Do we Need a New Central Heating System?

ed110220

Perhaps the first thing to do is some rough calculations on how much gas a new boiler would save you. If you don't use a lot of gas to start with, then the payback period for a new boiler may be too long for you to think worthwhile.

The Baxi Bermuda backboilers are generally regarded as long-lived and reliable, but inefficient by today's standards. I have the SL3 and I looked it up online (do a search on the SEDBUK site) and it's only 65% efficient - a new condensing boiler is about 90% efficient.

Do the maths and you should be able to work out how much money you'd save. As I don't use much gas to start with, I figured the saving wouldn't really be worthwhile at this point.

Some other things to think of are that Baxi makes a modern 90% efficient condensing back boiler called the Bermuda BBU HE which may go into your existing system with less disruption than a combi boiler (no need for resiting the boiler, less pipework change).

Also, boiler replacements should come under the government's Green Deal later this year, in which there won't be upfront replacement costs and the repayment will be through the savings on your energy bills.

Maybe others might know more about the Green Deal, but you may be better off waiting for that than shelling out for a new boiler now.

HappyMJ

ed110220 wrote: »

The Baxi Bermuda backboilers are generally regarded as long-lived and reliable, but inefficient by today's standards. I have the SL3 and I looked it up online (do a search on the SEDBUK site) and it's only 65% efficient - a new condensing boiler is about 90% efficient.

The Baxi Bermuda SL3 fire front has a 3.69kW output. It's tiny. What's the BBU model behind it? A new condensing combi boiler is a minimum 24kW output boiler.

The problem with the SL3 is that the pilot light uses 210W every hour 24/7 365 days of the year and you get virtually no benefit from it. That's about 1,800kWh per year wasted @ 3.5p/kWh that's about £65 a year.

DVardysShadow

HappyMJ wrote: »

... The problem with the SL3 is that the pilot light uses 210W

Are you sure? I would be surprised if it is 21W

ed110220

HappyMJ wrote: »

The Baxi Bermuda SL3 fire front has a 3.69kW output. It's tiny. What's the BBU model behind it? A new condensing combi boiler is a minimum 24kW output boiler.

The problem with the SL3 is that the pilot light uses 210W every hour 24/7 365 days of the year and you get virtually no benefit from it. That's about 1,800kWh per year wasted @ 3.5p/kWh that's about £65 a year.

AFAIK the model number SL3 refers to both the fire front and boiler which were supplied as a unit. I don't think 3.69 kW is small for a fire. Certainly on full it's capable of making the living room and attached dining room uncomfortably hot, so I usually have it on low or medium.

From memory the boiler is about 15kW. It does not struggle to keep a 3-bedroom 1949 semi that is not especially well insulated by modern standards at 20C even in cold weather. I haven't tried turning the thermostat higher, but as the boiler does not need to run continuously at 20C, it would probably go a fair bit higher.

A back boiler does not have to be as powerful as a combi as it can take longer to heat the water in the cylinder, rather than heating it at a rate sufficient to have a shower etc in real time.

I've used 1515kWh since moving in on 16 Dec, which at 3.5p/kWh works out at £1.52/day, so it would take a fair time to save the cost of a new boiler.

unclebulgaria

Border_Collie wrote: »

His reasoning for swapping to microbore is that it is more able to withstand the pressure involved with a new heating system and that the existing pipes might leak under pressure.
.

What a load of tosh! He isn't your friend. His reason for using microbore is he's lazy or wants to do it quickly to suit him not you!
Insist on 15mm!

HappyMJ

DVardysShadow wrote: »

Are you sure? I would be surprised if it is 21W

Suprising isn't it? It really is 210W. It's in the technical details in the installation manual. Do a bit of googling if you would like to check but most pilot lights use about that.

HappyMJ

ed110220 wrote: »

AFAIK the model number SL3 refers to both the fire front and boiler which were supplied as a unit. I don't think 3.69 kW is small for a fire. Certainly on full it's capable of making the living room and attached dining room uncomfortably hot, so I usually have it on low or medium.

From memory the boiler is about 15kW. It does not struggle to keep a 3-bedroom 1949 semi that is not especially well insulated by modern standards at 20C even in cold weather. I haven't tried turning the thermostat higher, but as the boiler does not need to run continuously at 20C, it would probably go a fair bit higher.

A back boiler does not have to be as powerful as a combi as it can take longer to heat the water in the cylinder, rather than heating it at a rate sufficient to have a shower etc in real time.

I've used 1515kWh since moving in on 16 Dec, which at 3.5p/kWh works out at £1.52/day, so it would take a fair time to save the cost of a new boiler.

I agree with you. The SL3 fire front can be added onto many back boiler models even the latest high efficiency one. I thought you might have updated the back boiler since it was first installed many years ago so was just querying that.

My own boiler has an output of 11.76kWh and people on here tell me it's undersized for a 3 bedroom semi but it keeps the house nice and warm but then my house is only 17 years old and quite well insulated. It's just a normal conventional wall boiler with no additional gas fire like you have.

ed110220

HappyMJ wrote: »

I agree with you. The SL3 fire front can be added onto many back boiler models even the latest high efficiency one. I thought you might have updated the back boiler since it was first installed many years ago so was just querying that.

My own boiler has an output of 11.76kWh and people on here tell me it's undersized for a 3 bedroom semi but it keeps the house nice and warm but then my house is only 17 years old and quite well insulated. It's just a normal conventional wall boiler with no additional gas fire like you have.

The Baxi Bermuda BBU HE can only take an electric fire which it comes bundled with, as it is a room-sealed boiler ie it takes its air supply through a special double flue. The SL3 is non-room sealed and takes its air from the room, which needs a ventilator. As far as I'm aware, you aren't allowed to install non-room sealed gas fires/boilers any more.

katejo

MX5huggy wrote: »

Firstly whoever works on your old or new boiler needs to be gas safe registered, not corgi (although they may be in both).

Sounds like you should go for a new boiler, you don't need to swap to micro, the only reason to use micro is to save money over, using 15mm pipe for a new install.

British gas would probably be the most expensive people to install a new boiler. Try local installers.

Corgi doesn't exist anymore. It was replaced by Gas Safe. I would never use British Gas. i always use a local installer who has being doing my maintenance for several years.

katejo

keystone wrote: »

OK so thinking long term, a new combi will last how long? 5 or six years? How long will the current Baxi last with a decent system clean (which will have to be done for a new install anyway), 2 years, 5 years, 10 years? Are we confident that their DHW and heating requirements can be met by a combi? Is the supplied water pressure/flow rate suitable for a combi? Sorry but the logic of a bald statement of fact to install a combi escapes me TBH.

Cheers

My combi is now about 9 years old and is going strong. No problems so far at all.