New Boiler - 8000/35 or CDI36

[jonwestuk]

Hi, I’m looking for some advice from professional plumbers on what boiler to choose for my house. I live in a terraced house with two bathrooms and four bedrooms. I have very good water pressure and flow. I currently have a 17-year-old faulty Worcester Bosch 25si which is probably underpowered for the house but has been perfectly adequate for our needs. It may be nice to be able to run two water taps at the same time, but that may not be feasible anyhow with any option.

I’m considering between a Worcester Bosch 8000/35 and a Worcester Bosch CDI36. I’ve done some research online and found some information about these two models, but I’m still not sure which one is better for me. I also have a Tado Smart Thermostat system that I would like to use with the new boiler.

So, based on this information, which boiler would you recommend for me? I have some specific questions that I hope you can answer:

• Is there any difference in reliability between the two boilers? I’ve read some reviews that say the 8000/35 is more durable and less prone to breakdowns than the CDI36 , but I’m not sure how reliable these sources are.
• Do you have any concerns about the CDI36 being discontinued by Worcester Bosch? I’ve heard that they are planning to phase out this model and replace it with a newer one. Will this affect the availability of spare parts and service in the future?
• Is there any practical advantage of the 8000/35 over the CDI36 other than it looking pretty in my cupboard? I know it has more power and updated controls, but will I notice any difference in performance or comfort in my house? Is the 8000 being hydrogen ready realistically an advantage in the next 15-20yrs?

I appreciate any input or suggestions from you. Thank you in advance.

 

[Swwils]

You want a boiler that is properly sized and modulates the lowest.

 

[jonwestuk]

You want a boiler that is properly sized and modulates the lowest.

So they are both roughly the same in size, but the 8000 has a 1:10 modulation vs 1:6 on the CDI. They are both the right power for my flow, house size etc.

The thing that has me thrown off, is the the 36CDI is older, proven, smaller and more powerful 13% on the hot water. Normally you pay more for smaller and more powerful but it is £200 cheaper than the 8000 Life and £300 vs the 8000 Style.

This thing will live in a cupboard, so I don’t care about looks and smaller size is always helpful storage wise. I have the Tado TRV system so don’t care about smart features. Yet 2 of 3 plumbers recommended the the 8000, the other didn’t see the point and said to get the CDI.

Is there any good reason to go for the flashier 8000?

 

[Swwils]

Your tado TRVs will be absolutely ruining any modulation efficiency of the boiler.

If your flow temp and sizes are correct just go for a decent installer and an alpha.

 

[jonwestuk]

Your tado TRVs will be absolutely ruining any modulation efficiency of the boiler.

If your flow temp and sizes are correct just go for a decent installer and an alpha.

Thanks for your help…. Sorry what is an alpha?

 

[Swwils]

Alpha are a boiler manufacture who are often looked down on but they actually produce decent units when they are installed and controlled properly. They also deeply modulate down to around 4.3kW.

You need to be very specific with your installer about what you are actually getting.