Boiler size

Discussion in 'Plumbers' Talk' started by Chore, Oct 1, 2016.

  1. Chore

    Chore New Member

    Hi. Don't know if anyone fancies giving me there opinion. I'm having a new oil fired central heating system installed. It's a 4 bed semi. With the new rads heating output is about 12kw. One main bathroom with combi fed shower. On suite with Elec shower. I'm fitting a grant combi external and can't decide between the 21kw or 26kw model. I hear oil boilers like to be worked so don't want to go overboard but don't want to undersize either. Any thought would be great.
     
  2. sospan

    sospan Screwfix Select

    Would it be cheaper to go Calor gas ? Slightly more to run but boiler is a lot cheaper to buy and install ?
     
  3. Chore

    Chore New Member

    Hi sospan, I did go down that route but due to having a small garden couldn't get a tank to fit other than right in the middle of the garden. Could have bottles but would cost a fortune to run.
     
  4. How are you going to fit a diesel tank if you cannot fit a calor tank?
     
  5. sospan

    sospan Screwfix Select

    They can bury them these days but of course it is extra cost. A lot of rural people where I am are now swapping from oil to gas as the prices as they replace their systems
     
  6. Dave does Gas

    Dave does Gas Screwfix Select

    Way to size a boiler by rule of thumb is to count all the radiators, multiply by 1.5 then add 3 for hot water the total will be the Kw you need. Do not go under that figure but go up. Most modern boilers can be range rated down to suit a property, but you cant go up.
     
  7. Chore

    Chore New Member

    Because the oil tank needs to be 100mm away from firewall and gas tank 1.5m away with firewall and 3m without
     
  8. Chore

    Chore New Member

    I have ten rads going in so that's 15 plus 3 total 18. So I'm guessing the 21 will be ample
     
  9. Chore

    Chore New Member

    Looked into this aswell but because I have a main sewer running through middle of garden can't get the clearance needed around it. Really think I'm stuck with a smelly oil tank lol. Would have preferred gas as the oil boiler is like £2700 and the tank another 1100
     

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