We are in the process of getting quotes to get our boiler replaced – several of the plumbers have been leaning towards combi boilers as soon as they have walked through the door.

At the moment we have a ‘traditional’ boiler with a hot water cylinder, which I had originally planned to just replace the boiler with a similar system and keep the hot water tank – is this seen as out-dated?

Are combi boilers the way forward?

How big is the house? How many people? How many bathrooms? Any power showers?

3 bedroom, with large attic room (currently un-heated, but we may be putting a radiator up there when we do the boiler)

1 bathroom, shower currently pumped type – it gets hot water from the water tank, so we would have to get a different shower if we change to a combi-boiler.

2 adults and 2 children

Plumbers like them because they are easier to install and probably give them better margins. You loose the tank which you might like, but might get fed up running off a lot of water waiting for some hot, especially if you just want to wash your hands in the bathroom. I can’t believe they are very efficient either, cutting in and out whenever anyone uses a hot tap. The thing will scarcely reach temperature, and won’t be running efficiently unless you are pouring a path.

And if you ever want some solar thermal on your roof (way to go), then forget it. Keep a tank.

Not for me.

Combi boilers are great, but are not for every house.
My personal choice is an unvented cylinder with the kind of heat only boiler you have now.
It’s certainly not the cheapest option, you’re looking at 600 quid for the cylinder, plus the boiler. The advantages are amazing water flow and pressure, incoming main permitting.

Don’t have a combi! Not all us plumbers like them. Second the unvented cylinder route, but you could just change your boiler and connect to exist cylinder. Mail me for any more info timATj-twren.eclipse.co.uk.

Repeat don’t get a combi!

Advantage of a HW tank is you can use an immersion heater when the new boiler’s circuit board dies (which it will do approx once a year).

Why you getting the boiler replaced – is there anything wrong with it? It’s probably better built than the cheap electronic filled boilers produced today. Get it serviced and it’ll probably last another 10-20 years.

If combi boilers are naff as some are suggesting..

Why would the government warmfront scheme be ripping out boiler and tank combinations to replace them with combi boilers on new central heating installs..?

Surely it’s not a cheaper or less labour intensive option..?
They are toting them as the cutting edge in efficiency..

Keep the tank.
You’ll need it when micro chp fuel-cell boilers become available in the next 5yrs or so.

argghh! My head is spinning!!

teef – Member

Why you getting the boiler replaced – is there anything wrong with it? It’s probably better built than the cheap electronic filled boilers produced today. Get it serviced and it’ll probably last another 10-20 years.

we have the existing boiler serviced under a BG Homecare service contract, and they have said that some of the parts may no longer be available to fix it if it breaks. Its around 15 years old.

Its proving to be a **** minefield – as with everything – everybody has their own opinion, and its matter of filtering out the ‘noise’ and making a decision – its just that its a lot of money to spend and then think ‘have I made the wrong choice?’

I’m really interested as a relative just got the combi-boiler installed on the warmfront scheme and I’ll be a bit miffed if they’ve been hoodwinked..

@yunki

Surely it’s not a cheaper or less labour intensive option..?

was this missing the 😉 /irony tag?

if Combi’s ARE cheaper/fitter’s get better margins/quicker to fit/ easier to fit – its no wonder they are being pushed as the ‘in’ thing

they have said that some of the parts may no longer be available to fix it if it breaks

Cross that bridge when you come to it – in many years time probably.
They weren’t trying to sell you a new boiler were they?

@teef – we have had a couple of breakdowns in the last 3 years, and being aware of its age, decided to be pro-active

Our system was fitted five years ago – it worked out cheaper/better to have a decent boiler/water tank than have a combi boiler. Big house and oil fired which might make a difference.

Only slight hitch was when the water tank fell over in the Summer – nearly came through the roof onto mine and my son’s head! So if you do get a water tank, get it fitted PROPERLY!

Interesting couple of articles by Jeff Howell who writes for the Telegraph:

http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/7072722/Jeff-Howells-DIY-advice-combi-boilers.html

http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/6438737/Jeff-Howells-DIY-advice-condensing-boilers.html

The advantages of the combi is that you dont need to heat a tank of hot water to get enough water just to wash your hands or do the dishes,yes you do need to run some water to get the hot water out. Also you dont have to havea hot water cylinder and coldwater storage tank, thus freeing up some space, should that be required?

The disadvantages of the combi is that if the combi breaks down, which as others have said is only a matter of time but to be honest its the pcb that goes in them and the conventional boilers are also controlled by these and are just as likely to break down, you have no way of getting any hot water. Additionally if the mains water is shut off in the street for whatever reason, you will also have no water as you will have probably removed the cold water storage tank, this means that there is no flushing of the toilet!

If you have the conventional system you will need to heat at least part of the cylinder to give you any hot water,which can seem wasteful. You have to play this off against the waste of water, your choice. Yes when the heating is on this will not really cost anything extra if you heat the water when the heating is on, but in the months when the heating is not used you will need to run the boiler just to get hot water. Also if the mains go off you can still at least flush the toilet, also with the cylinder you can run the immersion and get some hot water.

I have a conventional system with a tiny hot water cylinder ,which has a double coil inside it which heats the water up really quickly after its been used.

I live in a small flat and have an electric instantaneous shower and use the kettle to get hot water to do the dishes.

If it was me I would consider a combi if you live alone or maybe with one other, but keeping the cold water storage, but if you have kids about then definitely not and consider the un-vented system.

If yo have no kids and could live without the boiler for a few days when it goes then I would run it till it has a fatal breakdown.

Surely it’s not a cheaper or less labour intensive option..?

was this missing the /irony tag?

no no… I wasn’t being ironic.. I watched them fit the system and was a bit surprised that they appeared to do it the hard way..

I think it is your choice here – your circumstances aren’t really definitely in one camp or the other – a bit bigger house and two bathrooms and I would definitely say traditional tank system, a bit smaller and no children I would say combi.

But do remember that with a combi, every time someone flushes a loo, turns on a tap, uses the washing machine, switches on the dishwasher etc, pressure will drop and shower performance will be effected. And if you are on a shared main (ie on a row of houses), other properties will take pressure from yours too. This means skin-peelingly hot water which then becomes Arctic cold as it comes out in a trickle.

(Of course that is an extreme, but it is a problem with combis).

Of course that is an extreme, but it is a problem with combis

Indeed, I have never ever noticed any transient pressure drop or temperature variation at all in my shower, which is run off a combi, even when the washing machine is on, which sucks a LOT of water.

You do get some occassional tap dripping as water main pressure flutcuates as your neighbours use appliances. Thats it, a few drops. But then we have good main pressure to the combi, and a modern install, which helps.

mastiles is right I think, borderline case. Either combi or unvented give you mains pressure hot water so you can do away with the shower pump and just use a thermostatic valve, lovely hot showers. I have unvented and am very happy, never noticed any effect from other people turning taps on etc but maybe the thermostatic valves act quick enough?

I’m tight though so in your situation I would be getting every bit of use out of the existing boiler before replacing.

But then we have good main pressure to the combi, and a modern install, which helps

Ours was fitted last year, but have low water pressure and on a shared main.

And of course you did note that I had already said it is an extreme. (But in our case, very annoying some mornings when wanting a really powerful shower blast to wake us up).

Unvented and an old (20 years) oil boiler but it all works great, we do have more bathrooms and occupants though.
Unvented cylinders rock, are expensive but def worh it – we even ran 120m of new mains pipe so we could have one!
On boilers I’m of the opinion that if it aint broke don’t fix it, but I may well have to eat my words at some point. I was thinking of changung boiler to get better efficiency but the numbers just didn’t add up.

Have a combi, and given the choice again I would go for a conventional setup: Not convinced they are more efficient; in the summer when the heating is off it can take 45sec to get hot water out the tap.
My main gripe is their complexity: Diverter valve with silly rubber membrane that perishes after a few years and requires a complete strip-down to replace is the most obvious culprit, main circuit board another.

Disadvantage of Combi is you can’t have a shower when the washing machines on – well you can if you’ve got good water pressure.

we have the existing boiler serviced under a BG Homecare service contract, and they have said that some of the parts may no longer be available to fix it if it breaks. Its around 15 years old.

We get that letter every year, had four now. The stuff that goes wrong on these old boilers are things like thermocouples…there isn’t much to them. Last time I had it serviced I mentioned this…he said it’ll probably last until the heat exchanger rusts through. He also let on that if a key part of my system was replaced under the homecare, it would be free, but as a key part of the system is replaced certain other things like ventilation/flue would need to be brought up to current standards, I and would have to pay for that. Kept the homecare purely for the annual service, but downgraded to a flex option or similar where there is a call out to pay.

Personally I will go for a combi when it does break, the hot water tank/cupboard takes up valuable space in an upstairs bedroom, its a small house (only 5 rads and two people) and if we get an IP rated boiler in the bathroom (only spare wall space for the boiler and outside flue) all the plumbing except the central heating will be confined to the the kitchen and adjoining bathroom which is a step down from the rest of the house. As the central heating would be closed loop this means there is next to no risk of flooding/water damage to the main house.

To the OP…wouldn’t you just be able to remove/turn off the pump on your shower? Both hot and cold should be mains pressure and equal.

Wow! thanks for all the input folks – lots to think about.

@spooky – we’ve been told that the type of shower isn’t suited to running without a pump. Running it till it dies isn’t an option when winter is approaching and you have kids – hence my trying to be proactive

BUT

that may be a moot point

because of the idea of putting an extra (9th radiator) in the attic that would be at the same level as the header tank we would need a sealed/system boiler if we don’t go for a combi which would mean the shower is unaffected

I had a boiler / tank system replaced with a combi in March this year. Live on my own and this summer I’ve used 20% of the gas compared to previous summers. Winter will be hard to compare as it’s related to the weather. But I don’t expect to save much – the radiators have to pump out the same amount of heat to warm the rooms up as before. Biggest difference will be the room thermostat – for a 16C setting, old one switched off at 18C, the new one at 16.5C. Again as live on my own no problem with water pressure and washing machine over night on Economy 7.

Despite the £400 bribe grant to replace the boiler I won’t save money. savings = less gas used. expense = interest on installation cost and annual service which I didn’t pay before. I decided to be proactive as the old boiler as the original was from circa 1980 and the casing was showing signs of warping plus getting any installers round here without paying extortionate prices is easier than getting STW to agree on the best bike (I got someone to travel).

New boilers are not as reliable as older ones. Older ones have very few parts that go wrong and if it’s a popular model there should be loads of spares around – you could always buy some in if you think they are going to run out.

IMO combis are good for small flats / houses. As said above if when they go wrong then you have nothing. With a tank you have a reserve of hot water and can use an immersion. i imagine new well insulated water tanks are very efficient – my old one with jacket type insulation kept water warm for 24 hours.

As for spares, my boiler is approx 25 years old and I can still get all the spares for it. They (Potterton) have just stopped making original spare parts, but you can buy OEM parts, so I fitted an OEM pressure switch last winter when the original one died – cost £30 plus half an hour to fit. You can keep these things going for a very long time if you want to.

So what’ve I got then? Hot water tank, but still very high pressure in the shower?

get one that will work well with a thermal store so you can get some solar heat if you want in the future.