1 / 7

Boiler Over Sizing Anthony McGarry, Senior Engineer RPS Group

Boiler Over Sizing Anthony McGarry, Senior Engineer RPS Group. Hotel A. Maximum boiler capacity installed 3,100 kW Capacity reduced to 1,800 kW by; Removing one Jet on 1,100 kW boiler Reducing flow rate of existing jet by 11%

jada-hebert
Download Presentation

Boiler Over Sizing Anthony McGarry, Senior Engineer RPS Group

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Boiler Over Sizing Anthony McGarry, Senior Engineer RPS Group

  2. Hotel A • Maximum boiler capacity installed 3,100 kW • Capacity reduced to 1,800 kW by; • Removing one Jet on 1,100 kW boiler • Reducing flow rate of existing jet by 11% • Actual capacity used is 450 + 480 = 930 kW for both heating, leisure centre and hot water.

  3. Energy Consumption at Hotel A • EPI for 2006 of 342 kWh/m2/pa which is at the Good practice levels of 340kWh/m2/pa (260 kWh/m2 – fossil fuels & 80 kWh/m2 – Electricity) based on CIBSE Guide F- • This was achieved by having a very large hot water buffer!

  4. How was Boiler over sized in Hotel A? • Difficult to say with certainty – could not contact designer, but the possibilities are; • Heat loss not calculated i.e. U-values for wall, windows, floor and flues etc. • Heat loss factor too high • Maximum heat, hot water and leisure centre load added together with a large error margin and subsequently leisure centre had its own dedicated boiler. • Boiler capacity duplicated with second back-up boiler • Design changes • Hot water demand per occupant too high • Nobody was sued for over sizing boilers

  5. How should Boilers be sized • Elementary heat loss calculation to determine heat load • State all assumptions/specification made, any building changes should be communicated and a revaluation of the heat loss carried out. • Hot Water load – best to have separate boiler for hot water. • Again specification/assumptions stated, any future design should trigger a revaluation of load • One Boiler for HW & Heating the ‘Maximum Simultaneous’ load should be calculated not the maximum load. • Boiler size (X2) at 50-60% of max load, modulating control down to 10% of design capacity • Hot water load typically 1 hour recovery, if less boiler size will increase

  6. In Reality • Heat loss guessed at • No time invested in engineering the boiler • Cheapest available boiler – Budget constraints • Maximum load calculated plus excessive margin for heating efficiency, distribution losses, system poor insulation, future expansions etc etc. • Excessive boiler size margin for possible engineering changes • No designer employed or changes made by M&E engineer, Supplier, Customer etc • Boiler sized duplicated for back-up • The just in case syndrome! – Better looking at it that looking for it!

  7. Boiler Sizing Thank You Anthony.mcgarry@rpsgroup.ie

More Related