Boiler replacement

[matt1001]

Hi,

I was after some advice on a replacement gas boiler and possibly changing to a system or combi boiler.

The current boiler is Glow Worm space saver 50 with a cold water tank and expansion tank in the loft & cylinder in the airing cupboard. Our house is a 1960's well insulated 3 bedroom semi with one bathroom.

I am a bit worried about a system boiler in case of leaks in the pipework and whilst i like the idea of a combi boiler because of the extra space it will give in the loft are they less reliable than heat only boilers?

Also the current boiler is on an inside wall with its flue on the roof. Will a new boiler need a new flue and need to be installed on a outside wall?

Any advice on system options and brands of boiler would be very welcome.

 

[SimonH2]

Combi boilers are much less reliable than an equivalent system (or heat only) boiler. Not only that, when it breaks down it will leave you with no hot water and no heating. Flow rate will be limited as well - nothing like what you can probably get from your cylinder when (for example) filling the bath.

Personally I would not give one house space, especially as you already have your hot water cylinder (probably with an immersion heater you can switch on if the boiler breaks down). Though I know some people are quite happy with their combi.
Developers love combi boilers because it means they can reduce the size of a property by all of 10 sq foot or less, and of course they don't have to live with the cheap **** they fit.

As to flues, the new one will almost certainly need a new flue. Technically, I believe concentric flues are supposed to be standardised, but it seems every manufacturer only covers using their own in the installation instructions - and so it will be standard practice to fit a new flue. The boiler can be inside with the flue through the roof - and this has some advantages in not having to worry about where the plume points as can be the case with a through the wall flue.

One important thing is that your new boiler will be a condensing boiler. These need a drain, and this is most commonly taken outside even when the boiler is in the kitchen near a sink. If it is at all possible, keep this inside as it will then avoid the problems caused by the drain freezing and the boiler either tripping or being damaged as the condensate backs up and floods the boiler.

 

[dcawkwell]

A combi boiler will be the cheapest to run and do away with all your old tanks. Some combi boilers have some very high water delivery rates
up to the old vented system you have.

Since it is most likely your hot water tank is quite old with a large coil
that reheats only slowly it will be necessary to replace this as well.

So your ideal choices would be
1. Combi boiler with a high delivery flow rate with an electric shower as backup should boiler fail.
2. System boiler with an unvented hot water tank mains pressure hot
water to the hot taps. (also doing away with you header tanks in the loft)

Job done.

 

[mickyg]

The boiler you have is very reliable and could potentially last many more years. If, however your serious about replacement then yes you can just fit another heat only boiler, I fit many every year, for reasons of simplicity and reliability for the end user.
I wouldn't however put off a combi on the condition of reliability, as a good quality, well installed boiler shouldnt generally break down more than twice in its first 12 yrs and should last up to 20yrs. Considering turn around for most combi repairs from a reputable company is no more than aprx 48 hours, your looking at maybe 96hrs down time in 12 yrs, and then there's every chance your heat only boiler could break down also, albeit with the benefit of back up hot water.
There's pro's and cons to both types of systems which are best discussed with a good quality installer.
As for the flue, you'll probably find its best to relocate the boiler. Vertical flues are neater and negate plume issues, again these points can be discuessed with your installer.
You don't however say why you are thinking of changing the existing boiler.

 

[SimonH2]

I wouldn't however put off a combi on the condition of reliability, as a good quality, well installed boiler shouldnt generally break down more than twice in its first 12 yrs and should last up to 20yrs.

Really ?
Firstly, I strongly suspect that long before the boiler is 20 years old you will have your maintainers pushing you to replace it. I don't see a lot of comments in various threads on here that dispel that thought.

Secondly, if they are that reliable, why are there so many comments about unreliability ? OK, some of it is down to make/model choice, but when the response to comments about an average of more than one breakdown every two years is along the lines of "you're doing well" then that doesn't bode well - and that's for a heat-only boiler without all the combi stuff to go wrong.

It could be that you've been particularly lucky with your installed base, but it's clear that isn't everyone's experience.

There's also the issue of repair times. I can assure you "fixed within 48 hours" is far from guaranteed. It will depend on the ability of the people doing the repairs, and as I'm sure you'll be aware that will vary considerably. It also depends on availability of spares - and even with the spares holding of British Gas and a common boiler, some of my parents repairs have taken longer than that (boilers know when the weekends, especially bank holidays, are and seem to breakdown then ) Using an independent with an above average reputation, I've had them take over a week to repair a simple fault - by the time them come and misdiagnosed a simple problem, "fixed" that, been called out, had to order spares for an old model (cf your comment about it lasting 20 years), and finally I've diagnosed the failed microswitch for them.

I'd recommend the OP asks around his friends to see who has a combi, and get their experiences and views before taking the plunge.

A combi boiler will be the cheapest to run...

Really ?
It can be, it can also cost more to run that stored heat. If you can live with long times from "tap on" to "hot water" then yes, they consume very little when not running. However, once you enable any function to reduce the heat up delay then they aren't as good as you might think. After so many arguments (usually deriding thermal stores for their heat wastage), I actually did measurements. The thermal store I put in the flat has standing losses of around 80W, the combi (6 year old BG badges Worcester Bosch) with eco mode turned off was using something like 160W worth of gas.

I won't deny though that a combi, if you are changing the boiler anyway, is by far the cheapest way of getting mains pressure hot water.

 

[matt1001]

Hi,

Thanks for all your replies. The reason it is being replaced is that it has broken at least once a year for the last 4 years and our gas costs appear very high considering how often we have the heating on and the no. of radiators we have.
Also we have had an engineer round this morning and as we have a flaky asbestos flue we have been advised that the whole lot needs to come out.

He recommended a Worcester Bosch combi but will get a couple of people for advice & quotes.

 

[SimonH2]

He recommended a Worcester Bosch combi ...

Ask him if it has a mode for keeping it hot to provide "instant" hot water. Then ask him how much gas it uses with this turned on, and how long it takes to provide hot water (from cold) with it turned off.

On the 6 year old model (RD532 from memory) in the house, the answers are the equivalent of about 160W worth of gas, and 20 seconds before it even fires up (40 seconds minimum before water runes hot). The former negates the arguments that storing a tank of hot water is wasteful, and the latter would not be acceptable to me - but that's a personal preference.

I would hope that newer models are better, but I wouldn't count on it.

 

[DeltaT2]

Hi,

Thanks for all your replies. The reason it is being replaced is that it has broken at least once a year for the last 4 years and our gas costs appear very high considering how often we have the heating on and the no. of radiators we have.
Also we have had an engineer round this morning and as we have a flaky asbestos flue we have been advised that the whole lot needs to come out.

He recommended a Worcester Bosch combi but will get a couple of people for advice & quotes.

OMG, don't fit a Worcester Tupperware Bosch!!! Here's what to do, given that spares for your boiler will be available until 'forever', get your so-called expert to stick a FGA in the flue of your old boiler & check how efficient it is, you could well be surprised!! If it's over 90% keep it. Also ask him how much it'll cost to upgrade the controls on your current system.

Everyone is paying far too much for energy, so you're not alone.
HTH

 

[expertgasman]

old boiler & check how efficient it is, you could well be surprised!! If it's over 90% keep it.

Over 90%.!! Are you drunk? I would BUY it let alone keep it!

 

[mickyg]

get your so-called expert to stick a FGA in the flue of your old boiler & check how efficient it is

how does that work then? im very interested. ....

 

[mickyg]

I wouldn't however put off a combi on the condition of reliability, as a good quality, well installed boiler shouldnt generally break down more than twice in its first 12 yrs and should last up to 20yrs.

Really ?
Firstly, I strongly suspect that long before the boiler is 20 years old you will have your maintainers pushing you to replace it. I don't see a lot of comments in various threads on here that dispel that thought.
Secondly, if they are that reliable, why are there so many comments about unreliability ? OK, some of it is down to make/model choice, but when the response to comments about an average of more than one breakdown every two years is along the lines of "you're doing well" then that doesn't bode well - and that's for a heat-only boiler without all the combi stuff to go wrong.
It could be that you've been particularly lucky with your installed base, but it's clear that isn't everyone's experience.

yes really. I should have maybe added though this is only providing you find a decent independant installer and don't use a service provider.
I certainly won't be pushing my customers to replace the boiler I fitted at any time. If your installer fits a good quality boiler, and fits it well, then what i said remains, this is my experience with my customers and also customers of manufacturers who I've worked for, i cant speak for others, and no its not luck either. Anyone who has a breakdown every 2 years probably has a rubbish boiler, a dirty system, poor servicing or a combination of all 3.

There's also the issue of repair times. I can assure you "fixed within 48 hours" is far from guaranteed

it is for my customers, and no doubt for many other independants. 99% of parts for the boilers i install and probably over 90% of the boilers I look after are stocked locally or available next day delivery. Again i cant speak for the likes of BG who wont collect normally priced parts, only order them from their own vastly discounted spares stock in Leicester, then pretened they're not in stock because the engineers planner won't issue an appointment in the next few days.

Using an independent with an above average reputation, I've had them take over a week to repair a simple fault - by the time them come and misdiagnosed a simple problem, "fixed" that, been called out, had to order spares for an old model (cf your comment about it lasting 20 years), and finally I've diagnosed the failed microswitch for them.

you need to find better engineers.

 

[manortim]

Hi,

Thanks for all your replies. The reason it is being replaced is that it has broken at least once a year for the last 4 years and our gas costs appear very high considering how often we have the heating on and the no. of radiators we have.
Also we have had an engineer round this morning and as we have a flaky asbestos flue we have been advised that the whole lot needs to come out.

He recommended a Worcester Bosch combi but will get a couple of people for advice & quotes.

OMG, don't fit a Worcester Tupperware Bosch!!! Here's what to do, given that spares for your boiler will be available until 'forever', get your so-called expert to stick a FGA in the flue of your old boiler & check how efficient it is, you could well be surprised!! If it's over 90% keep it. Also ask him how much it'll cost to upgrade the controls on your current system.

Everyone is paying far too much for energy, so you're not alone.
HTH

Do you understand the difference between burn efficiency and appliance efficiency?.....clearly not.

Upgrading the appliance to a modern unit will pay for itself with 5 years or less.

Worcester aren't that good and over priced in my opinion.....they just advertise lots to get their brand out there so people think they're good.


I would say, viessmann, atag, intergas or vaillant as good options.