How much to replace a conventional boiler with a combi?

[400bandit]

Hi All,

Obviously the first place to go for plumbing advice is here on good ole' BCF so here it goes.

So, current boiler is probably as old as the house (around 16/17 years) and is an "Ideal NF40". It currently makes all manner of noises and is probably about as efficient as Concord...

The whole system looks to have been manipulated over the years but currently the set-up is a thermostat in the front room and then a tank in a cupboard in the bathroom with a danfoss control unit controlling a 3 port valve for either water, central heating or both. Oh, and it has a circulation pump (which I had to replace 2 years ago, grr).

As you can see, quite the monstrosity:

https://i258.photobucket.com/albums/hh258/JoeSnowden/20151004_120513_zps1bv7qusn.jpg

What I want is to get rid of the whole set up that's in the bathroom so we can get rid of the cupboard and just have a combi boiler in the kitchen and then a control unit in the front room where the thermostat is. The house is a reasonably sized 3 bed semi with only 8 radiators throughout. It's probably worth mentioning that water pressure isn't great and I like a decent shower (there's also a shower pump in the mix which gives a good (but loud!) shower and does a good job of emptying the hot water tank in no time at all...)

Firstly, I have no idea about rough costs as a starting point and all that I've seen seems to vary wildly in cost.


What sort of set up would I need to be able to heat up the house in a reasonable amount of time and provide water for the shower at decent pressure and sort of costs would I be looking at to remove the existing system (hot water tank and associated plumbing), supply and install the new one?

Any advice from either plumbers or those who have had similar work carried out would be much appreciated.

Thanks,

Joe
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[Keir]

when I refurbished my house it had a very basic heating system installed with a tank like yours. similar house, 3 bed, 7 rads.
I ripped it all out and started from scratch with a plumber installing all new pipework, rads and combi. it cost £3200.

The shower now comes straight off the combi so it never runs out and shower pressure is fine, not quite pump pressure but much better than an electric shower.
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[Polarbear]

I had the same system as you, immersion heater and crappy central heating boiler. I had it completely ripped out, new all singing and dancing combi boiler, pipework, rads etc. Five grand for everything done, even the sweeping up after.
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[Andy_Pagin]

Word of warning about combis, reliability is unpredictable and they have nothing like the working life of conventional systems. I'm on my third combi since 2004. When they go wrong there's nothing that can be fixed by anything less that a fully trained heating engineer, and most parts are big expensive sealed units. If I legally could I would go back to the old system and to hell with the extra on the gas bill.
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[arry]

If you've got a poor flow rate, don't be fooled into buying a combi that can heat more litres per second than you can flow to it. It's a total waste unless at some point in the future your water pressure improves.

For your size of house, you'd do alright with a low end Valliant with a digital (moveable, remote so you can stick it where you like) thermostat and one of those fully fitted by a GasSafe engineer as a replacement for an existing combi is ~£1500 - £2000. The removal of your existing set up and associated pipework, plus the re-plumbing for the new boiler position is going to add to that but no-one can really guess I'm afraid not having seen it.

[stinkwheel]

Combi boilers are unreliable pices of shit which render your heating system incapable of utilising any of the developing eco energy systems, all of which rely on having a heat store of some sort.

Think carefully before fitting one.

I want to fit solar heating an and a solar powered, ground-source heat pump but to do so would mean re-doing all the plumbing to fit a heat store again as well as installing a new, even more expensive combi that can cope with being fed pre-heated water.

I've had the engineer out to my combi boiler at least six times in the four years I've lived in this house. That's not counting the countless hours I've spent tracking down and fixing faults myself when I realised boiler engineers have no diagnostic skills whatsoever and simply replace bits (charged to you) until it starts working again. They have a certificate qualifying them as a boiler engineer but that just means they know how to fit parts safely without risking an explosion, it doesn't mean they actually know how to fix one.

Also remember that hot water tank is made of enough copper to be worth driving it down to the scrappy and cashing it in when they ask if you "like us to get rid if this for you" as if they're doing you a favour.
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[J4mes]

If you want to free up space could you get the tank fitted in the loft?

Our neighbours have just done it in order to remove the airing cupboard and extend the bathroom in to it.

[MCN]

The deal is Corgi (GasSafe) is required by law to install/repair gas equipment.
Fitting a new boiler is pimps as most of the stuff is already in place from the old one.

Fitters charge a small fortune as they know their market is somewhat 'protected' by legislation.

I even looked at getting myself Gas Safe registration but there are a lot of restrictions on that too. The baistirts.

I couldn't even find a price for a new boiler. I guess a good one will cost about £1200 for a condensing unit with 95%+ efficiency.
Fitting should only cost £500. After mark-ups fitters probably want +£2500 min.

If you need maintenance it will be extra.

My boiler is over ten years old and works a treat. But it want's replacing as most of the green sites advise. My logic is that the savings I make won't pay for a new boiler at £2500-5000 ofver ten years so why change unless the boiler shit's it's self?

It is still spotless inside the burner and tubes etc.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Andy_Pagin]

I look at OP's current installation and think,

There's nothing there I couldn't quickly diagnose a fault with,
nothing I couldn't easily remove and replace for less than £100,
and it all looks to be in good order and reasonably modern and efficient.

If it ain't broke...
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[sickpup]

[Polarbear]

My combi has been fine. It would be cause I have British Gas home care for my house.

Of course if I cancelled it the damn thing would break down a day later.
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[Andy_Pagin]

[Nobby the Bastard]

[MCN]

Your plumber should have plumbed in the pump to blend hot with cold water.
It saves tonnes of hot water and means that tank could easily make 4-5 decent 7-10 min showers.

Noisy boiler is normally air or a kack build up in the boiler tubes.
Normally due to none or insufficient inhibitor in the system.
If you can light the air that comes out the bleeders then there is no inhibitor. The gas produced is Rotten Egg Gas/H2S.
Scale can block the boiler too. and make all those crinking noises as it heats up.
You can flush the system with fresh water.

I use Fernox

Determine if you have an open system with a little top up tank or a closed system with a sealed accumulator/pressure tank. (If the later you need a filling loop if there is not one there. Buy a short hose from B&Q for that.)
Drain the system off.
Add a cleaner or de-scaler if required.
Flush again with fresh three or four times.
Add inhibitor and Boiler Silencer then
Fill with fresh water.
Bleeding as required.
If the boiler otherwise runs OK then it may save you a bob or two or even let you put a few quid away in a New Boiler account so it's not so painful.

It is quite a big purchase and there are deals for so much per month giving you 'piece of mind'.
As said my boiler is over ten years old and has cost me £150 to fit a new fan in that time. But I treat the system myself.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[arry]

[stinkwheel]

Last two "PCB's gone" in my boiler turned out to be an ineptly fitted flow switch. So £100 each plus labour as compared to rotating the flow switch so the arrow pointed in the direction of flow and not off on the piss.

Took me two hours, having never worked on one before, with a wiring diagram to come up with a diagnostic algorithm for the fault. Five minutes to remove the front panel to get at the (numbered) terrminal blocks. Approximately 5 minutes with a voltmeter to find the faulty componant, 10 minutes with screwdriver to get to the switch and five seconds to rotate it 30 degrees so it clicked every time instead of just some of the time.

Less time in total than it takes either of two "qualified" boiler engineers to diagnose and fit a PCB that didn't need changing.

There is of course an unnamed third party, neither of the two "engineers" who attended (or not that they are admitting to) who fitted the switch on the piss in the first place.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[arry]

[Robby]

Whenever combi boilers come up there are always tales of woe. To counter this, I bought my flat 6 years ago and the boiler was 5-10 years old at that point and had not been maintained. I have never had a problem with it. I pay about £15/month for boiler cover - which includes an annual service. I have never had to use the cover.

I wonder if the horror stories come from people that bought an ultra-efficient model around the time of boiler scrappage. They were new tech and being churned out quick to meet demand. New tech is often problematic.

You don't have to buy ultra-efficient. The real world difference in fuel burn between something quoted as 95% efficient and something quoted as 85% efficient is pretty small. The price of the unit can be quite different - the difference between buying a low end efficient boiler, or a high end (old model) less efficient one.

[400bandit]

Thanks for the feedback, I'm quite surprised by all the horror stories, my parents have had one for over 10 years and it's been awesome despite never being serviced!.

I'm not doing it for the efficiency, that will be a bonus, payback period is likely to be 20+ years (like double glazing!). Having a hot water tank just seems so old fashioned, like storage heaters almost!.

Thanks,

Joe
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[Ste]

[MCN]

Get to B&Q ASAP and buy yourself a boiler blanket. Wrap it around your boiler. You're probably are aware it's toastie warm in there. That's all your s heating up the sky.

Boiler blankets pay for them self in a couple of years and the psychological effect alone that your not paying a Spanish Money Magnate several pounds a year to buy his power is a comfort on it's own.

(There is a little bit of this heat adds to the 'overall heat' in the house which would/will be topped up by the heating system but the constant waste is the dog.)
Turn your tank thermostat down to about 60ºC. Cold is dangerous as you can encourage bad bacteria in cooler temps (legionella).

Buy and fit radiator reflector material on the wall behind radiators on all external walls
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Tracey Suntan-King]

I've had a few combis both older as well as newly installed in different houses and all have been fine.

My only observation is that it can take ages to run a bath if other sources are calling for water/heat all at the same time.
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[grr666]

I think MCN means cylinder blanket.

My combi is fitted in my loft, it doesn't get in anybodies way there.
Had a Bosch Worcester fitted after having
the rubbish BAXI fireplace and back boiler setup removed.
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[Cyclingbiker]

Currently mulling over getting our 25 year old Glow Worm boiler replaced under a discounted installation scheme from SEE. Looking at £700 or so to have it replaced like for like with a conventional boiler and retaining hot water tank and associated piping or pay an additional sum of an undetermined amount and have a combi boiler fitted and the pipework altered to suit.

The current boiler has had one major breakdown in the last 5 years which left us without heating or hot water for around a month in the middle of December whilst we scraped and saved for a BG engineer to come and fix the thing. I am unsure of how reliable this will be in the coming years. A combi boiler makes sense to me because of the wastage that must occur heating up a full tank of hot water for just 2 people having 1 shower each per day and the odd sinkful of washing up etc.
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[MCN]