Replace Hot Water Tank with a Combi Boiler - How much??

pealy

The house I moved into a year ago has a single gas boiler which works the central heating and hot water via a timer. The heating's fine but the hot water comes from a tank and is annoying me in so many ways I don't know where to begin..

I'd really like to change the system to supply hot water on demand and wondered how much I should expect to pay, a few questions if anyone's feeling helpful:

- Is there a middle ground where I keep the tank but can also get hot water after someone's used it all in the bath?
- Do I need to replace much pipework or can most of the existing pipes be re-used?
- How much & what spec is a suitable boiler (12 radiators a couple of which are enormous)?

Thanks..

Flimber

Quick reply: We're getting a 15yr old boiler/tank system replaced by a combi. Quotes were £1400 and £1800 inc. VAT. You can expect to pay a bit more now that condensing boilers are compulsory (plus £200-ish after April 1st this year).

HTH,
Mike.

Jazzycat

Hi Pealy,

with a combi boiler you won't need a tank for reserve hot water. It literally heats to demand so will provide a constant flow, therefore no tank required.

Your existing pipework will be fine, you don't need to make any changes. You will need to have new pipework to relay the water from your combi boiler into your existing set up - this is generally done with new as taking old pipes out would prove far too costly and problematic, but cost of pipework is not the biggest factor its the labour. You do need a fair bit of space to house your combi - we have ours in the garage which is integral.

Combi boilers come a wide range of prices. Its best to avoid the really cheap ones as they have a far higher tendency to go wrong. We have a Worcester one which is made by Bosch. This is a link to their website http://www.worcester-bosch.co.uk
We have a 4 bed semi and have the 28CDi

Another make which comes recommended is the Valliant. Their condensing boiler range is well respected.

Both boilers are in the £700-£800 range but that excludes pipework, labour etc etc.

Hope this helps a little and good luck.

Just as an afterthought, most people that have combis would prefer a tank system and not normally the other way round. I'm sure you've thought about it but you may just want to change your existing boiler rather than system

pealy

Jazzycat wrote:

Just as an afterthought, most people that have combis would prefer a tank system and not normally the other way round. I'm sure you've thought about it but you may just want to change your existing boiler rather than system

Thanks Jazzycat - very useful.

Is there an advantage to a tank system which I'm missing? I find it really annoying that we run out of hot water so much. I can't even fill the bath properly before it goes cold and if someone has a bath in the morning there's nothing until the timer kicks in that evening.. Hot water on demand seems the obvious choice to me.

robv_3

pealy wrote:

Thanks Jazzycat - very useful.

Is there an advantage to a tank system which I'm missing? I find it really annoying that we run out of hot water so much. I can't even fill the bath properly before it goes cold and if someone has a bath in the morning there's nothing until the timer kicks in that evening.. Hot water on demand seems the obvious choice to me.

Having stored water has a few advantages over combis. In general they supply more hot water quicker, more suitable for multi bathroom houses and can be more efficient. Showers can be improved by adding a pump but could be noisy.

A combi is good for showers, saving space and....err nothing else.

If you current system is not fully pumped with modern controls and dipped cylinder it could be time for a upgrade.

MarkyMarkD

I don't personally rate combi systems, precisely because the water pressure is generally poor. Additionally they don't work that well in large houses (in my experience).

If you currently are always running out of hot water, and can't fill a bath, I'd suggest that your water temperature is too low. Obviously you need a lot less hot water in a bath if it's hotter!

"If someone has a bath in the morning there's nothing until the timer kicks in that evening". Change the timer then! Or turn the hot water on to stay on while the first person is in the bath and it should be hot in time for the second bath!

I wouldn't rush into replacing the whole system when a bit of work on the existing one might achieve a better overall result.

Jazzycat

Hi Pealy,

I think the last few posts have explained that your system may be better from being tweaked rather than replaced.

Again change your settings on your timer and when you want to run a bath put the water heating on - I know this sounds obvious but it will make a difference. If you are still struggling you could also put the immersion on, this will also heat water in the tank without relying on the boiler. So you could run a bath, put the water onto heat from the boiler, and turn the immersion switch on on the tank (this is the main wired switch which connects to your tank). When done make sure you turn the immersion off as it eats electricity by the bucket load.

Even though I have a combi Iwould rather have tank system but not to the extent of paying a £2k conversion cost.

Good Luck

FIZZYLIZZY_4

I have just got an estimate to replace a 13 year old Worcester combi, which I was told was very inefficient, with a Worcester Brit/Scot gas RD532i. The quote for change of boiler, no radiators is £3,324 including discounts. I must say I was shocked and thought £1500-2000 at the very most. While I would like to be greener and reduce my bills, this does seem to be less than money saving

JimArnold

You may wish to consider fitting a double element immersion This gives you a long element which heaats water at the bottom of the tank and a smaller one that just heats the top bit.

So you can make sure the whole tank is hot overnight (I assume your timer means you have cheap off peak power) then switch to the smaller element during the day eg
http://www.tlc-direct.co.uk/Manufacturers/Redring/Immersion_Heaters_3/

The best advice however is what is your water temp We can fill 2 baths form our tank and by then it's heated up again. I assume you haven't got a space saving tank

If you switch to a combi you will find the bath takes an age to fill

spendaholic

We moved into a 4 yr old house that also has a boiler firing the c/h and a hot water tank in the airing cupboard. And ours is rubbish too. We have a separate immersion that does nothing when it's switched on, yet the electrician says that everything is working properly.

If I wash my hair and then run a bath, I often run out of hot water. And we can't have one bath after another. When I called up to get the boiler checked under warranty they said it had expired as the boiler was 2 years old before Barratt even fitted it. Had we bought the house brand new we would have had all the necessary paperwork to blow this argument out of the water.

We have one stat in the lounge (stupid place for a stat) that fires both the c/h and the hot water. But if the c/h is switched off, the hot water really struggles to get hot.

About 1 month ago our boiler blew its printed circuit board. It cost us £150 to have a new pcb (we got the labour cheap), and the hot water has been performing much better since. But we still run out after just one bath.

How can a combi be worse than this? To increase our water pressure we opened the main stop tap more (and we're on a water metre). Would that not work with a combi?

grumbler

robv wrote:

If you current system is not fully pumped with modern controls ... it could be time for a upgrade.

YES!

pealy wrote:

...if someone has a bath in the morning there's nothing until the timer kicks in that evening...

spendaholic wrote:

...if the c/h is switched off, the hot water really struggles to get hot...

You need modern flexible programmer (time-switch):
http://www.diyfaq.org.uk/plumbing/plumbingpage2.html#timeswitch