New Central heating system **UPDATE**

[pleasenospam]

I thought I would give an update to a post I made last year (below). I recently had a completely new central heating system installed. All the old pipes, radiators and tanks in the loft removed and a brand spanking new combi-condensing boiler, all new copper pipe work and all new radiators installed. My original post caused quite a difference of opinion, people who thought combi boilders were crap, to those who thought they were great.

In my opinion my new system is great, it beats my old setup hands down (gravity fed). My house is now warm, something it has never been, and the water pressure is much better than before and heats up quicker.

From memory I've had a Potterton Gold 28 HE boilder installed. Best

thing I ever did, so glad I didn't take the advice I was given to keep the original system and just replace the radiators and tank !!!

***************************************************************************= ********** MY ORIGINAL POST IN JULY 2006

Excuse my ignorance however I know nothing about plumbing or central heating systems but need help with some advice.

I live in a 1930's averaged sized 3 bedroom semi-detached house. The heating system needs replacing as its not efficient and old. The radiators we have are too small for the rooms and do not heat them very well. We currently have a back-boiler that we want removed and have what I think is called a 'conventional heating system' (tank in the loft and storage tank in a cupboard.

A heating engineer came round to quote and advise on what we should do.

His recommendation was to stay well clear of condensing boilers (because they are not reliable and hard to fix??) and didn't suggest a combi boilder because our pipework wasn't suited.

He suggested keeping the current set-up but replacing the tank, boiler and putting new radiators up and heating controls. We are having a single-storey extension built and the tank would be piped into the new extension.

All this was priced at =A34000 which seems a lot to me, however I don't know for sure.

Are condensing boilers that bad and does the pipework make any difference if you want a combi boiler? Does that price seem excessive or is that about right?

Any help or advice would be appreciated

***************************************************************************= ************

[Dave Plowman (News)]

I doubt anyone advised you to keep a back boiler.

I don't think you quite understand the combi versus storage system pros and cons if you say 'it heats up quicker'.

[Owain]

Could have been worse, could have been a Suprima :-)

Best keep raden's site bookmarked, just in case.

Owain

[Roger Mills]

It's horses for courses! The main limitation with combis is that they can't deliver hot water to the point of use anything like as fast as a stored hot water system can. However, if you have good mains pressure and flow, have only one bathroom, and rarely need to fill a bath (preferring to shower instead) they can sometimes be the best solution.

I don't remember this particular thread, but there have many on the combi vs conventional theme - often dominated by one particular combi zealot (who shall remain nameless, but everyone will know who I mean!) who believes that combi boilers - often in multiples! - are the solution to every maiden's prayer. Others have therefore felt compelled to put the counter-argument - perhaps more strongly than is sometimes justified.

[David Hansen]

On 26 Mar 2007 19:57:04 -0700 someone who may be [e-mail] wrote this:-

The same thing could have been achieved in a number of ways without using a combination boiler.

Time will tell whether the original heating engineer was right about combination boilers breaking down.

[Lobster]

Presumably the "it" is the house, not the water, though!

David

[pleasenospam]

When I posted the original message I was getting quite heated arguments, some singing the combis praises others telling me to steer clear because they were unreliable and things like running a bath were bad because of low water pressure. Some people recommened I kept the old system (gravity fed) and storage tank, now I have changed it I cannot see any benefits from this old system.

So far all I can say is the combi works fantastic for me. I'm not sure what you mean that they don't deliver hot water anywhere near as fast as stored water, to be honest its takes seconds for hot water to come through, hardly noticible and the obvious benefit is I'm not heating a full tank of water for nothing.

My mate who fitted it has had a combi boiler for 8 years in his home and has fitted several for friends and has never had any problems, so fingers crossed the nightmare stories I was getting that they break down all the time won't happen to me.

[Roger Mills]

You'll start to get hot water very soon after opening the tap - but that's not the point I was making. The point is that a combi is taking incoming cold water and heating it as it passes through. The flow rate is limited by how fast it can heat it - particularly in the winter when the incoming water is very cold. So it can take quite a long time to fill a bath compared with the time taken to dump a cylinder full of already hot water into the bath. Have you done any comparative timings?

[Mike]

I'm in a situation very similar to pleasnos pre new system (except existing pipe work is compatible with a combi). Would be very interested in reading the alternatives? I don't have a problem with retaining the old back boiler if possible, but I have a major problem with the monstrosity of a 70's gas fire which is attached to it and juts out into the room about 2 feet. Have been told that they either have to be removed or retained as a job lot and that replacing just the gas fire is not possible. Anyone know if the plumber I had round is being a bit economical with the truth? He is doing his best to flog me an entire new system and combi

[Dave Plowman (News)]

Likely the point was made that a combi can't fill a bath as fast as a decent storage system. This may or may not matter to you.

Sounds like you had a poor old system. They're not all the same.

You don't take baths, then? That's where it noticeable. Or where you might need more than one hot tap or shower etc running at once. A combi is limited in how much water it can deliver at any one time, whereas a well designed storage system less so.

If you've chosen a good make it should be ok. But I'm wondering what made you choose a Potterton?

[pleasenospam]

was getting quite heated

Thats my point though, the bath runs just as quick, if not quicker than before. My old system was very bad and old, believe me our house was never warm even with the heating on constantly, now its almost tropical :-)

I've only got one bathroom so I won't have any instance to run baths and showers together so I can't see that being an issue for me.

The fitter recommended the Potterton (its not the model on Watchdog !!) and I bought the boiler direct myself so its not like he had a deal on with someone or one laying around. Like I said he's never had any problems with any combi he's fitted but he did say problems can occur when people just change the boiler and leave old pipework as that can cause problems.

The thing that I like is its hot water on demand as opposed to heating a tank for nothing, so I should notice lower bills as well.

[Ed Sirett]

For a while the manufacturers offered update fire fronts to accompany their BBUs.

In general not only are updated fire fronts no longer available to go with the back boiler but a BBU is so poor in terms of efficiency it wants to be slung if at all possible.

Replacing BBUs is an all or nothing matter and the disruption is always substantial.

[Dave Plowman (News)]

Basically you're comparing a badly designed and installed system with one which has been done properly - I hope. Nowt really to do with the difference between combi boilers open vented and storage hot water. A back boiler can heat the house perfectly ok - but of course isn't anything like as efficient as a modern one, but again a different argument.

Running the kitchen hot while showering? Running cold? Plenty of houses don't have high enough mains pressure to allow this without disruption.

I'm rather surprised if all the combis he's fitted have worked perfectly for ever. Or near any modern boiler, come to that.

Hot water doesn't cost that much in the scheme of things. And a well insulated cylinder doesn't loose much heat.

[pleasenospam]

I'm not trying to say my system is better than any other system, I guess they all have plus and minuses. The point of my post was just to say that the system I now have works for me, the impression I was getting from some last year was I should steer clear of this method. Why the original fitter I saw recommended keeping the old system I don't know, maybe it was just easier for him to do?

All I can say is it now works for me and works really well. I certainly wouldn't go back to the old system, and I have had the old systems in previous houses, that did work well, and even they don't compare to the combi set-up. My biggest gripe was always heating a big tank of water up, or having to heat a tank of water up if you needed a bath. I don't have this problem now I just turn the tap on and its hot whenever I want it. To me it was money well spent.

I spoke to the fitter about why some people didn't like combi boilers and he said it was because many of the early ones were from abroad and engineers over here didn't know how to fix them. As the years have gone on he said Britain started making their own boilers and they have got better and better. He seemed to think many fitters remember the problems from years ago and have steered clear since, still assuming they are the same.

He did say however that combis being fitted onto crap pipework, or cheap combis being fitted do cause problems.

[David Hansen]

On 28 Mar 2007 21:25:28 -0700 someone who may be [e-mail] wrote this:-

As others have said, you are not comparing like with like. A cylinder fitted today will be properly insulated and will maintain a sensible temperature all day if no water is drawn off. It will only need re-heating as water is drawn off.

[David Hansen]

On 28 Mar 2007 11:45:09 -0700 someone who may be "Mike" wrote this:-

Keeping the house warm is firstly a function of how well the house is insulated. Get that sorted out first.

After that the method of heat distribution within the house becomes important. However, this system can be connected to any sort of boiler.

Back boilers are inefficient. When they get near the end of their life it is time to replace them with a modern boiler. This might be a combination boiler, but there is no need to have a combination boiler. A lot of people appear confused by what a condensing boiler is and what a combination boiler is.

At the same time it is worthwhile looking at the heat distribution system to avoid two lots of disruption.

[Dave Plowman (News)]

You seem still not to have taken on board the disadvantages of a combi for many people. That your domestic circumstances are such that it is fine for you means either you don't really understand what was being explained or it was explained badly.

Basically pipes don't wear out. Neither do rads if inhibitor has been used. So if they were both well designed and in good condition replacing them is just throwing money away. Of course other factors may apply - which are impossible to know without seeing and assessing the system. If the old system never worked properly then replacing it all could well be the best approach - but posts on here usually give general advice since the posters haven't seen your actual installation.

Again you seem to be remembering some crude system. Most will be automatic so you never have to wait for a tank to heat up. It also sounds like your hot water use is tiny compared to most

What he won't have mentioned is that combis are easier to install so give bigger profits...

'Crap' pipework will cause problems with any system. However a mains pressure system doesn't need anything like the care installation wise to 'work' - another reason plumbers like them.

And you still seem to be confusing what a combi does. The reference to crap pipework applies to any boiler type. Hot water pipework that worked ok with a storage system will work ok with a combi - obviously with some modification. The reverse isn't usually the case.

[Roger]

The message from [e-mail] contains these words:

Are you sure about that? I don't recall any regular singing the praises of a gravity system. (But then I don't read all contributions these days and often come late to a thread as in this instance.) A storage system with pumped circulation is a different ball game however and don't forget that as far as the central heating is concerned there is no difference between conventional and combi. It is just the domestic hot water supply that is different. And it is a fact (whatever Dribble may say to the contrary) that a well ordered storage system will deliver a hot bath considerably faster than any domestic combi.

[The Natural Philosopher]

Indeed it will, and it won't slow to a trickle when someone is washing their hands..

Combis are great in a house or flat with a space problem and up to three people only..beyond that a pressurised storage system is the only way to go really.

If you get a combi that WILL deliver the peak output for a larger house, its bigger and more expensive and needs some pretty big pipework to keep the flows up..the pressurised how water cylinder ends up no more expensive AND it can be ticked in any old corner really. Whereas a 30KW combi cannot.

[timegoesby]

I disagree. I have fitted high flow rate combis and they are as good, if not better, than old gravity storage water systems.

You really should get to know the market in modern combis

The pipework is not bigger than a gravity storage system.

I disagree. Do some pricing and the savings in pipework, labour and time.