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Problems sizing a Strada... to replace stell panel ride. MOving from Gas Combi to ASHP

Posted on 17/11/2012 3:08am

Hi, I am strugling with the Calcs to Size a Strada. room size is 4mx4.5mx2.5m moving to an ASHP to replace combi. Room has excellent insulation and required temp is 20 degrees. my calcs point me to a whopping 2000 x 650 type 11 strada. Currently we have a 1600x600 steel panel rad, single emitter with combi set to output 60-65 degrees. The property was built circa 1900 but is now very well insulated. I must be dng my cals wrong .. I hope

1 Replies
  • Justin_Jagauk
    Commented on 10/03/2013 4:09pm


    Just having a quick look at this one and the steel panel rad 600mm x 1600mm with single convecting fins will give 1600 watts at design temperature of 75/65. If your boiler is running at 65/60 with a room temp of 20c then that unit will be giving approximately 1296 watts.

    I have done a quick heat loss based on 30 watts per cubic M and I calculate that you need about 1485 watts for that room. Now, using an ASHP you are going to be running the system at around 45/35 which will mean no matter which manufacture you use the radiators are going to be bigger to compensate for the lower flow and returns.

    To heat that area the unit will need to be a 650mm x 2400mm T16 Strada giving 1522 @ DT20 (45/35/20).
    if you wanted to use a Strada with our DBE units you can reduce the size of this unit to a 650mm x 1400mm T16 DBE giving 1600 watts @ DT20 (45/35/20). However, you would need to a power socket to each unit for the fans to work.


    Having had a quick look at a steel panel rad using the same design temps (45/35/20) you would need a 600mm x 2800mm x double panel with fins to obtain approximately the same output.

    Hope this helps but if you would like to discuss in more detail please contact Jaga on 01531 631 533.



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