RE: Could you please provide details on how Hevacomp calculates system contents on both cooling and heating systems ?

Bruce Crawford — Tue, 07 Sep 2021 13:44:52 GMT

Duncan, could you clarify the reference to "other emitters" in the Wiki article linked above? Does it apply only to Chilled Water? As far as I'm aware there is only one type of emitter available in the Heating sizing so the water content will always be calculated using the 'output x 0.00462' formula. This may be realistic in some circumstances but if your emitter is, say, a coil in an air handling unit or HWS cylinder, these would typically have far lower water content per W output in comparison to a radiator.

This answers something which has baffled me for several years - why Hevacomp calculates apparently very high water content on systems which are not using radiators as emitters. I can now see I need to subtract the total output of all emitters x 0.00462 from the water content stated in the results output, which then leaves a net water content for the pipework only. Then manually add the real world figures for the actual emitter coils to give the corrected total.

This was highlighted in a calculation I have done today for a circuit serving only 38.8kW of HWS cylinder coils, for which the pipework water content is just under 20 litres but Hevacomp is stating a system water content of 198 litres!

I realise Hevacomp is no longer being updated but am leaving this here as useful info for others in future. Please correct me if anything I've said above is wrong.

RE: Could you please provide details on how Hevacomp calculates system contents on both cooling and heating systems ?

Duncan Brown — Wed, 25 Jul 2018 08:40:03 GMT

Hi Neil

Most of the answers to common queries can be found in our Wiki - Please see this article to answer your query.

Regards,