that you want the pre heat to work :)

I would recommend the 831 or 837 ;)
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Thanks for the advice and help guys, a little more reassured I suppose, I had been looking at 30kw combis with a view to getting an idea of price. Been recommended Greenstar as a model although they do seem a bit more costly than others of semingly similar ratings and outputs. Are they worth the exra in terms of reliabiliity and performance? All comments appreciated whether on this typ or alternatives?

As regards your comments tryitandsee about the length of run, the combi would be installed in the kitchen and the run would therefore be 5 or 6 metres to basin in loft, so it could be a problem. I had thought about the compromise of an electric instantaneous water heater to feed the loft sink. Although in principle this seems a bit of a bodge??
I'm in a similar situation so though i would highjack this thread.

Currently i have a 24Kw combi condensing boiler in the kitchen. By time the loft conversion is finished it will have to feed:
12x radiators
1x first floor bathroom
1x ensuit loft shower room

I'll be using the loft conversion, whilst renting out the other rooms on the first floor. My question is: will the boiler cope? Assuming there are 4 adults living in the house all wanting showers in the morning, will the boiler be able to feed both showers at the same time? I've been considering getting a 10.5kW electric shower for the loft to take some of the strain off the boiler (therefore needing a 10mm dedicated cable putting in). Someone else has suggested getting a "pump and normal shower that runs off a 6amps and therefore doesn't need a dedicated cable" (does that make sense to anyone?).
Or should i try to find the money for a new boiler that will cope with all that hot water? (A Vaillant EcoTec Plus maybe with the timer)?
Hi there fella,

Not always good to hi-jack a thread, not good etiquette, especially when the thread you hi-jack is 3 YEARS OLD.

Post again under a new subject.


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