DIY Doctor UK DIY Forums

Hi all,

I am currently getting in quotes for an extension on a new house that I have just bought. The house has been vacant for some time and we have decided to do up the central heating when doing the extension as we are not living there. As this is the case we could have any type of system.

I havn been quoted various prices ranging from 4k to 12k. I don't really know how much it should cost but I have requested the same type of system to ensure the quotes are on a level playing field.

I have asked for the standard open gravity fed system with a new boiler, with a new radiator in each room, header tank and hot water cylinder. The property is in South East London and will be a 3 bed semi after the extension. 1 bathroom, 1 ensuite, 1 study, dining room, large lounge, ground wc.

My gut feeling is that it should be 3-4k with a decent boiler, perhaps 5k tops.

What do people think it would cost or am I getting seriously ripped off.

Thanks in advance

Hi,
£12K does sound steep - but to give you an idea, here are some costings for a DIY job based on the costs I have seen whilst doing up my own system (from suppliers like Wickes and local plumbers merchant):

Boiler - Approx 1K for a decent open vent boiler with controller and 1 x thermostat.
Hot Water Storage Tank - £200
Cold header tank - £40
Radiators - about £500 for the 8 you appear to need
Rad valves - thermostatic + lock shields - £100 for 8 rads

So you are looking at £1840 so far with no copper pipe, fittings or labour

Copper pipe is currently about £10 for 3m in 15mm, and £12 for 3m in 22mm, so if you are replacing all the pipework, you need to calculate the approx length required at these prices.

I would then uplift the cost of the pipe by 20% to get a rough estimate for fittings.

Add £25 for condensate drain parts if you have a convenient foul water sewer , or £150 if you need to use a separate condensate pump.

Add 20% for the plumbers markup on the parts - don't forget it is a business and he needs to make a profit on the goods as well as his services.

Hiring a core drill to make the hole for the flue (we were relocating the boiler) cost me £50 for the day (yes I thought that was expensive too).

If electrical work needs doing, then remember your plumber needs to get in a "competent person" to perform the work - probably won't take the electrician long, but he will have a minimum charge (probably £100+)

Then add labour - and don't forget that it this is a complete replacement (including pipes) you need to factor in the strip out time as well as the fitting time. BTW the plumber will take the old copper to the scrap man and make a few bob there too.

I'm not sure what the going rate is for a self employed plumber - but I suspect it is a minimum of £20 per hour. guesstimate how many man days are required to do the work and multiply up. If it isn't a self employed plumber then add 70% for "employment costs" then add some profit.

All of a sudden, £3k sounds too cheap, especially if any of the pipe work is being replaced.

Hi Mate

Thanks very much for the reply.

It all sounds about right with a decent boiler around 1k. Copper pipes I reckon about £500. Have heard plastic pipes that would be half the cost but thats a seperate debate. So with say parts at 2.5k..labour at £200 per day? for say 5 days..no 10 days would be 4.5k plus VAT.

Its all speculative as we are not in the trade but it needs to Corgi to get cerificates to pass the building regs etc..

The place will be vacant and all carpets and floorings have been removed. So it a case of lifting floorboards without even making better after wards.

The range is just err steep.

Hoping that someone in the trade would be able to comment.

BTW ..have called a few plumbers for independent quotes.

LOL I am a diy'er and I am sure the other trade people will linch me for saying this.

I had a complete new central heating and shower system in my small 2 bed flat for about 4.5K about 5 years ago. It was a good recommended company based in p'mouth I think. They had 2 guys work 4.5 days. everything was easily laid in the atic and pipes run down the walls, so no board lifting or making good needed.

You will find this quotes song and dance with almost every trade you go to. Windows, Kitchens central heating.
Some trade will not want the work and will over price, others will charge 1 or2k over and hope.

Most when challenged won't even blink at reducing there costs by 2K.
I have friends quoted 20K for dbl galzing and then barter down to 7K which seemed a more reasonable price.

Seen kitchen estimates at almost double slashed in half when told a competitor has offered a lower bid. They are all trying it on.

I was really annoyed at British Gas. After asking them for a quote, chap came around and ended up quoting 2K extra. But I did not expect him to then sell my details including the fact that I have single glazing onto every single double glazing company. I have since disconnected my land telephone line.

A friend who is a trade build described kitchen fitters as normally having "room for maneuver " :-)

Basically all I can advise is get lots of estimates and throw out any which seem laughably high or low. With your costing research and advise from this forum you already know a lot more than most about what it should cost.
Also dont mention to anyone if it's for a wedding, then 30K would be more reasonable :P (sorry that's a rant for a different forum)

vu1974 wrote:Hi all,

I am currently getting in quotes for an extension on a new house that I have just bought. The house has been vacant for some time and we have decided to do up the central heating when doing the extension as we are not living there. As this is the case we could have any type of system.

I havn been quoted various prices ranging from 4k to 12k. I don't really know how much it should cost but I have requested the same type of system to ensure the quotes are on a level playing field.

I have asked for the standard open gravity fed system with a new boiler, with a new radiator in each room, header tank and hot water cylinder. The property is in South East London and will be a 3 bed semi after the extension. 1 bathroom, 1 ensuite, 1 study, dining room, large lounge, ground wc.

My gut feeling is that it should be 3-4k with a decent boiler, perhaps 5k tops.

What do people think it would cost or am I getting seriously ripped off.

Thanks in advance

Hi there mate, to supply and fit vaillant boiler new pressurized unvented system, new radiators, and removing all old pipework and certify the job the companny who i work for charges 6600 pounds supply and fit everything, to bring it up to euro spec!

Forget about open vent systems , coz they are antic's! you need unvented system, or combi, but in your case i will suggest unvented sysytem!

I'm not disagreeing with Alex above and I'm probably wrong, so apologies in advance but I've always thought an unvented system relied on the incoming mains pressure being up to scratch, that so, wouldn't the system struggle at peak times if 2 or more showers were running at the same time an then the kitchen tap or other is opened,