Central Heating Installation (Semi Detached, 3 Bedrooms)

Richie7

Just a quick update. Spoke to the company about the Boiler situation, and this is what they've come back to me with -

- If you prefer a Worcester Greenstar 2000 30kw combination boiler along with 7 year warranty ADD £235.00 plus VAT @ 20% 

- If you prefer a Worcester Greenstar 4000 30kw combination boiler along with 10 year warranty ADD £405.00 plus VAT @ 20%


I'm leaning toward the extra cost of the 4000 to be honest. I feel like it would pay for itself in terms of efficiency and double the warranty.

Any opposing thoughts?

Albermarle

Richie7 said:

Just a quick update. Spoke to the company about the Boiler situation, and this is what they've come back to me with -

- If you prefer a Worcester Greenstar 2000 30kw combination boiler along with 7 year warranty ADD £235.00 plus VAT @ 20% 

- If you prefer a Worcester Greenstar 4000 30kw combination boiler along with 10 year warranty ADD £405.00 plus VAT @ 20%


I'm leaning toward the extra cost of the 4000 to be honest. I feel like it would pay for itself in terms of efficiency and double the warranty.

Any opposing thoughts?

No, the extra cost seems reasonable in the context of the overall job.

Just note that to get good efficiency the boiler flow temperature should not be too high. 
The condensing part of the boiler, needs the water returning to the boiler ( after it has been around the house/radiators) to be below a certain temperature, for the boiler to work efficiently.
On the other side, you want the radiators to get reasonably hot in the Winter, so the compromise is often to have the Boiler flow temperature at around 60 degrees, but there is leeway in both directions.
For some reason heating engineers tend to set it too high, probably so they can show it all works and heats the house quickly. Every time I have even just had a service, I have had to turn it down again afterwards.

Richie7

Thanks @Albermarle much appreciated.

Are you of a similar mind @FreeBear if you don't mind me tagging you. 

FreeBear

Both the Greenstar 2000 and 4000 have similar modulation ranges and go down to ~3.2kW (good for performance & efficiency). So it boils down to warranty - The 4000 appears to have a better following, probably driven by the (up to) 10 year warranty, so that would probably be the one I'd go for if it was a choice of Worcester Bosch or Worcester Bosch - But what is equally important is the thermostat. To get the best out of the boiler, it needs to be able to talk to the boiler using the EMS* bus rather than just switching it on/off. Not all thermostats can talk EMS, so it would be wise to see what Worcester Bosch recommend.

Was there any discussion about radiator sizes and design flow temperature ?

Low flow temperatures are needed if you want to squeeze maximum efficiency out of the boiler, but this requires larger radiators.

*) EMS is the WB version of OpenTherm if you wanted to research the benefits.

Richie7

Thanks for that, much appreciated.

I explained it to her and I think my mum is leaning toward a 2000. To save on the extra cost, and because frankly I don't think she feels she'll need anything longer than 7 years - as in I don't think she expects to be in the house longer than that. If it performs the same as the 4000, then it's just a matter of warranty as you say.

I will check out the EMS you have described.

Richie7

Hi 

So the installation went ahead and we're pleased with how it went. The installers were very experienced with 30+ years on the job. The 4000 Boiler was definitely the right choice.

There is however one small wrinkle. Two of the radiators have cold spots at the bottom. An engineer came a week after it was done and flushed the system. I noticed these cold spots before they did that however. I think the engineer hoped the flush would fix it. Bleeding has failed as well.

So the question I have, is do I have faulty radiators? Bearing in mind they're meant to be brand new.

Any suggestions perhaps?

Much obliged as always.