Derating Grant Oil Combi

[wcavanagh]

Has anyone had any experiance on derating a Grant Vortex Oil Combi?

Heatload for my new house is looking likr 16Kw and the smallest they do is a 21Kw but reading the book of words it can be derated. Seems to be a air disk change, but no mention of nozzle size. Seems odd.

 

[muggles]

Bear in mind that if you reduce the output to heating you're also reducing the output to hot water on oil boilers. 16kW is going to give you quite poor hot water performance - it's one of the many reasons why oil-fired combis are rarely recommended and a heat-only boiler and cylinder setup is preferred

 

[wcavanagh]

Is that right? Never thought of that? Guess you have to balance out between rating etc. I guess its better to have it working in condensing mode for efficiency and forgo some short cycling.

 

[oilboffin]

You can do it by using a smaller nozzle and changing oil pressure and air and if you ring riello up they will tell you what pressure and nozzle size to use but you'll need someone with a FGA to check the readings and efficiency.Bob

 

[oilboffin]

Grant also do a 15/21 kw boiler

 

[wcavanagh]

Many thanks, I will speak to Grant tomorrow before buying. Cheers

 

[Hairymelon]

Muggles is right Grant combis are minimum 21 kw. Some boffin !

 

[oilboffin]

My mistake but you can easily derate any oil boiler by nozzle and oil and air it's quite simple to do and get a friendly oil man to check it with a FGA and you're away.Bob.By the way there is no need for abuse on this forum after all we are only tryingto help.

 

[oilboffin]

Just remembered knew a lad once he was a karate expert but a bit dimm,he joined the army but
he killed himself with his first salute.Bob