Which Worcester Bosch Boiler For Our Home? Please Help!

[Bazzy]

Hi All,

We may need to replace our boiler - the OLDER version Worcester Bosch 35Cdi (see images attached)

1. Our home is a 1920's Semi
2. 5 Bedrooms
3. 2 Bathrooms
4. 5 x Large (1800mm) Double Panel Radiators
5. 1 x Large (1800mm) Single Panel Radiator
6. 3 x Medium (1400mm) Double Panel Radiators
7. 2 x Short Height Double Panel 1400mm Radiators
8. 3 x Bathroom Towel Radiators

We had a WB Engineer come round to try & fix the boiler but said parts were no longer available & recommended that we upgrade to the 42Cdi - he said this model will allow use to run as many hot water devices as we wish without one area losing out over another.

After he left, the boiler started leaking again so another WB Engineer came round & he was strongly recommending the 29Cdi Classic (insisted that we choose the Classic version).

Both are highly trained WB Professionals who know their stuff but I am a bit confused as to which one to believe since they both recommended two very different models so am wondering if anyone here can really help me out on which from the WB range is really best for our home?

I was surprised that the 2nd Engineer strongly recommended a much smaller capacity model than the one we currently have as from what little I know, is that one has to either maintain the size you have to ensure good performance or go for as bigger/next model up to allow fro extra headroom so the boiler does not have to work as hard? I may be totally wrong on this as I am a novice hence coming here for advice.

The 1st Engineer may have recommended the 42CDi as he believed that would service the size of our home best & the 2nd one might have recommended the 29Cdi instead as it has been over 15 years since we have had our current boiler & advances in boiler technology in this time might mean that these days a smaller capacity boiler may well be able to do the same job as a bigger one from yester-year - I do not know but I do believe Engineers were being sincere with their advice.

Please can anyone recommend ANY Combi Boiler from the WB Range that would best suit our needs? I do not know how boiler size & capacity affects things like energy use & how it affects bills - I do not want a small boiler that takes longer to do things & hence uses more energy meaning more running & energy costs but am worried that the same might then also apply to getting a much bigger one - i.e. - it uses more energy than actually needed, hence higher costs etc?

Flow rate is important since we have two bathrooms - my kitchen tap delivers about 17L/min & the 29Cdi delivers about 11L/min & the 42Cdi 16L/min if that has any bearing?

Finally, I read somewhere that if one has two bathrooms and/or a bigger property, instead of a Combi Boiler, one should also consider a System Boiler? I have no idea what the latter is & not being technical, get somewhat bemused by all this so can anyone explain what they are & if they might be a better option for us?

Would really welcome & be exceptionally grateful for any help/advice on which WB Boiler is best for our home!

Many Kind Thanks,
Bazzy.

 

[SimonG]

System boiler and unvented cylinder if water pressures and flow allow.

oh and not a Worcester botch.

 

[Bazzy]

Hi SimonG,

I will have to look into exactly what System Boiler & Unvented Cylinder is - how does it differ from a Combi Boiler may I ask? Is it all in one unit like a Combi or does it have lots of separate bits etc? Will there be lots of extra pipe work needed & will anything be have to be placed in the loft etc? It will be very difficult indeed for us to run new pipes etc from say the loft to elsewhere in the house.

What sort of water pressures & flow are required then for this option please?

May I ask why not a Worcester Bosch? I really know nothing about boilers but the reason the owner of the house wants to stick with WB is that when ever things have gone wrong with the current boiler, WB have been really great in getting it sorted - they can arrive usually within a day or so, usually always sort out the problems & their engineers have always acted very professionally regardless of who over all these years. It is this peace of mind that the owner really values with WB - they are round very quickly & always sort the problems out.

Do any other brands offer the same/similar? We usually have some sort of Boiler Servicing Contract.

Are there issues with WB that I must obviously be unaware of then that you good folks in the trade know about?

What brands & models would you recommend then for our home please?


Many Thanks,
Bazzy.

 

[Riley]

Combi boilers are not designed to run multiple outlets. A system boiler and invented would give you best results at multiple outlets. Service contracts are pointless in my humble opinion most decent manufacturers offer a decent warranty these days on the proviso that that an annual service is carried out. Employ a local independent engineer to fit it and maintain it for you. Worcester are not what they were. For my money Vaillant/Glowworm

 

[ShaunCorbs]

Viessmann 222 at a min

 

[gmartine]

How did you find your old boilers performance when running two bathrooms?

 

[Bazzy]

How did you find your old boilers performance when running two bathrooms?

Hi gmartine,

I cannot say for certain with two bathrooms running but on the whole it was not too bad really - there were lots of times when someone would be having a shower & either the washing machine, Dishwasher and/or other hot water taps were in use at the same time & although there was a flow drop, it was just about acceptable for the short times the other hot water taps etc were on.

Hope that helps!
Bazzy.

 

[Riley]

Don’t do combi you’d be so much happier with unvented

 

[Bazzy]

Don’t do combi you’d be so much happier with unvented

Hi Riley,

Can you please kindly give me some suitable examples of this unvented system so I can have a look & learn from - I am totally clueless about these things & have no idea what to look for & what might be any good.

Many Thanks,
Bazzy.

 

[Riley]

It’s a boiler and hot water cylinder set up but at a good pressure and flow rate as long as incoming mains allows

 

[Bazzy]

It’s a boiler and hot water cylinder set up but at a good pressure and flow rate as long as incoming mains allows

Hi Riley,

Thanks for that - so there is a boiler part which hangs on the wall like the 35Cdi we have & a separate tank cylinder which stores hot water?

Where is the cylinder installed may I ask? Next to the boiler or in the loft?

All I know is our kitchen cold water tap produces about 17L/Min - is that good enough pressure & flow rate?

Do you know how much these systems would cost & is this unvented type the same as a "System Boiler"?

One of the WB Engineers informed me about one of their floor-standing boilers with a hot water tank - I think it was a 440 or 550 model - is that the same thing as this unvented system or system boiler?

Many Thanks,
Bazzy

 

[Watermargin]

Hi i have a fully functioning 35cdi cw flue if your interested. Reason i kept it back was because it is a great boiler. Twin pumps and all that.

 

[Bazzy]

Hi i have a fully functioning 35cdi cw flue if your interested. Reason i kept it back was because it is a great boiler. Twin pumps and all that.

Hi,

Is it new or used may I ask? Is there any warranty on it & where in the UK are you please?

I am doing my best to research boilers/options at the moment but for me, it is proving to be very daunting as I am just not knowledgeable enough about the various differences in brands & stuff that those in the trade might know.

I know a few here have suggested an unvented system boiler with a separate tank but I really doubt that my home has/meets the absolute minimum required parameters to consider a unvented system boiler - I saw a video where someone in the trade stated that the absolute minimum incoming water flow must be at least 20L/mim but preferably much higher - mine is only 17L/min with the crude timed test I did. I have no idea what the water pressure is to my home but will try & get someone to check it for me - the person on the video said it must be an absolute minimum of 1.5 bar.

If my place is unsuitable for these system boilers with a tank, then I am assuming my only option is to be stuck with a Combi?

Many Thanks,
Bazzy.

 

[Watermargin]

Hi again mine is old but you could easily swap out your existing no pipework change as is exactly the same. If you are investing in new system then i like and am biased towards worcester. I would of thought a 35cdi classic system boiler with a unvented cylinder would be great would gibe you mains pressure hot water however this is a lot of parts and install could cost well over 5000. Combis great but not brilliant when you have multiple bathrooms as flow is 16l a minute at best.

 

[Bazzy]

Hi again mine is old but you could easily swap out your existing no pipework change as is exactly the same. If you are investing in new system then i like and am biased towards worcester. I would of thought a 35cdi classic system boiler with a unvented cylinder would be great would gibe you mains pressure hot water however this is a lot of parts and install could cost well over 5000. Combis great but not brilliant when you have multiple bathrooms as flow is 16l a minute at best.

Hi,

Whereabouts are you please & how much for the boiler? Any warranty left on it that is transferable?

I assume your a Gas Safe Registered Plumber & that it has been fully serviced in the time that you have had it?

How much would it cost to have the old one removed & yours put in? I am assuming it is the newer model of 35Cdi & not the older version like mine?

Many Thanks,
Bazzy.

 

[Old Account]

Me personally i would either go with a system boiler and an unvented cylinder if it was suitable. if you were going ahead with an unvented cylinder i would choose the Vaillant green IQ 627 and a Vaillant uniSTORE. Let it run via the Vsmart and you will have a very efficient central heating and hot water system.

Or

Vaillant combi storage boiler. I know many people would say it won’t be ideal etc. But based on my experience the ecotec plus 938 is a combi storage boiler which has a built in storage. It is designed for larger homes with a bigger hot water demand. It saves space and combined with the Vsmart it will Safe you Loads on your annual gas bill.

 

[Bazzy]

Me personally i would either go with a system boiler and an unvented cylinder if it was suitable. if you were going ahead with an unvented cylinder i would choose the Vaillant green IQ 627 and a Vaillant uniSTORE. Let it run via the Vsmart and you will have a very efficient central heating and hot water system.

Or

Vaillant combi storage boiler. I know many people would say it won’t be ideal etc. But based on my experience the ecotec plus 938 is a combi storage boiler which has a built in storage. It is designed for larger homes with a bigger hot water demand. It saves space and combined with the Vsmart it will Safe you Loads on your annual gas bill.

Hi!

Thank you so very much - as a complete novice & not knowing the differences between one brand & another and all the important stuff in between, this was just the type of excellent feedback & suggestions I was looking for - it is extremely helpful so huge thanks!

As many here did not seem keen on WB, I have been considering options from:

Valliant
Viessmann
ATAG
Intergas

& Possibly Baxi 636 - Allen Hart From YouTube rates them quite high as well as Ideal Vogue.

What I have learnt is to try a get a boiler with the least amount of plastic as possible - all brass fittings & a SS Heat Exchanger.

The other things that are really important are the warranty length & terms & customer service - I would want 10 years minimum & great customer service.

I have read in a few places that Valliant make great boilers but the Customer Service can be a very hit/miss affair - can you possibly shed some light on this? I read the same about Ideal as well which kind of puts me off.

How do Valliant stack up against Viessmann, ATAG & Intergas in your opinion? To a novice, they all sound great but I do not know what the issues/problems might be - especially with things like costs of parts, annual servicing & customer service - WB was great in this regard - had engineers round very quickly so would like something similar.

I will most definitely ask the Plumber/Installer to check if a System Boiler/Unvented Type is an option for us but if it is not, then what choice do I have apart from a Combi?

I have a Installer that was recommended by Valliant themselves coming round next week to give an assessment so I will see what he says & also mention the options you have stated & get back to you. Out of interest, how much would the two systems you mentioned cost to supply & install so I have an idea?

I may also call in approved installers from the other companies mentioned especially Viessmann/ATAG/Intergas as these seem most highly regarded along with Valliant or am I wrong about this?

Many Huge Thanks,
Bazzy!

 

[Old Account]

Hi Bazzy,

If you ask 10 plumbers you will most likely get 10 different boiler models 🙂

However, I can safely say that you ant go wrong with Vaillant boilers.

An acreddited Vaillant Installer can supply 10 years of warranty that can be achieved via fitting the Vaillant proctection kit or you can buy it.
I would always go with the protection kit which is a brass magnetic filter to keep the central heating clean.

The aftercare is top notch never had any problem with Vaillant. I can highly recommend them.

The parts inside the green IQ 627 are brass and Stainless steel but not to forget at the end of its life the boiler can be recycled to 85%

The combi storage has the same brass and stainless steel parts.

Me personally I would go with baxi, biasi, ideal but that’s my personal opinion.


Vaillant
Viessman

These are the ones I would go with. Vaillant is market leader so I hope that will answer your question in regards to “ how do Vaillant stack up against ....”

Both viessman or Vaillant are great boilers. If you had the space I probably would choose the green IQ 627 with a cylinder.

The boilers I mentioned are bale to modulate which means these boiler wont use the full amount of kilo watts if they do not require. For instance in the summer you may need 4-5kw to heat the hot water that means you will Safe a lot on your gas bill.

These are very quiet running boilers. My personal heart is with Vaillant but if you ask some other engineers you may get different opinions.

If you want something good ( Vaillant or viessmann).

About the prices I cannot give you an answer as it depends on many factors.
Where you based ?

 

[Aire]

I love how everyone has all jumped to the conclusion op must go for a system boiler and unvented cylinder. How does anyone know if one is suitable for the house? Let's not forget there is already and has been fitted for a long time a combi boiler that will no where near match the outputs of current models on the market and will be alot cheaper to install than an unvented setup.

Bazzy personally i would say a combi will work fine, the vaillant 843 for example has nearly 18 litres of hot water a minute which is impressive and will be a massive improvement on what you currently have fitted (yours is rated to between 12 and 13.5). May need an upgraded gas feed to what's currently feeding your boiler but that should be easily sorted.

You also mention the worcester highflow 550cdi, these are floor standing combi boilers which have a heat store (basically a mini cylinder in the boiler) which provide great flow rates of up to 25 litres a minute, when you run your hot tap, similar to a combi, the boiler fires up but instead of taking water directly from the plate heat exchanger, you get water from both the plate and the heat store so your able to have a much greater flow rate of hot water. That is however until the heat store is depleted and needs reheating which you then only take hot water from the plate so your flow will be reduced.

It all depends on how much demand you have for hot water, you have 2 bathrooms but how often are both bathrooms used at the same time?

As for boiler brand, most good manufactures now offer good warranties but check reviews on how good the warranties actually are, ideal for example offer up to 12 years but from what I've heard (not personal experience) they will find any get out they can not to fix the boiler under warranty. Baxi are apparently no quible but again that's only what I've heard.

Id get a few local installers to come have a look and see what they say, it's always good to get as many opinions as possible and then do your research as to what you think works best for you.

 

[Old Account]

I love how everyone has all jumped to the conclusion op must go for a system boiler and unvented cylinder. How does anyone know if one is suitable for the house? Let's not forget there is already and has been fitted for a long time a combi boiler that will no where near match the outputs of current models on the market and will be alot cheaper to install than an unvented setup.

Bazzy personally i would say a combi will work fine, the vaillant 843 for example has nearly 18 litres of hot water a minute which is impressive and will be a massive improvement on what you currently have fitted (yours is rated to between 12 and 13.5). May need an upgraded gas feed to what's currently feeding your boiler but that should be easily sorted.

You also mention the worcester highflow 550cdi, these are floor standing combi boilers which have a heat store (basically a mini cylinder in the boiler) which provide great flow rates of up to 25 litres a minute, when you run your hot tap, similar to a combi, the boiler fires up but instead of taking water directly from the plate heat exchanger, you get water from both the plate and the heat store so your able to have a much greater flow rate of hot water. That is however until the heat store is depleted and needs reheating which you then only take hot water from the plate so your flow will be reduced.

It all depends on how much demand you have for hot water, you have 2 bathrooms but how often are both bathrooms used at the same time?

As for boiler brand, most good manufactures now offer good warranties but check reviews on how good the warranties actually are, ideal for example offer up to 12 years but from what I've heard (not personal experience) they will find any get out they can not to fix the boiler under warranty. Baxi are apparently no quible but again that's only what I've heard.

Id get a few local installers to come have a look and see what they say, it's always good to get as many opinions as possible and then do your research as to what you think works best for you.

I do not know if you have read my post but I have mentioned not just boiler but two. One of the two I recommended was the Vaillant 938 combi storage boiler which is designed for larger homes with higher hot water demand. The boiler itself is not the cheapest but worth every single penny. Furthermore I suggested an unvented system ( uniSTORE) IF is suitable which means the op needs to get an engineers out to discuss their possibilities. And yes if I was him I might want something like an unvented cylinder with the Vaillant green IQ which again isn’t the cheapest but definitely highly efficient. The boiler is able to modulate between 3.4kw and 26.7kw in condensing mode which absolutely amazing. Furthermore it has a built in 3 way valve which doesn’t need any nasty zone valves, junction boxes or complex wiring. That designed with a great Vsmart which works on weather compensation is the system I would want in uk if I had 2 bathrooms and more. I also mentioned that everybody has got their favourite brand. I. Do not think that either one of my suggestions is wrong. Both options are incredibly energy saving and worth the money. The cheaper option would be the 938 as he doesn’t need the cylinder.