How much does a modern boiler save?

Dogbyte009

When I replaced my 1997 Ideal Classic with a condensing boiler I cut my gas usage by around a third.

FreeBear

ctdctd said:

I changed from a 1980's Baxi Bermuda back boiler to a Worcester Bosch condensing combi a few years ago and I reckon my total gas usage has fallen about 25% since then. 

Still got a Baxi back boiler here. Having the pilot light burning 24/7 wastes something in the order of 1500KWh to 2000KWh of gas each year - It is possible to get a kit to retrofit an intermittent pilot light (i.e. it only comes on when there is a demand for heat), but this kit is not "approved" in the UK.. I've taken' to shutting the gas off during the summer months and only lighting the pilot light on days when I think heat is required.

Not having a pilot light would account for a good chunk of your 25% saving.

pensionpawn

Dolor said:

This link explains why many condensing boilers rarely condense. Efficiency increases as the return water flow temperature reduces. Condensing boilers are not in themselves efficient. They have to run on a properly set up system. 

https://www.theheatinghub.co.uk/why-our-condensing-boilers-do-not-condense

Which the company I used, and many others from what I've read, didn't do. Mine was left with a flow temp of 82c which made the radiators scolding. Dangerous. Via plenty of reading I learnt how to reduce the flow temperature settling on 62c with a resultant return / flew temp of 50c +/- 5c. It can also modulate from it's maximum output of 19kWs down to 1.9kWs. They rarely condense because of poor training, poor configuration and poor handover by firms.

Grandad2b

It really does depend on an awful lot of factors. I have a quite old Goblin boiler which is probably well in excess of 30 years old. To get the efficiency touted by sales people I'd have to have the whole heating system replumbed for much larger rads.
Is it worth it? I don't know. If I'm going to those lengths I think I might as well have an air source heat pump and do the job properly.

victor2

TUVOK said:

I still have a 1995 boiler which according to my boiler maintenance engineer is working perfectly.
I am well aware that I could save on costs if I replaced it with a modern boiler.

In order to give me some insight into what savings with a replacement modern boiler against cost and installation of of a new boiler, can any members give me some idea of savings if they have replaced their old boiler.
Two people including myself live in my 1995 build semi detached house, and heating in a normal winter is restricted to evenings only.

We replaced our 1990's boiler and gravity fed hot water tank with a combi just over a year ago. Our annual gas usage has dropped from 23,000kWh to 15,000. So the combination of no more pilot light and no heating of a hot water tank unnecessarily, as it heated whenever the central heating was on, has contributed most to the saving. It was a big job and cost us about £4K, but with better heating controls mainly via a programmable thermostat, we are more comfortable than before.

Only downside is it takes longer for hot water to get through to the kitchen tap, and the bathroom radiator, which used to be warm whenever the hot water was on, now only warms the towels when the heating is on, which of course it isn't in the summer!

MuckChucker

victor2 said:

TUVOK said:

I still have a 1995 boiler which according to my boiler maintenance engineer is working perfectly.
I am well aware that I could save on costs if I replaced it with a modern boiler.

In order to give me some insight into what savings with a replacement modern boiler against cost and installation of of a new boiler, can any members give me some idea of savings if they have replaced their old boiler.
Two people including myself live in my 1995 build semi detached house, and heating in a normal winter is restricted to evenings only.

We replaced our 1990's boiler and gravity fed hot water tank with a combi just over a year ago. Our annual gas usage has dropped from 23,000kWh to 15,000. So the combination of no more pilot light and no heating of a hot water tank unnecessarily, as it heated whenever the central heating was on, has contributed most to the saving. It was a big job and cost us about £4K, but with better heating controls mainly via a programmable thermostat, we are more comfortable than before.

Only downside is it takes longer for hot water to get through to the kitchen tap, and the bathroom radiator, which used to be warm whenever the hot water was on, now only warms the towels when the heating is on, which of course it isn't in the summer!

Very similar situation here although we were happy to keep the gravity fed system as I'm not sure the plumping would be up to the pressure of a combi plus we do have multiple showers. I've been playing with tank heating and have it figured that during the mild months it only needs a 30 minute heat every 2nd day, this has now kicked up to everyday and this is mainly just for the kids showers/bath (we've a very costly electric shower for us adults!). However the massive saving has been from being able to put the heat on without the hot water - what an absolute waste of energy that was.

MuckChucker

Mstty said:

MuckChucker said:

New boiler and cylinder back in February - old boiler was a dear old dog (25+ yrs), I think the house was actually built around it (hopefully not considering it's a 1970s house) and it was a hell of a job getting it out. New boiler is a Veissmann 19kw heat only. House is a 4 bed semi in Essex. 2 adult and 2 kids under 7 years. Here are some actual figures

Gas consumption has fallen off a cliff!


With the crazy prices rises it doesn't look like a saving but I shiver to think what we would be doing/paying had we not swapped it out.

Don't forget extremely mild October and November. December will be the real comparison point through til end of March.

Yes, very aware. I'll be happy if December comes in under 900kwh (I had originally projected 600 but screw it, we're doing really well and I'm getting bored of keeping an eye on it/getting people to cooperate). I just want to highlight that we've cut down the summer months to ~10% of the previous years usage and this is purely down to the new boiler/cylinder/controls - I do stress that our boiler was OLD, I can't even think of the model, I'm sure I can pull out a picture.

Edit, now with pic of old boiler.
Look at the monster flu hole! And yes, we had to cut the kitchen counter to get it out.

ChesterDog

Dolor said:

This link explains why many condensing boilers rarely condense. Efficiency increases as the return water flow temperature reduces. Condensing boilers are not in themselves efficient. They have to run on a properly set up system. 

https://www.theheatinghub.co.uk/why-our-condensing-boilers-do-not-condense

Quotations from The Heating Hub...

"The heat turns back into water."

"The water returns at 600⁰C."

Okay...

Reminds me of one of those waste of space "I'm a heating expert and here's how to save money" pieces from a newspaper. The expert talked about reducing the amount of "gas flowing through the radiators".

BUFF

TUVOK said:

I still have a 1995 boiler which according to my boiler maintenance engineer is working perfectly.
I am well aware that I could save on costs if I replaced it with a modern boiler.

In order to give me some insight into what savings with a replacement modern boiler against cost and installation of of a new boiler, can any members give me some idea of savings if they have replaced their old boiler.
Two people including myself live in my 1995 build semi detached house, and heating in a normal winter is restricted to evenings only.

As already mentioned it all depends upon what you are replacing, how much your typical annual usage is & if you run the new boiler properly to let it maximise efficiency. An important part of the latter is modernising your controls - they will typically more than pay for themselves within the life of a boiler but at current rates probably much faster.

As an idea I moved from an old balanced flue non-condensing combi with a programmer & TRVs to a fan-flued condensing combi with programmer + room 'stat +TRVs. That pretty much slashed 40% off gas usage in the first year.
Over the following years of getting to know the system, adapting some of my behaviour (made possible by the higher level of control) & tweaking (longer firing with lower flow temps etc.) I have probably got that to ~50+% saving in an average year.
I wouldn't expect everybody to get that because some of the things that I do would be considered extreme but if you are an average or higher user coming from a non-condensing boiler you can make significant savings.

matelodave

Grandad2b said:

It really does depend on an awful lot of factors. I have a quite old Goblin boiler which is probably well in excess of 30 years old. To get the efficiency touted by sales people I'd have to have the whole heating system replumbed for much larger rads.
Is it worth it? I don't know. If I'm going to those lengths I think I might as well have an air source heat pump and do the job properly.

A heat pump wont necessarily save you money because leccy is around 3.5 times the price of gas at the moment and if you only turn it on a for a couple of hours a night then you wont see the benefit of longer running times at very low flow temperatures.

I've got a heatpump, had it for 12 years and I'm very happy with it but it's not everso cheap to run, especially when its very cold. If gas was available where I live then that's what I'd have

Yesterday the HP chewed through 48kwh of leccy at 35.5p/kwh = £17. I'm guessing that if I was lucky enough to get a COP of 2.5 that might equate to around 120kwh of gas at 10.33p/kwh = £12.40.

You'd have to have a really naff boiler to cost as much as a heat pump when it's really cold. Even with a COP of 3 that 120kwh would have cost £14.20 with a heatpump

As I said above, you really do need to do your sums and to work out what suits your lifestyle and budget.