Commercial heating A


very common problem Spirotech UK comes across is that of a poorly installed and maintained pressurisation system. Mike


Pitt, technical advisor UK, commented: “In a sealed system it is vital to ensure that there is a positive pressure at all points throughout the system and that the static height of the building is taken into consideration along with any other minimum pressure requirements. Negative or low pressures can cause air to be drawn into a system, along with increasing the effects and likelihood of cavitation. “Such elements should be factored into


consideration at design phase. If the numbers and principles are not given proper consideration from the outset, then the system will likely start with basic design flaws resulting in often unexpected and sometimes costly retrospective corrections. I’m a firm believer that more input should be taken from consultants, specialists such as ourselves, and also the engineers whom install and maintain the equipment from the very start of the process to give the best possible outcome. “We have a very experienced technical sales team


who will take the time to sort out the detail and issues that have not been covered. “Key values need to be identified and


incorporated at the design stage to deliver a solution that meets the needs of the building. The resulting recommendations need to be close to 100% and that is why we encourage clients to provide us with all the relevant information. “Often companies don’t specify a reserve volume in their fixed gas vessel calculation. At Spirotech we follow the requirements laid out in BS12828 which is to say our fixed gas vessel sizing is calculated to have a reserve fluid volume. This means that even when at cold fill pressure the system will still have a pressure resilience greater than just the static height of the building. It’s not just a matter of sizing the vessel correctly, it’s about sizing the vessel to allow a stable working pressure hysteresis. You do not want large or erratic fluctuations in pressure! “Basic principles tell us that bar is related to


pressure and metres in height. Therefore a change in height within the system will mean a change in static pressure seen. “That’s why it’s vital to know, at design phase,


“Basic principles tell us that bar is related to pressure and metres in height. Therefore a change in height within the system will mean a change in static pressure seen. This is why it is vital to know at design phase what the static height of the building is, the location of equipment and any minimum or maximum pressure requirements.”


16 March 2024


www.heatingandventilating.net


Above: Mike Pitt, Spirotech technical advisor UK


Futureproofing commercial heating systems


Up and down the country many heating systems – some relatively new – are running inefficiently and requiring more and more maintenance work to keep them going…. just because the initial design was not thought out sufficiently


what the static height of the building is, the location of equipment and any minimum or maximum pressure requirements. “A common problem we come across is equipment being installed in the wrong position within a system. Pressurisation units and fixed gas expansion vessels need to be fitted on the return leg and on the suction side of circulating pumps. However, from time-to-time, we find them incorrectly installed on the discharge side of


circulating pumps. In such cases, the pressurisation units see the discharge pressure of the pumps, not the true pressure of the neutral point in the system. This would give the impression that there was a positive pressure in the system - however, due to the delta pressure created by the pumps, we may actually be seeing a pressure deficit on the suction side. Of course there are exceptions to all rules but deviations to these should be carefully thought out and given the proper consideration.”


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