gas boiler cutout..overheat? Scottish Gas says buy new every Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[swwoodruff]

I have a (we think) 20 year old Ideal Elan gas boiler. At a service 18 months ago the engineer couldn't relight the pilot and replaced the gas valve. Later that month it went out, pilot and all, and I re-lit it. It repeated that 2 months later and now started to go out - main burner and pilot light - more and more frequently until its more than daily. Scottish Gas engineer changed the thermocouple in case it was falsly detecting an overheat, and now say buy a new boiler and all pipes and radiators since they assume corrosion in the system is blocking the heat exchanger. I notice on hot water only it hardly ever goes out, but once the radiators are switched on it goes off after 5 to 90 minutes. Often can restart it 4 or 5 times (which is tedious) then it runs OK for a day.
Today, after 4 weeks holiday during which the pilot was on but the timer off (ie it wasn't running) the pilot was still on OK on return. But for the first time I found running the hot water taps produced brown discoloured water for the first few litres.
Can anyone advise me on what to do - take up the advise of a new system? Is there something cheaper I can try first? I'd appreciate some advice!

[The Heating Doctor]

At 20 years old the boiler is at, or close to the end of it's usefull life. What I would not do is to let Scottish Gas do the replacement work. Get two or three quotes from local installers to carry out the work. Do not be affraid to ask for referances and never pay any money upfront.

[swwoodruff]

Is there a reason why not Scottish Gas? I have a service contract with them, and I assume the fault that really appeared since that started 3 or 4 months ago are coincidence!

[swwoodruff]

And is it necessary to buy new pipes and radiators, or is this salestalk?

[htg engineer]

Scottish gas will charge a fortune for a boiler swap or a full installation. Smaller companies, or even better someone doing the job "on the side" will save you alot of money.

If you're happy with Scottish gas and want to pay their prices, then there's no reason why you shouldn't. The boiler, quality of work will be or should be the same.

[The Heating Doctor]

Hi
The reason I caution against Scottish/British Gas is two fold the first being cost, these companies charge a very high cost which is well out of step for the industry as a whole, they trade on their established pre privtisation image. In the meantime they generate as much profit as they can to satisfy share holders. All fine except when it is your money which is paying the big bonuses to the directors and share holders of the company.

Secondly these gas companies negotiate large discounts from boiler manufacturers (not passed on to you the customer) and they then will only recommend boilers from the manufacturers that give them the best deals. Often these are boilers that have not got a good warrenty often only 1 or 2 years (so you are back to needing there service plan again) but there are better boilers out there with up to 5 years warrenty as standard which are more efficent than the one's SG or BG sell. I think you can work out why SG & BG do not like these boilers.

One final word, if you get some one in to do the work in their spare time make sure they as individuals are CORGI registerd and not the company they work for, as they will only be coverd by CORGI whille carrying out their employers business, a pit fall many have fallen foul of.

[swwoodruff]

Lots of useful info, thanks. Any recommendations of boilers to go for (small 3-bed terraced house, 2 people, like a good shower...)

[htg engineer]

Baxi 105HE or Potterton Promax, will meet your needs.

2 years manufacturers warranty
Boilers not too expensive to buy (unlike worcester bosch)
Replacement parts not too expensive.
Boilers fairly easy to work on (saves on labour costs IF it breaks down)
Very reliable

Promax will cost abit more than a Baxi. But are suitable for alot more installations as longer flue length's can be used

[The Heating Doctor]

Sorry; I have to disagree with you [b]htg engineer[/b], the two boilers you have recommended only have a one year warranty and are junk, both have cast aluminium heat exchangers and will last only a few years. They are also the less efficient band B energy rating, but I can not disagree with you that they are cheap however you get what you pay for.

You want a boiler which has a stainless steel heat exchanger and the ones with up to 5 year warranty are the Alpha CD range, Baxi Platinum, Viessmann 100 series, with the Viessmann the heat exchanger has a 10 year guarantee. Other makes to consider are Broag & Vaillant. If budget is a real issue the best of the budget models is probably the Haslstead Ace HE with a two years parts & labour warranty. All of these boilers are A band energy efficiency, with the Viessmann toping the bunch at 97% and all have that all important stainless steel heat exchanger.

[htg engineer]

We have been fitting Baxi 80e & 105e for around 5 years now, and I can assure you they're not junk.

We have never had any bother with the heat exchangers so they do last longer than a few years.

We have been fitting Baxi 105HE's and Potterton Promax's for around 2 years now, and again no major problems with them, a few problems but when you have a company installing around about 700 - 800 boilers per year, you are going to have some breakdowns.

The boilers we fit come with 2 years manufacturers warranty, probably a deal we get for fitting so many.

There may be better, more expensive boilers. More expensive for parts and more expensive to repair. I'm recommending 2 boilers that are fairly cheap and are very good reliable boilers.

I have a vaillant in my house, and it's coming out soon and will be replaced with a Baxi 105HE or Potterton Promax.

[AndyB]

I'll have to agree with htg engineer about the baxi and potterton range.we've been fitting them for afew years and never had any major problems with them.when you do have a fault they are very easy to work on ,easy accessable saving money for the customer.But I will agree with the heating doctor about the alpha cd range.A good boiler, with a 5 year warranty(when you buy the extra back plate)

[The Heating Doctor]

I did not say the 105e or 80e where junk, I said the 105HE & Promax are junk and I stand by that. Baxi Potterton did not have a dedicated condensing boiler ready for release in April 2005 when the goverment changed the legislation that gas boilers should be condensing. This company as a stop gap retro fitted the 105e & Promax with a secondary heat exchanger to turn these non condensing boilers in to condensing boilers. The problem is that where the likes of Worcester & Ariston made there aluminium exchangers thicker (ie turned them into sacraficial exchangers, which can cause other problems, but that is another debate) Baxi Potterton did nothing to theirs, so given time the condensate WILL eat the exchanger, if your unlucky this could be 2 to 3 years but can be as long as five. The standard warranty is one year, checked with them today, unless they are being installed into a development with a NHBC warranty, but year two is parts only not labour. These boilers are due for phase out 2008 when the new updated building regs state only A band boilers will be fitted. (this may be delayed until the next major change in 2010 the jury is out on that one still). One other point on these boilers a recent 'Which' report highlighted the fact that when put on test neither of these boilers could acheive past 'C' band energy efficency which 1) makes them illegal and 2) Was the energy efficency of the boiler before Baxi Potterton turned them in to "condensing" boilers. As this boilers has only been on the market for little over two years it is too early to see mass heat exchanger failures, but they will happen, as one man said "ye cana change the laws of physics". I have no vested interest in any particular boiler manufacturer but I do know what makes a good boiler and I know what makes a bad boiler.

[swwoodruff]

Many thanks guys, hope no one comes to blows over this.
But back to my question about replacing the whole pipework and the radiators. When the boiler switches off (overheats, the engineer said though he didn't see it happen, and I;ve heard no kettling or anything abnormal (its upstairs in a cupboard, but 10 years ago the pump failed and the bang crash of overheat was audible next door) when it switches off I can restart it, and often it runs for another day before stopping. Odd sort of oveheat, or rather odd sort of heat exchange blockage?
How do I ascertain whether i Need the floorboards up, the plasters in, and so on? Help! I'd hate to buy a boiler and have it killed by the old pipework, but still...
many thanks fo rthe expert advice - I'm trying to integrate it into my purchase.

[The Heating Doctor]

If your system is blocked/sludged up this may be cured by having the pipework powerflushed. However the Ideal Elan from what I can remember was a open vent boiler but there was a pressurised kit which could be purchased to upgrade to a sealed system. If your system is a open vent system and has been for 20+ years or so, I would suggest that the entire system would want replacing. Modern combination & system boilers operate in a closed pressurised loop i.e. there is no small feed & expansion tank required, as the expansion is taken up in a expansion vessel normally fitted with in the boiler. Subjecting old tired pipes & radiators to a sudden increase in pressure could lead to more leaks than the Titanic. If your system has had the kit added and therefor is a sealed system then you probably will not need to change pipework ect. It's a call for the installers who will quote you to replace the boiler as they will see the condition of your existing system.

[htg engineer]

How has he diagnosed overheating, if he hasn't seen or heard it overheat, and you've had no kettling problems ?

do the radiators or water get too hot ?

when the boiler stays on and reaches temperature does the main burner cut out then come back on when it has cooled down abit ? if it does, then it's not over heating and the thermostat is working correctly.

If you've never noticed this, put the thermostat on low and wait to see if it cuts out, then relights a few minutes later

It's worth checking the pilot flame when the burner is on. The pilot flame can sometimes lift away from the thermocouple when the boiler has been on for a while this will cause the main burner and pilot to extinguish. The pilot flame can be adjusted at the gas valve.

As for replacing any heating system of this age, I would advise renewing all pipework and radiator valves at least, as they are prone to leaks when connected to pressurised systems.