Quote for Boiler Works

lohr500

We have 17 radiators in our property which is an old and not particularly well insulated farmhouse with parts dating back to 1780.

I found an online radiator output calculator when we were looking to change the boiler and based on our radiator sizes and designs it worked out at a 16.0kW output using a T50 rating and 20.3kW at a T60 rating. We also get through a lot of hot water with baths and showers. 

The cost to upsize from a 26kW Grant to a 32Kw Grant wasn't massive and in agreement with the installer, we went for the larger boiler, but down rated to I think 30kW from memory.

Downrating is an easy process for a good installer and basically involves fitting a smaller size burner nozzle, tweaking the air mixture and I think reducing the high pressure burner pump pressure. We concluded it would be better to have the flexibility of a higher output. The old Ideal Standard oil boiler that was scrapped was also a 32kW model, downrated to 29kW

I went for Grant over WB due to the extra 3 years of warranty and also because the installer spoke highly of Grant boilers. The prices were very similar.

I don't have an issue with our boiler cycling and after some tweaking of the radiator balancing valves and pump speed, I am now seeing a flow of +/- 60C and a return of +/- 40C when the heating is running. So the boiler is operating in the optimum zone for condensing efficiency, whilst maintaining Grant's specified 40C return temperature.

Coming up to three years now since we went with the Grant and it hasn't missed a beat.

The only slight downer is that I went with a Blue Flame technology burner because it gave the best efficiency, but it isn't compatible with biofuel.So if biofuel ever becomes available at a comparable price to kerosene we will need to change the burner unit.
  

Alfster

@lohr500 thank you for such an incredibly detailed response; super useful!