Conventional (compact) boiler replacement: suggestions/advice pls.

[Laurence Harvey]

My most recent post (last week) was about my sons combi boiler problems,..now sorted thankfully;...however, my daughters (very old!) conventional boiler has just packed in,...again!...it needs replacing,...never rains but it pours.

She’d prefer a replacement conventional boiler (not a combi) as she likes her airing cupboard and power showers. She uses lots of hot-water. It’s a largish 3 bed detached house with 2 bathrooms.

For aesthetic reasons she wants a conventional boiler that will fit neatly inside a 30cm deep kitchen wall cupboard.

I had a large kitchen extension/renovation completed 2 years ago and I had my old boiler replaced with a (conventional) Baxi424 boiler. I'm really impressed with it;...it’s completely tucked away inside a standard kitchen wall cabinet and it’s whisper quiet in operation. All the piping is neatly hidden away and unless you open the cupboard door you’d never know it housed a C/H boiler.

However, things move on. Any up-to-date boiler suggestions or ones you think are best avoided?...any other suggestions/advice?

She’ll pay cash for the new installation,...doesn’t need a finance package or similar.

As ever, all replies gratefully received. Thanks in advance.

 

[muggles]

You won't be so impressed with that 424 when it breaks down outside the warranty period - they're extraordinarily expensive to repair.

What make/model boiler does your daughter have now? Has a heat loss calculation been done to determine the heat requirements for the property? If not, that's the first step. Look at www.heat-engineer.com for a good heat loss calculator. Can't recommend a boiler until we know what power is needed

 

[Laurence Harvey]

You won't be so impressed with that 424 when it breaks down outside the warranty period - they're extraordinarily expensive to repair.

What make/model boiler does your daughter have now? Has a heat loss calculation been done to determine the heat requirements for the property? If not, that's the first step. Look at www.heat-engineer.com for a good heat loss calculator. Can't recommend a boiler until we know what power is needed

In a recent communication to ‘tp’ I thought it was a Vaillant boiler but it’s actually a Glow Worm Micron 40FF,....I believe Vaillant absorbed Glow Worms portfolio at some time in the past,...but that’s by the by.

However, the house has had a ground floor extension since the boiler was installed so it may be underpowered, but saying that, heating the house even during the severest winters hasn’t been a problem and the boiler appears to be adequate, in practice if not in theory.

I don’t know how to use the heat calculator in your link, btw,...far too professional for me;...are there any other calculators that are a bit more user friendly?

 

[muggles]

Heat Engineer is the only one I trust to be accurate, but in any case you may have answered the question without having to use it. The Micron 40FF is an 11.5kW boiler, and if it's adequately heating the house now then there's no reason to think a more powerful one might be needed. In any case the range of boilers available at power outputs below that is small and undistinguished.

If you can stretch to 310mm depth and hang on for a couple of weeks, the new Worcester 4000 12kW looks like it'll be the one for you. I say hang on for a couple of weeks because it's not been released yet (although it still somehow managed to pick up a Which Best Buy award all the way back in September 2020, which maybe says more about the trustworthiness of Which than it does about the boiler...).

There aren't very many boilers which are less than 300mm deep. In fact, I can think of only one that I could happily recommend - the Intergas HRE 18OV. An excellent boiler and only 240mm deep, but a bit overpowered for your needs. It's also 450mm wide which means it needs a minimum 500mm wide cupboard to go in and ideally a 600mm, whereas the WB4000 is 400mm wide so would squeeze into a 450mm or fit comfortably into a 500mm cabinet

 

[Laurence Harvey]

I’ve just had a tinker on this online calculator and answered the generic questions; i.e. detached house, 3 beds, 2 bathroom (9 rads in total) in a York postcode and among the suggestions was this 21KW boiler that also meets the requirement of being able to fit into a 30cm wall cupboard: Worcester Bosch Ri 21kW.

There is also a recommendation of a 26KW Viessmann boiler, but that is not compatible with a 30cm cabinet.

So I guess a boiler circa. 24Kw will be adequate,...or perhaps not,...what do you guys reckon?

Is the online calculator adequate and accurate enough, or is it far too simplistic?

https://heatable.co.uk/

eta: my daughter is thinking of extending the house (one room side extension) in the next few years so a more powerful boiler than the existing one will probably(??) be needed.

 

[muggles]

Highly unlikely that 21kW is needed, especially as you've already said that 12 is currently heating the house perfectly adequately. An oversized boiler will suffer more wear and tear and be less efficient. 80% of the UK's current housing stock needs less than 10kW to heat it adequately, so unless your daughter's house is twice the size of 80% of the rest of the properties in the UK it definitely doesn't need over 20kW. Even with the future extension I'd be very surprised if more than 15kW was needed, and the 12 may still be enough.

 

[muggles]

To look at another way, I fitted a 25kW boiler to an 1800s manor house with 7 bedrooms last year, and they were perfectly warm all Winter

 

[vulcancontinental]

I've never found an online calculator to be worth bothering with. I've just finished a large 5 bed detached heat loss calc built post 1975 in Leeds (17 rads) and that comes out at 15kW at -5 degrees.

It irrelevant anyway as any decent larger output boiler can be range rated to match the property. The other hot potato at the moment for many installer is how low can the boiler modulate too because the majority of the heating season maximum output is not required so the boiler will produce too much heat and cycle switching itself on and off. I don't place as much emphasis on this as others do because although cycling is an inefficiency (10 seconds cycles can lead to a degradation of 12%), as long as the burn time exceeds 3 minutes it's around 1 to 1.5%. On an £800/annum space heating bill that's £8 and any wear and tear on the boiler is negated by using a decent boiler with a decent warranty.

If the emitters are radiators and occupation is intermittent Worcester or a boiler with an aluminium heat exchanger offer better efficiency, if underfloor heating or continuous heating at low output is required then stainless steel.

We're running a free webinar, Heating Optimization and Efficiency scheduled for July 1st at 7pm that might help. It does say Gas Safe Engineers only but members of the public will be allowed on (it's being updated to that effect today or tomorrow).

https://carrier.zoom.us/webinar/register/4015979243379/WN_ZXBPokfUTkCUbLgHL-ttDw

 

[sxturbo]

I've never found an online calculator to be worth bothering with. I've just finished a large 5 bed detached heat loss calc built post 1975 in Leeds (17 rads) and that comes out at 15kW at -5 degrees.

It irrelevant anyway as any decent larger output boiler can be range rated to match the property. The other hot potato at the moment for many installer is how low can the boiler modulate too because the majority of the heating season maximum output is not required so the boiler will produce too much heat and cycle switching itself on and off. I don't place as much emphasis on this as others do because although cycling is an inefficiency (10 seconds cycles can lead to a degradation of 12%), as long as the burn time exceeds 3 minutes it's around 1 to 1.5%. On an £800/annum space heating bill that's £8 and any wear and tear on the boiler is negated by using a decent boiler with a decent warranty.

If the emitters are radiators and occupation is intermittent Worcester or a boiler with an aluminium heat exchanger offer better efficiency, if underfloor heating or continuous heating at low output is required then stainless steel.

We're running a free webinar, Heating Optimization and Efficiency scheduled for July 1st at 7pm that might help. It does say Gas Safe Engineers only but members of the public will be allowed on (it's being updated to that effect today or tomorrow).

https://carrier.zoom.us/webinar/register/4015979243379/WN_ZXBPokfUTkCUbLgHL-ttDw

Just because I'm sad I'll sign up to that, when they have removed the gas Safe. Requirement

To the OP, I agree with Vulcan, if you go for an 18kw boiler that can be range rated you will have far greater choice.

What width cupboard do you require it to fit in?

 

[Laurence Harvey]

Just because I'm sad I'll sign up to that, when they have removed the gas Safe. Requirement

To the OP, I agree with Vulcan, if you go for an 18kw boiler that can be range rated you will have far greater choice.

What width cupboard do you require it to fit in?

60cm width, 30cm depth.

 

[Laurence Harvey]

You won't be so impressed with that 424 when it breaks down outside the warranty period - they're extraordinarily expensive to repair.

What make/model boiler does your daughter have now? Has a heat loss calculation been done to determine the heat requirements for the property? If not, that's the first step. Look at www.heat-engineer.com for a good heat loss calculator. Can't recommend a boiler until we know what power is needed

Oh dear,...that’s not good news. Are Baxi’s conventional boilers also extraordinarily unreliable? ...I guess I could (hopefully) opt for Baxi’s ‘care&repair’ plan when my warranty period is up in 3 years time.

My son has just taken out Ideals ‘care&repair’ plan,...Vaillant/Glow-Worm also offer the same’ish plan. The ‘care&repair’ plans from the 4 manufacturers are ostensibly the same and are all underwritten by the same insurance company, Domestic & General (D&G).

 

[Mottie]

If you are limited to the size of boiler, your choices are limited. I think a Worcester Greenstar 15ri compact regular boiler will fit in your cupboard (Dimensions (mm) height x width x depth of 600x390x270) although I suppose some on here will chip in with the Worshiiter Bosch quips.

 

[muggles]

They've not been the best unfortunately. The issue with these is that the burner, gas valve, fan, and PCB are all sold as one single part lumped together, so if any one of those parts fails you have to buy all four for around £400

 

[muggles]

If you are limited to the size of boiler, your choices are limited. I think a Worcester Greenstar 15ri compact regular boiler will fit in your cupboard (Dimensions (mm) height x width x depth of 600x390x270) although I suppose some on here will chip in with the Worshiiter Bosch quips.

As you know, I'd normally be one of the first to steer people away from WB, but the new 4000 series 12 & 15kW models look like they could be a genuinely decent option. Not perfect, they've still got the kebab heat exchanger which is more dirt sensitive than someone with brand new cream carpets, but if fitted to a high standard they should be OK

 

[Laurence Harvey]

If purchasing a new boiler how can one determine if said boiler can be ‘range rated’?

Does it mean the boiler has a temperature control bezel/dial that can be adjusted by the consumer?....or is it an internal adjustment that’s only accessible to a professional?