Should I replace my boiler

tony4147

My existing boiler is 20 years old, it's a Glow Worm Ultimate 70FF. For the last 5/6 years it's been on a maintenance contract due to it's lack of reliability.
This year my gas bills have increased substantially (25-30%) and I'm thinking it may be time to change the boiler.
My local gas fitter who I think is very good tells me that the Ultimate are quite a good boiler for reliability apart from the fan (bearings drying out).
I asked him about changing and he wasn't at all pushy but suggested that if I were to change then he would advise a Glow Worm or Valiant, not a Worcester Bosch as he thinks the heat exchanger is unreliable and difficult to replace in these.
I have British Gas coming round to quote, not that I will get them to do the job, but just to see what they say.

Any advice welcome.

Cardew

There are many threads on this subject and the consensus is never change a working boiler, especially at 'only' 20 years old.

As a matter of interest what is going wrong with the boiler to make it unreliable?

DirectDebacle

I have a Glow Worm Ultimate 120FF. Installed 1996. Worked perfectly until fan gave up 2 years ago. Replaced @£150 ish. Last year pilot jet and burner replaced @£35.00.

Going to hang on to it as long as possible. Agree with Cardew, keep it.

tony4147

I'm thinking of change more because of the high gas prices, also poor reliability has been boiler thermostats, pilot jet, fan

rogerblack

http://www.government-boiler-scrappage-scheme.co.uk/boiler-bands/band-e-74-78-percent/ gives the efficiency of your current boiler as 77%.
A new boiler is likely to not exceed 10% savings, even in the best case.

Looking at this compared to (say) £1.6K boiler install, flush, ... - it looks rather questionable, as you need to run £16K or so of gas through it to start saving.
Turning your heating down 1C will save about as much.

tony4147

Well my old boiler was 77% efficient, but that was when it was new 20 years ago, surely it wont be anything like that now?

rogerblack

tony4147 wrote: »

Well my old boiler was 77% efficient, but that was when it was new 20 years ago, surely it wont be anything like that now?

It depends.
First thing to realise is that energy doesn't go nowhere.
If you have 10kW of gas going into a boiler which would normally have 7.7kW of heat coming out, and 2.7kW of waste - there are limited places it can go.

Unburned gas, or CO production - highly dangerous and would be picked up on maintenance.
More case heating due to degradation of insulation - but it all ends up as heat in your house.
Furring up of the heat exchanger - but this slows heat transfer, and makes it a little less efficient, as it raises the effective output temperature, it doesn't stop it.

It's certainly not going to go from 77% to (say) 57%, unless there are other issues.
For example, thermostats set wrong, or it being on when it shouldn't be heating lengths of uninsulated pipe in the attic.

penrhyn

Most people gas consumption will have gone up by 20% last winter, 'cos it was cold.

Wywth

rogerblack wrote: »

It depends.
First thing to realise is that energy doesn't go nowhere.
If you have 10kW of gas going into a boiler which would normally have 7.7kW of heat coming out, and 2.7kW of waste - there are limited places it can go.

Unburned gas, or CO production - highly dangerous and would be picked up on maintenance.
More case heating due to degradation of insulation - but it all ends up as heat in your house.
Furring up of the heat exchanger - but this slows heat transfer, and makes it a little less efficient, as it raises the effective output temperature, it doesn't stop it.

It's certainly not going to go from 77% to (say) 57%, unless there are other issues.
For example, thermostats set wrong, or it being on when it shouldn't be heating lengths of uninsulated pipe in the attic.

I think most of the wasted energy of a gas boiler (ignoring a pilot light) goes out the flue.

I'm not sure if incomplete combustion of gas/CO going out the flue would be picked up on any inspection/service (unless it was perhaps really bad)

Cardew

tony4147 wrote: »

Well my old boiler was 77% efficient, but that was when it was new 20 years ago, surely it wont be anything like that now?

My boiler(not a Glow Worm) is 25 years old and, according to the full service manual there is nothing to adjust other than the size of pilot flame. Servicing consists of visual inspection and cleaning.

Overall gas consumption depends on the heating load and thus climatic conditions. However as far as I can ascertain my consumption in summer for, hot water only, has been constant over the years.

Look at a service manual for your boiler(they are available on-line) and see what can affect the efficiency of your non-condensing boiler.

MillicentBystander

penrhyn wrote: »

Most people gas consumption will have gone up by 20% last winter, 'cos it was cold.

Best reply of the thread so far for me. Everyone's gas consumption will have increased this year and it's not your boiler's fault - it's the crazily cold, long Winter we've endured. Replacing a working, safe boiler is rarely money saving. Plus the new, sophisticated boilers of today simply won't last as long as your Glow Worm and will probably need far more attention during this shorter lifespan (my boiler is a Glow Worm Economy Plus which is easily over 20 years old (the London phone number on the front starts with the 081 prefix!) and has never costs us anything apart from servicing costs.