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Is it worth replacing an old Alpha gas boiler?


I've recently moved to a house where the central heating system is run via a 14 year old Alph gas boiler. My meter readings seem high. Is this down to the age of the boiler? It has been regularly maintained. I'm wondering whether to replace it or not.
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Best answer by Transparent 12 April 2018, 11:28

Hi @aphrabenn
Your first Forum posting I notice! :8

Although 14 years may sound a long time ago, I would still expect the boiler to be rated SEDBUK "A". Type the model number into a search engine to confirm this.

"A"-rated can only be achieved if it is a condensing boiler with a condensate drain leading outside or to a waste pipe. It is certified to operate up to 95% efficiency under a predetermined set of operating conditions.

I also happen to know that Alpha boilers of about that age could have an optional GasSaver heat-recovery unit mounted on top to remove even more of the energy which would otherwise be wasted through the flue. Does yours have one?

Next, are you making a fair comparison with the boiler in your old house? The main issue is whether each of them was a Combi style.

Even if you understand this, for the sake of others reading this topic in future, can I define Combi as a boiler which not only provides heating (radiators) but also a direct supply of Domestic Hot Water (DHW) when you turn on a hot tap. A Combi boiler does not have a hot-water cylinder which it maintains at a preset temperature. Instead it fires up a few seconds after water flows from the hot tap.

Once you give me that background info, I'll be in a better position to advise where you are losing efficiency, resulting in higher than expected gas bills.

Oh... and please fill out your user-profile. I read this to better refine my answers on the Forum. Thanks.

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Userlevel 6
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Hi @aphrabenn
Your first Forum posting I notice! :8

Although 14 years may sound a long time ago, I would still expect the boiler to be rated SEDBUK "A". Type the model number into a search engine to confirm this.

"A"-rated can only be achieved if it is a condensing boiler with a condensate drain leading outside or to a waste pipe. It is certified to operate up to 95% efficiency under a predetermined set of operating conditions.

I also happen to know that Alpha boilers of about that age could have an optional GasSaver heat-recovery unit mounted on top to remove even more of the energy which would otherwise be wasted through the flue. Does yours have one?

Next, are you making a fair comparison with the boiler in your old house? The main issue is whether each of them was a Combi style.

Even if you understand this, for the sake of others reading this topic in future, can I define Combi as a boiler which not only provides heating (radiators) but also a direct supply of Domestic Hot Water (DHW) when you turn on a hot tap. A Combi boiler does not have a hot-water cylinder which it maintains at a preset temperature. Instead it fires up a few seconds after water flows from the hot tap.

Once you give me that background info, I'll be in a better position to advise where you are losing efficiency, resulting in higher than expected gas bills.

Oh... and please fill out your user-profile. I read this to better refine my answers on the Forum. Thanks.
Thank you for your reply with information. Most interesting. My Alpha boiler is a Combi boiler. It is an Alpha CB28X. The boiler in my previous house was a two year old Combi, a Worcester, but I can't remember which model.
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Thanks @aphrabenn.

I've just checked online: the CD28X is a non-condensing gas Combi-boiler which was manufactured between 2000-2005. Spare parts are readily available from several suppliers.

It's SEDBUK D rated at 80.1% efficiency (Central-heating mode on first firing-up). So although it clearly falls outside of current minimum standards, it's not in a bracket which I would label "condemned".

As you're new to this property you may not yet know how reliable it is, nor how often it's previously required spare parts to be fitted. Without knowing the average annual maintenance costs over the last 5 years it isn't possible to evaluate when it is cost effective to replace it.

Personally I would try to get it serviced by a local Heating Engineer who currently fits Alpha boilers. I employed one from Plymouth to install an Alpha in a renovation property a couple of years ago, which I was very pleased with. However I don't know where you are in the country (please fill out your Forum Profile!!)

You could check online to find the nearest Alpha trade-supplier in your area, and then phone them to ask the names of three installers they regularly supply. They're bound to tell you because it means more business for them and their trade customers in the future!
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Sorry, I should have added a comment about whether the type of Alpha boiler is likely to be the source of your higher-than-expected gas bills.

In short... yes, it's likely to have an impact. But I would question whether that makes it financially viable to spend £1500-plus on replacing it with a new model.

For most situations, the two factors most likely to give rise to high gas bills with modern boilers are:
  • that it's a Combi (no hot-water cylinder)
  • that the return water from radiators is still at a high temperature

Both of these factors take the boiler out of condensing mode within a short time after it fires up. So the SEDBUK "A" rating is meaningless because it's then certainly no longer running at 90% efficiency or better.

Simply replacing your existing Alpha Combi boiler with a modern condensing type doesn't alter either of these two predominate factors.

Now if you were asking me a different question:
"What about replacing the Alpha CD28X with a non-Combi condensing boiler, and installing a hot water tank with the option to later add a solar-thermal input?"
then I would be far more likely to say "Go for it!"

And if you then said you'd like to run underfloor-heating as well (instead of radiators), then there's no doubt you would get greater boiler efficiency. UFH has a much lower temperature for return-water to the boiler. This means it could stay in condensing mode.

So in a nutshell, I'd tend to retain your existing Alpha boiler at the moment...

... but give some thought to the medium-term possibility of a hot-water tank and (partial?) UFH because that's where you'll really increase boiler efficiency.

Finally, before anyone else points it out - yes, I know I've mentioned nothing about the differing levels of insulation between the old and new properties. That's another whole subject!
Thank you so much for your in depth reply. I've taken on board your Alpha repair man advice. I've already had to call out a local plumber at a cost £60 to replace a part (the boiler stopped working). I bought the house off a relative, and I've just looked at the service history. British Gas were contracted to service the boiler for a number of years, and there have been issues. I'm looking into having it replaced under the Government's Green Energy Scheme, or something akin. I live in the Chesterfield area of Derbyshire.

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